An intro to kidney and body fluids Flashcards
Total body water
60% body weight
Intracellular water
40% body weight (ICF compartment)
Extracellular water
20% body weight (ECF compartment)
What does osmosis determine?
The movement of water between ICF and ECF
What is the plasma compartment sometimes called?
Effective circulating volume. Normally 20%
What does the ECFV consist of?
Plasma (3L) Interstitial fluid (11L) Starling's forces determine fluid and solute movement between plasma and interstitial fluid
What is OSMOLARITY?
The total concentration of osmotically active solutes.
What electrolyte is the principle for ECF?
Sodium - important for ECF osmolarity
Why is control of body fluids important?
Cell structure and function - Large shifts between ECFV and ICFV will disrupt tissue structure and function.
Tissue perfusion - Depends and balance between circulating volume (plasma) and interstitial volume
Salt and water balance depends on what 2 processes?
Osmoregulation: maintain osmotic equilibrium between ICFV and ECFV
Volume regulation: maintain adequate ECFV to support plasma volume
Plasma osmolarity can be estimated by
2[Na] + 2[K] + [glucose] + [Urea] all in mmol-1
How does the body accomplish osmoregulation?
By adding or removing water not sodium
What happens when your plasma osmolarity rises?
More water is needed. So the kidney responds by producing a small volume of concentrated urine (water retention)
What happens when your plasma osmolarity falls?
There is too much water. So the kidneys respond by producing large volumes of dilute urine (water excretion)
What is volume regulation?
Refers specifically to the control of the circulating (plasma) volume
