Body fluids Flashcards
What is the composition of extracellular fluid?
plasma (8%) and interstitial fluid (30%)
what composition of body water does extracellular fluid take up?
60% roughly
what are the compositions of body water?
extracellular fluid & intracellular fluid
what are the constituents of body fluids
- electrolytes - charged e.g ions Na, K, Ca, and proteins (colloids) - negatively charged in solution
- Non electrolytes - uncharged e.g glucose
what does sodium do?
Its the main extracellular cation
- Contributes to osmotic pressure of ECF
- Sodium concentration gradient across the membrane provides potential energy for transport of other membranes
- Carries an inward current for membrane excitation
what is the main - extracellular cation and intracellular cation?
extracellular - Na
Intracellular - K
what are the main intracellular anions in intracellular and extracellular?
Extracellular - Cl
Intracellular - phosphates and proteins
role of potassium?
- Contributes osmotic pressure of cytoplasm
- Important in establishing the resting potential
- carries outward current which depolarises excitable membranes
Role of calcium ions? low [Ca] in cells
- regulates muscle contraction
- regulates activity of enzymes
- regulates exocytosis
Role of magnesium ions (intracellular & extracellular) ?
antagonist of Ca ion action
- cofactor for enzymes
- memory and learning
what are the role of HPO41-/HPO4 / HCO3- (phosphates)
Buffer H+ concentrations
What is the role of Cl ions
main anion of tissues - counter ion for cations and positively charged proteins
Describe 7 functions of electrolytes
- cofactors for enzyme reactions - Na, K, Mg, Zn
- Action potential generation. - Na, K
- Secretion and action of neurotransmitters - Ca
- Muscle contraction - Ca
- Acid base balance HCO3-, phosphate, proteins
- primary and secondary active transport - Na+/K+ ATPase , glucose co transport
- Osmosis - electrolytes and proteins promote water movement between fluid compartments across semi permeable membranes
