Long Term Control of BP

Question 1

What is the central organ involved in Long term control?

Answer 1

KIdneys

Question 2

How do the kidneys regulate Bp?

Answer 2

By controlling Plasma Volume

Question 3

Name the three systems involved.

Answer 3

Renin-Aniotensin-Aldosterone
ADH (vasopressin)
ANP & BNP

Question 4

Describe the path of water through a nephron.

Answer 4

Pushed out of blood by pressure filtration at the Bowman’s Capsule
passes down the loop of henle. Some water will be reabsorbed into the blood but the rest will pass out via the collecting duct and into the ureter.

Question 5

Define the Counter Current System

Answer 5

Creates a high osmolarity outside the collecting duct.

Question 6

What two factors affect the osmotic gradient?

Answer 6

Na transport- affects the size of the gradient

Permeability of the collecting duct to water controls the reabsorption of water into the blood.

Question 7

So how do we conserve Plasma Volume?

Answer 7

Increase the permeability of the collecting duct

Increase the amount of sodium reabsorbed.

Question 8

What effect would increased Plasma Volume have on BP

Answer 8

It would increase it.

Question 9

Describe RENIN

Answer 9

Made in the Juxtaglomerular cells of the kidney it is a hormone

Question 10

When is it secreted?

Answer 10

In response to Noradrenaline and Adrenaline

• decreased stretching of the afferent arteriole
• decreased return of sodium via the ascending loop of henle.

Question 11

What does Renin do?

Answer 11

Triggers conversion of Angiotensin to angiotensin I in the blood stream. Angiotensin I is then converted to Angiotensin II by ACE (angiotensin converting enzyme)

Question 12

What is the function of Angiotensin II?

Answer 12

• Stimulates release of Aldosterone from the adrenal cortex
• Increases secretion of ADH from the pituitary gland
• Causes vasoconstriction.

Question 13

Describe ADH

Answer 13

• Also known as vasopressin
• Decreases reabsorption of water in the kidneys= anti-diuretic by increasing the permeability of the collecting duct.
• powerful vasoconstrictor

Question 14

What triggers ADH?

Answer 14

Angiotensin II
Decreased blood volume
Increased osmolarity of ISF (high concentration of solute means there must be low volume)

Question 15

What is ANP/BNP?

Answer 15

Atrial Natriuretic Factor- produced in the myocardial cells of the atria and ventricles
Brain Natriuretic Factor- produced in the brain

Question 16

What does ANP/BNP do?

Answer 16

Increased excretion of Na
Inhibits release of RENIN
Central medulla to reduce MAP

Question 17

When is ANP/BNP released?

Answer 17

In high MAP detected by distension of atria and ventricles.