Ex 3 Hormone control of the heart

Question 1

What does RAS stand for?

Answer 1

Renin-Angiotensin System

Question 2

What is RAS?

Answer 2

The result of renin cleaving angiotensinogen (large liver protein) to form Angiotensin I, then Angiotensin II

Question 3

Where does angiotensinogen reside?

Answer 3

freely in the blood

Question 4

Which is the most active peptide in the Renin-Angiotensin system cascade?

Answer 4

Angiotensin II

Question 5

How is angiotensin form?

Answer 5

angiotensinogen is cleaved by Renin (from the kidney) to form angiotensin I

Question 6

How is angiotensin II formed?

Answer 6

angiotensinogen I is cleaved by angiotensin converting enzyme (ACE) in the lung to form angiotensin II

Question 7

How is the Renin-Angiotensin System regulated?

Answer 7

the rate limiting step is the release of renin

Question 8

Where is ACE found (angiotensin converting enzyme) in the body?

Answer 8

in the endothelial cells

Question 9

How are most effects of AngII are mediated through what?

Answer 9

AT1 receptor

Question 10

What are the effects of Angiotensin II on vasculature?

Answer 10

acute peripheral vasoconstriction

Question 11

What are the effects of Angiotensin II on the kidney?

Answer 11

decrease sodium and water excretion

Question 12

What are the effects of Angiotensin II on the stimulation of vasopressin (ADH) release?

Answer 12

increase thirst (dipsogenic), water retention by kidney

Question 13

What are the effects of Angiotensin II on aldosterone production?

Answer 13

increase sodium and water retention by kidney

Question 14

What are the chronic effects of angiotensin II?

Answer 14

growth factor which leads to vascular and cardiac hypertrophy

Question 15

Angiotensin II also activates central nervous system which contributues to what?

Answer 15

mediate sympathetic outflow

Question 16

Where is renin released?

Answer 16

juxtaglomerular cells

Question 17

This is a specialized structure formed by what?

Answer 17

distal convoluted tubule and glomerular afferent arteriole

Question 18

What is the main function of the juxtaglomerular apparatus?

Answer 18

regulate blood pressure and filtration rate

Question 19

What are the three types of cells in the juxtaglomerular apparatus?

Answer 19

macula densa
mesangial cells
granular cells

Question 20

Which kidney cells contain granules of renin, and when contracted, release renin?

Answer 20

granular (juxtaglomerular cells)

Question 21

What is the function of the macula densa?

Answer 21

sense salt concentration in the filtrate and repsond

Question 22

What is the function of mesangial cells?

Answer 22

specialized cells in kidney that have contracting and phagocytic function

Question 23

What trigger renin release from JG cells?

Answer 23

1. increases sympathetic nerve activity (B1 receptor)
2. decreased Ang-II at AT1 receptor
3. Decreased NaCl to macula densa
4. Decreased afferent arteriolar pressure

Question 24

What are the short term effects of Angiotensin II, within minutes?

Answer 24

vasoconstriction thirst

Question 25

What are the short term effects of Angiotensin II, within hourse?

Answer 25

retention of salt and water

Question 26

What are the short term effects of Angiotensin II, within days?

Answer 26

sympathetic stimulation

Question 27

What are the long term effects of angiotensin II, within months?

Answer 27

vascular and cardiac hypertrophy

Question 28

Cardiac Hypertrophy results in what?

Answer 28

increase systolic pressure, increase volume load

Question 29

What is the Law of Laplace?

Answer 29

T=PR, R is radius

Question 30

What does the Law of Laplace mean?

Answer 30

the larger the vessel radius, the larger the wall tension required to withstand a given internal fluid pressure

Question 31

What is increased wall tension is related to?

Answer 31

increased pressure, increased radius decreased wall thickness

Question 32

What is the significance of cardiac hypertrophy?

Answer 32

increased pressure results in increased wall tension and a response in smooth muscle hypertrophy in arteries and arterioles