Long Term Control of Blood Pressure

Question 1

what does long term control of blood pressure revolve around?

Answer 1

the regulation of plasma volume by the kidneys

Question 2

what 3 hormone systems are involved in the control of long term blood pressure?

Answer 2

renin-angiotensin-aldosterone
ADH
Atrial Natriuretic Peptide

Question 3

what are some functions of the kidney? (5)

Answer 3

excretion of waste products 
maintenance of ion balance 
regulation of pH
regulation of osmolarity 
regulation of blood plasma volume - which regulates MAP

Question 4

explain how kidneys work

Answer 4

Blood comes in through afferent arteriole and goes into glomerulus (which is inside bowman’s capsule). Hydrostatic pressures are very high in glomerulus so about 20% of plasma gets filtered into bowman’s capsule. This filtrate consists of water, electrolytes and low molecular weight organic solutes. It then goes into the proximal tubule,loop of henle,distal tubule and then collecting duct.

Question 5

how does the kidney conserve plasma volume?

Answer 5

increasing reabsorption of Na+ back into the blood, thus reducing diuresis and conserving plasma volume

Question 6

how does the kidney decrease plasma volume?

Answer 6

Make collecting ducts impermeable so very little filtrate reabsorption so more diuresis and reduced plasma volume

Question 7

what do very permeable collecting ducts result in?

Answer 7

small volume of hyper-osmotic urine

Question 8

what do very impermeable collecting ducts result in?

Answer 8

large volume of hypo-osmotic urine

Question 9

where is renin produced?

Answer 9

in the juxtaglomerular apparatus of the kidney

Question 10

what triggers renin production?

Answer 10

-sympethetic innervation at juxtaglomerular apparatus
-reduced delivery of Na+/Cl-
-reduced distension of afferent arteriole
= all which signal reduced MAP

Question 11

what does renin do?

Answer 11

converts inactive angiotensinogen –> angiotensin I

Question 12

what converts angiotensin I to angiotensin II?

Answer 12

Angiotensin Converting Enzyme

Question 13

what does angiotensin II do?

Answer 13

• stimulates release of aldosterone from adrenal cortex which increases reabsorption of Na+ back into blood
• stimulates release of ADH which increases permeability of collecting duct to water
• is a vasoconstrictor so increases TPR

Question 14

Where is ADH produced?

Answer 14

synthesised in hypothalamus and released from posterior pituitary

Question 15

what triggers ADH release?

Answer 15

-reduced blood plasma volume
-circulating angiotensin II
-

Question 16

what triggers ADH release?

Answer 16

-reduced blood plasma volume (sensed by cardiopulmonary baroreceptors which relay the signal through the medullary cardiovascular centre)
-circulating angiotensin II
-reduced osmolarity in interstitial fluid
=all which signal reduced MAP

Question 17

what does ADH do?

Answer 17

• increases permeability of the collecting duct TO WATER

- vasoconstriction so increases TPR and MAP

Question 18

where is ANP produced?

Answer 18

produced and released my myocardial cells in the atria

Question 19

what triggers ANP release?

Answer 19

increased distension of the atria, which is a sign of increased blood volume

Question 20

what does ANP do?

Answer 20

• stimulates secretion of Na+ back into collecting duct (natriuresis) and decreases blood volume
• inhibits renin
• stimulates medullary cardiovascular centres to reduce MAP –> arteriolar dilation