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75 Cards in this Set

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  • Back
What are amine hormones? what hormones are included in this group?
derivates of amino acid tyrosine. thyroid hormones and catecholamines.
What type of hormone is the catecholamines? why? describe their structure? what type of hormones are included in the catecholamines group?
amine hormones because derived from tyrosine. structure consists of a catechol ring (6-Carbons with 2 adjacent OH groups) and an amine group. dopamine, norepinephrine, epinephrine.
where are epinephrine and norepinephrine produced? where is dopamine produced?
ep and nor in adrenal medulla and dopamine in hypothalamus
where are the adrenal glands located? describe their structure. what types of hormones does each secrete?
one on top of each kidney. actually consists of two distincy glands.
the inner gland is the adrenal medulla which secrets amine hormones and surrounding it is the adrenal cortex which secrets steroid hormones.
what part of the immune system is the sympathetic nervous system? what type of information do the sympathetic ganglion deliver?
part of the autonomic nervous system. They deliver information to the body about stress and impending danger, and are responsible for the familiar fight-or-flight response.
which hormones does the adrenal medulla secrete? which is more? why?
epinephrine and norepinehprine. more epinephrine is secreted because in humans the adrenal medulla Xps phenyl-N-methyltransferase which catalyzes the conversion of N to E.
what is phenyl-N-methyltransferase? where is found?
converts norepinephrine to epinephrine and is found highly expressed in human adrenal medulla.
describe the synthesis cycle of a hormone.
peptide initially synthesized on ribosomes and known as preprohormones, which are cleaved to prohormones by proteolytic enzmes in rER. prohormone packaged into secretory vesicles by Golgi apparatus, where it is cleaved to yield active hormone.
describe structure of steroid. where are they primarily produced?
four interconnected rings of carbon atoms. formed in adrenal cortex and gonads and placenta.
describe general process of steroid hormone synthesis.
cells first stimulated by tropic hormone from pituitary to bind to plasma membrane receptor. receptor linked to G-protein, which activates adenylyl cyclase and forms cAMP, which activates PKA, which P cytosolic and membrane proteins.
what is main ingredient of steroid hormones? in what form does it enter cells? how does it enter? how is ingredient stored inside cells?
cholesterol. enters cells as LDL. receptors on cell surface bind to LDL. LDL/receptor complex internalized into cytocol by endocytosis. stored in esterified form.
What is cholesterol esterase? how is it activated?
enzyme that releases free choleterol from lipid droplet; activated by PKA
what happens after free cholesterol is released inside cells? what next and where specifically?
cholesterol is transported to mitochondria by StAR protein. cholesterol transported to inner mitochondria by peripheral-type benzodiazepine receptor where cytochrome p450 convert cholesterol into steroid hormone.
how are lipophilic steroid hormones stored?
they are not stored but diffused out through lipid bilayer into circulation.
what are five hormones secreted by adrenal cortex?
aldosterone, cortisol, corticosterone, DHEA, androstenedione
functions of aldosterone? what type of hormone? it is under the control of what hormone?
mineralocorticoid because its effects are on salt (mineral) balance; under control of angiotensin II
what type of hormones are cortisol and corticosterone?
glucocorticoids because effect metabolism of glucose and other organic nutrients.
list types of androgens?
DHEA, androstenedione, testosterone
what type of hormones are found in gonads? what is the function of the predominant enzyme in testes and ovaries?
hormones found in the androgen pathway. predominant enzyme converts androstenedione to testosterone in testes, and the androstenedione is converted to estradiol by aromatase.
how are water solube and lipid soluble hormones transported?
water soluble such as catecholamine are dissolved in plasma where as lipid soluble (steroid, thyroid hormones) are bound to plasma proteins.
what form of the hormone, free or bound to carrier, is physiologically important?
only free hormone can diffuse across capillary walls and encounter target cells.
what does a hormone's concentration is plasma depend on?
1. rate of secretion by endocrine gland
2. rate of removal from blood
how long do catecholamine and peptide hormones remain in blood? why?
minutes to hour because enzymes in blood and tissue rapidly excrete or attack hormones
how vulnerable are protein-bound hormones to excretion or metabolism by enzymes?
less vulnerable than free hormones
does metabolism always inactive hormone?
no, metabolism may activate.
where are the receptors located for catecholamines, peptide hormones, steroid hormones, and thyroid hormones?
peptide and catecholamine receptors are located in plasma membrane; steroid and thyroid receptors located INSIDE target cells.
in context of hormones, what is up and down regulation? how does this happen?
up is increase in number of hormones' receptors resulting from prolonged exposure to low concentration of hormone. this has effect of increase target cell responsiveness. down is decrease in receptor due to exposure to high concentration of hormone.
what is permissiveness?
faciliation of the action of one hormone by another
why are the receptors of catecholamines and pepide hormones located where they are?
these hormones are too large and hydrophilic to diffuse through plasma membranse.
what type of actions may be exerted by both peptide hormones and catecholamines?
rapid and delayed (gene transcription)
why are steroid and thyroid hormone receptors located where they are?
because the hormones are all lipophilic
what are pharmacological effects?
effects due to administration of very large quantities of hormone for medical purposes and the effects never been seen in a normal, healthy person.
what are the three types of control the regulate hormone secretion?
1. changes in plasma concentrations of mineral ions or organic nutrients
2. neurotransmitters releases from neurons impinging on endocrine cells
3. another hormone or para/autocrine agent acting on endocrine cell
what is the main function of the hormone controlled by [plasma] of mineral ions or organic nutrients?
regulate through negative feedback the [plasma] of the ion or nutrient controlling its secretion
what type of hormone not under control of autonomic neurons?
those secreted by hypothalamus and its extention posterior pituitary
define tropic hormone
a hormone that stimulates the secretion of another hormone
what is the anatomical part the connects the pituitary gland to the hypothalamus? describe it.
infundibulum; a stalk containing nerve fibers and blood vessels
what are the supraoptic and paraventricular nuclei? what is unique about them?
hypothalamic neurons that pass down infundibulum and end within the posterior pituitary gland in close proximity to capillaries. therefore these neurons don't form synapse with other neurons but end directly on capillaries
what is the anatomical structure that connects that hypothalamus to the anterior pituitary gland?
there is no neural connection but there is a blood connection via the hypothalamo-pituitary portal vessels
what is the advantage of the anatomical structure that connects the hypothalamus to the anterior pituitary gland?
rapid response and minimizes the amount of hypothalamic hormone that must be synthesized to reach an effective blood concentration (since the hormone is not diluted into general circulation of the body).
what is the physiological relationship between the posterior pituitary gland and the hypothalamus?
the posterior pituitary gland is really a NEURAL extension of the hypothalamus. the hormones are not synthesized in the posterior pituitary itself but in the hypothalamus
name two types of posterior pituitary hormones and their function.
1.oxytocin-stimulates contraction of smooth muscle cells in breast and uterus
2.vasopressin-acts on smooth muscle cells around blood vessels to cause muscle contraction, which constricts blood vessels and increases blood pressure.
what is anti-diuretic hormone (ADH)?
another name for vasopressin; in the kidney it acts to decrease water excretion in urine thus retaining fluid in the body and helping to maintain blood volume.
what are hypophysiotropic hormones? what are other names for these types of hormones?
hypothalamic hormones the regulate anterior pituitary function. hypothalmic releasing or inhibiting hormones.
describe the three hormone sequence.
1. a hypophysiotropic hormone controls the secretion of
2. an anterior pituitary hormone, which controls the secretion of
3. a hormone from some other endocrine gland.
this last hormone then acts on its target cells.
what class of hormones are the anterior pituitary hormones. Name the six hormones.
peptide hormones.
what is the collective term for the FSH and LH?
gonadotropic hormone because they stimulate gonads
what is peculiar about beta-lipotropin and beta-endorphin? describe their physiological role.
although secreted by anterior pituitary gland, their physiological role in humans is not known. in animals, beta-endorphin is a potent pain killer and beta-lipotropin can mobilize fats in circulation to provide extra fuel.
describe the target and function of FSH and LH.
target germ cell development and the gonads to secrete hormones.
describe the target and function of growth hormones.
act on liver to secrete insulin-like growth factor and in other organ and tissues is involved in protein synthesis and carbohydrate and lipid metabolism.
what is the target and function of the thyroid-stimulating hormone?
target the thyroid to secrete thyroxine and triiodothyronin.
what is the target and function of prolactin?
target breast development and milk production.
what is the target and function of adrenocorticotropic hormone (ACTH)?
target adrenal cortex to secrete cortisol.
what regulates the secretion of the anterior pituitary hormones?
the hormones produced by the hypothalamus and collectively called hypophysiotropic hormones.
what causes the release of the hypophyiotropic hormones?
action potentials in the neurons that originate in discrete ares of the hypothalamus and terminate in the median eminence around the capillaries that are the origin of the hypothalamo-pituitary portal vessels.
describe the ways in which the secretion of hormones in the anterior and posterior gland are similar.
the hormones are made in the hypothalamic neurons, pass down axons to the neuron terminals and are released in response to action potentials in neurons.
describe a crucial differences between the way hormones are secreted to the anterior and posterior glands.
1.the axons of the hypothalamic neurons that secrete the posterior pituitary hormones leave the hypothalamus and end in the posterior pituitary, whereas those that secrete the hypophysiotropic hormones remain in the hypothalamus ending in the median eminence.
describe another crucial differences between the way hormones are secreted to the anterior and posterior glands.
2.most of the posterior pituitary capillaries into which the posterior pituitary hormones are secreted immediately drain into the main bloodstream, which carries the hormones to the heart for distribution to the entire body. in contrast, the hypophysiotropic hormones enter capillaries in the median eminence of the hypothalamus that do not directly join the main bloodstream, but empty into the hypothalamo-pituitary portal vessels, which carry them to the anterior pituitary. if the cell has an appropriate receptor for a given hypophysiotropic hormone, that cell will respond by increasing/decreasing the secretion of its pituitary hormone. if pituitary hormone is secreted, it will diffuse into the SAME capillaries that delivered that hypophysiotropic hormone. these capillaries then drain into veins which enter the systemic cirulation where the pituitary hormones can come into contact with their target cells. thus, the anterior pituitary is exposed to much higher plasma concentrations of the hypophysiotropic hormones than those existing in the general bloodstream.
describe the nomenclature used in naming the hypophysiotropic hormone that directs the secretion of a particular anterior pituitary hormone and give an example.
each hypophysiotropic hormone is named for the anterior pituitary hormone whose secretion it controls. for example ACTH (cotrioctropin) is stimulated by corticotropin-releasing hormone.
name and describe the two hypophyiotropic hormones that inhibit the secretion of two anterior pituitary hormones.
1.somatostatin (SS) inhibits secretion of growth hormones
2.dopamine (DA) inhibits secretion of prolactin.
what controls the secretion of each hypophysiotropic hormones?
1.neuronal and hormonal input to the hypothalamic neurons the three-hormone sequences, the third hormone may exert a long-loop negative feedback effect on the secretion of the hypothalamic and/or anterior pituitary hormone.
which hormone does not have long-loop negative feedback?
prolactin since this is one of the anterior pituitary hormones that does not have major control over another endocring does not participate in three-hormone sequence.
how does prolactin regulate itself?
acts upon the hypothalamus to stimulate the secretion of dopamine which then inhibits the secretion of prolactin
what is short-loop negative feedback?
influence of anterior pituitary hormone on the hypothalamus
are thyroid hormones essential for life
what are the two main hormones synthesized by they thyroid gland? what feature is common is both?
thyroxine (T4)
triiodothyronine (T3)
both have iodide
name the enzyme that converts thyroxine to triiodothyronine?
what type of cells in the thyroid are responsible for the synthesis and secretion of thyroid hormones?
follicular cells
how does the iodide enter the follicular cells for hormone synthesis? how does iodide leave?
cotransported with sodium ions. bulky iodide cannot diffuse back out (iodide trapping)
once inside the follicle cell, what happens next to the iodide?
diffuses to the lumen (colloid) border of the follicular cell
what is the main protein held within the colloid? what is the main constituient of the protein and why?
thyroglobulin; oxidized iodide, now iodine free radical, attaches to the tyrosine molecules of thyroglobulin
where is thyroglobulin synthesized?
snythesized by follicular cless and secreted by exocytosis into follicle lumen
name the enzyme that oxidizes idodid into iodine free radical. what else does the enzyme do? where is it synthesized?
thyroid peroxidase; also responsible for attaching iodine free radical to thyrosine. enzyme is also synthesized in follicle cell
what is responsible for the activities of the follicular cell?
thyroid stimulating hormone (TSH), which in turn is controlled by thyrotropin-releasing hormone (TRH)
where are the receptors for the thyroid hormones? what is their main function?
on the nucleus of cells. act by inducing gene transcription and protein synthesis.