Long Term Control of Blood Pressure

Question 1

What does long term control of blood pressure revolve around?

Answer 1

The control of plasma volume by the kidneys

Question 2

What three systems does long term control of BP involve?

Answer 2

Renin-angiotensin-aldosterone system
Antidiuretic factor
Atrial natriuretic peptide

Question 3

What are the functions of the kidneys?

Answer 3

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

Question 4

What is controlling plasma volume used to regulate?

Answer 4

MAP

Question 5

Does the renal counter-current system create a high or a low osmolarity outside of the collecting duct?

Answer 5

Very high

Question 6

What determines how large the osmotic gradient is?

Answer 6

Control over Na+ transport

Question 7

What determines if water will follow the osmotic gradient or not?

Answer 7

Control over the permeability of the collecting duct

Question 8

What does control over Na+ transport and permeability of the collecting duct allow?

Answer 8

Control of how much water is lost in the urine and how much is retained

Question 9

What will result from making the collecting duct very permeable to water?

Answer 9

Lots of water reabsorption
Small volume of hyper-osmotic urine excreted
Conservation of plasma volume

Question 10

What will result from making the collecting duct less permeable to water?

Answer 10

Little water reabsorption
Large volume of hypo-osmotic urine excreted
Reduction in plasma volume

Question 11

Where is renin produced?

Answer 11

From the juxtaglomerular cells of the kidney

Question 12

What is renin production triggered by?

Answer 12

Activation of sympathetic nerves to the juxtaglomerular apparatus
Decreased distension of afferent arterioles
Decreased delivery of Na+/Cl - through the tubule

All of MAP

Question 13

What does renin convert?

Answer 13

Angiotensinogen to angiotensin I

Question 14

What does angiotensin converting enzyme convert?

Answer 14

Angiotensin I to angiotensin II

Question 15

What does angiotensin II stimulate?

Answer 15

Release of aldosterone from the adrenal cortex

Question 16

How does angiotensin II stimulate the release of aldosterone?

Answer 16

By;
Increasing Na+ reabsorption in the loop of Henle
Reducing diuresis
Increasing plasma volume

Question 17

How does angiotensin II increase the release of ADH from the pituitary?

Answer 17

Increasing water permeability of the collecting duct
Reducing diuresis
Increasing plasma volume
Increasing sense of thirst

Question 18

How does angiotensin II work as a vasoconstrictor?

Answer 18

Increases TPR which is part of the negative feedback system which detects any decrease in MAP and will stimulate the release of renin to increase MAP

Question 19

Where is antidiuretic hormone synthesised and released?

Answer 19

Synthesised by the hypothalamus

Released from the posterior pituitary

Question 20

What is the release of antidiuretic hormone triggered by?

Answer 20

Decrease in blood volume
Increase in osmolarity of interstitial fluid
Circulating angiotensin II triggered by the renin-angiotensin-aldosterone system

All of the above are signs of a low plasma volume +/- MAP

Question 21

What detects a decrease in blood volume?

Answer 21

Cardiopulmonary baroreceptors

Question 22

What detects an increase in osmolarity of the interstitial fluid?

Answer 22

Osmoreceptors in the hypothalamus

Question 23

What does ADH cause?

Answer 23

Increase in permeability of the collecting duct to water 
Reduced diuresis 
Increased plasma volume 
Vasoconstriction 
Increased MAP

Question 24

Where is atrial natriuretic peptide produced and released from?

Answer 24

Myocardial cells in the atria

Question 25

What triggers the release of atrial natriuretic peptide?

Answer 25

Increased distension of the atrium (sign of increased MAP)

Question 26

What does atrial natriuretic peptide cause?

Answer 26

Increased excretion of Na+ (natriuresis)
Inhibits release of renin
Acts on medullary CV centres to reduce MAP

Question 27

What percentage of hypertension is due to a known cause (secondary hypertension)?

Answer 27

5-10%

Question 28

What is the majority of hypertension with no known cause classed as?

Answer 28

Primary or essential