Long Term Control of Blood Pressure

Question 1

Which organ plays a major role in the long term control of blood pressure?

Answer 1

Kidney

Question 2

What are the main functions of the kidneys?

Answer 2

Excretion of waste, maintenance of ion balance, regulation of pH, regulation of osmolarity and regulation of plasma volume?

Question 3

How do the kidneys regulate MAP?

Answer 3

By controlling plasma volume

Question 4

What function does the renal counter current system have?

Answer 4

It creates a very high osmolarity outside the collecting duct

Question 5

What determines how big the concentration gradient across the collecting duct is?

Answer 5

Control of the sodium transport

Question 6

What determines whether water follows the concentration gradient or not?

Answer 6

The permeability of the collecting duct to water

Question 7

What will happen if the collecting duct is very permeable to water?

Answer 7

Lots of water will be reabsorbed, little urine will be produced and plasma volume will be conserved

Question 8

What will happen if the collecting duct very impermeable to water?

Answer 8

Little water will be reabsorbed, lots of urine will be produced and plasma volume will reduce

Question 9

Where is renin produced?

Answer 9

The juxtaglomerular (granule cells) of the kidneys

Question 10

What triggers renin production?

Answer 10

Activation of sympathetic nerves to the juxtaglomerular apparatus, decreased distension of afferent arterioles and decreased delivery of sodium and chloride ions through the tubules

Question 11

Are the triggers of renin production signs of high or low MAP?

Answer 11

Low

Question 12

What does renin do?

Answer 12

Converts inactive angiotensin to angiotensin 1

Question 13

What happens to angiotensin 1?

Answer 13

It is converted to angiotensin 2

Question 14

What does angiotensin 2 do?

Answer 14

Stimulates the release of aldosterone from the adrenal cortex, increases the release of ADH from the pituitary and acts as a vasoconstrictor

Question 15

What effect does the release of aldosterone have?

Answer 15

It increases sodium absorption in the loop of Henle and therefore reduces diuresis and increases plasma volume

Question 16

What effect does ADH have?

Answer 16

It increases the permeability of the collecting duct, which reduces diuresis and increases plasma volume, increases the sense of thirst and causes vasoconstriction

Question 17

What type of system are the Renin-angiotensin-aldosterone, ADH and ANP systems?

Answer 17

Negative feedback systems

Question 18

Where is ADH produced?

Answer 18

It is synthesised in the hypothalamus and is released from the posterior pituitary

Question 19

What triggers ADH release?

Answer 19

A decrease in blood volume, an increase of osmolarity of interstitial fluid and circulation angiotensin

Question 20

What detects a rise in the osmolarity of interstitial fluid?

Answer 20

Osmoreceptors in the hypothalamus

Question 21

Where is atrial natriuretic peptide produced?

Answer 21

It is produced in, and released from, myocardial cells in the atria

Question 22

What triggers ANP release?

Answer 22

Increased distension of the atrium

Question 23

Is ANP released in response to high or low MAP?

Answer 23

High MAP

Question 24

What does ANP do?

Answer 24

Increases excretion of sodium, inhibits the release of renin and acts on the medullary CV centres to reduce MAP