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98 Cards in this Set
- Front
- Back
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What are neurohormones? |
Hormones released by neurons into the blood |
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What are paracrines? |
Hormones secreted into the ECF that affect neighboring but different cells |
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What are autocrines? |
Hormones secreted into the ECF that affect the same cells as the original |
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What are three important structures of endocrine substances? |
Proteins/polypeptides Steroids Amino acid tyrosine derivatives |
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What is the inactive form of a hormone? |
Preprohormone |
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What is the usual stimulus for hormone release from vesicles? |
Increased [Ca2+]
Less common: increased cAMP |
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Where are peptides and proteins produced? What path do they take? |
Produced in the ER - move to Golgi for packaging into vesicles - exocytosed when needed |
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What are steroids synthesized from? How are they stored? |
From cholesterol
NOT stored; large amts of cholesterol ready to use are stored in cells |
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What is the structure of a steroid? |
Three cyclohexyl rings and one cyclopentyl ring |
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What are amine hormones derived from? What two types of hormones are amines? |
Derived from tyrosine
Adrenal medulla hormones Thyroid hormones |
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What are the adrenal medulla hormones? What ratio are they produced in? |
Epi and norepi
Epi 4x more than norepi |
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How are thyroid hormones stored? How do they travel to the tissues? |
Stored with globulins
Travel bound to plasma proteins |
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What scale do hormone concentrations tend to be on? |
Picograms |
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What is a long feedback loop? |
Target tissue sends messenger back to hypothalamus to provide feedback |
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What is a short feedback loop? |
The pituitary hormone providing feedback to the hypothalamus |
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What is an ultrashort feedback loop? |
Hormone from the hypothalamus inhibits its own secretion |
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What type of variation pattern does cortisol release display? |
Diurnal; peaks from 10am-2pm then a smaller rise at 7-8pm |
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How are hormones transported without being active in transit? (2 ways) |
Dissolved (peptides/catechols) Protein-bound (steroid/thyroid) |
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Where are the hormone receptors for steroids? For thyroid hormones? For peptides/catechols? |
Steroids: in the cytoplasm Thyroid: in the nucleus Peptides/catechols: on the membrane |
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What is the first step of hormone intracellular signalling? |
Formation of the hormone receptor complex |
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What are the three types of hormone signalling? |
Ion channel linked G protein linked Enzyme linked |
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What type of signalling do epi and norepi utilize? |
Ion channel linkage |
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What ion is particularly important for ion channel linked hormone receptors? |
Calcium |
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What type of hormone receptors tend to be G-protein linked? |
Transmembrane receptors |
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How many transmembrane segments are in a G protein linked receptor? |
Seven |
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How many subunits does a G protein have? Which subunit activates downstream activity? |
Three; α subunit |
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How many times do enzyme linked receptors pass through the membrane? |
Just once |
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Where is the enzyme binding site on an enzyme linked hormone receptor? |
On the side of the receptor that's inside of the cell membrane |
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What is an example of an enzyme linked hormone receptor? |
Leptin
Signals via tyrosine and JAK2, which activate STAT proteins |
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The more ________ a drug or hormone is, the faster it'll pass through the membrane and get to work. |
Lipophilic |
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What second messenger does calcium bind to when it enters the cell? |
Calmodulin |
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What type of substance does calmodulin work on as a second messenger? |
Protein kinases |
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What second messenger is activated by phospholipids? |
Phospholipase C |
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What does phospholipase C do as a second messenger? |
Promotes the breakdown of PIP2 into IP3 and DAG |
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What does IP3 do in the cell? |
Mobilizes Ca2+ |
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What does DAG do in the cell? |
Activates protein kinase C (PKC), a precursor for hormones like prostaglandins |
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What effect do steroid hormones have on the cell? What about thyroid hormones in particular? |
Increase protein synthesis; thyroid hormone increases the metabolism of the cell |
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How does thyroid hormone affect anesthesia? |
Cannot do anesthesia when hyperthyroid; hypermetabolic state predisposes pt to high stress response |
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What type of cell secretes hGH? |
Somatotropes |
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What type of cell secretes ACTH? |
Corticotropes |
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What type of cell secretes TSH? |
Thyrotropes |
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What type of cell secretes LH and FSH? |
Gonadotropes |
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What type of cell secretes PRL? |
Lactotropes |
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Which hormones are secreted by the anterior pituitary? |
FLATPiG
FSH LH ACTH TSH PRL GH |
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What hormone inhibits the release of GH? |
Somatostatin |
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What hormones inhibit/stimulate the release of prolactin? |
Prolactin inhibitory hormone Prolactin releasing factor |
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What hormones are made in the posterior pituitary? |
ADH Oxytocin |
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What vessels carry the hypothalamic hormones to the pituitary gland? |
Hypophysial portal vessels |
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What nervous structure is very close to the hypothalamus? |
Optic chiasm |
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What does GH do? |
Increased cell size, mitosis Increased protein synthesis |
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How does GH affect energy use? |
Increases use of fatty acids, decreases glucose utilization |
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What hormone increases glucose transport to the muscles? |
IGFI |
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How does GH impact gluconeogenesis in the liver and kidneys? |
Increases gluconeogenesis in the liver directly, but decreases it indirectly due to insulin release (net effect is decrease)
Decreases gluconeogenesis in kidneys |
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How does GH impact lipolysis? |
Increases it directly
Decreases it indirectly due to insulin release
(Net effect is increase) |
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When does GH production peak? |
Adolescence |
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What stimulates GH release? |
Starvation Hypoglycemia/hypolipidemia Exercise Excitement Trauma Ghrelin |
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What happens to people who don't produce ghrelin or leptin? |
They become morbidly obese |
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What organ produces ghrelin? What organ does it act upon? What hormone does it end up stimulating the release of? |
Produced by the stomach Acts on the pituitary gland Stimulates GH release |
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What organ produces IGF-1? What organ does it act upon? What hormone does it end up stimulating the release of? |
Produced by the liver Acts on the hypothalamus Stimulates GHIH/somatostatin release |
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What hormone is called T4? T3? What % are they found in? |
T4 - thyroxine; 93% T3 - triiodothyronine; 7% |
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How is triiothyronine different from thyroxine? |
Triiothyronine is four times as potent, in smaller quantities, and has a shorter duration of action |
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What cells produce thyroglobulins? What structures are they produced into? |
Thyroid gland epithelial cells produce thyroglobulins into the colloid filled follicles |
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What substance is required for thyroid production? |
Iodides |
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What is the NIS in a thyroid cell? |
Na+/Iodide Symporter |
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What substance potentiates the process of iodination and coupling? |
Peroxidase |
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What substance does the ER and Golgi apparatus produce and package in the thyroid cells? |
Thyroglobulin precursor (Tg) |
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What substances get combined in iodination and coupling? |
I2 and Tg (thyroglobulin precursor) |
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How does the iodinated thyroglobulin precursor return into the cell? |
Pinocytosis |
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What substances get deiodinated in the cell? |
MIT DIT |
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What proteins do thyroid hormones bind to? |
Thyroxine-binding globulin (most) Throxine-binding prealbumin Albumin |
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When is T4 converted to T3? |
Once it passes into the cytoplasm |
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What receptor forms a heterodimer with the thyroid hormone receptor? |
Retinoid X receptor (RXR) |
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Where does the RXR/THR heterodimer locate itself on the DNA? |
Thyroid hormone response elements (THRE) |
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What is the major regulatory step for thyroid hormone production? |
TSH release from the pituitary (short feedback loop with the tissues) |
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Where are catecholamines produced? |
In the adrenal medulla |
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What hormones are produced in the adrenal cortex? (3) |
Mineralocorticoids Corticosteroids Androgenic hormones |
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What is the role of glucocorticoids? |
Raise blood glucose levels Stimulate glucose production Reduce inflammatory response |
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What is the role of mineralocorticoids? |
Acts on DCT of nephrons Regulates uptake of Na+ and acid/base balance |
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What roles does aldosterone play besides its Na+ reuptake renal role? |
Genomic actions in the tubules Role in inflammation (makes reactive oxygen species) Causes protein transcription Influences cellular activities |
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What are the two biggest stimuli for aldosterone? |
Hypovolemia Hyperkalemia |
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Why does aldosterone respond to hyperkalemia? |
Moves Na+ into the blood and K+ out in the principal cells of the CT |
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What are the two cortisol feedback loops? |
Long loop from the adrenal cortex to the hypothalamus Ultrashort loop within the hypothalamus |
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What body systems does cortisol affect? |
Thermoregulation (fever) Immune system (suppressed) Liver (gluconeogenesis) Muscular (catabolism) Adipose tissues (lipolysis) Hemological (inflammatory markers) |
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How much plasma cortisol is protein-bound? |
90-95% |
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What plasma proteins does cortisol bind to? |
Cortisol-binding globulin Transcortin Albumin |
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What is the half-life of cortisol? |
60-90 minutes |
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How much circulating aldosterone is protein-bound? |
60% |
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What is the half-life of aldosterone? |
20 minutes |
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How much plasma calcium is in its ionized form? |
About 50% |
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How much plasma calcium is protein-bound? |
41% |
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Where is D3 converted to its useful form? (1,25-D) |
In the liver and kidneys |
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What is the function of parathyroid hormone? |
Releases Ca2+ from bone Tells kidneys to hang on to Ca2+ Tells intestines to absorb more Ca2+ |
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What two electrolytes does PTH regulate? |
Calcium and phosphate |
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What is the effect of PTH on renal transport? |
Decreases Ca2+ and increases phosphate excretion |
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What is the result of hypoparathyroidism? |
Hypocalcemia and tetany |
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How does PTH influence the intestines? |
Indirectly, via the kidneys
Kidneys activate vitamin D --> vitamin D helps intestines absorb calcium |
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What is calcitonin and where is it secreted from? |
Peptide hormone secreted by the thyroid gland |
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What stimulates calcitonin release? |
Increased plasma calcium |
