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Anatomy and Physiology
Terms and Definitions
741
Medical
Undergraduate 1
12/20/2010

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Term
Palmar
Definition
Palm of Hand
Term
pertaining to
Definition
ide
Term
a covering
Definition
integ-
Term
catabolism
Definition
vreactions that break down complex molecules into two or more smaller ones with the release of energy
Term
below, less, under
Definition
sub-
Term
narrowing
Definition
stric-
Term
hypertrophy
Definition
enlargement of an organ attributable to an increase in the size of the individual constituent cells
independant of the body's general growth.
Term
base
Definition
a substance that ionizes in water to release hydrogen (OH-) ions or other ions that combine with hydrogen ions;
a proton acceptor;

a substance with a pH greater than 7.0
Term
heat
Definition
(calor-)
Term
fat
Definition
lip/0
Term
inflamation
Definition
-itis
Term
neuron
Definition
Cell of the nervous system, specialized to generate and transmit electrical signals (action potentials and graded potentials)
nerve cell, including its processes; conducting cell of nervous tissue
Term
LBW
Definition
low birth rate
Term
carcinoma
Definition
a malignant growth derived from epithelial cells
Term
within, inner
Definition
end-
Term
tissue
Definition
hist-
Term
anaplasia
Definition
loss of differentiation of cells; reversion to a more primitive cell type; characteristic of malignancies
Term
bad, evil
Definition
malign-
Term
frontal plane
Definition
divides the body into anterior & posterior portions (perpendicular to both the sagittal & transverse planes);
sometimes called the coronal plane
Term
centimeter
Definition
c, cm
Term
excessive, above
Definition
hyper-
Term
biopsy
Definition
removal and microscopic examination of body tissue via needles, syringes, and chemical analysis
Term
clot
Definition
thromb-
Term
between or among
Definition
inter-
Term
endotracheal
Definition
ET (insidethe trache)
Term
epidemic
Definition
a sudden & widespread outbreak of a disease within a given population
Term
outpatient
Definition
(OP) patient that recieves patient care out of the hospital
Term
tumor, swelling, mass
Definition
-oma
Term
false
Definition
pseudo-
Term
myoma
Definition
benign tumor formed of muscle tissue
Term
matter
Definition
(-plasm)Anything that occupies space and has mass
Term
vital signs
Definition
(vs or VS)blood pressure, temperature, respirations, heart rate, blood sugar, oxygen level
Term
solution
Definition
soln
Term
large
Definition
macro-
Term
Marfan Syndrome
Definition
a congenital disorder of connective tissue characterized by abnormal length of the extremities & cardiovascular abnormalities
Term
nanogram
Definition
(ng) One billionth of a gram
Term
sweetness, sugar, glucose
Definition
gluc-
Term
posterior, dorsal
Definition
Toward or at the back of the body
Term
centigrade, Celsius
Definition
(C)
Term
sagittal plane
Definition
vertical plane that divides the body into right and left parts
Term
metaplasia
Definition
conversion of one cell type into another cell type
Term
bathroom privileges
Definition
BRP
Term
nosocomial infection
Definition
an infection acquired from the place of treatment
Term
endemic
Definition
found in a specific population or particular region of the world. The term is usually used to refer to a disease that occurs continuously or with a stable baseline incidence within a locale or a group of people.
Term
sarcoma
Definition
a malignant growth derived from connective tissue cells
Term
Neoplasm
Definition
any new or abnormal growth; a tumor
Term
gland
Definition
aden-
Term
both sides
Definition
ambi-
Term
scurvy
Definition
a condition caused by a deficiency of ascorbic acid because vitamin C has been discontinued in the diet, which results in abnormal collagen synthesis.
Term
tarsal
Definition
ankle & instep of foot
Term
tarsal
Definition
ankle & instep of foot
Term
papilloma
Definition
benign epithelial tumor; may occur on any epithelial surface or lining
Term
sacral
Definition
posterior region between hip bones
Term
osmosis
Definition
diffusion of water through a semi permeable membrane
Term
symptom
Definition
evidence of disease, such as pain or headache, that can only be observed or evaluated by the patient
Term
solvent
Definition
fluid in which substances dissolve
Term
pinocytosis
Definition
cell drinking; a form of endocytosis in which fluid droplets are taken into the cell
Term
Inferior
Definition
a part is below another part, or closer to the feet
Term
Cancer
Definition
Carcin-
Term
Ionic Bond
Definition
chemical bond that is formed when one or more electrons are transferred from one atom to another
Term
mast cells
Definition
immune cells that function to detect foriegn substanses against them; typically found clustered deep to an epithelium or along blood vessels.
Term
date of birth
Definition
DOB
Term
to form, produce
Definition
-genesis
Term
atom
Definition
the smallest unit of a chemical element that retains the properties of that element. Composed of protons, neutrons, and electrons
Term
basic
Definition
alkal-
Term
layer
Definition
strat-
Term
process, condition
Definition
-y
Term
a dried, hard body
Definition
skelet-
Term
protien-bound iodine
Definition
PBI
Term
aspirin
Definition
ASA
Term
Activities of daily living
Definition
ADL
Term
three
Definition
tri-
Term
one
Definition
mono-
Term
every
Definition
q
Term
poison
Definition
tox-
Term
collagenous fibers
Definition
strong and flexible connective tissue fibers that contain the protein collagen. Most abundant of the three fibers
Term
buccal
Definition
cheek
Term
genetic disorder
Definition
condition or disease that is caused by a defective gene and may appear at any time in life; also called a "hereditary disorder"
Term
sign
Definition
evidence of disease, such as fever, that can be observed, measured, or evaluated by someone other than the patient
Term
swelling, tumor
Definition
-cele
Term
out of, away from
Definition
ex
Term
tissue
Definition
group of similar cells specialized to perform a certain function. epithelial, connective, muscle and nervous are the primary....
Term
umbilical
Definition
naval; middle region of abdomen
Term
oxygen
Definition
oxy-
Term
base
Definition
a substance that ionizes in water to release hydrogen (OH-) ions or other ions that combine with hydrogen ions;
a proton acceptor;
a substance with a pH greater than 7.0
Term
gap, cleft, opening
Definition
hiat-
Term
meiosis
Definition
type of nuclear division in which the number of chromosomes is reduced to one half the number found in a body cell; results in the formation of an egg or sperm
Term
microgram
Definition
mcg
Term
pedal
Definition
foot
Term
process of
Definition
-ism
Term
state, condition
Definition
-esis
Term
total body weight
Definition
TBW
Term
cutaneous
Definition
skin
Term
water
Definition
hydro-
Term
many
Definition
poly-
Term
disease
Definition
path-
Term
condition of
Definition
-osis
Term
abdomen
Definition
abd
Term
distal
Definition
a part is further away from a point of attachment than is another part
Term
quality of life
Definition
QOL
Term
glue
Definition
glia-
Term
to control, stayin
Definition
-sta-
Term
low birth rate
Definition
LBW
Term
twice per day
Definition
(q2)bid
Term
congenital disorder
Definition
an abnormal condition that is present at birth and continues to exist from the time of birth
Term
element
Definition
simplest form of matter that cannot be broken down by ordinary chemical means
Term
eponym
Definition
name of a disease, structure, operation or procedure that is based on the name of an individual, usually the person who discovered or described it first
Term
to eat, devour
Definition
-phag-
Term
equal, same
Definition
iso-
Term
metastasis
Definition
the spread of a cancer from one body part or organ into another not directly connected to it.
Term
little, small
Definition
-elle
Term
leg
Definition
portion of lower extremity between knee & foot; also called crural region
Term
ion
Definition
electron with a positive or negative electric charge.
Term
molecule
Definition
a particle composed of two or more atoms that are chemically bound together;

smallest unit of a compound
Term
elastice fiber
Definition
yellow connective tissue fibers that are not particularly stong, but can be stretched & will return to their normal shape when released

A fiber formed from the protien elastin, which gives a rubbery & resilient quality to the matrix of connective tissue.
Term
systemic lupus erythematous
Definition
chronic autoimmune connective tissue disease characterized by injury to the skin, joints, kidneys, nervous system, & mucous membranes, but can affect any organ of the body
Term
life
Definition
bio-
Term
away from
Definition
ab-
Term
histology
Definition
branch of microscopic anatomy that studies tissues
Term
ears, nose, throat
Definition
ENT
Term
above elbow
Definition
AE
Term
inguinal
Definition
depressed region between abdomen & thigh; groin
Term
thoracic
Definition
chest; part of trunk inferior to neck and superior to diaphragm
Term
functional disorder
Definition
a disorder in which there are no detectable physical changes to explain the symptoms
Term
inflamation
Definition
-itis
Term
normal saline
Definition
NS
Term
anabolism
Definition
building up, or synthesis, reactions that require energy & make complex molecules from smaller ones
Term
four
Definition
quadr-
Term
fiber
Definition
fibro-
Term
solute
Definition
a substance that is dissolved ina solution
Term
passive transport
Definition
membrane transport process that does not require energy
Term
milliliter
Definition
ml
Term
below, less, under
Definition
sub-
Term
narrowing
Definition
stric-
Term
downward displacement, fall, sag
Definition
ptosis-
Term
anomoly
Definition
deviation from normal
Term
axial skeleton
Definition
consists of the head, neck & trunk (or torso, which includes the thorax, abdomen & pelvis)
Term
without, lacking
Definition
a-
Term
superficial
Definition
located on or ear the surface
Term
Below knee
Definition
BK
Term
nerve
Definition
neur-
Term
many
Definition
multi
Term
Cancer, Carcinoma
Definition
CA, Ca
Term
outside, beyond
Definition
extra-
Term
solute strength
Definition
ton-
Term
frontal
Definition
forehead
Term
atrophy
Definition
wasting away; a decrease in the size of a cell, tissue, organ, or part
Term
lumbar
Definition
region of lower back & side between lowest rib & pelvis
Term
necrosis
Definition
death of cells or group of cells
Term
lipoma
Definition
benign tumors derived from fat cells
Term
no complaint
Definition
N/C
Term
anion
Definition
a negatively charged ion

(gains an electron)
Term
popliteal
Definition
area behind the knee
Term
deoxyribonucleic acid
Definition
(DNA)a nucleic acid found in all living cells; carries organisms hrreditary information
Term
heart rate
Definition
HR
Term
vessel
Definition
(vas-)a tube, duct, or canal to convey the fluids of the body
Term
heart
Definition
cardi
Term
milk
Definition
lact-
Term
plantar
Definition
sole of foot
Term
cervical
Definition
neck region
Term
carbohydrate
Definition
(CHO) organic compound composed of carbon, hydrogen, and oxygen
Term
transvers plane
Definition
horizontal plane (perpendicular to the sagittal plane) that cuts across the body horizontally to divide it into superior & inferior portions;

sections cut this way are often called cross sections
Term
red
Definition
erythr-
Term
basin
Definition
pelv-
Term
nature, function
Definition
physi-
Term
nearest
Definition
proxim-
Term
visual examination
Definition
-scopy
Term
above or excessive
Definition
supra-
Term
to cut
Definition
-tom-
Term
internal organs
Definition
viscer-
Term
abduct
Definition
to move away from the midline of the body
Term
absolute refractory period
Definition
period following stimulation during which no additional action potential can be evoked
Term
absorption
Definition
process by which the products of digestion passt through the alimentary tube mucosa into the blood or lymph
Term
accessory digestive organs
Definition
organs that contribute to the digestive processbut are not part of the alimentary canal, include the tongue, teeth. salivary glands, pancreas, liver.
Term
accommodation
Definition
the process of increasing the refractive power of the lens of the eye; focusing
Term
acetabulum (ACh)
Definition
cuplike cavity on lateral surface of the hip bone that recieves the femur.
Term
acetylcholinesterase (AChE)
Definition
enzyme present at the neuromuscular junction and synapses that degrades acetylcholine and terminates its action.
Term
achilles tendon or calcaneal tendon
Definition
tendon that attaches the calf muscle to the heel bone.
Term
acid
Definition
a substance that releases hydrogen ions when in solution(compare with base) a proton donor
Term
acid base balance
Definition
situation in which the pH of the blood is maintaned between 7.35 and 7.45
Term
acidosis
Definition
state of abnormally high hydrogen ion concentration in the extracellular fluid
Term
actin
Definition
a contractile protien of muscle
Term
action potential
Definition
a large transient depolarization event, including polarity reversal, that is conducted along the membrane of a muscle cell or a nerve fiber.
Term
activation energy
Definition
the amount of energy required to push a reactant to the level neccessary for action
Term
active immunity
Definition
immunity produced by an encounter with an antigen; provides immunilogical memory
Term
active site
Definition
region on the surface of a functional (globular) protien where it binds and interacts chemically with other molecules of complementary shape and charge
Term
active transport processes
Definition
1. membrane transport processes for which ATP is required, e.g., solute pumping and endocytosis. 2. This also refers specifically to solute pumping
Term
anatomy
Definition
studies the structure of body parts and their relationshipa to one another. it is concrete. Body structures can be felt, seen and examined closely.
Term
physiology
Definition
the function of the body. How the body parts work and carry out their life-sustaining activities.
Term
gross or macroscopic anatomy
Definition
study of large body structures visile to the naked eye. The heart, lungs and kidneys.
Term
regional anatomy
Definition
all the structures (muscles, bones, blood vessels, nerves etc...) in a particular region of the body, such as the abdomen or leg, are examined at the same time.
Term
systemic anatomy
Definition
body structure is studied system by system.
Term
surface anatomy
Definition
study of internal structures as they relate to the overlying skin surface.
Term
microscopic anatomy
Definition
structures too small to be seen with the naked eye.
Term
cytology
Definition
subdivision of microscopic anatomy, chich considers the cells of the body
Term
developmental anatomy
Definition
traces structural changes that occur in the body throughout the life span.
Term
embryology
Definition
a subdivision of developmental anatomy, concerns developmental changes that occur before birth.
Term
pathological anatomy
Definition
studies structural changes caused by disease
Term
radiographic anatomy
Definition
studies internal structures as a visualized by x-ray images or specialized scanning procedures.
Term
molecular biology
Definition
the structure of biological molecules (chemical substances) is investicated.
Term
palpation
Definition
feeling organs with your hands
Term
ausculation
Definition
listening to organ sounds with a microscope
Term
renal physiology
Definition
concerns kidney function and urine production
Term
neurophysiology
Definition
explains the workings of the nervous system
Term
cardiovascular physiology
Definition
examines the operation of the heart and blood vessels
Term
principle of complementarity of structure and function
Definition
although it is possible to studt anatomy and physiology individually, they are really inseperable because function always reflects structure. that is, what a structure can do depends on its specific form.
Term
levels of structural organization
Definition
chemical level, cellular level, tissue level, organ level, organ system level, organismal level
Term
chemical level
Definition
the simplest level of the structural organization. Atoms, timy building blocks of matter, combnie to form molecules such as water and proteins. Molecules, in turn, associate in specific ways to form organelles, basic components of the microscopic cells.
Term
Cellular level
Definition
cells are the smalles units of living things. All cells have some common functions, but individual cells vary widely in size and shape, reflecting their unique functions in the body. The simplest living creatures are single cells.
Term
tissue level
Definition
in complex organisms such as human beings. A group of similar cells that have a common function.
Term
four basic tissue types in the human body are
Definition
epithelium tissue covers the body surface and lines its cavities, muscle tissue provides movement, connective tissue supports and protects body organs, and nervous tissue provides a means of rapid internal communication by transmitting electrical impulses.
Term
organ
Definition
a discrete structure composed of atleast two tissue types (four is more common)that performs a specific function for the body. Each organ of the body as a specializedfunctional center responsible for a necessary activity that no other organ can perform.
Term
organ level
Definition
extremely complex functions become possible.
Term
organ system level
Definition
organs that work together to accomplish a common purpose.
Term
organismal level
Definition
represents the sum total of all structural levels working together to keep us alive.
Term
organism
Definition
the highest level of organization is..., the living human being.
Term
A Band
Definition
The region of the myofribil’s striation that has the darker appearance; also called the dark band. Alternates with the light regions (I bands). The A band corresponds to the length of the thick filaments.
Term
Abdominal Aorta
Definition
The portion of the large descending aorta that begins inferior to the muscular diaphragm and ends at the division into the common iliac arteries.
Term
Absolute refractory period
Definition
The period of time following an action potential when an excitable cell cannot generate another action potential no matter how large a stimulus it receives.
Term
Acetyl CoA or Acetyl coenzyme A
Definition
a product of glycolysis and fatty acid metabolism that enters the Krebs cycle.
Term
Acetylcholine (ACh)
Definition
Neurotransmitter released by neurons that stimulate skeletal muscles, some neurons of autonomic nervous system (including parasympathetic postganglionic fibers), and some neurons in the brain.
Term
Acetylcholinesterase
Definition
An enzyme located in the synaptic cleft that rapidly degrades the neurotransmitter acetylcholine. In muscle cells, the immediate breakdown of acetylcholine prevents repetitive stimulation of the motor end plate in the absence of action potentials.
Term
Acinar cells
Definition
Pancreatic cell that produces enzyme-rich juice, an exocrine product.
Term
Acini
Definition
A histological term referring to a blind pocket, pouch, or sac. The acini in the pancreas are clusters of secretory cells surrounding ducts.
Term
Active channels
Definition
Ion channels that can be opened or closed by gates.
Term
Adaptive immunity
Definition
The branch of immunity that involves B and T lymphocytes, is specific to one particular antigen, and has memory. Also called specific immunity.
Term
Addison’s disease
Definition
A disease causing destruction of the adrenal cortex and subsequent deficiency of adrenal cortical hormones.
Term
Adenine
Definition
One of five major nitrogen-containing bases found in nucleic acids.
Term
Adenine nucleotide
Definition
The organic compound that contains ribose, a nitrogen base (adenine), and a phosphate group.
Term
Adenohypophysis
Definition
Anterior pituitary; the glandular part of the pituitary gland, and a small portion of the infundibulum.
Term
Adenosine monophosphate (AMP)
Definition
An adenine-containing nucleotide to which a phosphate group has been added.
Term
Adenosine triphosphate
Definition
ATP, an organic molecule that stores and releases chemical energy within the cell; composed of adenine, ribose sugar, and three phosphate groups.
Term
Adenylate cyclase
Definition
Membrane-bound enzyme that converts ATP to camp; activated by hormone-receptor interactions on the outer surface of the membrane.
Term
ADP
Definition
Adenosine diphosphate, one of the products of ATP hydrolysis; composed of adenine, ribose sugar, and two phosphate groups.
Term
Adrenal cortex
Definition
Outer portion of adrenal gland that produces steroid hormones.
Term
Adrenal glands
Definition
Paired endocrine glands located superior to the kidneys; each consists of an outer cortex and an inner medulla. Cortex secretes mineralocorticoids, glucocorticoids, and androgens. Medulla secretes catecholamines.
Term
Adrenal medulla
Definition
Modified sympathetic ganglion; the inner portion of the adrenal gland that produces catecholamines.
Term
Adrenergic
Definition
Associated with norepinephrine (NE) and epinephrine (adrenaline).
Term
Adrenergic receptor
Definition
Receptor that binds to norepinephrine or epinephrine.
Term
Adrenocorticotropic hormone (ACTH)
Definition
Anterior pituitary hormone that influences the activity of the adrenal cortex.
Term
Aerobic
Definition
As used here, the metabolic processes that require the presence of oxygen.
Term
Afferent arteriole
Definition
The renal arteriole branching from the cortical radiate artery and carrying blood into the glomerulus. Important in autoregulatory mechanisms.
Term
Afferent nerve
Definition
A nerve that carries impulses toward the central nervous system.
Term
Affinity
Definition
The degree of attraction between a molecule and the substance it binds to.
Term
Albumin
Definition
The most abundant plasma protein; functions to regulate the colloid osmotic pressure of the plasma.
Term
Aldosterone
Definition
Hormone secreted by the adrenal cortex which promotes sodium reabsorption and potassium secretion by the kidney.
Term
α cells
Definition
Pancreatic cell that secretes glucagon.
Term
Alternative pathway
Definition
A pathway of complement activation of the innate immune system. Occurs in the absence of antibody or lectin binding, when C3b spontaneously forms and binds to pathogens lacking complement-pathway inhibitors.
Term
Alveolar duct
Definition
An elongated air passageway completely lined by alveoli.
Term
Alveolar fluid
Definition
The liquid film that coats the alveolar walls, composed primarily of water.
Term
Alveolar sac
Definition
Clusters of alveoli that open into a common space.
Term
Alveolus
Definition
A thin-walled air-filled sac in the lungs where gas exchange occurs (plural alveoli).
Term
Amine hormone
Definition
Derivatives of single amino acids, either tyrosine or tryptophan.
Term
Amino acids
Definition
Organic compounds containing nitrogen, carbon, hydrogen, and oxygen; building blocks of protein.
Term
Aminopeptidase
Definition
Digestive enzyme that removes one amino acid at a time from the amine end of a peptide.
Term
Amniotic fluid
Definition
The fluid that surrounds and protects the developing fetus.
Term
Amplification
Definition
Mechanism by which a small amount of hormone produces large numbers of product molecules inside a cell.
Term
Amylase
Definition
Digestive enzyme that breaks down starch.
Term
Anabolic metabolism
Definition
Energy-requiring building phase of metabolism in which simpler substances are combined to form more complex substances.
Term
Anaerobic
Definition
As used here, the metabolic processes that do not require the presence of oxygen.
Term
Anal canal
Definition
The last segment of the large intestine; it lies outside the abdominopelvic cavity.
Term
Anaphylaxis
Definition
A life-threatening, systemic allergic reaction characterized by bronchoconstriction, vasodilation, edema, and cardiovascular collapse.
Term
Androgen
Definition
A hormone with testosterone-like actions.
Term
Androstenedione
Definition
An androgen hormone.
Term
Anergy
Definition
A state in which a lymphocyte fails to respond to an antigen. Occurs when an antigen is encountered without co-stimulation.
Term
Angiotensin (ANG)
Definition
A potent vasoconstrictor activated by renin; triggers release of aldosterone.
Term
Angiotensin-converting enzyme (ACE)
Definition
Enzyme that converts angiotensin I into angiotensin II.
Term
Angiotensin I
Definition
Protein molecule formed from angiotensinogen. Converted into angiotensin II by angiotensin-converting enzyme (ACE). Part of renin-angiotensin mechanism, which increases blood pressure.
Term
Angiotensin II
Definition
Molecule created by conversion of angiotensin I. Stimulates adrenal cortex to release aldosterone; also a potent vasoconstrictor. Part of renin-angiotensin mechanism, which increases blood pressure.
Term
Angiotensinogen
Definition
Plasma globulin made by the liver that is converted to angiotensin I by renin. Part of renin-angiotensin mechanism, which increases blood pressure.
Term
Anoxia
Definition
An absence of oxygen.
Term
Anterior interventricular artery
Definition
Branch of left coronary artery; supplies oxygenated blood to interventricular septum and anterior walls of both ventricles.
Term
Antibody
Definition
A protein molecule that is released by a plasma cell (a daughter cell of an activated B lymphocyte) and that binds specifically to an antigen. Also called an immunoglobulin.
Term
Antidiuretic hormone (ADH)
Definition
Posterior pituitary hormone that regulates water reabsorption in the kidneys. Also called vasopressin.
Term
Antigen
Definition
Any molecule that binds to an antibody or a receptor of a B or T lymphocyte.
Term
Antigen binding site
Definition
The portion of an antibody, or B or T lymphocyte antigen receptor, that binds to an antigen. Antibodies have two antigen binding sites at the ends of their arms.
Term
Antigen-presenting cells
Definition
Specialized cells that capture, process, and present antigens on their surface to T lymphocytes. Include dendritic cells, macrophages, and B cells.
Term
Antigenic determinant
Definition
The part of an antigen that is actually bound by an antibody or lymphocyte antigen receptor. Most antigens have many antigenic determinants. Also called an epitope.
Term
Antimicrobial protein
Definition
A protein that can attack microorganisms (especially bacteria).
Term
Antiport transport protein
Definition
A membrane-bound protein that will transport one substance in one direction in exchange for another specific substance moved in the other direction using the energy of the concentration gradient of one of the substances. A form of secondary active transport.
Term
Antivenom
Definition
A preparation of antibodies used therapeutically to neutralize the various toxic components of venoms from spiders, snakes, etc.
Term
Antrum
Definition
The wider, more superior part of the pyloric region of the stomach.
Term
Aorta
Definition
Largest artery in the body; receives oxygen-rich blood from left ventricle.
Term
Aortic arch
Definition
Arching portion of the aorta as it emerges from the heart.
Term
Aortic semilunar valve
Definition
Valve at entrance to the aorta; prevents backflow into left ventricle.
Term
Apoptosis
Definition
A process of cellular suicide, also known as programmed cell death; eliminates cells that are unneeded, infected, or cancerous.
Term
Appendix
Definition
A blind wormlike tube attached to the cecum of the large intestine; it contains lymphoid tissue.
Term
Arcuate artery
Definition
The renal arteries that lie at the medulla-cortex junction. Together with the arcuate veins, they arch over the bases of the renal pyramids and give rise to the cortical radiate arteries.
Term
Arcuate vein
Definition
The renal veins that lie at the medulla-cortex junction. Together with the arcuate arteries, they arch over the bases of the renal pyramids and drain into the interlobar veins.
Term
Arteriole
Definition
Smallest type of artery. Larger arterioles exhibit all three tunics but tunica media is mainly smooth muscle. Smallest arterioles consist of smooth muscle cells spiraling around tunica intima.
Term
Arteriosclerosis
Definition
A disease of the arteries in which vessel walls calcify, becoming less flexible. Atherosclerosis, in which fatty deposits called plaques accumulate in the artery wall, is a common form of arteriosclerosis.
Term
Artery
Definition
Type of blood vessel that transports blood away from the heart; exposed to the highest pressures of any vessels; has thickest tunica media of any vessels.
Term
Ascending colon
Definition
Portion of the colon extending from the cecum up the right side of the abdominal cavity to the right colic flexure.
Term
Ascending loop of Henle (thick segment)
Definition
The portion of the renal tubule loop that returns the filtrate back from the medulla toward the renal cortex.
Term
Asynchronous
Definition
Happening at different times; not synchronous.
Term
ATP
Definition
Adenosine triphosphate, an organic molecule that stores and releases chemical energy within the cell; composed of adenine, ribose sugar, and three phosphate groups.
Term
ATPase
Definition
A cellular enzyme that binds to ATP (adenosine triphosphate) and hydrolyzes ATP into ADP (adenosine diphosphate) and inorganic phosphate, liberating the energy within the high-energy phosphate bond.
Term
Atrial natriuretic peptide (ANP)
Definition
Peptide hormone from atria of the heart that regulates sodium and water excretion.
Term
Autoimmune disease
Definition
A disease characterized by the production of antibodies or effector T cells that attack a person’s own tissue; a failure of self-tolerance.
Term
Autonomic nervous system (ANS)
Definition
The efferent portion of the peripheral nervous system which innervates smooth muscle, cardiac muscle, and glands.
Term
Autophosphorylation
Definition
Addition of phosphate groups to a receptor molecule by another receptor molecule of the same type.
Term
Autoregulation
Definition
The automatic adjustment of blood flow within a localized region in response to its current tissue requirements.
Term
Autorhythmic cells
Definition
Cardiac cells localized in the intrinsic conduction system that initiate and distribute impulses to adjacent cells. Also known as nodal cells.
Term
AV bundle, also known as bundle of His.
Definition
Autorhythmic cells located in the inferior part of the interatrial septum; the only electrical connection between atria and ventricles (AV = atrioventricular)
Term
AV node
Definition
Mass of autorhythmic cells located in the inferior portion of the interatrial septum above the tricuspid valve (AV = atrioventricular); here, each impulse is delayed briefly, allowing atria to contract before ventricles.
Term
Axoaxonic synapse
Definition
Synapse between two axon terminals.
Term
Axodendritic synapse
Definition
Synapse between an axon terminal and a dendrite.
Term
Axon
Definition
A long, thin cytoplasmic process that extends from a neuron’s cell body. The axon may be insulated with myelin. Each neuron has a single axon, which transmits action potentials.
Term
Axon collateral
Definition
A branch of an axon.
Term
Axon hillock
Definition
The first portion, or initial segment, of the axon.
Term
Axon terminal
Definition
The swollen, distal end of an axon; contains a neurotransmitter substance within synaptic vesicles. Also called synaptic ending or synaptic bouton.
Term
Axosomatic synapse
Definition
Synapse between an axon terminal and the cell body (soma) of a neuron.
Term
B cell OR B lymphocyte
Definition
One of the two major classes of lymphocytes involved in adaptive immunity; when activated, B lymphocytes generate antibody-producing plasma cells, mediating humoral immunity.
Term
B cell antigen receptor
Definition
The antigen receptor found on the surface B lymphocytes; a membrane-bound antibody molecule.
Term
Bacteria
Definition
Single-celled microorganisms larger than viruses; some are pathogens; can be found extracellularly or intracellularly.
Term
Baroreceptors
Definition
Pressure-sensitive mechanoreceptors that respond to changes in arterial pressure and stretch. Located in aortic arch, carotid sinus, and most large arteries of neck and thorax.
Term
Basal lamina
Definition
Nonliving, adhesive material formed largely of glycoproteins secreted by epithelial cells; provides support to epithelium.
Term
Basal metabolic rate (BMR)
Definition
Rate at which energy is expended (heat produced) by the body per unit time under controlled (basal) conditions: 12 hours after a meal, at rest.
Term
Basal nuclei
Definition
Deep nuclei in the cerebral hemispheres that function in control of movement.
Term
Basal surface
Definition
The lower attached surface of an epithelium.
Term
Basement membrane
Definition
Extracellular material found between an epithelium and connective tissue.
Term
Bases
Definition
Chemical substances that accept hydrogen ion (H+).
Term
Basolateral membrane
Definition
The entire combined portion of the renal cell’s plasma membrane, which lies in contact with the interstitial space.
Term
Basophil
Definition
A white blood cell whose granules stain blue with basic dye. The granules contain histamine and other inflammatory mediators.
Term
β cells
Definition
Pancreatic cells that secrete insulin.
Term
Bicarbonate
Definition
The ion HCO3–; an important base in the body.
Term
Bicarbonate solution
Definition
A solution containing the ion HCO3–.
Term
Bile
Definition
Greenish-yellow or brownish fluid produced in and secreted by the liver, stored in the gall bladder, and released into the small intestine.
Term
Bile salts
Definition
Steroid derivatives in bile; responsible for the emulsification of ingested lipids.
Term
Bilirubin
Definition
The major bile pigment; a breakdown product of heme.
Term
Binding site
Definition
A specific region on a protein to which another molecule becomes attracted and attaches. Also called a receptor site.
Term
Blood pressure
Definition
The force that blood exerts against blood vessel walls. Expressed in millimeters of mercury (mm Hg), e.g., a blood pressure of 120 mm Hg = pressure exerted by a column of mercury 120 mm high.
Term
Body of stomach
Definition
The mid portion of the stomach continuous inferiorly with the funnel-shaped pyloric region.
Term
Bohr effect
Definition
The change in hemoglobin’s affinity for oxygen in response to changes in pH. By forming hydrogen ions, carbon dioxide loading facilitates oxygen unloading.
Term
Bolus
Definition
A rounded mass of food prepared by the mouth for swallowing.
Term
Bone marrow
Definition
Tissue found within the cavities of bones. Red bone marrow is the site of formation of all the cellular elements of blood, including many immune cells, and is the site of B cell maturation.
Term
Boyle’s Law
Definition
The pressure of a gas is inversely proportional to the volume of its container. Increasing the volume of a container decreases the pressure. Decreasing the volume of a container increases the pressure.
Term
BPG
Definition
2,3-bisphosphoglycerate, a unique compound that binds reversibly with hemoglobin. It is produced by red blood cells as they break down glucose by the anaerobic process called glycolysis.
Term
Brainstem
Definition
The part of the brain composed of the medulla oblongata, the pons, and the midbrain.
Term
Bronchial tree
Definition
The branching network of airways, from the main bronchi through the terminal bronchioles, that conducts air within each lung.
Term
Bronchiole
Definition
A very small air passage without supporting cartilage.
Term
Brush border
Definition
Name given to microvilli covering the luminal surface of intestinal and renal tubule epithelia.
Term
Brush border cells
Definition
The epithelial cells of the proximal convoluted tubule that have extensive microvilli on their luminal surfaces.
Term
Brush border enzymes
Definition
Digestive enzymes produced by cells of the small intestine and inserted into the plasma membrane of microvilli.
Term
Buffer
Definition
A chemical substance or a system that minimizes changes in pH by releasing or binding hydrogen ions.
Term
Bulk Flow
Definition
The movement of fluids and molecules, ions or other particles contained in the fluid in one direction due to pressure differences.
Term
Bundle branches
Definition
Two branches resulting from splitting of the AV bundle; conveys impulses down the interventricular septum.
Term
Bundle branches
Definition
Two branches resulting from splitting of the AV bundle; conveys impulses down the interventricular septum.
Term
C cells
Definition
Thyroid cells that secrete calcitonin.
Term
Calcitonin
Definition
Hormone released by the thyroid gland that promotes a decrease in calcium levels of the blood.
Term
Calcitriol
Definition
The active form of Vitamin D which promotes absorption of dietary calcium in the small intestine.
Term
Calcium channel
Definition
Transport protein in plasma membrane of autorhythmic cell that allows explosive entry of calcium (Ca2+) from extracellular space; channel is voltage-gated, opening and closing in response to specific voltage levels.
Term
Calcium ions
Definition
Calcium atoms with two positive charges; concentrated in the extracellular fluid and terminal cisternae, but then enter cytosol where they play an important role in many processes such as muscle contraction and the release of neurotransmitters.
Term
Calmodulin
Definition
Calcium-binding protein that mediates intracellular effects of calcium ions.
Term
Capillary
Definition
Smallest type of blood vessel; capillary walls consist only of thin tunica intima, which allows for exchanges of materials between blood and tissue cells.
Term
Capillary bed
Definition
Interweaving network of capillaries; consists of (1) a shunt that connects the arteriole and venule and (2) true capillaries, where exchanges take place between blood and tissue cells.
Term
Capsular space
Definition
The region within the glomerular capsule that collects the filtrate being forced out of the blood.
Term
Carbaminohemoglobin
Definition
The form of hemoglobin which is bound to carbon dioxide.
Term
Carbohydrate
Definition
Organic compound composed of carbon, hydrogen, and oxygen; includes starches, sugars, cellulose.
Term
Carbonic anhydrase CA
Definition
An enzyme that converts carbon dioxide and water into carbonic acid in a reversible reaction.
Term
Carboxypeptidase
Definition
Digestive enzyme that removes one amino acid at a time from the carboxyl end of a peptide.
Term
Cardia
Definition
The region of the stomach surrounding the opening through which food enters the stomach from the esophagus. Also called cardiac region.
Term
Cardiac muscle
Definition
Muscle tissue found in the wall of the heart.
Term
Cardiac myofibril
Definition
Bundle of contractile myofilaments (myosin and actin); varies in diameter; branches extensively.
Term
Cardiac output
Definition
Amount of blood pumped out by each ventricle in one minute.
Term
Cardinal sign
Definition
In medicine, a key finding made by observing a patient. For example, there are four cardinal signs of inflammation.
Term
Cardioacceleratory center (sympathetic)
Definition
Sympathetic cardiac center located in the medulla oblongata; accelerates heart rate and force of contraction.
Term
Cardioinhibitory center (parasympathetic)
Definition
Parasympathetic cardiac center located in the medulla oblongata; inhibits heart rate.
Term
Carotid arteries
Definition
Large arteries leading to the brain.
Term
Carotid sinus
Definition
Dilation in internal carotid arteries, the arteries that provide the major blood supply to the brain.
Term
Carrier-mediated transport
Definition
Transport of ions or organic substances across the cell membrane by integral proteins.
Term
Carrier molecule
Definition
A generic term for a transmembrane protein of the plasma membrane that transports substances across the membrane.
Term
Cartilage
Definition
A tough, flexible, supporting connective tissue.
Term
Cascade
Definition
A sequential process in which the products of one reaction bring about the next reaction. Examples include the blood clotting cascade and the complement cascade.
Term
Catecholamine
Definition
A type of organic compound that contains a benzene ring structure and an amine group. Dopamine, norepinephrine, and epinephrine are catecholamines.
Term
Cation
Definition
A positively charged ion.
Term
cc
Definition
Abbreviation for “Cubic centimeter”; a standard measure of volume used for syringes.
Term
CD4
Definition
A cell-surface protein on a T lymphocyte that acts as a co-receptor for MHC II. Its presence characterizes one of the two major classes of T lymphocytes.
Term
CD4 cell
Definition
One of two major classes of T lymphocytes, characterized by the presence of the cell-surface protein CD4. Naive CD4 cells give rise to helper T cells and regulatory T cells, which continue to express CD4.
Term
CD8 cell
Definition
One of two major classes of T lymphocytes, characterized by the presence of the cell-surface protein, CD8. Naive CD8 cells give rise to cytotoxic T cells, which continue to express CD8.
Term
CECUM
Definition
The blind-end pouch that lies below the ileocecal sphincter at the beginning of the large intestine.
Term
Cell adhesion molecules (CAMs)
Definition
Cell-surface proteins such as selectins and integrins that bind cells together.
Term
Cell body
Definition
The portion of the neuron containing the nucleus and organelles; also called the soma.
Term
Cell interior
Definition
Inside of cell.
Term
Cell-mediated immunity and Cellular immunity
Definition
The branch of adaptive immunity involving T lymphocytes that directly attack infected, cancerous, or transplanted cells, or that release chemicals which regulate other functions of the immune system.
Term
Central Nervous System (CNS)
Definition
The brain and spinal cord.
Term
Cephalic phase
Definition
The earliest phase of reflexes that control GI secretions; the meal is not yet ingested and receptors for these reflexes are in the head.
Term
Cerebellum
Definition
The brain region most involved in producing smooth coordinated skeletal muscle activity.
Term
Cerebral cortex
Definition
The outer layer of neurons that forms the covering of the cerebral hemispheres.
Term
Cerebrospinal fluid
Definition
Plasma-like fluid within the brain ventricles, the central canal of the spinal cord, and the subarachnoid space surrounding both the brain and spinal cord. It circulates in and around the brain and the spinal cord to protect and nourish the central nervous system. Abbreviated as CSF.
Term
Channel
Definition
A transmembrane protein of the plasma membrane that provides an opening for ions to pass through the membrane by passive transport.
Term
Chaperone protein
Definition
A protein bound to an intracellular hormone receptor that seems to prevent unbound receptors from binding to DNA and may protect the receptor from proteolysis.
Term
Chemical energy
Definition
The energy stored in the bonds of chemical substances. When the bonds are broken, the energy is released.
Term
Chemical synapse
Definition
A synapse formed by an axon terminal and neuronal cell membrane. A neurotransmitter conveys the signal from the axon terminal to the neuronal cell membrane.
Term
Chemically gated channels
Definition
Ion channels with gates that open or close when a neurotransmitter binds to them.
Term
Chemically gated ion channels
Definition
Integral proteins in cell membranes that serve as ion channels. When a specific chemical binds to the receptor site on the protein, the protein changes shape, opens the channel, and allows certain ions to move from one side of the membrane to the other.
Term
Chemoreceptors
Definition
Sensory receptors that respond to changes in various dissolved chemicals.
Term
Chemotaxin
Definition
A chemical that, in a concentration gradient, guides the movement of cells. For example, many of the inflammatory mediators act as chemotaxins to attract phagocytes.
Term
Chemotaxis
Definition
The movement of a cell up or down a chemical gradient. For example, phagocytes following a gradient of inflammatory mediators.
Term
Chief cell
Definition
A cell of the stomach that secretes pepsinogen.
Term
Cholecystokinin (CCK)
Definition
An intestinal hormone that stimulates gallbladder contraction and pancreatic juice release.
Term
Cholesterol
Definition
Steroid made by the liver; building block for steroid hormones.
Term
Cholinergic
Definition
Associated with acetylcholine (ACh).
Term
Chordae tendinae
Definition
Cords (“heart strings”) that anchor AV valve flaps to the papillary muscles.
Term
Chromaffin granules
Definition
Secretory vesicles in the cells of the adrenal medulla; site of synthesis and storage of epinephrine and norepinephrine.
Term
Chylomicrons
Definition
Relatively large droplets that may contain triglycerides, phospholipids, and cholesterol in association with proteins; synthesized and released by intestinal cells and transported to the venous blood by the lymphatic system.
Term
Chyme
Definition
Semifluid, creamy mass consisting of partially digested food and gastric juice.
Term
Chymotrypsin
Definition
Digestive enzyme that cleaves proteins into smaller peptides.
Term
Circadian rhythm
Definition
A biological variation or rhythm with a cycle of about 24 hours.
Term
Circular muscle
Definition
A circular layer of smooth muscle cells in the wall of the GI tract.
Term
Citric acid cycle
Definition
The Krebs cycle, a major metabolic pathway within the mitochondrion that yields carbon dioxide, small amounts of ATP, and reduced coenzymes that enter the oxidative phosphorylation pathway.
Term
Cl-
Definition
Symbol for the chloride ion.
Term
Class I MHC proteins
Definition
Cell-surface molecules that usually display antigens originating in the cytoplasm of a cell to CD8 T lymphocytes.
Term
Class II MHC proteins
Definition
Cell-surface molecules that display antigens originating outside the cell to CD4 T lymphocytes.
Term
Classical pathway
Definition
A pathway of complement activation of the adaptive immune system. Occurs when antibodies bind to pathogens.
Term
Cleft
Definition
Gap between capillary endothelial cells just large enough to allow limited passage of fluids and small solutes between capillaries and tissue cells.
Term
Clonal deletion
Definition
Elimination, by programmed cell death during their development, of immature B and T lymphocytes that bind self-antigens. A mechanism of immune tolerance.
Term
Clonal expansion
Definition
The antigen-induced series of cell divisions of a lymphocyte that precedes generation of effector cells specific for the triggering antigen.
Term
Clonal selection
Definition
The process by which antigens select only those naive lymphocytes with matching preexisting receptors, triggering their proliferation and differentiation.
Term
Clones
Definition
Descendants of a single cell.
Term
Clotting factor
Definition
Proteins and other chemicals that are involved in blood clot formation.
Term
Cofactors
Definition
Positive ions or organic molecules which are required for the activity of some enzymes.
Term
Collagen fiber
Definition
Strong connective tissue fibers made of the fibrous protein collagen.
Term
Collecting duct
Definition
Tubules that collect filtrate from several nephrons. An important site for regulated sodium and water reabsorption into the bloodstream.
Term
Colloid osmotic pressure
Definition
The osmotic effect due to the presence of protein.
Term
Colloids
Definition
Large particles, such as proteins, which are dispersed in a body fluid.
Term
Colon (ascending, transverse, descending, sigmoid)
Definition
Longest region of the large intestine; includes ascending, transverse, descending, and sigmoid portions.
Term
Columnar cells
Definition
Epithelial cells that are tall and column shaped.
Term
Columnar epithelium
Definition
An epithelium formed by columnar cells.
Term
Compensation
Definition
The mechanism for adjusting to an abnormal condition.
Term
Complement or Complement system
Definition
A set of plasma proteins, many acting as enzymes in a sequence to produce inflammatory mediators, enhancers of phagocytosis, and cell lytic proteins.
Term
Complete tetanus
Definition
The condition in which rapid multiple stimulations cause the contraction/relaxation cycles to fuse into a total contraction without evidence of any cyclical relaxation.
Term
Concentration gradient
Definition
The difference in the concentration of a particular substance between two adjacent areas.
Term
Conducting zone
Definition
The airways, from the nasal cavity through the terminal bronchioles, which conduct air to the respiratory zones of the lungs.
Term
Conduction velocity
Definition
The speed with which an action potential is propagated along an axon.
Term
Conformation
Definition
As used here, the shape of a transport protein.
Term
Congestive heart failure (CHF)
Definition
Condition in which the pumping efficiency of the heart is depressed so that circulation is inadequate to meet tissue needs.
Term
Connective tissue
Definition
Tissues of the body characterized by widely spaced cells with large amounts of intercellular matrix. The functions of these tissues vary considerably; generally, they serve to support, bind, insulate, transport, and provide storage.
Term
Connective tissue wrappings
Definition
The various layers of connective tissues surrounding the muscle cells, fascicles, and whole muscle. They are noncontractile structures that bind the contractile structures into a functioning unit.
Term
Contractile cell
Definition
Cell of the heart that contracts in response to an action potential.
Term
Contractility
Definition
Contractile strength of heart muscle; an increased contractility results in increased force of contraction at any give amount of muscle fiber stretch.
Term
Control center
Definition
One of the components of homeostatic control mechanisms; determines the normal range within which a variable is to be maintained, analyzes the input it receives and then determines the appropriate response.
Term
Coronary sinus
Definition
Vessel that collects oxygen-poor blood from cardiac veins; it empties blood into the right atrium.
Term
Corpus luteum
Definition
Ovarian structure that produces estrogen and progesterone after ovulation.
Term
Cortex
Definition
Outer surface layer of an organ; for example the cortex of the brain.
Term
Cortical collecting duct
Definition
The portion of the renal collecting duct formed by the joining of the distal convoluted tubules from many nephrons; it lies within the cortex.
Term
Cortical nephrons
Definition
Nephrons located mostly in the cortex, except for a portion of the loop of Henle, which dips into the medullary region.
Term
Cortical radiate artery
Definition
The artery that branches from the arcuate artery, continuing into the cortical region of the kidney. It branches to form the afferent arterioles.
Term
Cortical radiate vein
Definition
The vein that drains the peritubular capillaries and vasa recta. It connects to the arcuate vein.
Term
Corticosterone
Definition
Glucocorticoid hormone released by the adrenal cortex.
Term
Corticotropin-releasing hormone (CRH)
Definition
Hypothalamic hormone that regulates secretion of ACTH from the anterior pituitary.
Term
Cortisol
Definition
Glucocorticoid hormone produced by the adrenal cortex.
Term
Cortisone
Definition
Glucocorticoid hormone produced by the adrenal cortex.
Term
Co-stimulation
Definition
The process of delivering signals in addition to antigen binding to achieve activation of B or T lymphocytes; prevents inadvertent activation.
Term
Cotransport
Definition
A secondary active transport process in which two or more substances move across the plasma membrane. If substances move in the same direction, it is symport; otherwise antiport (countertransport).
Term
Countercurrent exchanger
Definition
The role played by the opposing flow of blood within the vasa recta to provide nutrients to and remove waste from the medullary interstitium without washing away the solutes that maintain the medullary osmotic gradient.
Term
Countercurrent multiplier
Definition
The role played by the opposing flow of filtrate within the ascending and descending loop of Henle to form the medullary osmotic gradient.
Term
Countertransport
Definition
A secondary active transport process in which two or more substances move through the plasma membrane in opposite directions. Most commonly, one of the substances is the sodium ion.
Term
Creatine phosphate
Definition
An organic compound in muscle cells that serves as a brief source of energy.
Term
Creatinine
Definition
The end product of creatine metabolism.
Term
Crenate
Definition
The shrinkage of red blood cells that occurs when they are placed in a hypertonic solution.
Term
Cross bridge
Definition
A structure formed by the globular head of the myosin protein of the thick filament when it attaches to the thin filament during muscle contraction. Flexing the cross bridge moves the thin filament toward the center of the sarcomere.
Term
Crypt
Definition
A cleft, recess, or pit. Also the tubular glands of the small intestine.
Term
CSF or Cerebrospinal fluid
Definition
plasma-like fluid within the brain ventricles, the central canal of the spinal cord, and the subarachnoid space surrounding both the brain and spinal cord. It protects and nourishes the central nervous system.
Term
Cuboidal epithelial cells
Definition
Cells with nearly equal dimensions of height, breadth, and depth. These cells are important for secretion and absorption and are the main cell type found in the renal tubules.
Term
Current
Definition
The movement of charged particles. In biological systems, the movement of ions.
Term
Cushing’s disease
Definition
Refers to hypercortisolism caused by pituitary tumors that secrete excessive ACTH.
Term
Cushing’s syndrome
Definition
A hormonal disorder caused by prolonged high levels of cortisol; also called hypercortisolism.
Term
Cyclic AMP (cAMP)
Definition
Important intracellular second messenger that mediates hormonal effects.
Term
Cytokines
Definition
Small proteins that act as chemical messengers between various parts of the immune system.
Term
Cytoplasmic vesicle
Definition
Small membrane-bounded sac that ferries materials through cells.
Term
Cytosol
Definition
The intracellular fluid in which the organelles are suspended and molecules and ions are dissolved.
Term
Cytotoxic T cell (TC)
Definition
An effector T lymphocyte characterized by the presence of CD8 cell-surface molecules. Cytotoxic T cells kill other cells that are infected, cancerous, or transplanted.
Term
Dalton’s Law
Definition
Dalton’s Law of Partial Pressures states that in a mixture of gases, the total pressure equals the sum of the partial pressures exerted by each gas. The partial pressure of each gas is directly proportional to its percentage in the total gas mixture.
Term
Defecate
Definition
To eliminate the contents of the bowels (feces).
Term
Defecation
Definition
Elimination of the contents of the bowels (feces).
Term
Defecation reflex
Definition
Reflex that initiates elimination of feces.
Term
Defensins
Definition
Small antimicrobial proteins found in skin and in neutrophil granules.
Term
Dehydration
Definition
Deficit of water only accompanied by increased osmolarity in all fluid spaces.
Term
Dehydration synthesis
Definition
The chemical process that combines two molecules into a single larger molecule. The process involves an enzyme, the removal of one water molecule, and the formation of a covalent bond to join the two molecules.
Term
Denaturation of protein
Definition
To uncoil or change the shape of a protein; usually causes the function of the protein to cease or diminish.
Term
Dendrite
Definition
A cytoplasmic process that extends from a neuron’s cell body. Neurons typically have many dendrites, which are usually shorter and thicker than axons and highly branched. Dendrites receive signals from other neurons.
Term
Dendritic cells
Definition
Found in many tissues, these key antigen-presenting cells capture antigens, migrate to secondary lymphoid organs, and present these antigens to T lymphocytes.
Term
Dental caries
Definition
Destruction of teeth; cavities.
Term
Depolarization
Definition
A change in membrane potential such that the cell interior becomes relatively less negative (more positive); this change is transmitted from cell to cell, creating a wave, or impulse, of electrical activity.
Term
Depolarize
Definition
To change the membrane potential of a cell to a value that is more positive than its resting membrane potential.
Term
Descending colon
Definition
Portion of the colon extending from the left colic flexure to the sigmoid colon.
Term
Descending loop of Henle (thin segment)
Definition
The portion of the renal tubule that extends from the proximal convoluted tubule to the “hairpin” turn in the loop of Henle. It is composed of flattened epithelial cells.
Term
Desmosome
Definition
Cell junction between adjacent cardiac cells that prevents cells from separating during contraction.
Term
Dextrinase
Definition
Digestive enzyme in the brush border that breaks down limit dextrins.
Term
Diabetes insipidus
Definition
A medical condition in which excessive urine production results from inadequate secretion or action of antidiuretic hormone.

























A medical condition in which excessive urine production results from inadequate secretion or action of antidiuretic hormone.
Term
Diabetes mellitus
Definition
A medical condition characterized by high blood glucose levels resulting in the presence of glucose in the urine. This condition results from insulin deficiency or lack of cellular response to insulin.
Term
Diacylglycerol (DAG)
Definition
Membrane phospholipid formed after hydrolysis of PIP2. Functions as a second messenger that activates protein kinase C.
Term
Diapedesis
Definition
The passage of white blood cells through intact vessel walls into tissue.
Term
Diaphragm
Definition
The muscle that separates the thoracic cavity from the abdominopelvic cavity; it contracts during inspiration.
Term
Diastole
Definition
Relaxation. Specifically, relaxation of the ventricles (ventricular diastole). Atrial diastole is relaxation of the atria. A part of the cardiac cycle.
Term
Diastolic pressure
Definition
Lowest pressure in the artery; result of ventricular diastole (relaxation); normally about 80 mm Hg.
Term
Dicrotic notch
Definition
Pressure fluctuation in graph of arterial pressure due to brief backflow of blood that closes the aortic semilunar valve.
Term
Diffusion
Definition
The movement of materials from a region of higher concentration to lower concentration as a result of their kinetic energy.
Term
Digestive enzymes
Definition
Enzymes that break down or hydrolyze nutrients.
Term
Dilation
Definition
The enlargement of the diameter of a tubular structure.
Term
Dipeptidase
Definition
Digestive enzyme that cleaves dipeptides.
Term
Dipeptides
Definition
Peptides composed of two amino acids.
Term
Disaccharide
Definition
A sugar formed by joining two monosaccharides; a double sugar.
Term
Disaccharide maltose
Definition
Disaccharide formed by joining the monosaccharides glucose and glucose.
Term
Dissociates
Definition
The separation of one thing or part from another. For example, acids, bases, and salts, dissociate when dissolved in water.
Term
Distal convoluted tubule (DCT)
Definition
The portion of the renal tubule that extends from the juxtaglomerular apparatus to the cortical collecting duct.
Term
Disulfide bond
Definition
A strong covalent bond formed between sulfurs of two cysteine amino acids within a protein. Also called disulfide bridges.
Term
Diuretic
Definition
A chemical that causes an increased urine volume.
Term
Diversity of receptors
Definition
A shared feature of B and T lymphocytes, arising from the fact that there are a huge number of different lymphocytes, each with its own unique antigen receptor.
Term
Dopamine (DA)
Definition
Hypothalamic hormone that regulates secretion of prolactin from the anterior pituitary. Also functions as neurotransmitter.
Term
Double-helical chain
Definition
Two strands of molecules twisted into a spiral or coil.
Term
Down-regulation
Definition
Decreased response to hormonal stimulation; involves a loss in the number of receptors and effectively prevents the target cells from overreacting to persistently high hormone levels.
Term
Duodenum
Definition
First part of the small intestine.
Term
Dynamic equilibrium
Definition
Sense that reports on angular or rotational movements of the head in space.
Term
ECF
Definition
Extracellular fluid. Located outside cells, the ECF includes interstitial fluid and plasma.
Term
ECG
Definition
An electrocardiogram (ECG) is a recording of the heart’s electrical events. Electrical currents generated by the heart spread throughout the body and can be monitored with an electrocardiograph.
Term
Edema
Definition
An accumulation of fluid in the interstitial space.
Term
Effector cells
Definition
The cells that carry out the functions of the immune system. In adaptive immunity the effector cells include plasma cells, cytotoxic T cells, and helper T cells.
Term
Effector organ
Definition
An organ innervated by the nervous system.
Term
Effectors
Definition
One of the components of homeostatic control mechanisms; provides the means for the control center’s response (output) to the stimulus. Information flows from the control center to the effector along the efferent pathway.
Term
Efferent arteriole
Definition
The renal blood vessel emerging from the glomerulus and distributing blood to the peritubular capillaries.
Term
Efferent nerve
Definition
A nerve that carries impulses away from the central nervous system.
Term
Efflux
Definition
The movement of molecules from the intracellular environment into the extracellular environment.
Term
Elastic artery
Definition
The type of artery with the most elastin in the tunica media; closest to the heart; expands during systole, recoils during diastole to propel blood onward.
Term
Elastin
Definition
A fibrous protein that has a randomly coiled structure, allowing it to stretch and recoil like a rubber band; forms elastic fibers.
Term
Electrical potential
Definition
An electrical force across a cell membrane that results from the separation of charged particles across that membrane.
Term
Electrical synapse
Definition
A synapse formed by gap junctions between two neurons. Ions flow between neurons at electrical synapses.
Term
Electrochemical gradient
Definition
The combined electrical and chemical forces on an ion. This force determines the net movement of charged particles.
Term
Electrolytes
Definition
Ions (charged particles) that are dissolved in the body fluids.
Term
Emulsification
Definition
Process of forming an aqueous suspension of fat droplets from a larger fat globule.
Term
End diastolic volume (EDV)
Definition
Amount of blood in each ventricle at the end of diastole (relaxation).
Term
End systolic volume (ESV)
Definition
Amount of blood remaining in each ventricle at the end of systole (contraction).
Term
Endocrine glands
Definition
Ductless glands that empty their hormonal products directly into the blood.
Term
Endocrine pancreas
Definition
That portion of the pancreas that secretes hormones.
Term
Endocrinologist
Definition
A doctor who specializes in diagnosing and treating hormone disorders.
Term
Endocytosis
Definition
Infolding of the plasma membrane around a substance that is taken into the cell.
Term
Endogenous
Definition
Originating or produced within the organism or one of its parts. For example, endogenous antigens come from within the cytoplasm of a cell.
Term
Endomysium
Definition
The connective tissue wrapping that surrounds individual muscle cells (fibers).
Term
Endoplasmic reticulum
Definition
Membranous network of tubular or saclike channels in the cytoplasm of a cell.
Term
Endothelial cell
Definition
Simple squamous epithelial cell; cell type that lines the walls of the heart, blood vessels, and lymphatic vessels.
Term
Endothelium
Definition
Epithelial tissue that lines the walls of the heart, blood vessels, and lymphatic vessels; composed of simple squamous epithelial cells.
Term
Enkephalins
Definition
Neuromodulators produced in the central nervous system and elsewhere; for example the enteric nervous system.
Term
Enteric nervous system
Definition
The submucosal and myenteric plexuses that make up the intrinsic nervous system of the gut; considered the third division of the autonomic nervous system.
Term
Enteroendocrine cells
Definition
Endocrine cells scattered among the epithelial cells that line the digestive tract.
Term
Enterogastric reflex
Definition
The reflexive inhibition of gastric secretion; initiated by the arrival of chyme in the small intestine.
Term
Enterohepatic circulation
Definition
The secretion of bile salts by the liver, followed by their absorption in the ileum and return to the liver by the hepatic portal vein.
Term
Enterokinase
Definition
An enzyme in the lumen of the small intestine that activates the proenzymes secreted by the pancreas.
Term
Enzyme
Definition
A protein that acts as a biological catalyst to speed up chemical reactions.
Term
Eosinophils
Definition
White blood cells whose granules readily take up an acid stain called eosin. They help defend against parasitic worms and are involved in allergy.
Term
Epiglottis
Definition
Elastic cartilage that covers the opening of the larynx (glottis) during swallowing.
Term
Epimysium
Definition
The connective tissue wrapping that surrounds the entire muscle.
Term
Epinephrine
Definition
Chief hormone produced by the adrenal medulla; also called adrenalin.
Term
Epithelial cells
Definition
Cells of a primary tissue that covers the body surface, lines its internal cavities, and forms glands. Classified into three basic shapes: squamous, cuboidal, and columnar.
Term
Epithelium
Definition
Epithelial tissue that lines blood vessels, the heart, and cavities of the digestive and respiratory systems.
Term
Equilibration
Definition
As used here, it is the process of balancing or equalizing the chemical concentration between two or more compartments.
Term
Equilibrium
Definition
A state of chemical stability in which no net change occurs. For an ion in equilibrium across a cell membrane, the amount moving out is equal to the amount moving in.
Term
Equilibrium potential
Definition
For a given ion, the membrane potential at which the electrical and chemical forces that drive that ion across the cell membrane is equal and opposite.
Term
Erythrocyte
Definition
A red blood cell
Term
Erythropoietin
Definition
Hormone that stimulates production of red blood cells.
Term
Esophagus
Definition
Muscular tube extending from the laryngopharynx through the diaphragm to join the stomach; collapses when not involved in food propulsion.
Term
Estrogen
Definition
Female sex hormone produced by the ovary; during puberty promotes development of secondary sex characteristics, and is necessary for production of the ovum.
Term
Excitable
Definition
Refers to a cell that responds to stimuli by generating an electrical signal at the cell membrane. Neurons and muscle cells are excitable.
Term
Excitatory postsynaptic potential (EPSP)
Definition
A local, graded, depolarization of an excitable cell. Function is to generate an action potential in the postsynaptic cell.
Term
Exocrine cells
Definition
Cells of the pancreas that secrete pancreatic juices.
Term
Exocrine glands
Definition
Glands that have ducts through which their secretions are carried to a particular site.
Term
Exocrine pancreas
Definition
That portion of the pancreas that secretes digestive juices.
Term
Exocytosis
Definition
Mechanism by which substances are moved from the cell interior to the extracellular space as a secretory vesicle fuses with the plasma membrane.
Term
Exogenous
Definition
Developing or originating outside of the organism or one of its parts. For example, exogenous antigens do not originate within the cell that displays them.
Term
Exophthalmos
Definition
Protrusion of the eyeballs.
Term
Expiration
Definition
Exhalation; act of expelling air from the lungs.
Term
Expiratory
Definition
Pertaining to exhalation; act of expelling air from the lungs.
Term
External anal sphincter
Definition
Sphincter of skeletal muscle surrounding the anal canal.
Term
External nares
Definition
The external openings leading into the nasal cavities; also called the nostrils.
Term
External respiration
Definition
The exchange of gases between the alveoli in the lungs and the pulmonary capillaries.
Term
Extracellular fluids (ECF)
Definition
All the fluids in the body, except the fluid within cells.
Term
Extracellular space
Definition
Space outside the cell that includes interstitial fluid with dissolved ions, nutrients, etc.
Term
Extracellular
Definition
Outside the cell.
Term
Extrinsic nerves
Definition
Nerves from outside the GI tract that innervate neurons of the enteric nervous system or other gut structures.
Term
Facilitated diffusion
Definition
A passive transport process that uses a carrier molecule to enable the passage of a complex molecule across a membrane.
Term
Fascicle
Definition
A bundle of muscle cells (fibers) bound together by connective tissue to form a functional unit.
Term
Fast sodium channel
Definition
Transport protein in plasma membrane of contractile cell that allows explosive entry of sodium ions (Na+) from extracellular space; channel is voltage-gated, opening and closing in response to specific voltage levels.
Term
Fast-twitch fibers
Definition
White muscle fibers. Large in diameter; light in color due to reduced myoglobin; surrounded by few capillaries; relatively few mitochondria; mainly use glycolysis to synthesize ATP; quick and powerful but fatigue rapidly; fast cross bridge cycling.
Term
Fat
Definition
Common name for solid neutral fats (triglycerides).
Term
Fatigue
Definition
The condition in which the muscle is no longer able to sustain its level of tension and gradually elongates even though adequate stimulation continues; results from the buildup of acidic compounds within the cell and a relative lack of ATP.
Term
Fatty acids
Definition
A major component of lipids (neutral fats and phospholipids).
Term
Fecal matter
Definition
Material discharged from the bowel; composed of food residue, secretions, bacteria; feces.
Term
Feces
Definition
Material discharged from the bowel; composed of food residue, secretions, bacteria.
Term
Fenestration
Definition
Pore in a capillary endothelial cell that may be open or covered by a delicate membrane; allows for freer passage of fluids and small solutes between capillaries and tissue cells.
Term
Fever
Definition
An increase in body temperature caused by a resetting of the body’s thermostat in the hypothalamus.
Term
Fibroblast
Definition
Young, actively mitotic cells that form the fibers of connective tissue.
Term
Fibrosis
Definition
The abnormal formation of fibrous connective tissue.
Term
Fibroblast
Definition
Young, actively mitotic cells that form the fibers of connective tissue.
Term
Filtrate
Definition
Fluid and solutes that are forced out of the blood into the glomerular capsule of the kidney, and then processed by the renal tubules to form urine.
Term
Filtration
Definition
The process of passing a solution through a selective membrane or barrier that separates the particles because of their size or other properties.
Term
Filtration in kidney
Definition
Movement of water, small molecules, and ions from the blood from the glomerular capillaries into the glomerular capsule.
Term
Filtration membrane
Definition
The three-layer barrier serving as a filter within the kidney. It is composed of fenestrated endothelium, basement membrane, and filtration slits formed by the pedicels of the podocytes.
Term
Filtration slits
Definition
The small spaces lying between individual pedicels of the filtration membrane.
Term
Fixed acids
Definition
Metabolic acids generated in the body that are eliminated in the urine. Carbonic acid is not a fixed acid because it can be eliminated via the lungs.
Term
Fixed macrophage
Definition
A macrophage that is resident in a tissue. Examples are Kupffer cells in the liver and microglia in the brain.
Term
Flaccid
Definition
The condition of being soft and limp; lacking firmness; flabby.
Term
Follicle
Definition
See lymphoid follicle.
Term
Follicle-stimulating hormone (FSH)
Definition
Hormone produced by the anterior pituitary that stimulates ovarian follicle production in females and sperm production in males.
Term
Fossa ovalis
Definition
Shallow depression in the interatrial septum marking the spot where an opening, the foramen ovale, existed in the fetal heart.
Term
Free macrophage
Definition
A macrophage that wanders through tissue in search of debris or pathogens.
Term
Frequency
Definition
The number of repetitions per unit time.
Term
Fundus
Definition
Base of an organ; that part farthest from the opening of the organ; e.g. the dome-shaped part of the stomach beneath the diaphragm.
Term
Fungi
Definition
A large group of single-celled or multicellular organisms with cell walls that obtain nutrients from their environment. The very few that are pathogenic in humans may be intracellular or extracellular.
Term
G cells
Definition
Cells of stomach that secrete gastrin.
Term
G proteins
Definition
GTP-binding regulatory protein tethered to the plasma membrane. Involved in transducing chemical signals to response of cells.
Term
GABA
Definition
Gamma-aminobutyric acid, an amino acid neurotransmitter. Important inhibitory neurotransmitter in the central nervous system.
Term
Gallbladder
Definition
Muscular sac beneath the right lobe of the liver used for bile storage.
Term
Gamma globulins
Definition
A group of plasma proteins that consists mostly of antibodies.
Term
Gap junction
Definition
A small tube or channel between adjacent cells formed by transmembrane proteins. Allows ions to pass freely from cell to cell. Found at electrical synapses.
Term
Gastric glands
Definition
The tubular glands of the stomach whose cells produce acid, enzymes, intrinsic factor, and hormones.
Term
Gastric juice
Definition
The secretions of gastric glands including acid, enzymes, and intrinsic factor.
Term
Gastric motility
Definition
The activity of muscles of the stomach wall that mixes and propels stomach contents.
Term
Gastric mucosa
Definition
Mucous membrane that lines the stomach.
Term
Gastric mucosal barrier
Definition
A protective coating of bicarbonate-rich mucus produced by the stomach that prevents gastric juices from leaking into underlying tissue layers.
Term
Gastric phase
Definition
The phase of reflexes that control GI secretions when the meal is in the stomach.
Term
Gastric pits
Definition
Indentations in the gastric mucosa that lead to gastric glands.
Term
Gastrin
Definition
Hormone secreted in the stomach; stimulates HCl production.
Term
Gastroesophageal sphincter
Definition
Sphincter between the esophagus and the stomach; also called lower esophageal sphincter (LES).
Term
Gastroileal reflex
Definition
A long reflex initiated by increased activity in the stomach that increases motility in the terminal ileum.
Term
Gated channels
Definition
Ion channels that are opened or closed by gates. The gates may be controlled by chemicals or by membrane voltage.
Term
GDP
Definition
Hydrolysis of guanosine triphosphate (GTP) yields GDP.
Term
Germinal center
Definition
A relatively pale-staining area in the center of a lymphoid follicle that has proliferating and differentiating B lymphocytes.
Term
Gland
Definition
Organ specialized to secrete or excrete substances for further use in the body or for elimination.
Term
Glial cells
Definition
Nonexcitable cells that provide structural support or that serve important physiological and immunological functions in the nervous system. Also called support cells.
Term
Globin
Definition
The protein portion of the hemoglobin molecule.
Term
Globular proteins
Definition
Proteins which are coiled up on themselves to form a particular shape, which determines the function of the protein.
Term
Glomerular (Bowman’s) capsule
Definition
The expanded cup-shaped proximal end of the nephron tubule. It surrounds the glomerulus and collects the filtrate from the blood.
Term
Glomerular filtrate
Definition
The liquid (water) and solutes that have passed through a filtration membrane and entered the renal tubule.
Term
Glomerular filtration
Definition
Movement of small solutes and water from the plasma in the glomerular capillaries into the glomerular capsule, beginning the process of urine formation.
Term
Glomerular filtration rate (GFR)
Definition
The rate at which the filtrate is formed by the kidney. It is usually measured in milliliters per minute.
Term
Glomerulus
Definition
The capillary bed where filtration occurs. Lies between the afferent and efferent arterioles, surrounded by the glomerular (Bowman’s) capsule.
Term
Glossopharyngeal nerve
Definition
Cranial nerve IX; a mixed nerve with many functions including carrying sensory and motor fibers to and from the tongue and pharynx, and carrying sensory fibers from the carotid bodies and the carotid sinus.
Term
Glottis
Definition
Opening between the vocal cords in the larynx.
Term
Glucagon
Definition
Hormone formed by alpha cells of islets of Langerhans in the pancreas; raises the glucose level of blood.
Term
Glucoamylase
Definition
Digestive enzyme in the brush border that breaks down maltose and maltotriose.
Term
Glucocorticoids
Definition
Adrenal cortex hormones that regulate blood glucose levels and aid the body in resisting stress.
Term
Glucocorticoids
Definition
Adrenal cortex hormones that regulate blood glucose levels and aid the body in resisting stress.
Term
Gluconeogenesis
Definition
Pathways through which noncarbohydrate precursors, especially amino acids, are converted into glucose.
Term
Glucose
Definition
Often called blood sugar; the principal sugar in the blood.
Term
Glucose-dependent insulinotropic peptide (GIP)
Definition
GI hormone that causes feedforward release of insulin.
Term
Glutamate
Definition
An amino acid neurotransmitter. Major excitatory neurotransmitter in the central nervous system.
Term
Glycerol
Definition
A modified simple sugar (a sugar alcohol) containing three carbons; part of the structure of triglycerides.
Term
Glycine
Definition
An amino acid neurotransmitter. Important inhibitory neurotransmitter in the central nervous system.
Term
Glycogen
Definition
A polysaccharide composed of glucose subunits; found primarily in the muscle and liver cells of animals.
Term
Glycogenesis
Definition
The synthesis of glycogen from glucose.
Term
Glucose
Definition
Often called blood sugar; the principal sugar in the blood.
Term
Glucose-dependent insulinotropic peptide (GIP)
Definition
GI hormone that causes feedforward release of insulin.
Term
Glutamate
Definition
An amino acid neurotransmitter. Major excitatory neurotransmitter in the central nervous system.
Term
Glycerol
Definition
A modified simple sugar (a sugar alcohol) containing three carbons; part of the structure of triglycerides.
Term
Glycerol
Definition
A modified simple sugar (a sugar alcohol) containing three carbons; part of the structure of triglycerides.
Term
Glycine
Definition
An amino acid neurotransmitter. Important inhibitory neurotransmitter in the central nervous system.
Term
Glycogen
Definition
A polysaccharide composed of glucose subunits; found primarily in the muscle and liver cells of animals.
Term
Glycogenesis
Definition
The synthesis of glycogen from glucose.
Term
Glycogenolysis
Definition
The breakdown of glycogen.
Term
Glycolysis
Definition
A cellular metabolic process involving a series of enzymes and reactions to break down glucose into pyruvic acid. Produces two net ATP molecules per glucose molecule. Does not require oxygen.
Term
Glycoprotein
Definition
A chemical compound consisting of a carbohydrate and a protein.
Term
Goblet cells
Definition
Individual cells (unicellular glands) that produce mucus.
Term
Goiter
Definition
A chronic enlargement of the thyroid gland.
Term
Golgi apparatus
Definition
Organelle that modifies and packages proteins into vesicles.
Term
Gonadotropin
Definition
The gonadotropins consist of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), both released by the anterior pituitary.
Term
Gonadotropin-releasing hormone (GnRH)
Definition
Hypothalamic hormone that stimulates release of gonadotropins (FSH and LH) from the anterior pituitary.
Term
G-protein
Definition
An integral membrane protein that uses GTP as an energy source.
Term
Gradient
Definition
As used here, the difference in solute concentration between two regions.
Term
Granular cells
Definition
Modified smooth muscle cells in the walls of afferent arterioles associated with the glomeruli in kidney. They play a role in autoregulation and blood pressure regulation by releasing the enzyme renin in response to low blood pressure and other stimuli.
Term
Granulosa cells
Definition
Cells of the ovarian follicle that secrete estrogen.
Term
Graves’ disease
Definition
An autoimmune disease characterized by hyperthyroidism.
Term
Great cardiac vein
Definition
Cardiac vein in anterior interventricular sulcus; collects oxygen-poor blood from capillary beds of myocardium.
Term
Growth hormone (GH)
Definition
Anterior pituitary hormone that stimulates growth and energy metabolism. Also called somatotropin.
Term
Growth hormone-releasing hormone (GHRH)
Definition
Hypothalamic hormone that influences growth hormone secretion.
Term
Guanosine diphosphate (GDP)
Definition
A guanine containing nucleotide to which two phosphate groups have been added. G proteins are inactive when GDP is bound to them.
Term
Guanosine triphosphate (GTP)
Definition
A guanine containing nucleotide to which three phosphate groups have been added. G proteins bind GTP when they are activated.
Term
H zone
Definition
A lighter stripe in the center of the dark (A) band, corresponding to the region between thin filaments. Its width varies depending upon the degree of muscle contraction. The H zone is widest when the muscle is relaxed and stretched.
Term
Haldane effect
Definition
The increase in carbon dioxide unloading from hemoglobin in response to oxygen unloading.
Term
Haustra
Definition
Bulging pocket-like sacs of the large intestine wall.
Term
Heart rate
Definition
Number of times the heart beats in one minute.
Term
Helper T cell (TH)
Definition
A functional subtype of T cell that helps orchestrate the humoral and cellular immune responses by releasing chemical messengers called cytokines and by direct cell-to-cell contact. Also activates macrophages.
Term
Hematocrit
Definition
The percentage of red blood cells in the total blood volume. The hematocrit can increase as a result of either more red blood cells or less plasma in the blood; it can decrease because of either fewer red blood cells or more plasma.
Term
Heme
Definition
Iron-containing pigment that is essential to oxygen transport by hemoglobin.
Term
Hemoglobin
Definition
A molecule found in red blood cells which functions in oxygen and carbon dioxide transport; it is composed of 4 polypeptide chains and 4 red iron-containing heme groups.
Term
Hemolysis
Definition
When a red blood cell breaks open.
Term
Hemorrhage
Definition
Loss of blood from vessels by flow through ruptured walls.
Term
Henry’s Law
Definition
The amount of gas which dissolves in a liquid is proportional to both the partial pressure and the solubility of the gas.
Term
Hepatocyte
Definition
A liver cell.
Term
Hepatopancreatic sphincter
Definition
Sphincter that controls the entry of bile and pancreatic juice into the duodenum; also called sphincter of Oddi.
Term
High-energy phosphate bond
Definition
Covalent bond between two phosphate groups that contain relatively large amounts of stored energy; found in ATP. Breaking this bond releases energy that can be used to power cellular activity.
Term
Histamine
Definition
A chemical messenger (neurotransmitter or paracrine); causes vasodilation and increased capillary permeability.
Term
Homeostasis
Definition
A state of body equilibrium or stable internal environment of the body.
Term
Hormones
Definition
Steroidal or amino acid-based molecules released to the blood that act as chemical messengers to regulate specific body functions.
Term
Humoral immunity
Definition
The branch of adaptive immunity that involves antibodies and the B lymphocyte-derived plasma cells that secrete them.
Term
Hydrochloric acid (HCl)
Definition
Acid produced by gastric parietal cells; acids protein digestion in the stomach and sterilizes chyme.
Term
Hydrolysis
Definition
A chemical process in which an enzyme uses water to split one molecule into smaller parts.
Term
Hydrolytic enzyme
Definition
An enzyme that splits a molecule by the addition of water.
Term
Hydrolyzed
Definition
Broken down by the process of hydrolysis, in which an enzyme uses water to split one molecule into smaller parts.
Term
Hydrostatic pressure
Definition
The pressure of fluid within a system or container.
Term
Hypercalcemia
Definition
An excess of calcium in the extracellular fluid greater than 11 mg/dL.
Term
Hyperglycemia
Definition
The condition in which the blood glucose level is elevated above normal.
Term
Hyperinflation
Definition
Excessive inflation of the lungs during very deep inspiration.
Term
Hyperkalemia
Definition
An excess of potassium in the extracellular fluid greater than 5.1 mEq/L.
Term
Hypernatremia
Definition
An excess of sodium in the extracellular fluid greater than 145 mEq/L.
Term
Hyperpolarization
Definition
The process by which the membrane potential of a cell changes to become more negative than its resting membrane potential.
Term
Hyperpolarize
Definition
To change the membrane potential of a cell to a value that is more negative than its resting membrane potential.
Term
Hyperthyroidism
Definition
A condition in which there is excessive activity of the thyroid gland.
Term
Hypertonic solution
Definition
A solution with a higher concentration of nonpenetrating solutes.
Term
Hyperventilation
Definition
Ventilation that is higher than necessary to maintain normal blood gas levels.
Term
Hypervolemia
Definition
Excess of fluid volume accompanied by normal osmolarity in all fluid spaces.
Term
Hypocalcemia
Definition
A concentration of calcium in the extracellular fluid less than 9 mg/dL.
Term
Hypoglycemia
Definition
The condition in which the blood sugar (glucose) level drops below normal.
Term
Hypokalemia
Definition
A concentration of potassium in the extracellular fluid less than 3.5 mEq/L.
Term
Hyponatremia
Definition
A concentration of sodium in the extracellular fluid less than 136 mEq/L.
Term
Hypophyseal portal vessels
Definition
Blood vessels that connect two capillary beds in the hypothalamic-pituitary axis.
Term
Hypophysis
Definition
The pituitary gland.
Term
Hypothalamus
Definition
Region of the brain located inferior to the thalamus. Autonomic control center; center for emotional response and behavior; body’s thermostat; regulates food intake, water balance, thirst, sleep-wake cycles, endocrine system.
Term
Hypotonic solution
Definition
A solution with a lower concentration of nonpenetrating solutes.
Term
Hypoventilation
Definition
Ventilation that is too low to maintain normal blood gas levels.
Term
Hypovolemia
Definition
Deficit of fluid volume accompanied by normal osmolarity in all fluid spaces.
Term
Hypoxia
Definition
Condition in which inadequate oxygen is available to tissues.
Term
I band
Definition
The light region of the myofibril’s striation that alternates with dark (A) bands; contains only thin filaments. Its width is the distance between adjacent thick filaments. Therefore, the I-band gets narrower during muscle contraction.
Term
I cells
Definition
Cells of the small intestine that produce the hormone CCK.
Term
IgA
Definition
Antibody active against bacteria and viruses; found in saliva.
Term
Ileocecal sphincter
Definition
A muscular valve that separates the ileum from the cecum.
Term
Ileum
Definition
Last part of the small intestine; between the jejunum and the cecum of the large intestine.
Term
Immnuocompetent
Definition
Possessing immunocompetence, the ability of a lymphocyte to recognize specific antigens (by binding); reflects the presence of lymphocyte antigen receptors.
Term
Immune surveillance
Definition
The process by which cytotoxic T cells and NK cells examine the cells of the body, searching for abnormal cells such as cancer cells.
Term
Immune system
Definition
The organs, tissues, cells, and molecules that function to protect the body from foreign invaders.
Term
Immunoglobulin
Definition
An antibody.
Term
In vivo
Definition
In the living body.
Term
Incomplete tetanus
Definition
A condition of rapid, shortened contraction/relaxation cycles resulting from increased frequency of stimulation. Some degree of cyclical relaxation is visible. Also called unfused tetanus.
Term
Inferior vena cava
Definition
Vein that returns blood to right atrium from body regions inferior to the diaphragm.
Term
Inflammation
Definition
An innate (nonspecific) defensive response of the body to tissue injury; includes dilation of arterioles and an increase in capillary permeability.
Term
Inflammatory mediator
Definition
A chemical messenger that promotes vasodilation, increased capillary permeability, and chemotaxis.
Term
Influx
Definition
The movement of molecules from the extracellular environment into the intracellular environment.
Term
Infundibulum
Definition
A stalk of tissue that connects the pituitary gland to the hypothalamus.
Term
Inhibin
Definition
Peptide hormone from the gonads that regulates secretion of FSH. Inhibits FSH secretion.
Term
Inhibitory postsynaptic potential (IPSP)
Definition
A local, graded, hyperpolarization of an excitable cell. Functions to prevent generation of an action potential in a postsynaptic cell.
Term
Inhibitory reflexes
Definition
Reflexes that inhibit or negate the stimulus.
Term
Innate defense mechanism or Innate immunity
Definition
The branch of immunity that provides immediate defense against a pathogen, relies on mechanisms that exist before infection, and whose response does not increase with repeated exposure to the same pathogen. Also called nonspecific immunity.
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