Long term control of blood pressure

Question 1

What is in charge of short term control of blood pressure?

Answer 1

Arterial baroreflex

Question 2

What is in charge of the long term control of blood pressure?

Answer 2

Revolves around the control of plasma volume by the kidneys, involving at least 3 different hormone systems:

• renin-angiotensin-aldosterone system
• antidiuretic hormone (ADH/vasopressin)
• atrial natriuretic peptide

Question 3

What determines the osmotic gradient?

Answer 3

Na transport

Question 4

Where is renin produced?

Answer 4

Juxtaglomerular cells in the kidneys, which are found near the golerulus in media of afferent arterioles in the kidneys

Question 5

What does renin do?

Answer 5

Increases BP by converting angiotensinogen to angiotensin I

Question 6

What triggers renin production?

Answer 6

Activation of sympathetic system
Decreased distension of afferent arterioles
Decreased delivery of Na/Cl

(signs of low MAP)

Question 7

What converts angiotensin I to angiotensin II?

Answer 7

Angiotensin converting enzyme

Question 8

What does angiotensin II do?

Answer 8

Stimulates aldosterone release
Increases ADH release
Acts as a vasoconstrictor (increases TPR)

Question 9

What does aldosterone do?

Answer 9

Increases Na reabsorption in to the loop of Henle, causing water to follow (with help of ADH) and increase plasma volume, therefore increasing blood pressure

Question 10

Where is aldosterone released from?

Answer 10

Adrenal cortex

Question 11

What does ADH do?

Answer 11

Increases water permeability of the collecting duct (and thirst)
Also causes vasoconstriction (hence name vasopressin)

Question 12

Where is ADH produced and then released?

Answer 12

Produced in the hypothalamus

Released from the pituitary gland

Question 13

What triggers ADH release?

Answer 13

Decrease in blood volume
Increased osmolarity of interstitial fluid
Angiotensin II in circulation

(signs of low plasma volume or MAP)

Question 14

Where is atrial natriuretic peptide produced and released from?

Answer 14

Myocardial cells in the atria

Question 15

What triggers ANP release?

Answer 15

Increased distension of the atria

Question 16

What does ANP do?

Answer 16

Aims to decrease MAP by:

• increasing excretion of Na
• inhibits release of renin
• acts on medullary CV centre to reduce BP

Question 17

What % of hypertension cases are found to be secondary to a known cause?

Answer 17

5-10%, rest is due to an unknown cause

Question 18

What drug targets have been identified to try and target blood pressure?

Answer 18

Ca channel antagonists
B-receptor blockers
Thiazide diuretics (inhibit Na and Cl absorption)
ACE inhibitors 
Angiotensin II antagonists