Long Term Control of BP

Question 1

What is long term BP controlled by?

Answer 1

The kidneys

Question 2

List some of the general functions of the kidney.

Answer 2

Excretion of waste products
Maintenance of ion balance
Regulation of pH
Regulation of osmolarity
Regulation of plasma volume

Question 3

Which function of the kidney is useful when trying to regulate MAP?

Answer 3

Controlling plasma volume

Question 4

How do the kidneys regulate plasma volume?

Answer 4

-Renal counter-current system creates a very high osmolarity outside the collecting duct.
-Control of sodium transport determines how big osmotic gradient is.
-Control over the permeability of the collecting duct to water determines if water follows that osmotic gradient or not
-Therefore can control how much water is lost via urine and how much is retained.

Question 5

Describe some of the ways you can modulate how much water is retained and how much is lost via urine.

Answer 5

1. Modulating Na+ transport will affect how big the osmotic gradient is in the first place
2. Making the collecting duct very permeable to water will result in lots of water reabsorption, little urine, and conserve plasma volume
3. Making the collecting duct very impermeable to water will result in little reabsorption, lots of urine (= diuresis), and a reduction in plasma volume

Question 6

What is the role of the Renin-angiotensin-aldosterone system?

Answer 6

Feedback system which sense disturbances in plasma volume and MAP

Question 7

Which hormone does the Renin-angiotensin-aldosterone system produce?

Answer 7

Renin

Question 8

Where is renin produced?

Answer 8

From the juxtaglomerular (= granule cells) of the kidney

Question 9

What triggers renin production?

Answer 9

Activation of sympathetic nerves to the juxtaglomerular apparatus
Decreased distension of afferent arterioles (the “renal baroreflex”)
Decreased delivery of Na+/Cl- through the tubule

Question 10

When do you get sympathetic activation?

Answer 10

When BP is low

Question 11

If BP is low, is there more or less filtration and, as a result, delivery of calcium and sodium?

Answer 11

Less filtration and less delivery

Question 12

What does renin do?

Answer 12

Converts inactive angiotensinogen to angiotensin I

Question 13

What is angiotensin I converted to?

Answer 13

Converted by angiotensin converting enzyme to angiotensin II

Question 14

What biological molecule is renin?

Answer 14

Enzyme

Question 15

What do angiotensin II do?

Answer 15

Stimulates release of aldosterone from the adrenal cortex
Increases release of ADH from the pituitary
Is a vasoconstrictor and increases TPR

Question 16

What does angiotensin II stimulating the release of aldosterone from the adrenal cortex do?

Answer 16

Increases Na+ reabsorption
Therefore reduces diuresis and increases plasma volume

Question 17

What does angiotensin II increasing release of ADH do?

Answer 17

Increases water permeability of the collecting duct
Therefore reduces diuresis and increases plasma volume
And increases sense of thirst

Question 18

If you drink more water, will it increase or decrease plasma volume?

Answer 18

Should increase

Question 19

Where is ADH (Antidiuretic hormone) synthesised from?
Where it is then released from?

Answer 19

Synthesised in the hypothalamus
Released from the posterior pituitary

Question 20

What can trigger ADH release?

Answer 20

A decrease in blood volume
An increase in osmolarity of interstitial fluid
Circulating angiotensin II

Question 21

What senses a decrease in blood volume?

Answer 21

Sensed by cardiopulmonary baroreceptors and relayed via medullary cardiovascular centres

Question 22

What sense an increase in osmolarity of interstitial fluid?

Answer 22

Osmoreceptors in the hypothalamus

Question 23

What do the following suggest?

A decrease in blood volume
An increase in osmolarity of interstitial fluid
Circulating angiotensin II

Answer 23

Low plasma volume and/or MAP

Question 24

What does ADH do?

Answer 24

Increases the permeability of the collecting duct to H2O, therefore reduces diuresis and increases plasma volume
Causes vasoconstriction, increasing MAP

Question 25

Where are Atrial natriuretic peptide and brain natriuretic peptide produced?

Answer 25

ANP-Produced in and released from myocardial cells in the atria

BNP-produced in and released from myocardial cells in the ventricles.

Question 26

What triggers the release of ANP and BNP?

Answer 26

Increased distension of the atria and ventricles

Question 27

What do ANP and BNP do?

Answer 27

Increase excretion of Na+ (natriuresis)
Inhibit the release of renin
Act on medullary CV centres to reduce MAP

Question 28

Therefore, give three examples of negative feedback systems.

Answer 28

1. Production of renin
2. Production of ADH
3. Production of ANP/BNP

Question 29

Give five examples of the types of drug used to help hypertension.

Answer 29

Ca2+ channel antagonists
β-adrenoceptor antagonists
Thiazide diuretics
Angiotensin converting enzyme inhibitors
Angiotensin II antagonists

-ik you hate drugs, just write them out pls