Tuesday, February 13, 2007


Second Messengers:

(a) Phosphodiesterase (PDE) convert cAMP to AMP + inorganic phosphate.
(b) PDE inhibiors augment the effects of cAMP by slowing down its degradation.
(c) The cGMP pathway is atleast as widespread as the cAMP pathway.
(d) Phosphatidyl inositol bisphosphate (PIP2) is a second messenger.
(e) IP3/Ca2+ is a very widespread chemical transduction system.

(2) Intracellular signalling:

(a) Inositol is a lipid.
(b) Inositol normally occurs in a bound form in the body.
(c) Cortisol combines with a specific protein receptor on an intracellular organelle.
(d) G proteins couple cell surface receptors with intracellular effectors.
(e) Increased G protein activity is typical of generalized resistance to hormone action, e.g. resistance to PTH (parathyroid hormone), thyrotrophin, and gonadotrophins.

(3) Concerning iodine and the thyroid:
(a) Iodine is converted to iodide before absorption in GIT.
(b) Iodide trapping is helped by an electrical gradient into the follicle cell.
(c) Iodide trapping is a primary active process.
(d) TSH stimulates iodide uptake at all iodide trapping sites in the body.
(e) Perchlorate is a competitive inhibitor for iodide trapping.

(4) In the hormonal control of calcium:
(a) Calcitonin comes from cells of neuroectodermal origin.
(b) Calcitonin is an important physiological regulator of plasma calcium.
(c) Hypocalcaemia is the main stimulus for calcitonin release.
(d) Parathyroid hormone (PTH) is essential for life.
(e) PTH is stored in granules in the parathyroid.

(5) Atrial natriuretic factor (ANF):
(a) type A is chiefly found in the myocytes of the right atrium.
(b) type A is released in hypovolaemia.
(c) inhibits the renin-angiotensin-aldosterone axis.
(d) causes natriuresis and vasodilation.
(e) has its actions potentiated by neutral endopeptidase inhibitors.

(6) In the normal function of the adrenal medulla:
(a) The basal secretion of catecholamines is important for maintaining vascular tone.
(b) Adrenaline causes vasoconstriction in the skin.
(c) Basal NA secretion has a significant biological effect.
(d) Significant secretion is only stimulated by sympathetic activity.
(e) Adrenaline inhibits lipase in adipose tissue.

(7) Cortisol:
(a) is the only glucocorticoid secreted in significant amounts in humans.
(b) acts at cell level by directly stimulating/inhibiting enzymes.
(c) increases liver glycogen stores.
(d) stimulates the use of glucose in peripheral tissues.
(e) helps to mineralize bone.

(8) Concerning aldosterone formation and secretion:
(a) Aldosterone is formed only in the zona glomerulosa.
(b) Angiotensin II is the most important regulator of aldosterone.
(c) The renin-angiotensin system is found in the adrenal cortex.
(d) ACTH has no effect on aldosterone secretion.
(e) Potassium sitmulates aldosterone release.

(9) Insulin:
(a) is the most powerful hypoglycaemic agent in the body.
(b) inhibits free fatty acid (FFA) release from tissues.
(c) inhibits lipoprotein lipase (LPL).
(d) inhibits hormone-sensitive lipase.
(e) facilities transport of amino acids secondary to glucose.

(10) Glucagon:
(a) consists of a double polypeptide chain similar to insulin.
(b) stimulates the secretion of somatostatin.
(c) stimulates gluconeogenesis at physiological levels.
(d) is the most important hormone in preventing fasting hypoglycaemia.
(e) is a strong lipolytic agent in adipose tissue.

(11) Prolactin (PRL):
(a) is synthesized in the same cells as GH.
(b) plasma levels are only slightly higher in females than in males.
(c) inhibiting factor (PIF) is tonically released from the hypothalamus.
(d) release is stimulated by cortisol.
(e) excess in hyperprolactinaemia is treated with 5-HT or 5-HT agonists.

(12) Posterior pituitary hormones:
(a) Oxytocin and arginine vasopressin (AVP) are formed in the pars nervosa of the pituitary (posterior pituitary).
(b) Oxytocin and AVP are stored with specific proteins in the pituitary.
(c) Oxytocin effects are inhibited by progesterone.
(d) Oxytocin secretion is stimulated by the enlarging uterus in pregnancy.
(e) Oxytocin is a strong lactogenic hormone.
Endocrinology:ans.True or false

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