Physiology-Aldosterone & Catecholamines

Question 1

5 mechanisms for regulating fluid and electrolyte balance

Answer 1

1) ADH 2) Thirst 3) RAAS 4) ANP 5) Na Appetite

Question 2

Regulation of aldosterone secretion

Answer 2

RAAS, serum K+ and to a lesser degree ACTH

Question 3

What does aldosterone do at the distal nephron?

Answer 3

Excretion of K+ and H+. Reabsorption of Na+

Question 4

How does the body deal with an increased sodium load?

Answer 4

Osmoreceptors in macula densa decrease aldosterone release and inhibit RAAS -> Na secretion & K reabsorption -> K uptake in cells to prevent hyperkalemia -> normal Na level restored -> RAAS starts again -> Na reabsorption & K secretion begins

Question 5

What are the functional components of the juxtaglomerular apparatus?

Answer 5

Baroreceptors, chemosensor and neuroendocrine transducer. Granular cells secrete renin, macula densa cells do the sensing.

Question 6

Principle drivers for renin output

Answer 6

1) Low sodium 2) Low volume 3) Low pressure 4) Hyperkalemia

Question 7

Strongest vasoactive compound

Answer 7

ATII

Question 8

How does hyperkalemia affect the adrenal cortex?

Answer 8

It acts directly on the zona glomerulosa to stimulate aldosterone secretion

Question 9

How do ACTH and ATII affect synthesis of cortisol and aldosterone?

Answer 9

ACTH has a greater effect on cortisol synthesis when it binds the zona fasciculata. ATII has a greater effect on aldosterone synthesis when it binds the zona glomerulosa.

Question 10

What happens if you have too much aldosterone?

Answer 10

Hypernatremia, hypertension and hypokalemia

Question 11

A patient presents with hypertension, weakness, polyuria and metabolic alkalosis. She is fluid overloaded and you determine she has primary hyperaldosteronism. What is likely causing her condition?

Answer 11

Adrenal tumor secreting aldosterone on its own or renin suppression causing hypernatremia and hypokalemia.

Question 12

A patient presents with low blood pressing, edematous legs and hypokalemia. He is low on blood volume and you determine he has secondary hyperaldosteronism. What is likely causing his condition?

Answer 12

Adrenal hyperplasia driven by RAAS due to ascites and fluid leaving the vasculature, making the JG cells sense low blood volume. Renal artery stenosis can also cause this.

Question 13

How does congenital adrenal hyperplasia in a genetic female occur?

Answer 13

The enzyme deficiency in 21-hydroxylase causes cholesterol intermediate shunting towards androgens instead of making aldosterone & cortisol. The hypothalamus continues to sense deficiency in cortisol so CRH is continually released, the adrenal gland grows and more androgens are produced. Too much androgen in a developing female causes masculinization of the genitalia.

Question 14

What do chromaffin cells do?

Answer 14

Synthesize, store and secrete NE and EPI.

Question 15

Integrated response for alpha and beta adrenergic stimulation during fight or flight response.

Answer 15

Alphas always win (example of insulin secretion being inhibited by alpha stimulation be activation by beta stimulation)

Question 16

Name some symptoms that occur during or following paroxysms in people with pheochromocytomas.

Answer 16

Headache, sweating, palpitations, impending death feeling, tremor, exhaustion, nausea, chest/abdominal pain or visual disturbances.

Question 17

Symptoms between paroxysms in people with pheochromocytomas.

Answer 17

Sweating, cold hands/feet, weight loss and constipation

Question 18

Why do most people with pheochromocytomas die?

Answer 18

MI, stroke, arrhythmia, shock, renal failure, aortic dissection. This is all from severe fight or flight stimulation.

Question 19

How do you treat someone with a pheochromocytoma?

Answer 19

1) Surgery. Alpha blockers to decrease BP, beta blockers to decrease HR, contractility and renin production, Ca-channel blockers to decrease HR and contractility and catecholamine synthesis inhibitors.

Question 20

A cell responding to a hormone has an immediate increase in intracellular concentrations of cAMP and Ca2+. The hormone is A) Progesterone B) Cortisol C) Aldosterone D) Testosterone E) Epinephrine

Answer 20

E. EPI is the only one not a steroid and acts on cell surface receptors. It is also the only one that causes an immediate change.

Question 21

Sectioning of the pituitary stalk will result in?

Answer 21

Polyuria, polydipsia and hyperprolactinemia

Question 22

A rapid expansion of the intra-vascular volume by an infusion of 2L isotonic saline will normally be compensated by?

Answer 22

Decrease in AT II production

Question 23

Cirrhosis of the liver results in ascites and decreases the effective blood volume (from intravascular fluid leakage). Appropriate compensatory responses to correct this condition include?

Answer 23

Increased sodium reabsorption by the nephron

Question 24

A substance isolated in the blood has the following characteristics: small, lipid soluble, binds to receptors located in the nucleus and increases blood volume when administered over time. The isolate substance is most likely?

Answer 24

Aldosterone