Renin-angiotensin System

Question 1

Physiology of RAAS

Answer 1

• regulation of BP
• regulation of plasma volume
• modulation of sympathetic nervous system
• stimulation of thirst

Question 2

Where is renin formed and stored?

Answer 2

JG cells

Question 3

What is the primary regulator of formation and maintenance of Ang II?

Answer 3

Renin

Question 4

Is Ang I active or inactive?

Answer 4

Inactive

Question 5

Is Ang II active or inactive?

Answer 5

Active

Question 6

What does ACE do?

Answer 6

• convert Ang I to Ang II

- breakdown bradykinin to inactive metabolites

Question 7

Bradykinin can cause what?

Answer 7

• vasodilation (cough, angioedema)

- decrease MAP

Question 8

Ang II AT1 causes what?

Answer 8

• vasoconstriction (increased TPR, Increased MAP)

- aldosterone release (Na and water retention, increased MAP)

Question 9

Level of Ang II is dependent on what?

Answer 9

Amount of circulating renin and angiotensinogen

Question 10

Angiotensinogen is formed and secreted continuously by what?

Answer 10

Liver

Question 11

Synthesis of angiotensinogen is increased by what?

Answer 11

Insulin
Estrogens
Glucocorticoids

Question 12

Renin is secreted from ____ in response to changes in ____

Answer 12

Kidney

BP/volume

Question 13

What is the clinical test for renin activity? What is the relationship with dietary Na?

Answer 13

PRA

Inverse relationship with dietary Na intake

Question 14

Renin secretion is regulated by (3)

Answer 14

1. Blood volume/pressure (baroreceptors)
2. Na Cl flux across macula
3. Sympathetic nervous system activity

Question 15

Baroreceptors and renin

Answer 15

Decreased bp/volume —> decreased stretch —> increased renin

Question 16

The macula densa is sensitive to what changes?

Answer 16

NaCl reabsorption

Question 17

Macula densa and renin

Answer 17

Decrease NaCl reabsorption —> increase renin

Question 18

Stimulation of what receptors on JG cells cause renin release

Answer 18

B1

Question 19

SNS activity and renin

Answer 19

Increase SNS activity —> increase renin release

Question 20

What are the 2 negative feedback loops of renin?

Answer 20

1. Ang II stimulation of AT1 receptors on JG cells (short)

2. Ang II induced increases in BP (long)

Question 21

How is Ang I formed?

Answer 21

Angiotensinogen —> Ang I

**renin RLS

Question 22

Where is ACE found?

Answer 22

On endothelial cell surface

Question 23

What is the major active component of RAS?

Answer 23

Ang II

Question 24

Ang II and K

Answer 24

Increase excretion of K

Question 25

Ang II and afferent arteriole

Answer 25

Constrict —> decrease glom pressure —> decrease GFR

Question 26

Ang II and efferent arteriole

Answer 26

Constrict —> increase glomerular pressure —> increase GFR

Question 27

Normal conditions of Ang II and GFR

Answer 27

Afferent constricts slightly more than efferent | **no change or slight decrease GFR

Question 28

Renal arterial hypotension and Ang II

Answer 28

Afferent is maximally dilated | GFR maintained by Ang II mediated constriction fo efferent

Question 29

T/f you can 100% inhibit ACE

Answer 29

False! | There are alternative pathways for ang II synthesis that do not involve renin or ACE

Question 30

How does Ang II alter cardiovascular structure?

Answer 30

AT1 receptor activation

Question 31

Ang II VT1 activation

Answer 31

- stimulate migration, proliferation and hypertrophy of VSM cells - increased production of extracellular matrix - hypertrophy of cardiac myocytes

Question 32

2 major subtypes of Ang II

Answer 32

AT1 (Gq) | AT2 (Gi)

Question 33

Which receptors mediate most biological effects of Ang II?

Answer 33

AT1

Question 34

Where are Ang II AT1 receptors found?

Answer 34

VSM

Question 35

Where are AngII AT2 receptors found?

Answer 35

Fetal tissue

Question 36

What receptor are poorly defined and may exert antiproliferative, proapoptotic, vasodilatory and antihypertensive effects?

Answer 36

AT2

Question 37

What is the prototype ACEI?

Answer 37

Captopril