Renin Angiotensin

Question 1

Renin

Answer 1

Renin is an enzyme that acts in the Renin-angiotensin system by converting angiotensinogen into angiotensin I when there is a drop in blood pressure.

Question 2

Where is Renin released from?
* Liver
* Pancreas
* Kidney

Answer 2

Kidney

Question 3

Where is angiotensinogen released from?

• pancreas
• liver
• kidney

Answer 3

Liver

Question 4

Which enzymes has high levels in the lungs ?

Answer 4

Angiotensin-converting enzyme [ACE]

NOTE: It is NOT released from the lungs. It lines the endothelial cells that face the blood vessel. Ergo, ACEs interact with angiontensin I when it passes by in the blood circulation.

Question 5

What does ACE do?

Answer 5

Converts angiotensin I to angiotensin II.

It also cleaves bradykinin into an inactive metabolite.

Question 6

Angiotensin I

Answer 6

An inactive substance that circulates the blood once formed.

Question 7

Angiotensin II

Answer 7

A vaso-active molecule.
* Binds to AT1 on smooth muscle cells -> causes vasocontriction.
* Binds to receptors on the adrenal glands -> stimulates aldosterone release.
*Aldosterone release causes an increase in water and salt reabsorbed into the blood.

All of this increases blood pressure

Question 8

Indirect cause of Noradrenaline binding to α1 receptor

Answer 8

The release of renin
* More water & salt reabsorption.
* Vasocontriction.

Increases BP

Question 9

Direct cause of noradrenaline at α1 receptors

Answer 9

Binding onto α1 smooth muscle cell causes vasocontriction

Increases BP

Question 10

What is noradrenaline also known as ?

Answer 10

Norephenedrine

Question 11

Aldosterone

Answer 11

A hormone that causes the production of new proteins in the nephron. These new proteins act as new channels and pumps .
* Potassium is secreted from the blood onto the distal tubule via ROMK channels.
* Sodium is reabsorbed into the blood via ENaC channels.

Question 12

ACE inhibitor

Answer 12

Inhibits the angiotensin-converting enzyme from cleaving angiotensin I to angiotensin II.
This:
* Reduces vasocontriction and therefore total peripheral resistance.
* Reduces the cardiac load.
* Causes vasodilation though bradykinin.

Example: Lisinopril

ACE is not the only enzyme that can convert A1 to A2.

Question 13

Angiotensin II type 1 antagonist

ARB drug

Answer 13

Blocks the AT1 receptor.
Allows more Angiotensin II to bind to unaffect AT2 receptors which cause vasodilation .

Example: Losartan and Valsartan

Question 14

What enzyme converts A2 to A3?

Answer 14

Aminopeptidase

Question 15

Angiotensin III

Answer 15

A vaso-active molecule that is converted to from Angiotensin II.

• Has ~40% vasoconstricting activity of Angiotensin II. ->[Ergo not as active]
• Same aldosterone stimulation activity.

Increases blood pressure

Question 16

3 types of ACE inhibitors

Answer 16

• Sulfahydryl inhibitors [No longer used]
• Dicarboxylate inhibitors [Most common]
• Phosphonate inhibitors

Question 17

Total peripheral resistance

Answer 17

The force exerted on circulating blood by the vascular system. TPR impacts blood pressure.

Question 18

What affects TPR?

Answer 18

• Blood viscosity
• Arteriole radius

Question 19

Which nervous system regulates vasoconstriction?

Answer 19

Sympathetic Nervous System

Question 20

What two factors affect the blood pressure?

Answer 20

• Cardiac output
• Total peripheral resistance

Question 21

ACE inhibitor side effects

Answer 21

• Dry cough
• Hyperkalemia
• Headache
• Fatigue

Question 22

ACE inhibitor - Dry cough

Answer 22

It is caused by the inhibition of breakdown of bradykinin. This leads to an increase of bradykinin in the lungs.