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AP 2 18
ENDOCRINNNE!!
117
Anatomy
Undergraduate 1
03/31/2012

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Term
• THE ENDOCRINE SYSTEM
Definition
• Composed of glands that pour secretions into blood instead of into ducts (ductless)
Term
• Chemicals produced are called
Definition
hormones
Term
– Nervous system (nerve impulses) produce
Definition
rapid, short-lasting responses
Term
hormones have a
Definition
slower, longer-lasting effect
Term
– Cells that are acted on and respond to hormones are called
Definition
target organ cells (contain receptors)
Term
– Local hormones
Definition
paracrine factors chemicals that affect neighboring cells; autocrines act on cell that secreted them
Term
Endocrine system function
Definition
help maintain homeostasis
 Regulate chemical composition and volume of internal environment
 Help regulate metabolism and energy balance (Thyroxin)
 Help regulate contraction of smooth and cardiac muscle fibers and secretion of glands
 Regulate some activities of immune system
 Play role in smooth, sequential integration of growth and development (Growth Hormone and Thyroid Hormone)
 Contribute to basic process of reproduction (FHS and LH-Female,
Term
• Lipid-soluble
Definition
– Steroids
Term
• Lipids structurally similar
Definition
to cholesterol
Term
Lipid Soluble released by
Definition
by male and female reproductive organs, adrenal glands and kidneys
Term
– Nitric oxide (gas)
Definition
both hormone and neurotransmitter
Term
• Water-soluble
Definition
– Amines, Peptide hormones, Eicosanoids
Term
– Amines
Definition
• Structurally similar to amino acids
• Released by adrenal medulla, thyroid, and pineal gland
• Most are synthesized from amino acid tyrosine
Term
– Peptide hormones
Definition
• Chains of amino acids
• Largest class and includes all hormones secreted by hypothalamus, pituitary gland, heart, thymus, digestive tract, and pancreas
Term
– Eicosanoids
Definition
• Small molecules with 5-carbon ring at one end
• Includes prostaglandins and leukotrienes and are important paracrine factors
Term
• For hormone to affect target cell, it must first
Definition
interact with appropriate receptor
Term
• Hormone receptors may be
Definition
on cell membrane or inside cell
Term
• Hormones and cell membrane
Definition
water soluble - cannot penetrate cell membrane
Term
– Receptors for catecholamines, peptide hormones, and eicosanoids are found in
Definition
cell membranes
Term
– Hormone acts as
Definition
first messenger that causes appearance of second messenger in cytoplasm
Term
– Second messenger may serve as
Definition
enzyme activator, inhibitor, or cofactor (net result is change in rates of various metabolic reactions)
Term
– Most important second messengers are
Definition
cyclic AMP, cyclic GMP, and calcium ions
Term
– Binding of hormone to receptors may lead to
Definition
release of many (thousands) of 2nd messengers--called amplification
Term
– Link between 1st messenger and 2nd messenger usually involves
Definition
G-protein, an integral membrane protein that interacts with the membrane receptor
Term
• Two hormones may have opposing or
Definition
antagonistic effects
Term
• Two hormones may have additive or
Definition
synergistic effects
Term
• One hormone may have
Definition
permissive effect on another
Term
first hormone is needed for
Definition
second to produce its effect
Term
• Hormones may produce different but
Definition
complimentary results (integrative effects)
Term
• Amount of hormone released by endocrine gland is determined by
Definition
body’s need for the hormone at any given time
Term
• Negative feedback is common method for hormonal control-
Definition
low level of substance may cause release of hormone
Term
• Hormone may be released as result of
Definition
nerve impulses
Term
• Other hormones may regulate
Definition
endocrine glands
Term
• Pituitary gland
Definition
– In sella turcica of sphenoid bone
– Consists of 2 endocrine glands: anterior lobe (adenohypophysis) and posterior lobe (neurohypophysis)
Term
• Anterior portion divided into
Definition
larger pars anterior and small pars intermedia
Term
– Hormones of anterior pituitary are stimulated by
Definition
releasing hormones of hypothalamus and suppressed by inhibiting hormones
Term
– Hypophyseal portal system connects pituitary to
Definition
hypothalamus and is means by which regulatory hormones travel to pituitary
Term
• Prolactin (lactogenic hormone or luteotropic hormone [LTH])
Definition
– During pregnancy, promotes breast development
– After delivery, initiates milk secretion
– Helps in maintaining corpus luteum
Term
• Growth hormone (somatotropin or somatotropic hormone)
Definition
– Accelerates protein anabolism (synthesis), so promotes growth; skeletal muscle cells and chondrocytes particularly sensitive
Term
• Disorders caused by excess growth hormone
Definition
gigantism and acromegaly
Term
• Disorders caused by deficient growth hormone
Definition
dwarfism
Term
– Liver and other cells produce
Definition
insulinlike growth factors (IGFs) that increase amino acid uptake
Term
• Growth hormone tends to accelerate
Definition
fat mobilization from adipose cells and fat catabolism by other cells, thereby decreasing glucose catabolism and tending to increase blood glucose concentration (hyperglycemic effect); prolonged excess may produce diabetes
Term
• Tropic hormones
Definition
hormones that have a stimulating effect on other endocrine glands) (18.4 table)
Term
 Thyrotropin
Definition
- thyroid-stimulating hormone (TSH)
Term
• Tropic hormones
Definition
 Promotes growth and development of thyroid gland
 Stimulates thyroid gland to secrete thyroid hormone
Term
 Adrenocorticotropin (ACTH)
Definition
 Promotes growth and development of adrenal cortex
 Stimulates cortex to secrete cortisol and other glucocorticoids
Term
– Follicle-stimulating hormone (FSH)
Definition
• Stimulates primary Graafian follicle to start growing and to develop to maturity
• Stimulates follicle cells to secrete estrogens
• In male, stimulates development of seminiferous tubules and maintains spermatogenesis by them
Term
– Luteinizing hormone (LH)
Definition
• Acts with FSH to cause complete maturation of follicle and brings about ovulation
Term
• Stimulates formation of
Definition
corpus luteum (luteinizing effect) and stimulates corpus luteum to secrete progesterone and estrogens
Term
• In male, LH called
Definition
interstitial cell stimulating hormone (ICSH); stimulates interstitial cells in testes to develop and secrete testosterone
Term
• Melanocyte
Definition
stimulating hormone (MSH) or intermedin (Found in skin!)
– Produced by pars intermedia
– Tends to produce increased pigmentation of skin
Term
– Releasing hormones
Definition
neurosecretions produced in hypothalamus that reach anterior pituitary gland via blood in pituitary portal system to regulate hormone production (pg 691)
Term
– Negative feedback mechanisms operate between
Definition
target glands and anterior lobe of pituitary
Term
• Antidiuretic hormone (ADH) or vasopressin
Definition
– Synthesized by neurons in supraoptic nucleus of hypothalamus
Term
– Stimulates water reabsorption by
Definition
distal and collecting tubules of kidney (causes retention of water)
Term
– In large (pharmacological) doses will
Definition
stimulate smooth muscle of blood vessels
Term
– Lack of ADH results in diabetes insipidus
Definition
(Urine production increases. no ADH=no water retention. YO GON’ BE THIRSTY!)
Term
• Oxytocin
Definition
– Synthesized by neurons in the paraventricular nucleus of hypothalamus
– Stimulates contractions of pregnant uterus and release of milk by lactating breast
Term
– ADH
Definition
• Increased extracellular fluid osmotic pressure leads to decreased ADH secretion
• Decreased ECF leads to increased ADH secretion
• Stress leads to increased ADH secretion
Term
– Oxytocin
Definition
• Not fully known but stimulation of nipples by infant leads to increased oxytocin secretion and stretch receptors in cervix send impulses to hypothalamus during delivery
Term
• Thyroid gland
Definition
– In neck just below larynx
– Two lateral lobes connected by isthmus
– Contains microscopic spherical sacs called thyroid follicles
Term
• Follicular cells manufacture thyroid hormones by
Definition
attaching iodine to the amino acid tyrosine
Term
• Parafollicular or C cells produce
Definition
calcitonin
Term
– Thyroid hormone (thyroxine - T4; triiodothyronine - T3) (4 and 3= how much iodine is attatched)
Definition
• Stimulates rate of oxygen consumption (metabolic rate) of all cells
-Essential for normal metabolism
• Regulates physical and mental development, development of sexual maturity, and numerous other processes (table 18.6)
Term
– Calcitonin
Definition
• Decreases blood calcium concentration
• Inhibits bone breakdown with calcium release into blood and/or increases calcium deposition in bone
Term
– Hypersecretion leads to
Definition
exophthalmic goiter (Grave’s disease) (hungry-and losing weight, extra metabolism going on-because of all the muscle contractions (sweat easily, get hot easily. Have difficulties concentration. )
Term
– Hypothyroidism in adult is
Definition
myxedema; in infant called cretinism
Term
– Lack of iodine leads to
Definition
simple goiter
Term
• Parathyroid glands
Definition
– Attached to posterior surfaces of thyroid gland
– Small round bodies, usually 4 or 5 in number
– Contain principal (chief) cells which produce parathyroid hormone (parathormone-PTH)
Term
Parathyroid hormone Increases blood calcium by
Definition
stimulating bone breakdown releasing calcium and phosphate into blood from bone
Term
– Increases blood calcium by
Definition
by accelerating calcium absorption from kidney tubules
Term
– Accelerates kidney excretion of
Definition
phosphates from blood into urine
Term
– Acts on kidneys to promote
Definition
formation of calcitriol, active form of vitamin D, which acts on intestines to increase calcium, phosphate, and magnesium absorption
Term
– Hypersecretion causes
Definition
decrease in bone mass with replacement by fibrous tissue; more easily fractured (Making bones weaker) (Calcium used for muscle contraction)
Term
– Hyposecretion produces
Definition
hypocalcemia leading to muscle twitches, spasms, and convulsions (called tetany); may lead to death in few hours
Term
• Adrenal glands
Definition
– Located atop kidneys
– Outer portion of gland called cortex and inner portion called medulla
Term
• Zones or layers (from outside in)
Definition
Zona glomerulosa and – Zona fasciculata – Zona reticularis
Term
– Zona glomerulosa
Definition
secretes mineralocorticoids
Term
– Zona fasciculata
Definition
secretes glucocorticoids
Term
– Zona reticularis
Definition
secretes small amounts of glucocorticoids and sex hormones
Term
• Glucocorticoids (mainly cortisol, smaller amounts of corticosterone)
Definition
– Accelerate tissue protein mobilization; mobilized amino acids circulate to liver cells where they are changed to glucose
– Accelerate fat mobilization and catabolism
– Necessary for norepinephrine’s vasoconstricting effect on blood vessels and thus *** essential for maintaining normal blood pressure
Term
– Glucocorticoids plus epinephrine promote
Definition
normal recovery from injury by inflammatory agents (*** anti-inflammatory effect)
Term
– Blood concentration increases
Definition
during stress
Term
• Mineralocorticoids
Definition
– Accelerate renal tubule reabsorption of sodium ions and [Indirectly if you retain a negative ion, you lose a positive ion] excretion of potassium ions (or hydrogen ions)
– Increased renal tubule reabsorption of bicarbonate ions (or chloride ion) and water result from increased sodium reabsorption (Because of what aldosterone does, we get water retention as well)
Term
• Sex hormones (3rd layer)
Definition
– In both sexes, amount of male hormones secreted by adrenal cortex is physiologically significant, but amount of female hormones is insignificant
Term
• Control of secretion
Definition
mineralocorticoids
Term
– Renin
Definition
angiotensin mechanism, an important regulator of aldosterone
Term
– Blood potassium concentration also helps regulate
Definition
aldosterone secretion
Term
high blood potassium conc. stimulates and low blood potassium conc. inhibits
Definition
aldosterone secretion
Term
– Addison’s disease
Definition
- hyposecretion of aldosterone and glucocorticoids; muscle weakness, mental lethargy, weight loss, increased ACTH may lead to pigmentation of certain areas of skin (resembles MSH) [Can’t Think]
Term
– Cushing’s syndrome
Definition
hypersecretion of glucocorticoids characterized by redistribution of fat
Term
– Congenital adrenal hyperplasia
Definition
lack of glucocorticoid production with increased ACTH; leads to virilism or masculinization (BEARED LAAADYY!!)
Term
• Adrenal medulla (FYI we could get by without it)
HORMONES
Definition
mainly epinephrine; some norepinephrine
Term
• Functions of epinephrine
Definition
– Affects visceral effectors (smooth and cardiac muscle, glands) in same way as sympathetic stimulation of these structures (Increase heart rate, increase respiratory rate, decrease gastrointestinal)
– Epinephrine from adrenal glands intensifies and prolongs sympathetic effects
Term
• Adrenal medulla
Control of secretion
Definition
stress stimulates hypothalamus, which sends impulses to adrenal medulla via preganglionic sympathetic neurons, stimulating medulla to increase secretion of epinephrine
Term
• Pancreas
Hormones
Definition
– Insulin– Glucagon
Term
– Insulin
Definition
beta cells of islets of Langerhans
Term
– Glucagon
Definition
alpha cells of islets of Langerhans
Term
– Growth hormone inhibiting hormone (GHIH) or somatostatin (delta cells) - [in pancreas]
Definition
acts as paracrine to inhibit secretion of insulin and glucagon
Term
– F cells
Definition
pancreatic polypeptide which regulates release of pancreatic digestive enzymes
Term
– Insulin
Definition
decrease blood glucose levels
Term
• Promotes glucose transport into cells, thereby
Definition
increasing glucose utilization (catabolism) and glycogenesis and decreasing blood glucose levels
Term
• Promotes fatty acid transport into
Definition
cells and fat anabolism (lipogenesis or fat deposition) in them
Term
• Promotes amino acid transport into
Definition
cells and protein anabolism
Term
– Glucagon
Definition
increase blood glucose levels
• Accelerates liver glycogenolysis
• Promotes formation of glucose from lactic acid (gluconeogenesis)
Help proteins and fatty acids being turned into glucose!! 
• Enhances release of glucose into blood
Term
– Diabetes mellitus
Definition
• Deficiency of insulin leading to hyperglycemia
Term
• Two types
Definition
Insulin-dependent (Type I) and Non-insulin dependent (NIDDM) (Type II)• Characterized by polyuria, polydipsia, and polyphagia
Term
– Hyperinsulinism leads to
Definition
hypoglycemia and insulin shock
Term
• Ovaries - hormones
Definition
– Ovarian (Graafian) follicles secrete estrogens
– Corpus luteum secretes progesterone
Term
• Testes
Definition
hormones - androgens, most important of which is testosterone
Term
• Pineal gland (epiphysis cerebri) -
Definition
melatonin - may be involved with establishment or maintenance of circadian rhythms(sleep cycle, wake cycle)
Term
• Thymus – thymosin (decreases in size as we age
Definition
– Needed for maturation and development of immune system
– Increases numbers of T cells in lymphocyte population
– Promotes an increase in many types of lymphocyte functions
Term
• Prostaglandins
Definition
• Regulate endocrine activity at the cellular level by influencing adenyl cyclase and cyclic AMP activity
Term
– Prostaglandin A (PGA)
Definition
help in regulation of blood pressure
Term
– Prostaglandin E (PGE)
Definition
vascular effects involving rbc “deformability” and platelet aggregation; effect on HCL secretion in stomach
Term
– Prostaglandin F (PGF)
Definition
important in reproductive function
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