long term control of blood pressure

Question 1

What is changed in order to control plasma volume in the long term?

Answer 1

The control of plasma volume by the kidneys

Question 2

What are the three hormone systems used to control blood pressure long term?

Answer 2

Renin-angiotensin-aldosterone system, antidiuretic factor (vasopressin), atrial and brain natriuretic peptide

Question 3

What are the functions of the kidneys?

Answer 3

Excretion of waste products, regulation of ion balance, pH, osmolarity, plasma volume

Question 4

What determines how big the osmotic gradient is in the collecting duct?

Answer 4

The control over Na+ transport

Question 5

What determines whether water flows down the osmotic gradient in the collecting duct?

Answer 5

The permeability of the collecting duct to water

Question 6

What happens to the urine when the collecting duct is very permeable to water?

Answer 6

Results in lots of water reabsorption, small volume of hyperosmotic urine and conservation of plasma volume

Question 7

What happens to urine when the collecting duct is very impermeable to water?

Answer 7

Little reabsorption of water so lots of hypo-osmotic urine and a reduction in plasma volume

Question 8

What s diuresis?

Answer 8

The production of a large volume of urine

Question 9

Where is renin produced?

Answer 9

The juxtaglomerular (granular cells) of the kidney

Question 10

What 3 things trigger Renin production?

Answer 10

Activation of sympathetic nerves to the juxtaglomerular, decreased distension of afferent arterioles (renal baroreflex), decreased delivery of NA+/CL- through the tubule

Question 11

Which part of the nephron detects the decreased sodium and chloride ion concentration which causes the release of Renin?

Answer 11

The macula densa

Question 12

What does renin do?

Answer 12

Converts inactive angiotensinogen into angiotensin I. this angiotensin I is then converted into angiotensin II by angiotensin converting enzyme (ACE).

Question 13

What does angiotensin II do?

Answer 13

Stimulates the release of aldosterone from the adrenal cortex, increases the release of ADH from the pituitary, it is also a vasoconstrictor

Question 14

What does aldosterone do?

Answer 14

Increases the Na+ reabsorption in the loop of Henle therefore reduces diuresis and increases plasma volume

Question 15

What does an increase in ADH release do?

Answer 15

Increases water permeability of the collecting duct, therefore reducing diuresis and increasing plasma volume. It also increases the sense of thirst

Question 16

How does renin being a vasoconstrictor affect MAP?

Answer 16

It increases TPR, increasing MAP

Question 17

Where is ADH synthesised and released?

Answer 17

Synthesised in the hypothalamus and released from the posterior pituitary gland

Question 18

What triggers ADH release?

Answer 18

– A decrease in blood volume (as sensed by cardioplumonary baroreceptors and relayed via medullary cardiovascular centres)
– An increase in osmolarity of interstitial fluid (as sensed by osmoreceptors in the hypothalamus)
– Circulating angiotensin II (triggered by the renin-angiotensin-aldosterone system)

Question 19

What does ADH do?

Answer 19

Increases the permeability of the collecting duct to water so reduces diuresis and increases plasma volume, also causes vasoconstriction increasing MAP

Question 20

Where is atrial natriuretic peptide (ANP) produced?

Answer 20

The myocardial cells of the atria

Question 21

Where is brain natriuretic peptide (BNP) released from?

Answer 21

The myocardial cells of the ventricles

Question 22

What triggers the release of ANP and BNP?

Answer 22

Increased distension of the atria for ANP and ventricles for BNP

Question 23

What do ANP and BNP do?

Answer 23

Increase the excretion of Na+ from (natriuresis), Inhibits the release of renin, Acts on medullary CV centre to reduce MAP (all these reduce MAP)

Question 24

What are some classes of anti-hypertensive drugs?

Answer 24

– Ca2+ channel antagonists
– beta-adrenoceptor antagonists
– Thiazide diuretics
– Angiotensin converting enzyme inhibitors