Regulation of water, sodium and ECF

Question 1

Fluid entering the LOH from the PCT has a higher conc of … than plasma

Answer 1

Urea

Question 2

What is normal fluid intake?

Answer 2

2mls/kg/hr

Question 3

What the example of sensible water loss?

Answer 3

The kidneys

Question 4

Give examples of insensible water loss

Answer 4

Skin, breathing, excretion, faeces

Question 5

What monitors plasma osmolarity?

Answer 5

Osmoreceptors in the hypothalamus

Question 6

An increase in osmolarity results in the release of what?

Answer 6

ADH

Question 7

How does ADH increase the permeability of the collecting ducts to water?

Answer 7

By inserting aquaporins into the principle cells

Question 8

In which other scenario is ADH released?

Answer 8

• If an animal haemorrhages – it is losing fluid and blood volume
- large changes in blood volume cause ADH to be released

Question 9

What % of an adult is made up of water?

Answer 9

60%

Question 10

How can the % of body water be further divided?

Answer 10

ICF = 40%
ECF = 20%

Question 11

Which ion is not regulated?

Answer 11

Sodium

- so all ingested is absorbed

Question 12

How do kidneys regulate ECF volume?

Answer 12

By adjusting excretion of sodium

Question 13

Which receptors monitor

1. blood volume
2. blood pressure

Answer 13

1 = stretch receptors in atria and veins
2 = baroreceptors

Question 14

Which 3 hormones regulate renal Na+ and Cl– reabsorption or excretion?

Answer 14

• Angiotensin II
• Aldosterone
• Natriuretic peptides

Question 15

What is the function of natriuretic peptides?

Answer 15

Promote excretion of Na+ and Cl– followed by water excretion to decrease blood volume

Question 16

Reduced blood volume increases … absorption

Answer 16

Sodium