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Endocrinology Study Guide

by: Natasha Hede

Endocrinology Study Guide BIOL 4354

Marketplace > University of Houston > Biology > BIOL 4354 > Endocrinology Study Guide
Natasha Hede
GPA 3.2
Margaret Warner

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About this Document

Sum up of terms and brief details we'll need to know for the second exam.
Margaret Warner
Study Guide
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Popular in Endocrinology

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This 4 page Study Guide was uploaded by Natasha Hede on Sunday March 8, 2015. The Study Guide belongs to BIOL 4354 at University of Houston taught by Margaret Warner in Spring2015. Since its upload, it has received 767 views. For similar materials see Endocrinology in Biology at University of Houston.


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Date Created: 03/08/15
Endocrinology Sum Up Guide What You Need To Know HypothalamicPitaitary Hormone Properties All related hormones are water soluble Pulsatile hormonerelease system except thyroid system HypothalamicPitaitary Hormone Production Neuronal cell bodies in the arcuate and paraventricular nuclei TRH CRH GHRH somatostatin PIF Preoptic nucleus GnRH Hormone Transport Hypothalamus to hypophysealportal system to anterior pituitary Pituitary stalk Connects hypothalamus and anterior pituitary if cut only prolactin increases causing hyperprolactinemia HypothalamicPitaitary Hormone Effects TRH affects TSH CRH affects ACTH GnRH affects LH FSH GHRH affects GH Somatostatin affects GH PIFdopamine affects prolactin Sheehan Syndrome Pituitary in pregnancy is enlarged and vulnerable to infection Hyperprolactinemia Causes medications or diseases affecting hypothalamus or pituitary stalk Findings in men galactorrhea decreased libido impotence hypogonadism Findings in women amenorrhea galactorrhea Treatment surgically remove tumor or give bromocriptine Layers of the Adrenal Gland Adrenal cortex is divided into 3 zones zona glomerulosa outer zona fasciculata middle and zona reticularis Zona Glomerulosa 15 of adrenal gland secretes mainly mineralocorticoids Zona Fasciculata 50 of adrenal gland secretes glucocorticiods Zona Reticularis 7 of adrenal gland secretes androgens Role of Cholesterol Cells in all three layers have high lipid content mainly cholesterol esters Cholesterol is used for the synthesis of steroid hormones This cholesterol is absorbed from LDL uptake from blood and synthesis from acetylCoA All adrenocortical hormones represent chemical modifications of the steroid nucleus a 21 carbon atom4 ring structure derived from cholesterol Control of Hormonal Secretion Secretion by zona fasciculata and zona reticularis is mainly controlled by the hypothalamic pituitary system Secretion by zona reticularis may be controlled by ACTH through a negativefeedback cycle 0 Low blood levels of glucocorticoids mainly cortisol stimulate neurosecretory cells in the hypothalamus to secrete corticotroinreleasing hormone CRH which promotes release of ACTH from anterior pituitary Role of ACTH and Protein Kinase A ACTH ows in the blood to adrenal cortex stimulating glucocorticoid secretion ACTH binds to its receptors on the plasma membrane of zona fascitulata and reticularis cells activating protein kinase A 0 Protein kinase A increases activity of cholesterol ester hydrolase increasing conversion of cholesterol esters to free cholesterol which also leads to the formation of pregnenolone a rate limiting step in steroid synthesis 0 Thus cortisol is produced from cholesterol esters FACTORS INFLUENCING ACTH ACTIVITY STIMULATION CRH Cortisol decrease adrenalectomy metyrapone Sleepwake transition 0 Stress ADH alphaadrenergic agonists betaadrenergic antagonists Others serotonin Ach interleukins gastrointestinal peptides INHIBITION Cortisol increase Encephalins GABA Opioids ACTH Plasma Cortisol level increased by 0 Factors increasing ACTH production 0 Stress Surgery 0 Burns Infection Fever Psychosis Acute anxiety Prolonged and strenuous exercise Hypoglycaemia Cortisol Metabolism Cortisol isn39t broken down in tissues where it exerts its functions but is converted to a less active state called cortisone Some is excreted in urine unchanged 0 Some is degraded in liver to inactive dihydrocortisol and tetrahydrocortisol which are conjugated with glucuronic acid Thus renal excretion of corticosteroids and their metabolites can measure steroid output and metabolism over a 24hour period Mineralocorticoids Aldosterone is a major mineralocorticoid It is Synthesised exclusively in the zona glomerulosa cells 0 It regulates homeostasis of two mineral ions Na and K that help regulate blood and volume Aldosterone secretion is controlled by the renninangiotensinaldosterone pathway Dehydration gt decrease in blood volume gt decrease in BP gt stimulation of juxtaglomerular cells in kidneys gt increased rennin gt liver produces angiotensin gt increased angiotensin I gt ACE converts angiotensin I to angiotensin II gt adrenal cortex produces aldosterone gt increased Na and water absorption in kidneys gt increased blood volume gt increased BP gt vasoconstriction of arteries ANP inhibits synthesis and release of aldosterone Some converted in the liver to tetrahydroaldosterone glucuronide Some conjugated with glucuronic acid in liver and kidney at 18 oxoposition Very little free aldosterone in urine Aldosterone stimulates K secretion in renal tubes Adrenocorticoretical Sex Hormones Sex hormones are produced mostly in zona reticularis ACTHCortisol connection ACTH controls secretion of cortisol and adrenal androgens Low dose dexamethasone suppresses pituitary ACTH secretion and therefore 17 hydroxycorticosteroid production and excretion in people with a normal pituitary response to the negative feedback action of glucocorticoids Angiotensin II controls secretion of aldosterone Regional Adrenal functions Zona glomerulosa Produces aldosterone Damage results in Na loss decreased ECF volume low BP circulatory shock death Zona fasciculate and zona reticularis Produces cortisol and androgens Damage results in circulatory failure inability of release glucose and fatty acids in plasma Medulla Produces epinephrine Damage results in inability of release glucose and fatty acids in plasma C21 steroids Cortisol excreted as HZOsoluble metabolites C19 steroids Adrenal androgens DHEA Testosterone C18 steroids Estrogens eg estradiol Aromatase converts androgens into estrogens See Synthesis and Deficiencies of Adrenal Hormones Actions of Glucocorticoids These include GH glucagon corisol and epinephrine Released under stress Insulin decreases under stress Metabolic Actions of Cortisol Protein degradation lipolysis mobilized plasma glucose Permissive Actions of Cortisol Enhances activity of glucagon and catecholamines Control of ACTH and Cortisol Secretion Stress releases CRH increased in morning and decreased during night ACTH endorphins released in end ACTH causes release of cortisol excessive secretion darkens skin Addison39s disease Endorphin pain modulators Cashing Syndrome Secondary hypercortisolism due to pituitary malfunction Physiologic Actions of Aldosterone Aldosterone tells collecting ducts in kidneys to absorb Na in exchange of K Tubule lumen becomes charged attracts H and K Control of Aldosterone Secretion ACTH stimulates aldosterone secretion Renninangiotensin system promotes aldosterone secretion 0 RA system stimulated by sensory cells in juxtaglomerular apparatus monitor afferent arteriole pressure Angiotensin II Secreted due to low BP low Na increased simulation of juxtaglomerular cells 0 Causes vasoconstriction increased TPR release of aldosterone Aldosterone Control Increased in hemorrhage sweating hyperkalemia etc Decreased in weightlessness eg outer space water Addison 39s Disease Primary hypoaldosteronism Primary adrenal insufficiency High ACTH and hyperpigmentation Hypotension decreased glucocorticoids and mineralocorticoids Increased renin and angiotensin Loss of female body hair due to decreased androgens Decreased glucocorticoids decreased glucose Increased ADH Secondary Hyperaldosteronism Blood collects in venous system Decreased CO BP Caused due to CHF hepatic cirrhosis constriction of vena cava


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