L25: Renal System III

Question 1

aldosterone

Answer 1

a steroid hormone released from the adrenal cortex that regulates both Na+ reabsorption and K+ secretion

Question 2

aldosterone pathway step 1

Answer 2

aldosterone binds to cytosolic receptors in renal tubule cells of the distal tubule and collecting duct

Question 3

aldosterone pathway step 2

Answer 3

hormone-receptor complex initiates transcription in the nucleus

Question 4

aldosterone pathway step 3

Answer 4

the synthesis of new channels and Na+/K+ pumps

Question 5

aldosterone pathway step 4

Answer 5

aldosterone-induced proteins modify existing channels

Question 6

aldosterone pathway result

Answer 6

increased Na+ reabsorption and K+ secretion

Question 7

aldosterone increases Na+ reabsorption and K+ secretion __

Answer 7

simultaneously

Question 8

the most important factor in the control of aldosterone release

Answer 8

renin-angiotensin-aldosterone (RAAS)

Question 9

__ secrete renin

Answer 9

granular cells in the juxtaglomerular apparatus

Question 10

renin

Answer 10

proteolytic enzyme

Question 11

__ within the walls of the distal tubule detect changes in the Na+ and Cl- concentrations in the flow of the tubular fluid

Answer 11

macula densa

Question 12

when sodium concentration in the tubular fluid decreases,

Answer 12

renin secretion increases

Question 13

juxtaglomerular apparatus is formed where

Answer 13

the distal tubule travels close to the afferent and efferent arterioles

Question 14

___ inputs to the granular cells to trigger Renin release

Answer 14

three distinct

Question 15

first input to trigger renin release

Answer 15

a decrease in blood pressure, more specifically, in afferent arteriole pressure, because granular cells are directly sensitive to the degree of stretch of the afferent arterioles

Question 16

second input to trigger renin release

Answer 16

a decrease in blood pressure causes GFR decrease, leading to Na+ and Cl- decrease in the distal tubules; this triggers macula densa cells secrete a chemical signal stimulating renin release

Question 17

third input to trigger renin release

Answer 17

a decrease in blood pressure, baroreceptor reflex, sympathetic activity

Question 18

renin release from the granular cells into the bloodstream

Answer 18

starts a series of reactions that lead to Aldosterone release

Question 19

1: renin act on the protein ___, that is always secretes in the plasma by __

Answer 19

angiotensinogen, the liver

Question 20

2: renin cleaves off some __ from ___ converting it to ___

Answer 20

amino acids, angiotensinogen, angiotensin I

Question 21

3: angiotensin I is converted to __ by __ enzyme, which is bound to ___

Answer 21

angiotensin II, angiotensin-converting-enzyme (ACE), inner surfaces of capillaries

Question 22

angiontensin II important functions

Answer 22

stimulation of aldosterone release from the adrenal cortex; the increase of mean arterial pressure by acting as a vasoconstrictor; acting in the hypothalamus to stimulate vasopressin release and thirst

Question 23

angiotensin II increases MAP by four mechanisms

Answer 23

vasoconstriction of systemic arterioles (TPR up, MAP up);
stimulation of hypothalamic neurons for thirst and fluid intake (volume up, MAP up);
stimulation of ADH secretion to minimize fluid loss and maintain plasma volume (volume up, MAP up);
stimulation of aldosterone secretion by adrenal cortex (water reabsorption up)

Question 24

atrium natriuretic peptide (ANP) is secreted by cells

Answer 24

in the atria of the heart

Question 25

ANP are released in response to

Answer 25

distension of the atrial wall, which occurs when plasma volume has increased

Question 26

ANP increases

Answer 26

sodium excretion by increasing GFR and by decreasing Na+ reabsorption

Question 27

ANP affect on kidney arterioles

Answer 27

dilation of afferent arterioles, constriction of efferent arterioles

Question 28

what does dilation of afferent and constriction of efferent lead to?

Answer 28

increase in glomerular capillary pressure, GFR increase, the filtered sodium load increase

Question 29

increase in GFR causes

Answer 29

increased Na+ excretion

Question 30

AND decreases sodium reabsorption

Answer 30

by decreasing the number of open sodium channels in the apical membranes of renal tubular cells

Question 31

ANP ___ secretion of ___

Answer 31

decreases, renin and aldosterone