Water/fluid balance

Osmotic regulation

control of tissue osmotic pressure and osmotic pressure affects cell volume + cell/organelle function

Ionic regulation

control of ionic composition of body fluids

Nitrogen excretion

ammonia + end products of protein catabolism

IONIC Environment

intracellular DOES NOT equal extracellular

concentration is lower for NaCl, chloride, calcium

concentration is higher for K, phosphate, protein

Osmotic environment

intracellular IS approx = extracellular

Plasma membrane

CANT regulate osmotic balance but CAN regulate ionic

Epithelia

can regulate BOTH, specialized in kidneys = digestive tract

ICF

65% of fluid compartment

ECF

35% of fluid compartment

interstitial fluid

25% of ECF + contains tissue

intravascular fluid

8% of ECF + contains plasma/lymph

transcellular fluid

2% of ECF and contains everything else

Sources of water IN

metabolic water

food

drink

Sources for water OUT

feces

evaporation

urine

How can water be lost?

high body temperature

hot/humid = low water loss

cold/dry = high water loss

Nasal mucose/conchae

incoming is warmed/humidified/cooling nose

outgoing is cooled + loses water to wet nose