adrena physiology

Question 1

what are the products from the Zona glomerulosa of the adrenal cortex

Answer 1

• mineralcorticoid = aldosterone

Question 2

what are the products from zona fasciculata

Answer 2

• glucocorticoids = corisol and cortiocosterone

Question 3

what are the products from zona reticularis

Answer 3

• androgens = DHEA and aldrostenedione

Question 4

How does ACTH increase adrenal steroid synthesis

Answer 4

• ACTH controls the conversion of Cholesterol to Pregnenolone by P450cc (Pregnenolone is required by all sterioid)
• ACTH binds to and activates the GPCR melanocortin 2 receptor on the surface of adrenal cortex cell
• upregulates steroidogenic enzyme expression

Question 5

what are the effects of cortiosl

Answer 5

• increases blood glucose
• Increases bone matrix reabsorption and calcium excretion
• increased cardiac output
• increased expression of receptors for epinephrine and norepinephrine
• inhibits immune system
• decreases fibroblast proliferation (leads to decrease in CT)

Question 6

what are the effects of aldosterone

Answer 6

• increases blood volume and pressure

- increases Na and H20 reabsorption and decreases K reabsorption

Question 7

how does cortisol increase plasma glucose levels?

Answer 7

• in liver, increased gluconeogenesis and glycogenesis
• in skeletal muscle decreased gluc. uptake and increased glycogenesis and protein catabolism
• in adipose, decreased gluc. uptake and increased lipolysis

Question 8

how does aldosterone increase water and sodium reabsorption

Answer 8

• aldosterone binds to and activates mineralocorticoid receptors (MR) in distal convoluted tubule and colelcting ducts cytoplasm
• MR translocates to nucelus to increase gene transcription of ENaC and Na/K pumps
• ENaC transports Na into cell and Na/K ATPase transports it out to blood
• WATER FOLLOWS SODIUM

Question 9

What catecholamines are released by adrenal medulla

Answer 9

• epinephrine and norepinephrine

Question 10

how does cortiosl regulate synthesis of epinephrine

Answer 10

• cortisol increases expression of the enzyme that converts norep into epinephrine

Question 11

How does cortisol facilitate the effects of norepinephrine and epinephrine

Answer 11

cortisole induces expression receptors for norep and ep

Question 12

describe cushings syndrome

Answer 12

• pituitary hypersecretion of ACTH –> leads to over secretion of cortisol
• Adrenal adenoma –> hypersecretion of cortiosl and neg feedback on pit so low ACTH
• Ectopic ACTH production occurs in lung cancer
• Latrogenic cushing syndrome (prescribe cortisol can cause this)

Question 13

describe addison’s disease (primary)

Answer 13

• autoimmune destruction of adrenal cortex zones
• causes deficiency in cortiosl, aldosterone and androgens
• High levels of ACTH and CRH
• Hypotension from unresponsiveness of smooth muscle to catecholamines
• Hypoglycemia, hyponatremia, hyperkalemia, wt loss, hyperpigmentation etc

Question 14

describe secondary adrenal insufficiency

Answer 14

• caused by pituitary or hypothalamic disorders or chronic glucocorticoid therapy
• symptoms are similar to primary.
• aldosterone secretion is usually preserved however

Question 15

describe the effects of 21-hydroxylase deficiency

Answer 15

• aldosterone and cortisol can’t be formed
• most newborns screened for this
• virilization due to accumulation of androgens
• Females with male genitalia, or males with adult size sex organs
• aldosterone deficiency can lead to salt wasting, shock and dehydration

Question 16

Describe the effects of 17alpha-hydroxylase deficiency

Answer 16

• normal values of aldosterone but no glucocorticoids or androgens

Question 17

describe the effects of 3beta-hydroxysteroid dehydrogenase deficiency

Answer 17

• results in no aldosterone or glucocorticoids but normal values of androgens

Question 18

describe the effects of 11beta-hydroxylase deficiency

Answer 18

• results in no glucocorticoids and mineralocorticoids (aldosterone and cortisol)