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endocrine phys
ENDO
55
Medical
Graduate
11/13/2010

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Term
what is a hormone?
Definition
a polypeptide/protein secreted by one cell cluster/organ which is then secreted into the bloodstream or bodily fluid and acts on a target tissue elsewhere in the body.
Term
what is a local hormone?
Definition
a hormone which acts on the same organ that secretes it such as secretin, ACh, and CCK
Term
what are some examples of general hormones?
Definition
epinephrine, norepinephrine, growth hormone and thyroid hormone
Term
what are the different medical methods for controlling hormones?
Definition
blocking synthesis, blocking release, blocking receptors, inactivating the molecule, and blocking the overall effect
Term
what is the role of the pineal gland?
Definition
regulation of the circadian rhythm via integration of light input and modulation of the endocrine system
Term
what is the role of the hypothalamus?
Definition
receiving input from the cortex/autonomics in the brain and translating it to the pituitary
Term
can ischemia affect hormone efficacy?
Definition
yes - b/c hormones require blood for transport (both arterial and venous flow).
Term
what stimuli lead to release of local hormones?
Definition
nerve impulses, synaptic transmission, and pH changes
Term
what are examples of general hormone effects?
Definition
fight/flight, increased/decreased metabolic rate, and disproportionate growth
Term
how does the endocrine work with the CNS?
Definition
they work together to stimulate a response, then shut it down via feedback mechanism
Term
what is another name for the pituitary?
Definition
the "master gland"
Term
what do the parathyroid glands deal with?
Definition
Ca++ metabolism
Term
why do you need to taper pts off steroids such as cortisol?
Definition
exogenous administration can lead to negative feedback of endogenous production
Term
how does the heart function as a endocrine organ?
Definition
if the heart is not getting enough volume, it can release beta natriuretic peptide which signals the kidney/adrenals to retain more water
Term
why is the pituitary particularly vulnerable to inflammation?
Definition
all of the nerves and arteries supplying it are inside the thin infundibular stalk (located behind the optic chiasm) - which if constricted by inflammation = problems w/hormone release.
Term
what is the super optic nucleus?
Definition
a structure in the brain located above the optic chiasm which produces impulses that travel down into the posterior pituitary
Term
why does the pituitary require a large venous plexus?
Definition
in order to absorb hormones which are intended for release
Term
why is the anatomical location of the pituitary so important?
Definition
nasal infections may affect it easily (if sphenoid sinus/sella turcica is compromised) or if the gland enlarges - the optic chiasm may be affected, causing vision disturbances
Term
what does the anterior pituitary produce? (*test question*)
Definition
growth hormone (GH), adrenocorticotropin (ACTH), thyroid hormone (TSH), follicle stimulating hormone (FSH), luteinizing hormone (LH), and prolactin
Term
what does the posterior pituitary produce? (*test question*)
Definition
antidiuretic hormone (ADH/vasopressin) and oxytocin
Term
what characterizes the adrenal gland's role in the endocrine system?
Definition
ACTH from the anterior pituitary comes down and stimulates production of cortisol and androgens (from cholesterol). aldosterone is also produced in the adrenals (zona glomerulosa) which enhances Na+ reabsorption in the kidneys (increases water levels).
Term
what characterizes the role of the thyroid gland in the endocrine system?
Definition
the thyroid produces thyroxine (T4 - becomes triiodothyronine/T3 in periphery) which affects vasometabolic rates, potentiates reproduction, and potentiates other organ systems etc in response to TSH. tyrosine/iodine are necessary substrates for thyroid production.
Term
what characterizes the pancreas as an endocrine organ?
Definition
the pancreas produces insulin via its beta cells (decreases blood sugar levels) and glucagon via its alpha cells (increases blood sugar levels).
Term
how does insulin decrease blood sugar levels?
Definition
by increasing glucose transport into cells *along w/potassium*
Term
what can occur with the pancreas if the exocrine portion of its function is blocked?
Definition
pancreatic enzymes, including proteases/lipases can accumulate - leading to pancreatitis and autodigestion. HCO3- may also not be able to reach the duodenum and perform its protective function. if this occurs, Ca++ drops, WBCs increase, calcifications may be apparent on x-ray and the pts glucose/Na+ may be affected.
Term
what do the parathyroids help regulate?
Definition
parathyroid hormone increases Ca++ blood levels, which affects bone density and reabsorption of Ca++ by the kidney
Term
how does the placenta function as an endocrine organ?
Definition
the placenta produces hCG when its chorionic villi form as well as estrogen, progesterone, and human somatotropin (helps maintain the right water, electrolyte balance and growth and fetal food in the form of glucose).
Term
what are the three general classes of hormones?
Definition
steroids (*cortisol, *aldosterone etc - from cholesterol nucleus), tyrosine derivatives (*thyroxine, *triiodothyronine, *epinephrine etc - why pts need all essential amino acids), and proteins/peptides (everything else)
Term
how can certain antibx mess w/the endocrine system?
Definition
some antibx have effects on human ribosomes, which are needed to make the proteins found in some hormones
Term
what is the progression of protein derived hormone creation?
Definition
protein derived prehormones become prohormones in the RER, which are then packaged in the golgi complex and sent to secretory vesicles until their release.
Term
what is the progression of tyrosine derived hormone creation?
Definition
tyrosine derived hormones are created via cytoplasmic synthesis involving enzymes - meaning temp, pH, and nutrient levels all affect their synthesis.
Term
what level of quantity are hormones active in?
Definition
minute
Term
what is the onset of action for hormones?
Definition
seconds to days (may be related to negative feedback mechanism)
Term
where do proteins, peptides, and catecholamines bind in their target tissue? how does this affect the time from binding to effect?
Definition
on cell membrane receptors - which allows an immediate effect
Term
where do steroids bind in their target tissue? how does this affect the time from binding to effect?
Definition
steroids bind in the cellular cytoplasm, which means they will take longer to have an effect (likely a couple of hours)
Term
where do thyroid hormones bind in their target tissue? how does this affect the time from binding to effect?
Definition
thyroid hormones bind to chromosomes and associated proteins in the cell nucleus - meaning their effect may not be evident for days to weeks.
Term
what is receptor up-regulation? down-regulation?
Definition
up-regulation of cell membrane receptors for certain hormones/drugs can increase their effectiveness w/the same level of hormone/drug being released. down-regulation of these receptors will decrease the efficacy of certain hormones/drugs at the same level of release.
Term
what are the MOAs generally attributed to hormones?
Definition
changes in *membrane permeability (aldosterone in DCT), intracellular *enzyme activation (speed up normal reactions), and *gene activation (directly affect DNA expression)
Term
what is the second messenger mechanism employed by many hormones?
Definition
a mechanism where adenyl cyclase is stimulated to produce *cAMP which is then used to activate a *cascade reaction which leads to *amplification of the intended effect
Term
what hormones use the secondary messenger mechanism? (*test question*)
Definition
*ACTH (adrenocorticotropin), *TSH (thyroid stimulating hormone), *LH (luteinizing hormone), *FSH (follicle stimulating hormone, and *ADH (vasopressin). other hormones, not as likely to be on test, but which use the secondary messenger mechanism: PTH, glucagon, catecholamines, and secretin
Term
what characterizes the action of calmodulin?
Definition
calmodulin is the "other 2nd messenger", operating in a different pathway than cAMP via 4 Ca++ binding sites which when activated, lead to conformational steric effects. therefore, drugs used to bind Ca++ can have endocrine effects through this mechanism.
Term
what is the overall path of steroid hormones?
Definition
adrenal cortex -> target cell cytoplasm -> binds to receptor proteins -> hormone+protein diffuse/are transported to nucleus -> transcription is activated -> mRNA diffuses out to the cytoplasm to ribosomes for translation
Term
how are hormone levels determined?
Definition
radioimmune assay
Term
what is the effect of pituitary tumors on vision?
Definition
pituitary tumors may grow into the optic chiasm which may create a visual disturbance
Term
what are some symptoms of damage to the pituitary stalk?
Definition
somnolence, obesity/emaciation, diarrhea, loss of libido, loss of muscle mass, etc.
Term
what are some indications of anterior pituitary pathology?
Definition
wrinkles, myxedema facies, loss of hair, loss of sexual characteristics, low blood sugar, and fatigue
Term
what are signs/symptoms of hypo and pan hypopituitarism?
Definition
changes in skin color, adrenal insufficiency, hypotension, decreased libido, and diabetes (if pt has bizarre symptoms that don’t seem to make sense, we’re looking in the wrong place)
Term
what is the effect of pituitary growth hormone?
Definition
enhanced AA transport into cells, increased DNA transcription, increased RNA translation, *increased protein synthesis*, decreased catabolism of proteins/AA, decreased use of glucose for energy, enhancement of glycogen deposition, increased blood glucose/less cellular uptake, and increased secretion of insulin ("diabetogenic effect"). appropriate GH is necessary for growth and maintenance of muscle tissue and RBC production.
Term
what are pituitary somatomedins?
Definition
insulin-like growth hormones, the most important of which: somatomedin C/IGF-1.
Term
what are stimuli for GH release? (*test question*)
Definition
starvation, protein deficiency, hypoglycemia, low FFA in blood, exercise, excitement, trauma, and deep sleep.
Term
what are abnormalities of GH secretion?
Definition
dwarfism, levi-lorain dwarf, and incompatible hGH tx
Term
what is gigantism?
Definition
an acidophilic tumor in the pituitary *prior to puberty can lead to maximum growth of all tissue prior to puberty
Term
what is acromegaly?
Definition
an acidophilic pituitary tissue post puberty = big face/hands
Term
what is the effect of ADH?
Definition
stimulation of thirst/reabsorption of water by the kidney. ADH comes from the posterior pituitary
Term
what is the effect of oxytocin?
Definition
stimulation of parturition and colostrum release from the breasts
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