23. Renin Angiotensin System

Question 1

What converts angiotensinogen to angiotensin 1?

Answer 1

Renin

Question 2

What converts Angiotensin 1 to Angiotensin 2?

Answer 2

Angiotensin Converting Enzyme

Question 3

Where is angiotensinogen produced?

Answer 3

Liver

Question 4

What are some symptoms of low BP?

Answer 4

Lack of concentration
Dizziness
Nausea
Fainting

Question 5

How is the activity of the Renin Angiotensin System measured clinically?

Answer 5

PRA (Plasma Renin Activity)

Question 6

Where is renin produced?

Answer 6

Juxtoglomerular cells of kidneys

-Specialised smooth muscle cells in afferent arterioles

Question 7

What is the half life of renin?

Answer 7

80 mins

Question 8

How does renin convert angiotensinogen to angiotensin 1?

Answer 8

Cleaves bond between leucine and valine

Question 9

What increases rennin secretion?

Answer 9

1. Low BP in afferent arteriole
2. Decreased NaCl reabsorption by MD
3. Increased adrenergic activity
   - Rennin release via B-adrenoceptors
   - AA constriction via a-adrenoceptors
4. GsPCRs and cAMP

Question 10

What inhibits rennin release?

Answer 10

1. Increased NaCl reabsorption by MD
2. Increased afferent arteriolar pressure
3. Decreased sympathetic activity
4. Angiotensin 2
5. GqPCRs and Ca++

Question 11

What type of molecule is angiotensinogen?

Answer 11

Glycoprotein

Question 12

Where is angiotensin converting enzyme found?

Answer 12

Endothelial cells in the lung

Question 13

What is the carboxypeptidase action of angiotensin converting enzyme?

Answer 13

Removes His and Leu from carboxy terminus of angiotensin 1

Question 14

Name an angiotensin converting enzyme inhibitor

Answer 14

Captopril

Question 15

What is the effect of ACE inhibitors?

Answer 15

Decrease BP

Question 16

Which Angiotensin 2 Receptor is found in blood vessels?

Answer 16

AT1A

Question 17

Which Angiotensin 2 Receptor is found in adrenal cortex and anterior pituitary?

Answer 17

AT1B

Question 18

Which Angiotensin 3 Receptor is found in the foetus and neonate?

Answer 18

AT2R

Question 19

What type of receptors are AT1Rs?

Answer 19

GPCRs

Linked to phospholipase C and Ca++

Question 20

What are AT1R blockers used to treat?

Answer 20

Hypertension

Cardiac failure

Question 21

Name 2 AT1R blockers

Answer 21

Candesartan

Eprosartan

Question 22

What are the functions of angiotensin?

Answer 22

1. Increased Na+ reabsorption
2. Vasoconstriction of renal arterioles
3. Synthesis of aldosterone
4. Stimulation of ADH secretion

Question 23

What receptor does aldosterone activate?

Answer 23

Mineralocorticoid Receptor

Question 24

What is the half life of aldosterone?

Answer 24

20 mins

Question 25

What is the function of aldosterone?

Answer 25

Enhances reabsorption of Na+ from DCT - ENaC - Na/K

Question 26

What is primary hyperaldosteronism?

Answer 26

``` Adrenal adenoma (Conn's syndrome) or idiopathic adrenal hyperplasia Decreased serum rennin, increased aldosterone ```

Question 27

What is secondary hyperaldosteronism?

Answer 27

Decreased renal perfusion due to heart failure, nephrotic syndrome or liver cirrhosis Increased renin and aldosterone

Question 28

How is secondary hyperaldosteronism treated?

Answer 28

Aldosterone antagonists

Question 29

Name an aldosterone antagonist

Answer 29

Spironolactone

Question 30

What is primary hypoaldosteronism?

Answer 30

Addison's: autoimmune destruction of adrenal gland

Question 31

What are the symptoms of Addison's syndrome?

Answer 31

``` Hypovolaemia Urinary Na+ loss Hyperkalaemia Postural hypotension Dehydration Decreased serum aldosterone, increased serum renin ```

Question 32

What is secondary hypoaldosteronism?

Answer 32

Caused by renal injury (diabetes, obstructive nephropathy) | Decreased serum aldosterone and renin

Question 33

How is secondary hypoaldosteronism treated?

Answer 33

Mineralocorticoids: Hydrocortisone | Fludrocortisone

Question 34

What receptor does ADH act on?

Answer 34

AVP Receptors

Question 35

What is the half life of ADH?

Answer 35

20 mins

Question 36

What are the functions of ADH?

Answer 36

1. Vasoconstriction 2. Increased water reabsorption 3. Promotes expression of urea transporters (UT-A) in the CD

Question 37

How does ADH cause vasoconstriction?

Answer 37

Acts on AVP1R | Releases Ca++

Question 38

How does ADH increase water reabsorption?

Answer 38

Acts on AVP2R Increase cAMP production Increases expression of aquaporin 2