11 Volume Regulation

Question 1

What does the kidney use to measure body volume?

Answer 1

effective circulating volume

Question 2

When might effective ciculating volume and actual volume change independently?

Answer 2

heart failure

Question 3

What is the structure of the juxtaglomerular apparatus?

Answer 3

the late distal tube comes into contact with the afferent arteriole

Question 4

What secretes renin?

Answer 4

granular cells of the afferent arteriole

Question 5

What is the thickening in the distal tubule called?

Answer 5

macula densa

Question 6

What does the macula densa detect?

Answer 6

low Na+ in the distal tubule

Question 7

What do juxtaglomerular cells do?

Answer 7

release renin

Question 8

What does renin do?

Answer 8

converts angiotensinogen into angiotensin 1

Question 9

Where is angiotensinogen formed?

Answer 9

liver

adipose tissues

Question 10

What happens to angiotensin 1?

Answer 10

converted to angiotensin II by angiotensin converting enzyme (ACE) in the lungs

Question 11

What does angiotensin II do?

Answer 11

efferent arteriole vasocontristion

stimulates aldosterone release

increases sodium reabsorption

Question 12

What are the 2 main triggers for aldsoterone?

Answer 12

ATII

Hyperkalaemia

Question 13

What does aldosterone do in the collecting ducts?

Answer 13

reabsorbs sodium, and drives potassium excretion

Question 14

What broad effect does inhibiting the renin angiotensin system do?

Answer 14

reduces blood pressure, acting as an antihypertensive

Question 15

Name 4 types of antihypertensives associated with the renin angiotensin system

Answer 15

ACE inhibitors
AT(1) receptor antagonists
aldosterone receptor antagonsits
renin inhibition

Question 16

Name 2 types of ACE inhibitors?

Answer 16

captopril

enalopril

Question 17

What is the problem with using ACE inhibitors?

How is this avoided?

Answer 17

ACE has other functions, like breaking down bradykinin, an inflammatory marker

people hence get a dry cough

we just put them on something else lol, that acts downstream of ATII

Question 18

What is the familial pharmaceutical name for AT(1) receptor antagonists?

Answer 18

sartans

Question 19

What is the agonist for AT(1)?

Answer 19

ATII

Question 20

Name a type of aldosterone receptor antagonist

Answer 20

spironolactone

Question 21

Name a type of renin inhibitor

Answer 21

aliskiren

Question 22

what do AT(1) receptors do?

Answer 22

Gq linked so vasoconstriction in efferent arteriole

Question 23

How does angiotensin II increase circulating volume?

Answer 23

increases Na / H+ exhcnage in proximal tubule and hence proximal Na+ absorption
increase in aldosterone release
causes ADH release
causes thirst

Question 24

How does Haemorrhage lead to increased renin release

Answer 24

…. decreased circulating volume, decreasing blood pressure and increasing sympathetic activity
sympathetics act on granule cells

Question 25

What are the 3 key sympathetic effects on the afferent arteriole?

Answer 25

vasoconstriction upstream of granule cells (amplifies apparent fall in volume) direct stimulation of renin release from granule cells afferent arteriole vasoconstriction to lower GFR

Question 26

What does noradrenaline binding to alpha 1 adrenoreceptors cause?

Answer 26

vasoconstriction

Question 27

what does noradrenaline binding to beta 1 adrenoreceptors cause? why is this unusual?

Answer 27

on granule cells to regulate renin release these receptors are usually found in the heart!

Question 28

What are the 3 key stimuli to renin release?

Answer 28

intrinsic renal mechanisms because of less Na+ sympathetic mediated release decrease in venous pressure

Question 29

How does decreasing venous pressure stimulate renin release?

Answer 29

it is transmitted to vesa recta capillaries, decreasing hydrostatic pressure this increases uptake of fluid from renal interstitial space, increasing water reabsorption this decreases sodium delivery to the distal tubules

Question 30

what stimulates ADH release?

Answer 30

change in osmolality | change in volume a lil bit

Question 31

how does changing volume affect ADH?

Answer 31

decreased cardiac output, decreased activation of baroreceptor reflex AtII increases ADH release following haemorrhage (increases water reabsorption, lowering osmolality, this mechanism does not retain Na+)

Question 32

What will the acute response to haemorrhage be?

Answer 32

hyponatraemia

Question 33

Why does beer cause diuresis?

Answer 33

it increases water load and also inhibits ADH

Question 34

Why do spirits dehyrdrate you?

Answer 34

you aren't really taking in enough water to facilitate that loss

Question 35

What is ANP and what does it do?

Answer 35

Atrial Natriuretic Peptide atrial stretch in volume overload cuases its' release travels to the kidney acting on ANP receptors increasing cGMP this increases renal Na+ excretion

Question 36

Name a peptide similar to ANP produced in the kidney

Answer 36

Urodilatin

Question 37

What do prostaglandins do?

Answer 37

PGE2 and PGI2 increase Na+ excretion

Question 38

Why do we have to watch out when giving renally compromised people NSAID's?

Answer 38

they have problems with volume retention anyway, and NSAID's tend to be nephrotoxic on top of this

Question 39

What does dopamine do?

Answer 39

angonist to D1 receptors, increasing cAMP, decreasing activity of Na+ / H+ exchanger in the proximal tubule this increases Na+ excretion