Flashcards in Fluid and Salt Balance Deck (16):
What is the total body water?
42 litres (0.6 x body weight)
What is the total intracellular fluid?
28 Litres (0.4 x body weight)
What is the total extracellular fluid?
14 litres (0.2 x body weight)
What can extracellular fluid be divided into?
1. Plasma (3.5L)
2. Interstitial fluid (10.5L)
What does the extraceullar fluid contain in terms of ions?
Na+, K+, Cl-, HCO3-
What is osmolarity?
(Na+ + K+) x 2 = (145 + 4) x 2 = about 300 milliosmoles/litre
How much water do we gain and lose a day?
What is hypovolaemia?
A decrease in circulating blood volume
What senses the changes in circulating blood volume and causes the release of angiotensin II?
What is hypertonicity?
When blood osmolarity increases (dried out cells)
What sense the changes in blood osmolarity?
What does the hypothalamus do in times of hypovolaemia or hypertonicity?
Cause vasopression (anti-diuretic hormone) release from the posterior pituitary and also thirst
What receptors does ADH (vasopressin) act on?
What happens when ADH binds V2 receptors?
Activates adenylate cyclase to convert ATP to cAMP
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