Long Term Control of Blood Pressure

Question 1

what three hormone system are involved in long term control of blood pressure?

Answer 1

> renin-angiotensin-aldosterone system
antidiuretic factor
atrial natriuretic peptide

Question 2

what are the functions of the kidneys?

Answer 2

> excretion of waste products
> maintenance of ion balance
> regulation of pH
> regulation of osmolarity
> regulation of plasma volume

Question 3

how does the kidney regulate plasma volume?

Answer 3

the kidney controls the sodium transport system determining how big the osmotic gradient is. it also controls the permeability of the collecting duct to water determining how much water follows the osmotic gradient or not.
this controls how much water is lost and retained in the urine.

Question 4

what happens if the collecting duct is made very permeable to water?

Answer 4

lots of water will be reabsorbed resulting in little urine, conserving plasma volume

Question 5

how does the kidney reduce the plasma volume?

Answer 5

it makes the collecting duct very impermeable to water resulting in little reabsorption of urine

Question 6

where is renin produced?

Answer 6

from the juxtaglomerular (granule cells) of the kidney

Question 7

what triggers renin production?

Answer 7

> activation of the sympathetic nerves to the juxtaglomerular apparatus
decreased distension of afferent arterioles
decreased delivery of sodium and chlorine through the tubule (macula densa)

Question 8

what are the three triggers of renin production signs of?

Answer 8

low mean arterial pressure

Question 9

what does renin do?

Answer 9

it converts inactive angiotensinogen to angiotensin 1.

Question 10

what happens to angiotensin 1?

Answer 10

it gets converted to angiotensin 2 by an angiotensin converting enzyme

Question 11

what is the regulating step in the renin-angiotensin-aldosterone system?

Answer 11

how much renin is produced

Question 12

what does angiotensin2 do?

Answer 12

> stimulates release of aldosterone from the adrenal glands
increases release of ADH from the pituitary
causes vasoconstriction

Question 13

what does aldosterone do?

Answer 13

increases sodium reabsorption in the loop of Henle reducing diuresis and increasing plasma volume

Question 14

what does the increase in release of ADH from the pituitary gland do?

Answer 14

it increases water permeability of the collecting duct therefore reducing diuresis and increasing plasma volume. it also increase a sense of thirst.

Question 15

what is the effect of angiotensin 2 as a vasoconstrictor?

Answer 15

this increases the total peripheral pressure

Question 16

can the renin-angiotensin-aldosterone system be described as a negative feedback system?

Answer 16

yes: multiple mechanisms detect any decrease in mean arterial pressure which stimulates the release of renin. this evokes multiple mechanisms which increase mean arterial pressure

Question 17

why is ADH produced?

Answer 17

it is synthesised in the hypothalamus and released form the posterior pituitary

Question 18

what triggers ADH release?

Answer 18

> decrease in blood volume
increase in osmolarity of interstitial fluid
circulating angiotensin 2
these are signs of low MAP

Question 19

where is atrial natriuretic peptide produced?

Answer 19

the myocardial cells of the atria and the ventricles and brain

Question 20

what triggers atrial natriuretic peptide release?

Answer 20

increased distension of the atrium as a sign of increased mean arterial pressure

Question 21

what does atrial natriuretic peptide do?

Answer 21

it increases the excretion of sodium and inhibits the release of renin. it acts on the medullary cardiovascular centre to reduce mean arterial pressure

Question 22

how is the atrial natriuretic peptide system a negative feedback system?

Answer 22

it detects increase in MAP and stimulates release of ANP which evokes multiple mechanisms which reduce MAP.