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127 Cards in this Set
- Front
- Back
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What hormones does the hypothalmus secrete?
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TRH, CRH, GnRH, GHRH, SRIF, PIF
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When is a G protein active?
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When the α subunit is bound to GTP, the G protein is active. When bound to GDP, the G protein is inactive.
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general steps in hormone synthesis
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1. preprohormone synthesized in rER; 2. signal peptides cleaved--> prohormone transported to Golgi; 3. more cleavage in golgi and HORMONE then packaged in secretory granules
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Major actions of TRH?
(thyrotropin-releasing hormone) |
stimulates secretion of TSH and prolactin
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What does activated adenylate cyclase do?
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Activated adenylate cyclase catalyzes the conversion of ATP to cAMP. cAMP activates protein kinase A which phosphorylates specific proteins.
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amine hormones
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derivates of TYROSINE, include thyroid hormone, Epi, NE
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Major actions of CRH?
(corticotropin-releasing hormone) |
stimulates s/c of ACTH
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What the metabolism of cAMP? What inhibits this degradation?
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cAMP is degraded to 5'-AMP by phosphodiesterase, which is inhibited by caffeine.
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active form of G protein?
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ATP-bound to alpha subunit
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how does caffeine work?
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inhibits phosphodiesterase which degrades cAMP (get more cAMP)
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Major actions of GnRH?
(gonadotropin-releasing hormone) |
stimulates s/c of LH and FSH
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How does a Gq protein function?
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Activation of a Gq protein activates phospholipase C. Phospholipase C liberates diacylglycerol and IP3 from membrane lipids.
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IP3 signalling mech
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hormone + R--> Gq --> PLC --> DAG and IP3 --> PKC
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Major actions of GHRH?
(growth hormone releasing hormone) |
stimulates s/c of growth hormone
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What does Inositol 1,4,5-triphosphate do?
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IP3 mobilizes Ca2+ from the endoplasmic reticulum. Together Ca2+ and diacylglycerol activate protein kinase C, which phosphorylates proteins.
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which hormones of anterior pituitary most homologous to TSH?
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FSH, LH (identical alpah subunits)
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Major actions of SRIF?
(somatotropin release-inhibiting factor, aka somatostatin) |
inhibits s/c of growth hormone
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How do steroid hormones (and thyroid hormones) function?
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1. Steroid (and thyroid) hormone diffuses across the cell membrane and binds to its receptor.
2. Hormone-receptor complex enters nucleus and dimerizes. 3. Hormone-receptor dimers are transcription factors that bind to steroid-responsive elements (SREs) of DNA and initiate transcription. 5. New mRNA is produced. |
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"children" of POMC
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ACTH, MSH, beta-lipotropin, beta-endorphin
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Major actions of PIF?
(prolactin-inhibiting factor, aka dopamine) |
inhibits s/c of prolactin
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How is the hypothalamus linked to the anterior pituitary and posterior pituitary?
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The anterior pituitary is linked to the hypothalamus by the hypothalamic-hypophysial portal system. Blood from the hypothalamus is delivered directly to the anterior pituitary.
The posterior pituitary is derived from neural tissue. The nerve cells bodies are located in hypothalamic nuclei. Posterior pituitary hormones are synthesized in the hypothalamus and transported to the posterior pituitary for release into circulation. |
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which hormone of anterior pituitary most related to GH?
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prolactin
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What hormones are released by the anterior pituitary?
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TSH, FSH, LH, GH, prolactin, ACTH, MSH
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What are the hypothalamic hormones?
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Thyrotropin-releasing hormone (TRH)
Corticotropin-releasing hormone (CRH) Gonadotropin-releasing hormone (GnRH) Growth hormone-releasing hormone (GHRH) Somatotropin release-inhibiting hormone (SRIF; Somatostatin) Prolactin-inhibiting factor (PIF; dopamine) |
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what increases the pulsatile secretion of GH?
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sleep, stress, puberty, starvation, exercise, hypoglycemia
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Major actions of TSH?
(thyroid-stimulating hormone) |
stimulates synthesis and s/c of thyroid hormones
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What hormones are derived from the precursor pro-opiomelanocortin (POMC)
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ACTH, melanocyte-stimulating hormone (MSH), β-lipotropin, and β-endorphin.
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what decreases GH secretion?
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somatostatin, somatomedins, obesity, hyperglycemia, preggers
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Major actions of FSH?
(follicle-stimulating hormone) |
stimulates growth of ovarian follicles and estrogen s/c; OR promotes sperm maturation
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What is the most important hormone for normal growth to adult size?
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Growth hormone (somatotropin)
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what does GH do in liver?
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causes production of somatomedins (insulin-life growth factors)
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Major actions of LH?
(lutenizing hormone) |
stimulates ovulation, formation of corpus luteum, synthesis of estrogen and progesterone; OR stimulates synthesis and s/c of testosterone
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When is secretion of growth hormone increased? Decreased?
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Secretion is increased by sleep, stress, hormones related to puberty, starvation, exercise, and hypoglycemia.
Secretion is decreased by somatostatin, somatomedins, obesity, hyperglycemia, and pregnancy. |
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4 direct actions of GH
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1. dec'd glucose uptake into cells; 2. inc'd lipolysis; 3. inc'd protein synthesis in mm; 4. inc'd production of IGF
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Major actions of GH?
(growth hormone) |
stimulates protein synthesis and overall growth
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What are the actions of growth hormone?
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a) Decrease glucose uptake into cells
b) Increase lipolysis c) Increase protein synthesis in muscle and increase lean body mass d) Increase production of IGF |
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actions of GH via IGF
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inc'd protein synthesis! In chondrocytes--> growth spurt; in mm-->inc'd lean body mass; inc'd organ size
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Major actions of prolactin?
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stimulates milk production and breast development
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What are the actions of growth hormone via IGF?
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a) Increase protein synthesis in chondrocytes and increase linear growth (pubertal growth spurt)
b) Increase protein synthesis in muscle and increase lean body mass c) Increase protein synthesis in most organs and increase organ size |
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how is prolactin secretion regulated?
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tonic inhibition by dopamine (which is stimulated by PRL); TRH increases PRL secretion
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Major actions of ACTH?
(adrenocorticotropic hormone) |
stimulates synthesis and s/c of adrenal cortical hormones
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What is the difference between gigantism and acromegaly?
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Gigantism is caused by excess growth hormone before puberty.
Acromegaly is caused by excess growth hormone after puberty. |
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4 actions of PRL
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1. stim milk production; 2. stim breast development (w/estrogen); 3. inhibits ovulation via GnRH inhibition; 4. inhibits spermatogenesis
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Major actions of MSH?
(melanocyte-stimulating hormone) |
stimulates melanin synthesis (? humans)
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What occurs in growth hormone deficiency?
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Growth hormone in children causes failure to grow, short stature, mild obesity, and delayed puberty.
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how treat PRL excess?
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bromocriptine (DA agonists)
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What test is used to measure hormone concentrations in bodily fluids?
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Radioimmunoassay
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What are the actions of prolactin?
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a) Stimulates milk production in the breast
b) Stimulates breast development c) Inhibits ovulation (by decreasing GnRH) d) Inhibits spermatogenesis |
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hormones of the posterior pituitary?
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ADH (supraoptic hypothal), oxytocin (paraventricular hypothal)
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How is a radioimmunoassay performed?
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1. soln w/known amt antibody + known amt radioactively labeled hormone, and UNKNOWN amt of target (unlabeled) hormone
2. labeled and unlabeled hormones compete for antibody binding sites 3. high bound/free radioactive hormone = low conc of unlabeled hormone (and vice versa) |
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What hormone stimulates prolactin release?
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Thyrotropin-releasing hormone (TRH)
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what inhibits the iodide pump/trap in thyroid follicular epithelial cells?
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thiocyanate and perchlorate anions
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What are the intermediates in the synthesis pathway from DNA -> hormone?
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DNA -> mRNA -> preprohormone -> prohormone -> hormone
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Where does ADH originate? Where does oxytocin originate?
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ADH: Supraoptic nuclei of the hypothalamus
Oxytocin: Paraventricular nuclei of the hypothalamus |
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Wolff-Chaikoff effect?
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high levels of I- inhibit I- pump
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Where is the DNA transcribed?
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nucleus
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What are the actions of ADH? Where does ADH act?
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1) Increases H2O permeability of the principal cells of the late distal tubule and collecting duct (via V2 receptor, a Gs protein)
2) Constriction of vascular smooth muscle (via V1 receptor, a Gq protein) |
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significance of propylthiouracil?
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inhibits peroxidase enzyme (which first catalyzes oxidation of I- to I2..and then other steps); used for treatment of hyperthyroidism
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Where is the mRNA translated? What is the resulting peptide?
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is translated on ribosomes (on RER) in cytoplasm; end result is preprohormone
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What inhibits the iodide pump (Na-I cotransporter) from transporting I- into the thyroid follicular cells?
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Thiocyanate and perchlorate anions
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what happens when TSh stimulates thyroid?
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iodinated thyroglobulin is taken back into follicular cells, digested and T3, T4 released into circulation. Leftover MIT, DIT deiodinated by thyroid deiodinase
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What must occur to convert a preprohormone to a prohormone?
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signal peptide binds to RER and is cleaved
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What inhibits the oxidation of I- to I2?
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The organification of I- to I2, catalyzed by a peroxidase enzyme, is inhibited by propylthiouracil.
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what happens to T3, T4 in circulation?
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mostly bound to TBG (inc'd in preggers); peripherally, T4-->T3 or rT3
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What must occur to convert a prohormone to a hormone?
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prohormone is transferred to golgi and packaged in secretory vessels, additional peptide sequences are cleaved, resulting in final hormone
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What is the Wolff-Chaikoff effect?
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High levels of I- inhibit organification and therefore inhibit synthesis of thyroid hormone.
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bone manifestation of thyroid deficiency?
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bone age < chronologic age, b/c TH stimulates bone maturations
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What is the precursor for steroid hormones?
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cholesterol
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Which is more active, T3 or T4?
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T3 is more active, though more T4 is synthesized.
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effect of TH on heart?
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upregulates beta 1 R
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What is the common derivative of amine hormones?
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tyrosine
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What converts T4 to T3?
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5'-iodinase
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effect of TH on O2 consumption?
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increases b/c of upregulation of Na-K ATPase (which uses ATP..which comes from O2..kinda)
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What controls the regulation of thyroid hormone?
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TRH stimulates the secretion of TSH, which increases both synthesis and secretion of thyroid hormones.
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which part of adrenal cortex makes mineralocorticoids?
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(outermost) zona glomerulosa (works on kidneys..which have glomeruli)
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What is the effect of thyroid hormones in te heart?
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Increases β1 receptors in the heart, leading to increased cardiac output, heart rate, stroke volume, and contractility.
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which part of adrenal cortex makes glucocorticoids?
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(middle) zona fasciculata
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How does thyroid hormone increase the basal metabolic rate (BMR) of tissues?
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Thyroid hormone increases the synthesis of Na-K ATPase and consequently increases O2 consumption related to Na-K pump activity.
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which part of adrenal cortex makes androgens (DHEA, androstenedione)
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(innermost) zona reticularis (b/c you should be really particularis of your sex partners)
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What are the metabolic effects of thyroid hormone?
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Glucose absorption from the GI tract is increased.
Glycogenolysis, gluconeogenesis, and glucose oxidation are increased. Lipolysis is increased. Protein synthesis and degradation are increased. The overall effect of thyroid hormone is catabolic, however. |
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effect of ACTH on adrenal cortex?
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stimulates cholesterol desmolase thereby increasing steroid synthesis; also upregulates own R
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When are cortisol levels the highest?
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Just before waking up.
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control of aldosterone secretion?
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tonically--ACTH; also Ang II stimulates aldosterone synthase (corticosterone--> aldosterone)
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What is the effect of ACTH?
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ACTH increases steroid hormone synthesis in all zones of the adrenal cortex by stimulating cholesterol desmolase and increasing the conversion of cholesterol to pregnenolone.
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4 actions of glucocorticoids
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1. stim gluconeogenesis; 2. anti inflamm; 3. immunosuppressive; 4. upregulate alpha 1 R on arterioles
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What controls the secretion of aldosterone?
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Aldosterone secretion is under tonic control of ACTH, but is separately regulated by the renin-angiotensin system and by potassium.
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how do glucocorticoids stimulate gluconeogenesis?
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1. increase protein catabolism in mm (more aa available); 2)decrease glucose utilization and insulin sensitivty of fat; 3) increase lipolysis (more glycerol available)
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How does potassium control aldosterone secretion?
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Hyperkalemia increases aldosterone secretion. Aldosterone increases renal K+ secretion, restoring blood [K] to normal.
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how are glucocorticoids anti-inflammatory?
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induce synthesis of lipocortin (inhibits PLA2); inhibit production of IL-2, thereby inhibit proliferation of T cells; inhibit relase of His and serotonin from mast cells, platelets
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What are the general actions of cortisol?
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a) Stimulation of gluconeogenesis
b) Anti-inflammatory effects c) Suppression of the immune response d) Maintenance of vascular responsiveness to catecholamines |
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Name the dz: Increased ACTH, hypoglycemia, hyperpigmentation, ECF volume contraction
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Addison's disease
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What are the stress hormones?
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Growth hormone, Glucagon, Cortisol, Catecholamines
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how is secondary adrenocortical insufficiency different from Addison's?
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no hyperpigmentation; no volume contraxn ,hyperKalemia, metab acidosis
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What is the difference between cortisol and the other stress hormones?
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Cortisol is the only one that does proteolysis (catecholamines and glucagon have no effect on proteins.
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Conn's syndrome leads to?
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HTN, hypokalemia, metab alkalosis, dec'd renin
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What are the anti-inflammatory effects of cortisol?
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a) Induces the synthesis of lipocortin, an inhibitor of phospholipase A2.
b) Inhibit the production of IL-2, which inhibits the proliferation of T lymphocytes c) Inhibit the release of histamine and serotonin. |
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name the dz: decreased cortisol and aldosterone, increased adrenal androgens, virilization, suppression of gonad function
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21 hydroxylase deficiency
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What are the diseases of cortisol?
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Addison's disease
Cushing's syndrome |
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name the dz: decreased androgen and glucocorticoid levels, increased aldosterone, hypoglycemia, lack of pubes
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17 hydroxylase deficiency
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What are the diseases of aldosterone?
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Addison's disease
Conn's syndrome |
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3 major cell types and their main export in islets of Langerhans?
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alpha--glucagon; beta--insulin; delta--somatostatin, gastrin
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How do you differentiate the congenital bilateral adrenal hyperplasias?
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21-hydroxylase deficiency: Hypotension
17α-hydroxylase deficiency: decreased sex hormones 11β-hydroxylase deficiency: increased 11-Deoxycorticosterone (11-DOC) |
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what do delta cells islets of Langerhans secrete?
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somatostatin, gastrin
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What are the actions of glucagon?
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Increases glycogenolysis and gluconeogensis.
Increases blood fatty acid and ketoacid concentration. Increases urea production (from amino acid) |
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what stimulates glucagon release from alpha cells?
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decreased blood glucose
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What are the actions of insulin?
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Insulin decreases blood glucose concentration by:
- increasing uptake of glucose - promoting formation of glycogen - decreasing gluconeogenesis Insulin decreases fatty acid and ketoacid concentrations. Insulin decreases amino acid and K+ concentration. |
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3 actions of glucagon
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1. increase blood glucose; 2. increase blood FA, ketoacids; 3. increase urea production
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What are the actions of PTH?
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- Increases bone resorption, bringing both Ca and phosphate into ECF.
- inhibits renal phosphate reabsorption - increases renal Ca reabsorption in the distal tubule - increases production of Vitamin D (increasing intestinal Ca absorption) |
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mechanism of insulin secretion?
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glucose binds GLUT 2 on beta cell membrane--> depolarization of membrane--> Ca channel opens, influx --> insulin secretion
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What are the actions of Vitamin D?
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- Increases intestinal Ca absorption
- increases intestinal phosphate absorption - increases renal reabsorption of both Ca and phosphate - increases bone resorption (providing Ca and phosphate from "old" bone to mineralize "new" bone) |
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why get hyPOtension in uncontrolled DM?
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high [glucose] exceeds Tm in kidney so urine is very sugary-->osmotic diuretic
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what stimulates secretion of PTH?
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dec'd Ca; mildly dec'd Mg (severe hypoMg inhibits PTH secretion!)
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"goal" of PTH
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increase calcium, decrease phosphate
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4 actions of PTH
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1. increase bone reabsorp.; 2 inhibit renal phosphate reabsorp.(PCT); 3. increase renal Ca reabsorp.; 4. stimulate production of active vit D
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Albright's hereditary osteodystrophy
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pseudohypoparathyroidism cause by defective Gs in kideny and bone-->end organ resistance to PTH
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how does chronic renal failure lead to hypocalcemia?
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increased GFR--> increased sr phosphate which complexes with Calcium, thereby decreasing free Ca; also decreased vit D
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"goal" of vit D
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increase calcium and phosphate in ECF for bone mineralization
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Calcitonin: a) where b)stim'd by c)action
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a)parafollicular thyroid cells; b) increased sr Ca; c) inhibit bone reabsorp.
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what do Leydig cells make?
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testosterone
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why can't Leydig cells make glucocorticoids and mineralocorticoids?
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no 21 beta hydroxylase or 11 beta hydroxylase
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significance of 5 alpha reductase?
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enzyme that converts testosterone to DHT, found in accessory sex organs like the prostate
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significance of finasteride?
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inhibits 5alpha reductase (can tx BPH)
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FSH acts on Sertoli cells to?
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stimulate production of inhibin which has negative feedback effect on FSH
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what do theca cells make?
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androgens which are converted to estrogens by aromatase in granulosa cells
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2 causes of end organ ADH resistance
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1. drugs (Li!!! Inhibits Gs); 2. severe hypercalcemia (inhibits AC)
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which diuretics can also be used for treatment of acute mountain sickness?
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carbonic anhydrase inhibitors like acetazolamide (metabolic acidosis to combat respiratory alkalosis)
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why get HTN in 11beta hydroxylase deficiency?
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the precursor that the enzyme would act on is a weak mineralocorticoid
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