Fluid and Salt Balance Flashcards Preview

Physiology > Fluid and Salt Balance > Flashcards

Flashcards in Fluid and Salt Balance Deck (16):
1

What is the total body water?

42 litres (0.6 x body weight)

2

What is the total intracellular fluid?

28 Litres (0.4 x body weight)

3

What is the total extracellular fluid?

14 litres (0.2 x body weight)

4

What can extracellular fluid be divided into?

1. Plasma (3.5L)
2. Interstitial fluid (10.5L)

5

What does the extraceullar fluid contain in terms of ions?

Na+, K+, Cl-, HCO3-

6

What is osmolarity?

(Na+ + K+) x 2 = (145 + 4) x 2 = about 300 milliosmoles/litre

7

How much water do we gain and lose a day?

2.5L/day

8

What is hypovolaemia?

A decrease in circulating blood volume

9

What senses the changes in circulating blood volume and causes the release of angiotensin II?

Baroreceptors

10

What is hypertonicity?

When blood osmolarity increases (dried out cells)

11

What sense the changes in blood osmolarity?

Osmoreceptors

12

What does the hypothalamus do in times of hypovolaemia or hypertonicity?

Cause vasopression (anti-diuretic hormone) release from the posterior pituitary and also thirst

13

What receptors does ADH (vasopressin) act on?

V2 receptors

14

What happens when ADH binds V2 receptors?

Activates adenylate cyclase to convert ATP to cAMP

15

What does an increase in cAMP lead to in cells with V2 receptors?

Insertion of aquaporin into the cell membrane which lets water in to return the cell to normal from hypertonic

16

What is retained in order to retain water?

Sodium ions