Renin-Angiotensin-Aldosterone System

Question 1

where is the RAAS controlled?

Answer 1

kidney

Question 2

what structure in the kidney controls the RAAS?

Answer 2

juxtaglomerular apparatus

Question 3

what does the juxtaglomerular apparatus consist of?

Answer 3

JG cells & macula densa

Question 4

where are JG cells located?

Answer 4

afferent & efferent arterioles

Question 5

what is the function of JG cells?

Answer 5

make and secrete renin (enzyme)

Question 6

where is the macula densa located?

Answer 6

distal convoluted tubules between afferent & efferent arterioles

Question 7

what is the macula densa sensitive to?

Answer 7

• low NaCl
• low BP
• increased sympathetic stimulation (beta adrenergic stim by E)

Question 8

what is the function of the macula densa?

Answer 8

(turns on RAAS)
- stimulate JG cells to release renin
- release NO

Question 9

what is the effect of NO released from the macula densa?

Answer 9

dilate afferent arteriole

Question 10

what happens to GFR when the afferent arteriole is dilated?

Answer 10

increases

Question 11

what does renin do?

Answer 11

convert angiotensinogen (from liver) -> angiotensin I (in blood)

Question 12

where is angiotensin coverting enzyme (ACE) located?

Answer 12

lung

Question 13

what is the function of ACE?

Answer 13

converts angiotensin I -> angiotensin II (in blood)

Question 14

what are the functions of angiotensin II?

Answer 14

• release aldosterone from zona glomerulosa (adrenal glands; increases Na/K pump)
• constrict efferent arteriole

Question 15

what happens when the efferent arteriole is constricted?

Answer 15

• increases GFR & decreases urine volume
• leads to increased blood volume & BP

Question 16

what is the function of aldosterone in the RAAS?

Answer 16

• causes increase in blood Na concentration
  -> causes release of ADH
  -> increases blood volume & BP

Question 17

what are the only 2 things that can constrict the efferent arterioles?

Answer 17

ADH and angiotensin II

Question 18

if a tumor or pathology exists in a pathway, what happens to everything before and after that step?

Answer 18

decrease before
increase after

Question 19

if a drug functions to block a step of a pathway, what happens to everything before and after that step?

Answer 19

• increase before (attempt to increase next step)
• decrease after (blocks action)

Question 20

what percent of filtrate is reabsorbed?

Answer 20

99%

Question 21

what happens to blood volume and urine volume when filtrate is reabsorbed?

Answer 21

increased blood volume
decreased urine volume

Question 22

dilation of the afferent arteriole leads to what physiological changes?

Answer 22

• vasodilation
• increased compliance
• increased hydrostatic P
• increased blood flow
• decreased resistance

Question 23

constriction of the efferent arteriole leads to what physiological change?

Answer 23

vasoconstriction

Question 24

dilation of the afferent arteriole in combination with constriction of the efferent arteriole leads to…

Answer 24

increased GFR
increased BP

Question 25

what effect would a 50% decrease in efferent arteriolar resistance have on GFR?

Answer 25

large decrease in GFR (greater than 10%)

Question 26

increases in both renal blood flow and GFR are caused by what mechanism?

Answer 26

dilation of afferent arterioles
(increases glomerular hydrostatic P -> increases GFR & renal blood flow)