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nervous system, cardiology
ns, cardio, special senses
109
Anatomy
Undergraduate 1
11/11/2008

Additional Anatomy Flashcards

 


 

Cards

Term
Four Primary Brain Regions:
Definition

Telencephalon

Diencephalon-stays Diencephalon

Mesencephalon

Metencephalon

Myelencephalon

Term

TELENCEPHALON

Definition

"CEREBRUM"

 

Term

ORGANIZATION OF THE NERVOUS SYSTEM

 

 

Definition

CNS- BRAIN AND SPINAL CORD

 

PNS-CRANIAL NERVES 12 PAIRS

SPINAL NERVES 31 PAINSFROM THE SPINAL CORD

Term

DIVISION OF THE PNS

(DIVIDED INTO 2 GROUPS BASED UPON THE FUNCTIONS OF THEIR NERVE FIBERS)

Definition

SENSORY-AFFERENT FIBERS, RECEIVE STIMULUS, SENDS IMPULSE TO THE CNS

 

MOTOR- EFFERENT FIBERS, TRANSMIT IMPULSES FROM THE CNS, IMPULSE TO EFFECTOR (MUSCLE OR GLAND), THE EFFECTOR PRODUCES A RESPONSE

Term

DIVISION OF MOTOR FIBERS

BECAUSE OF THEIR RESPONSES MOTOR FIBERS ARE VOLUNTARY OR INBOLUNTARY, MOTOR FIBERS ARE CLASSIFIED INTO 2 DIFFERENT MOTOR SYSTEMS:

Definition

SOMATIC MOTOR SYSTEM- MOTOR FIBERS TO VOLUNTARY EFFECTORS (SKELETAL MUSCLES)

 

AUTONOMIC MOTOR SYSTEM: MOTOR FIBERS TO INVOLUNTARY EFFECTORS (SMOOTH AND CARDIAC MUSCLE AND GLANDS)

Term

DIVISIONS OF THE AUTONOMIC NERVOUS SYSTEM

THE ANS IS FURTHER DIVIDED INTO 2 SYSTEMS BASED UPON THE ACTIONS OF THEIR EFFECTORS

Definition

PARASYMPATHETIC NERVOUS SYSTEM-(CRANIOSACRAL DIVISION)

TTHE RESTIN

Term

CENTRAL NERVOUS SYSTEM:

THE BRAIN

Definition
THE BRAIN IS THE ENLARGED ANTERIOR END (SUPERIOR IN HUMANS) OF THE CNS PROTECTED BY BONY ARMORMENT, THE SKULL
Term

BRAIN EMBRYOLOGY

Definition
Development begins in about 3 weeks from the ectoderm, by the 4th week a portion of the ectoderm invaginates to form the neural tube.  By the 5th week the rostral end of the neural tube forms three "primary brain vesicles"
Term
3 PRIMARY BRAIN VESICLES
Definition

PROSENCEPHALON: FOREBRAIN

MESENCEPHALON: MIDBRAIN

RHOMBENCEPHALON: HINDBRAIN

The caudal end of the neural tube, beyond rhombencephalon becomes the spinal cord

Term
5 secondary Brain Vesicles develop at the 5th week.  They are:
Definition

formed from the PROSENCEPHALON

1.Telencephalon (end brain)

2. Diencephalon (between brain)

3. Mesencephalon (FORMS NOTHING NEW)

formed from RHOMBENCEPHALON

4. Metencephalon (after brain)

5. Myelencephalon (spinal brain

Term

FROM THE SECONDARY BRAIN VESICLES, THE 4 "PRIMARY BRAIN REGIONS" DEVELOP:  THEY ARE:

Definition

1. TELENCEPHALON (CEREBRUM)

2. DIENCEPHALON remains Diencephalon

3.MESENCEPHALON (Brainstem in part)

4. METENCEPHALON (Brainstem in part and Cerebellum)

5.MYELENCEPHALON (brainstem in part)

Term

FOUR PRIMARY REGIONS OF THE BRAIN

Definition

1. CEREBRUM

2. DIENCEPHALON

3. BRAINSTEM

4. CEREBELLUM

Term
CEREBRUM
Definition

Most superior massive portion of the brain. 83% of the total brain mass.  Highly convoluted with shallow sulci and deep fissures. Ridges between sulci are called gyri.

The cerebrum is divided into 2 cerebral hemispheres by the longitudinal fissure.  Both hemisphers are supported from the cerebellum by the transverse fissure

Term

Lobes of the Cerebrum:

Each hemisphere is divided by fissures and sulci into 5 anatomically and functionally distinct lobes.  They are:

Definition

1. frontal lobe-anterior to the central sulcus

2. parietal lobe-between the central sulcus and parieto-occipital sulcus

3.occipital lobe-posterior to the parieto-occiptial sulcus

4. temporal lobe- inferior to the lateral sulcus

5. Insula (island of reil) within the lateral sulcus

Term

FUNCTIONAL REGIONS OF THE CEREBRUM

Like most of the CNS, the cerebrum contains myelinated and unmyelinated axons.  Myelinated ares constitutes "white matter" and unmyelinated "gray  matter"  There are 3 regions:

Definition

1. Cerebral cortex-superficial layer 1/8' thick of gray matter, area of conscious thought and higher brain functions

2. cerebral medulla- inner white matter forming the bulk of the cerebrum, provides communication pathways between the cortex and other brain areas.

3. basal nuclei- caudate nucleus, putament, and globus pallidus, regions of gray matter deep within the medulla, serve in muscle contraction

Term
DIENCEPHALON
Definition
gray matter forming the central core of brain between the cerebral hemispheres
Term
Diencephalon is divided into 3 regions.  They are:
Definition

1. Thalamus

2. Hypothalamus

3. Epithalamus

Term

THALAMUS

Definition
80% OF DIENCEPHALON FORMING THE LATERAL WALLS OF THIRD VENTRICLE; RELAYS INFORMATION TO THE CEREBRAL CORTEX FROM SEVERAL DIVERSE REGIONS OF THE BRAIN; INFORMATION FROM EVERY SENSORY SYSTEM (EXCEPT OLFACTIONS) SYNAPSE HERE BEFORE REACHING THE CEREBRAL CORTEX, SERVES AS A SWITHBOARD FOR THE BRAIN
Term
HYPOTHALAMUS
Definition

(BELOW THALAMUS) ANTERIOR-INFERIOR EXTENSION OF THALAMUS SUPPORTING THE PETUITARY GLAND; FUNCTIONALLY, THE HYPOTHALAMUS IS RESPONSIBLE FOR MANY HOMEOSTATIC ACTIVIES (BLOOD PRESSURE, BODY TEMP, FLUID AND ELECTROLYTE BALANCE, AND BODY WEIGHT

Term
EPITHALAMUS
Definition
(ABOVE THALAMUS) DORSAL POSTERIOR COVERING OF DIENCEPHALON SUPPORTING THE PINEAL GLAND WHICH PORDUCES MELATONIN, AND THE CHOROID PLEXUS WHICH PRODUCES CSF
Term
BRAINSTEM
Definition
INFERIOR PORTION OF BRAIN, JOINS SPINAL CORD
Term
3 REGIONS OF THE BRAINSTEM
Definition

1. MIDBRAIN: Develops from the embryonic mesencephalon connecting the hindbrain and the forebrain.

2.PONS (BRIDGE): From embryonic metencephalon, contains nuclei concerned with sleep, posture, respiration, swallowing and bladder control

3. MEDULLA OBLONGATA: from embryonic myelencephalon; contains nuclie to control heart rate, vasoconstriction, breathing rate, coughing, sneezing, hiccupping, sweating, vomiting and other functions

Term
MAJOR REGIONS OF THE MIDBRAIN
Definition

1.CEREBRAL PEDUNCLES- Spinal tracts to the medulla oblongata

2.CORPORA QUADRIGEMINA (quadruplet bodies)-a pair of superior colliculi (hills) for visual reflexes and a pair of inferior colliculi for auditory reflexes.

Term

CEREBELLUM (LITTLE BRAIN)

Definition
from the embryonic metencephalon, consists of right and left cerebellar hemispheres connected by a vermis.  Modulates and coordinates voluntary movement of the limbs, maintains muscle tone and posture, coordinates eye movements, and helps in learning motor skills
Term

3 primary structures protect the CNS:

Definition

Bones

Meninges

Cerebrospinal fluid

Term

MENINGES

Definition

Connective tissue membranes separating the brain and spinal cord from the skull and vertebrae

Term
3 Mininges
Definition

1. Dura Mater- tough mother

a. periosteal layer

b. meningeal layer

2. Arachnoid Mater- spider mother

a. middle meninx

b. arachnoid fibers

c. arachnoid villi

3. Pia mater- gentle mother

Term
PERIOSTEAL LAYER
Definition

continuous with periosteum of skull, this layer is absent in vertebrae

Term
Meningeal layer
Definition

surrounds brain and spinal cord; forms the dura septa (falx cerebri) in the longitudinal fissure separating the cerebral hemispheres (reduces brain movement)

 

Term
Dura Mater (tough mother)
Definition
superficial, very fibrous meninx; double layered in the skull
Term
Middle meninx
Definition
separated from dura mater with serous fluid in the subdural space.  Deep to the arachnoid mater is the subarachnoid space filled with CSF
Term
Arachnoid fibers
Definition
located in the subarachnoid space, anchor arachnoid mater to the surface of the brain
Term

Arachnoid Villi

Definition
extensions of the arachnoid mater penetrating the dura mater and the superior saggital sinus returning CSF to circulation
Term
Pia Mater (gentle mother)
Definition
Deepest meninx on surface of brain, very thin and delicate.  Separates brain tissue from CSF and provides attachment site for arachnoid fibers and blood vessels
Term

Central Nervous System: The Spinal Cord

Definition

The spinal cord is a continuation of the medulla oblongata within the spinal cavity

It begins at the foramen magnum and ends as the conus terminalis, or conus medullaris (medullary cone) at the level of L1 or L2

It gives rise to 31 pairs of spinal nerves, each exits the spinal cavity via intervertebral or sacral foramina, or the sacral hiatus

Beyond the conus terminalis, spinal nerves of lumbar, sacral, and coccygeal travel within the spinal cavity as the cauda equina [horse tail] before exiting at their respective level

The spinal cavity terminates by an extension of the pia mater which anchors the spinal cord to the coccyx, the filum terminale [terminal thread]

Term

Cross-Sectional Anatomy of the Spinal Cord

Definition

The spinal cord consists of a central area of gray matter divided into two dorsal horns, and two ventral horns.  The right and left halves are connected by the gray commissure; in the center is the central canal.

Sensory fibers enter the dorsal horn, sometimes synapse with an interneuron, and exit by way of the ventral root (motor fibers) of the spinal nerve

White matter consists of bundles of myelinated axons that run up and down the cord, to and from the brain. White matter is arranged into dorsal, lateral, and ventral columns

Term

Peripheral Nervous System

Definition

The peripheral nervous system includes all nervous system structures outside of the brain & spinal cord

Term

Nerves

Definition

bundles of nerve fibers (axons) in the PNS.

Term

Three connective tissue tunics organize & compartmentalize nerve fibers to form a nerve:

Definition

1. Endoneurium: wraps each nerve fiber

2. Perineurium: wraps groups of fibers into fascicles

3. Epineurium: encloses all fascicles forming the outer tunic of the nerve; areas enclosed between fascicles, the interfascicular space, contains adipose & areolar connective tissue, and blood & lymph vessels

Term
Functional Types of Nerves:

Three type of nerves based on how they transmit impulses between the CNS & PNS; with sensory and/or motor fibers:

Definition

1. Sensory (afferent) Nerves: CNS ! PNS (sensory fibers only)

2. Motor (efferent) Nerves: CNS " PNS (motor fibers only)

3. Mixed Nerves: CNS D PNS (both sensory & motor fibers)

Term

Spinal Nerves

Spinal nerves connect the CNS to sensory receptors, muscles, and glands

Because they are to the periphery of the spinal cord, they are all in the PNS

 

Definition

The 31 pairs of spinal nerves are named according to adjacent vertebrae

8 cervical pairs, C1-C8, (C1 emerge etween atlas & skull)12 thoracic pairs, T1-T12

5 lumbar pairs, L1-L5; cauda equina in part; 5 sacral pairs, S1-S5; cauda equina in part; S1-S4 exit via sacral foramina, S5 exits via sacral hiatus 1 coccygeal pair, C0; cauda equina in part; exits via sacral hiatus

Term

Spinal nerves have two separate attachment points:

Definition

1. Ventral root: contains motor fibers

2. Dorsal root: contains sensory fibers from dorsal root ganglion

Term

 

From the spinal nerve, primary branches develop called rami

Definition

1. Dorsal rami: serve skin & muscles dorsally

2. Ventral rami: of T2-T12 form the intercostal nerves which serve skin & muscles laterally & ventrally; all other rami C1-T1, L1-C0, form nervous plexuses which serve the appendages

3. Rami communicantes (communicating branches): serves the autonomic nervous system by forming the sympathetic chain ganglia (paravertebral ganglia)

Term

Sense (sensation) is a stimulus:

 

Definition

Information communicated to the CNS about changes in the environment (internal or external) so that the body can react (voluntary or involuntary) with an appropriate response

Term

Two Classes of Senses

Definition

1. General Senses:

2. Special Senses:

Term

GENERAL SENSES

Definition
associated with skin, muscles, joints, & other organs Tactile: touch, pressure, stretch, vibration

Temperature: heat & cold

Pain: information concerning tissue damage or excessive stimulation (e.g. too much heat, pressure, etc.)

 

Term

SPECIAL SENSES

Definition

 “special” senses because they are limited to the head with specific sense organs innervated by specific cranial nerves:

 

Term

Special Sense   Cranial Nerve   Stimulus    Organ

Smell                    CN I         Chemical    Nose

Vision                   CN II        Light          Eye

Taste              CN VII & IX     Chemical    Taste buds

Hearing                 CN VIII      Sound       Ear

Equilibrium             CN VIII      Gravity      Ear

Definition
Term

Receptor

Definition

 any structure specialized to detect a stimulus; the simplest receptors are dendrites

 

Term

Sense Organ

Definition

 receptors with supporting tissues to enhance or moderate the response to a stimulus

Term

I. Smell (olfaction) [olfact=smell]

Definition

Olfactory epithelium: the special sense organ of smell; located on the superior nasal concha; functions as a chemoreceptor. Histology of olfactory epithelium: pseudostratified ciliated columnar epithelium; basal cells for replacement, supporting cells, and olfactory receptor cells. Olfactory receptor cells: dendrites from olfactory cranial nerve (CN I) fibers; directed through the cribriform plate of the ethmoid to the olfactory bulb which is in turn directs tracts to the temporal lobe of the cerebrum. Olfactory gland: produces mucus to dissolve odor molecules; continuously replenishes the covering of mucus for new odors; to be detected, chemicals must be volatile and water-soluble

Term

Seven primary odors have been identified

Definition

Floral

Musky

Camphorous

Pepperminty

Etheral

Pungent [stinging]

Putrid [rotten]

Term

II. Sight (vision)

Definition

Structures of the eye are divided between the eyeball and accessory structures of the eye

Term

Medial & lateral canthus (commissure):

Definition

where the eyelids meet

 

Term

Eyebrows:

Definition

thickened, hair covered, supraorbital ridges of skin; protect eye from sweat, sunlight, foreign matter, and cushions impacts to the eye & forehead; also instrumental in communication

Term

2 SPECIAL SENSES AND ORGANS

Definition

1. SMELL

2. SIGHT

Term

Eyelids (palpebrae):

Definition

 two (upper & lower) thin, movable folds capable of enclosing the eye; protecting it from injury and desiccation

 

Term

Plica semilunaris [half-moon fold]:

Definition

vestigial nictitating membrane (third eyelid) in medial canthus

Lacrimal caruncle [small fleshly mass]: upon the medial margin of the plica semilunaris; contains sebaceous & sudoriferous glands; produces “sleep” in eyes

 

Term

Lacrimal caruncle [small fleshly mass]:

Definition

 upon the medial margin of the plica semilunaris; contains sebaceous & sudoriferous glands; produces “sleep” in eyes

 

Term

Levator palpebrae superioris muscle

Definition

within the larger, more movable upper eyelid; functionally, it retracts the upper eyelid (the lower eyelid lacks such a muscle)

Term

Eyelashes:

Definition

2-3 rows of hairs along the free edges of the eyelids; most numerous & longer on upper eyelid; upper & lower eyelashes curve away from each other to prevent interlacing; functionally, eyelashes act as strainers to divert foreign matter from the eye

Term

Tarsal (Meibomian) glands (glands of Zeis):

Definition

 sebaceous glands within the eyelids; ducts open on the free margins of the lids; oily secretion reduces evaporation of the tears; blockage of tarsal glands develops “chalazia” (cysts)

 

Term

Ciliary glands (glands of Moll):

Definition

sudoriferous glands associated with the eyelash follicles; lubricates margins of eyelids; infected tarsal glands develop “styes” (abscesses, or “boils”)

 

Term

Conjunctiva [joined together]:

Definition

mucous membrane extending from inner eyelids onto the surface of the “white” of the eye (sclera); prevents foreign matter from penetrating behind the eye; the mucus produced keeps the eyeball lubricated; the space formed between the inner eyelid and the surface of the eyeball is the conjunctival sac; inflammation of the conjunctiva is conjunctivitis (i.e. “pinkeye”)

Term

Lacrimal apparatus [tear]:

Definition

cleans & protects the eyeball with a supply of lacrimal fluid (tears)

Term

the passage of tears includes the following structures:

Definition

1. Lacrimal gland & ducts:

2. Lacrimal punctum [prick point]:

3. Lacrimal canals:

4. Lacrimal sac:

5.Nasolacrimal duct:

Term

Lacrimal gland & ducts:

Definition

 exocrine gland which produces a dilute saline mucus with antimicrobial properties; tears are secreted into the conjunctival sac of the superior-lateral orbit

Term

Lacrimal punctum [prick point]:

Definition

 small openings on the eyelids in the medial canthus for tear drainage

Term

Lacrimal canals:

Definition

 small ducts extending from the puncta to the lacrimal sac

Term

Lacrimal sac:

Definition

 common chamber which collects tears from lacrimal canals; situated in the lacrimal fossa

Term

 

Nasolacrimal duct:

Definition

Duct which passes through the lacrimal foramen to drain the lacrimal sac into the nasal cavity at the level of the inferior meatus

Term
Accessory structures of the eye
Definition

1. eyebrows

2. eyelids

3. conjunctiva

4. lacrimal apparatus

5. extrinsic eye muscles

Term
structures of the eyeball includes three tunics
Definition

1. fibrous tunic

2. vascular tunic

3. sensory (nervous) tunic 

Term

 Fibrous tunic

Definition

avascular, superficial covering; includes two structures:

Sclera [hard]: the “white” of the eye; continuous with the dura mater; serves as attachment site for extrinsic eye muscles

Cornea: clear, anterior extension of sclera; suspended from the surface of the iris by the anterior chamber which is filled with aqueous humor

 

Term

Vascular tunic

Definition

 also known as the uvea [grape]; the middle coat of the eyeball; contains three regions: Choroid [membrane-like]: accounts for all, except the anterior 15%, of the uvea; highly vascular & highly pigmented; forms a dark chamber to absorb light

Ciliary body: apparatus to modify the shape of the lens; smooth muscles (ciliary muscles) act on suspensory ligaments which, in turn, are attached around the perimeter of the lens Iris: colored portion of the eyeball; continuous with the ciliary body; contains smooth muscle to regulate light into the eye by controlling the diameter of the pupil; it separates the anterior chamber, filled with aqueous humor, from the posterior chamber, filled with vitreous humor

Term

Sensory (Nervous) tunic

Definition
 also known as the retina; the functional portion of the visual sensory organ; contains two types of photoreceptor cells:

Rods: most numerous, active in dim light and for peripheral vision

Cones: active in bright light only for color vision

 

Term

Other structures of the retina include:

Definition

Macula lutea [yellow spot]: area of high concentration of photoreceptor cells; the number of cones increases proportionally from its periphery toward the center

Fovea centralis: center of the macula lutea; contains cones only for the most detailed vision

Optic disc (blind spot): area of the retina devoid of photoreceptor cells; where optic nerve exits the eye, and also the location of vessels entering & exiting the eye

Term

Taste (gustation)

Definition

Taste receptor cells for taste are chemoreceptors located on the special sense organ, the taste bud (gustatory calyculus)

Cytology of the taste bud includes basal cells for replacement, supporting cells, and gustatory (taste) cells to stimulate sensory nerve fibers

Taste buds are located throughout the oral mucosa although they are concentrated on lingual (tongue) papillae

Term

Four classes of lingual papillae:

Definition

1. Filiform [thread-like] papillae:

2. Fungiform [mushroom-like] papillae:

3. Foliate [leaf-like] papillae:

4. Circumvallate (vallate) papillae:

Term

 Filiform [thread-like] papillae:

Definition

most numerous over surface of tongue for added texture to facilitate food manipulation; no taste buds present

Term

Fungiform [mushroom-like] papillae:

Definition

 secondly most abundant papillae; forms “dots” on surface of tongue; moderate taste buds

Term

Foliate [leaf-like] papillae:

Definition

confined to the lateral margins of the tongue; includes numerous sensitive taste buds

Term

 Circumvallate (vallate) papillae:

Definition

largest, but least numerous; confined to the back of the tongue in a “V” formation

Term

Five Primary Taste Sensations have been identified:

 

Definition

1. Salty: salts usually contain metal ions (Na+, K+, etc.) which are important electrolytes

2. Sweet: produced by sugars which are included in high energy foods

3. Sour: produced by acids (e.g. citric acid in citrus fruits)

4. Bitter: produced by alkaloids (e.g. caffeine, nicotine, etc.); most alkaloids exist as botanical toxins rendering them unpalatable

5. Umami [delicious]: The most recent taste sensation described be the Japanese identifying a “savory” or “meaty” flavor. Produced by free glutamates commonly found in fermented foods (e.g. cheeses), mushrooms, and meats. The sensation is intensified in the presence of sodium; hence, MSG (monosodium glutamate) is popularly used in cooking to enhance flavor

 

Term

The ear contains three anatomical divisions:

Definition

 

1. Outer ear

2. Middle ear

3. Inner ear

Term

Structures of the Outer Ear

Definition

1.Auricle (not pinna in humans):

2. External auditory canal

3. Tympanic membrane

Term

AURICLE

Definition

directs sound waves into the external auditory canal; includes the following substructures:

1. Helix: narrow, outer cartilaginous rim

2. Antihelix: broad, inner cartilaginous rim

3. Triangular fossa: superior depression of the antihelix

4. Concha [shell]: bowl-like space surrounded by the antihelix

5. Tragus [goat]: fleshy flap projecting posteriorly over the external auditory meatus

6. Antitragus: tubercle across from the tragus forming the inferior base of the antihelix

7. Lobule (earlobe): inferior fleshy extension of the two helices, devoid of cartilage, composed of loose connective tissue

Term

External auditory canal

Definition

Tunnel-like chamber within the temporal bone; channels sound waves to the tympanic membrane (eardrum)

Location of the modified apocrine glands, ceruminous glands; cerumen is produced to trap debris & repel insects

Term

Tympanic membrane (eardrum)

Definition

Integumentary membrane closing over the middle ear cavity

Vibrates in response to sound waves; initiates the stimulus for hearing

 

Term

Structures of the Middle Ear

Definition

Also known as the tympanic cavity, the middle ear is an air filled cavity within the petrous portion of the temporal bone; structures within include:

Auditory ossicles: malleus [hammer], incus [anvil], & stapes [stirrup]; the ossicles conduct vibrations from the eardrum to the inner ear

Term

Auditory muscles:

Definition

The auditory muscles contract in response to sounds of sustained high intensity; thereby, protecting the ossicles by reducing the intensity of mechanical vibrations upon them

Tensor tympani: inserts on the malleus to create tension on the eardrum during contraction

Stapedius: inserts on the stapes to displace it from the inner ear during contraction

Term

Eustachian (pharyngotympanic) tube

Definition

 

Passage between the middle tympanic cavity and the nasopharynx

Normally flattened & closed; opens during swallowing or yawning

Functionally, it allows for drainage of the tympanic cavity into the nasopharynx, and it equalizes pressure between the tympanic cavity and the external auditory canal

Term

 

Osseous Labyrinth [bony maze]

(structures of the inner ear)

Definition

Complex hollow spaces within the temporal bone; contains three regions:

Cochlea [snail]

Vestibule [entrance chamber]

Semicircular Canals (superior, posterior, & horizontal)

Term

Two opening of the osseous labyrinth:

 

Definition

1. Oval (vestibular) window: covered by the base of the stapes; where mechanical vibrations enter the inner ear

2. Round (cochlear) window: covered by the secondary tympanic membrane; where vibrations exit the inner ear

 

Term

Membranous Labyrinth

Definition

Collection of membranous ducts & sacs suspended within a fluid, perilymph, inside the chambers of the osseous labyrinth.

The hollow spaces within the membranous labyrinth are filled with a second fluid, endolymph

Term
Structures of the membranous labyrinth:

 

Definition

1. Cochlear duct: within in the cochlea; contains the spiral organ of corti for hearing

2. Saccule: within the vestibule, connected to the cochlear duct; receptor cells are located within maculae [spots] for static equilibrium

3. Utricle: within the vestibule, connected to the semicircular ducts; also contains maculae for static equilibrium

4. Semicircular ducts: within the semicircular canals, attached to the utricle; swollen bases, ampullae, contain receptor cells within cristae ampullares for dynamic equilibrium

Term

Innervation of the inner ear:

The vestibulocochlear nerve (CN VIII) is formed form the union of two sensory nerves:

Definition

1. Vestibular nerve: from the vestibule for equilibrium

2. Cochlear nerve: from the cochlea for hearing

Term

The Pericardium:

 

Definition

      1. The heart is enclosed in a double- 

      walled sac called the pericardium.

2. The parietal pericardium consists of a tough fibrous layer of dense connective tissue with a thin, smooth, moist serous layer.

3. The serous layer turns in at the base of the heart, forming the visceral pericardium covering the heart surface.

4. Between the parietal and visceral pericardia is a space called the pericardial cavity. It contains pericardial fluid that lubricates the membranes and allows the heart to beat almost without friction.

Term

The heart consists of three layers:

 

Definition

 

1. The epicardium .

2. The myocardium

3. The endocardium

Term

The epicardium

Definition

(visceral pericardium) is a serous membrane overlying a thin layer of areolar tissue. In many areas, it has thick deposits of adipose tissue.

 

Term

 The myocardium

Definition

is composed of cardiac muscle and forms the bulk of the heart. It performs the work of the heart.

Term

 The endocardium

Definition

is made up of a layer of endothelium overlying a thin layer of areolar tissue. It forms the smooth inner lining of the chambers and valves and is continuous with the endothelium of the blood vessels.

 

Term
The Chambers

 

Definition

1. The heart has four chambers.

2. The right and left atria receive blood flowing to the heart. Each atrium has a small, earlike extension called an auricle that slightly increases its volume.

3. The two inferior chambers, the left and right ventricles, pump the blood into the arteries for distribution elsewhere.

4. Other features of the heart include the atrioventricular sulcus, the anterior and posterior interventricular sulci, and the interventricular septum.

Term

The Valves

 

Definition

 

1. Valves prevent the backflow of blood into the heart.

2. The pulmonary semilunar valve guards the opening from the right ventricle to the pulmonary trunk.

3. The aortic semilunar valve guards the opening from the left ventricle to the aorta.

4. An atrioventricular (AV) valve guards the opening between each atrium and ventricle. The right AV valve is also known as the tricuspid valve; the left is also called the bicuspid or mitral valve. String-like chordae tendineae attach the valve cusps to papillary muscles.

5. The opening and closing of the heart valves is the result of pressure gradients from one side of the valve cusps to the other.

Term

The Coronary Circulation

 

Definition

1. The first branches off the aorta are the left and right coronary arteries.

2. The left coronary artery supplies blood to the left side of the heart and divides into the anterior interventricular and circumflex arteries.

3. The right coronary artery supplies blood to the right side of the heart and divides into the marginal and posterior interventricular arteries.

4. A myocardial infarction (heart attack) occurs when any of the coronary arteries become occluded and a portion of the heart muscle dies from lack of blood flow.

5. Venous drainage refers to the route by which blood leaves an organ; blood leaving capillaries collects in small veins (venules) that merge to form larger veins.

6. The great cardiac vein drains the anterior aspect of the heart, the middle cardiac vein that collects blood from the posterior aspect of the heart, and the small cardiac vein drains the right side of the heart.

7. All cardiac veins drain into the coronary sinus which empties into the right atrium.

8. In most of the body, arterial blood flow is greater when the ventricles are contracting than when they relax. In the coronary arteries, however, flow is greater when the ventricles relax.

Term

Circulatory Routes

Definition

1. The usual route of blood flow around the body is heart to arteries to arterioles to capillaries to venules, then veins, and back to the heart.

2. An artery is any vessel that carries blood away from the heart. A vein is any vessel that carries blood toward the heart.

3. Usually, blood flows through only one capillary bed before returning to the heart. An exception is a portal system in which blood flows through two separate capillary beds on its return to the heart. Portal systems are found between the hypothalamus and anterior pituitary, in the kidneys, and between the intestines and liver.

4. Anastomoses are places where two or more vessels merge without including a capillary (e.g. vein to vein, artery to artery, or artery to vein).

Term

The Vessel Wall

The walls of arteries and veins are made up of three layers called tunics:

Definition

1. The tunica externa (tunica adventitia) is the outermost layer, made up of loose connective tissue. It anchors the vessels in place and provides passage for the vasa vasorum that supply blood to the vessel wall.

2. The tunica media, or middle layer, is the thickest layer of the vessel, made up mostly of smooth muscle. It is responsible for vasoconstriction and vasodilation.

3. The tunica interna (tunica intima) consists of endothelium overlying a basement membrane and a sparse layer of fibroconnective tissue. It provides a smooth surrounding through which blood passes.

Term

Anatomy of the Pulmonary Circuit

 

Definition

A. The pulmonary circuit begins with the pulmonary trunk that branches into the right and left pulmonary arteries, each of which leads to a lung.

B. In the lung, pulmonary arteries branch into lobar arteries that carry blood to each lobe of a lung. These arteries further subdivide and lead to capillary beds that surround each alveolus.

C. After leaving the alveolar capillaries, pulmonary blood, now carrying oxygen, flows into venules and veins, ultimately leading to the two pulmonary veins that leave the lungs and drain into the left atrium.

Term

Hepatic Portal System

 

Definition

The hepatic portal vein is formed from the union of the superior mesenteric and gastrosplenic vein.

The superior mesenteric vein drains the entire small intestine and the proximal portions of the large intestine.

The gastrosplenic vein is formed from the union of the inferior mesenteric and splenic vein. The splenic vein drains the spleen and pancreas, and the inferior mesenteric vein drains the distal portion of the large intestine.

Before entering the liver, the hepatic portal is joined by the right and left gastric veins, which drain the lesser curvature of the stomach.

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