renal 7 - aldosterone secretion? 3 things effect it

Question 1

What is aldosterone?

Answer 1

primary influencers of sodium by controling reabsorbtion

Question 1

what stimulates aldosterone secretion?

Answer 1

renin-angio-system

atrial natriuretic peptide (opp of renin)

potassium balance

Question 2

name the 5 step on how aldosterone acts on principle cells

Answer 2

1 aldosterone combines with cytoplasmic receptor

2 hormone-receptor starts transcription in nucleus

3 protien synthesis makes new protien channels and pumps

4 aldosterone connects with a protien to modulate the channels and pumps

5 lets Na+ through to reabsorb & K+ in back in to secrete (symport)

Question 3

what benefits does secreting K+ have using aldosterone?

Answer 3

i) K+ acts on adrenal cortex which protects the body from hyperkalema (too much K+)

ii) decreased blood pressure makes RAS pathway activate which acts on adrenal cortex which releases aldosterone which leads to K+ secretion

iii) large drops in Na+ can sometimes stimulate K+ secretion

Question 4

_____ osmolarity acts directly on the adrenal cortex during dehydration to INHIBIT K+ release

Answer 4

increased

Question 5

What is Renin-angiotensin-system (RAS)

Answer 5

a multi-step pathway for maintaining blood pressure

Question 6

In RAS, what happens when blood pressure drops?

Answer 6

the drop will increase symathetic activity which tells Granular cells in afferent arteriole to produce RENIN (enzyme) which tells Angiotensinogen to cook up angiotensin 1

Question 7

what does ANG 2 do?

Answer 7

tells hypothalamus to increase Vasopressin which helps maintain osmolarity

tells adrenal cortex to increse aldosterone which increases Na+ reabsorbtion and K+ secretion

tells medulla oblongata to increase Cardiovasular response which increases blood pressure

Question 8

what THREE stimuli does RENIN need to begin secreting

Answer 8

a) low blood pressure

b) when low blood pressure - sypathetic neurons CV controlcenter

c) paracrine feedback (prostoglandins) from macula desa cells signal to granular cells to start cookin some RENIN

Question 9

what are GRANULAR CELLS also known as?

Answer 9

juxtaglomerular cells

Question 10

what is RENINS main role? (Renin-agiotensin pathway)

Answer 10

renins main role is convert Angiotensinogen, into Angiotensin 1

Angiotensin 1 is turned into Angiotensin 2 by the ACE enzyme

ANG 2 drivesto adrenal cortex and tells it to cook up some aldosterone

Question 11

When ANG2 tells adrenal cortex to cook up some aldosterone, what are some effects?

Answer 11

1. increase sypathetic
2. Na+ reabsorbtion K+ secretion
3. THIRST
4. potent vasocontriction to increase blood pressure
5. Pituitary gland: ADH or AVP secretion: H2O absorbtion
6. increse vasopressin secretion

ALL THIS is used to RESTORE blood pressure!!

Question 12

What are pharmacies doing to combate hypertension?

Answer 12

ACE inhibitors, so that ANG1 cant become ANG2

relaxes vasculature and lowers BP

Question 13

Atrial natriuretic Peptide, ANP

Answer 13

promotes Na+ and WATER excretion

Question 14

when increase blood volume causes artial strech, what happens?

Answer 14

natriuretic peptides pull up.

4 things

1. hypothalamus: less vasopressin
2. kidney: increased GFR & reduced RENIN
3. Adrenal cortex: inhibits Aldosterone
4. medulla: acts on CVCC to decrease blood pressure

ALL OF EM decrease BP

Question 15

What is the third thing that effects aldosterone secretion?

Answer 15

Potassium Balance

Question 16

where is potassium reabsorbed?

Answer 16

proximal tubule and ascending limb of loop henle

Question 17

where is potassium secreted?

Answer 17

at distal tubule and cortical collecting duct

Question 18

normally, how much K+ is excreted

Answer 18

10-20% of th filtered load

Question 19

what does low K+ do?

Answer 19

decreases aldosterone release, reducing secretion which reduces excretion by about 2% yur

Question 20

what does high K+ do?

Answer 20

stimulates aldosterone relase, increases secretion and excretion goes up to 10-150%

Question 21

what is the narrow range that K+ needs to be kept at in plasma?

Answer 21

3.5 - 5 mM

otherwise can alter resting membrane potiental

Question 22

potassium imbalace can lead to ___kalemia

Answer 22

hypokalemia - difficult to fire AP’s

hyperkalemia (dangerous) - cells cant repolarize and become less excitable (leads to heart failure)