fluid status

Question 1

describle three triggers which lead to release of renin from granular cells in the renal corpuscle.

Answer 1

1. systemic baroreceptors detect low BP and induce sympathetic discharged to kidney which then releases renin
2. reduced afferent arteriole distension leads to renin release.
3. reduced tubuloglomerular feedback (reduced adenosine release from macula densa in response to reduced GFR)

Question 2

what converts angiotensinogen to angiotensin I?

Answer 2

renin

Question 3

what converts angiotensin I to angiotensin II?

Answer 3

angiotensin converting enzyme

Question 4

what are roles of angiotensin?

Answer 4

1. vasoconstrictor
2. induces release of aldosterone from adrenal cortex
3. stimulates na reabsorption in the proximal tubule by increasing NHE3 activity

Question 5

what are the causes of oedema?

Answer 5

1. Increased capillary hydrostatic pressure eg venous obstruction, excess blood volume, cardiac failure.
2. decreased plasma oncotic pressure eg causes of hypoproteinaemia (nephrotic syndrome, cirrhosis)
3. increased capillary permability eg allergic bacterial disease and sepsis.
4. Increased tissue oncotic pressure eg. lymphatic blockage

Question 6

Define oedema

Answer 6

a collection of excess intersitial fluid IE interstitial fluid pressures become positive

Question 7

define osmolality

Answer 7

osmolaLity is the number of particles (osmoles) of solute dissolved in one Kg of solution, usually measured in lab or using an osmometer

Question 8

define osmolaRity

Answer 8

R rita USEFUL,

OsmolaRity is the number of particles dissolved in a litre of solution (mosmol/L)

Question 9

how do you calculate plasma osmolaRity?

Answer 9

2(Na +K) + glucose +urea

Question 10

what is the normal plasma osmolaRity?

Answer 10

normal plasma osmolaRity 280-295mosmol/L

normal urine osmolaRity=300-1400mosmol/L