ILA 2 - water and salt balance Flashcards
Water distribution
Total body water = 60%, 42L
Intracellular = 40% body, 28L –> stable
Extracellular = 20% body, 14L –> intravascular, plasma, interstitial
Plasma (ECF) composition
high concentration of sodium, chloride, urea, bicarbonate and protein
Interstitial fluid (ECF) composition
high concentration of sodium, chloride, bicarb but low concentrations of protein
Intracellular fluid composition
high potassium, phosphate, magnesium and protein
Osmolality
The concentration of a solution expressed as the total number of solute particles per Kg, largely determined by sodium and anions
Plasma osmolality formula
2(Na) + 2(K) + urea + glucose. normal = 275-295
oncotic pressure
type of osmotic pressure that is exerted by proteins (albumin) in the plasma. It pulls water into the circulation system (from interstitial fluid to plasma)
osmosis
Movement of water from an area of high water (low solute) concentration to an area of low water (high solute) concentration through a semi-permeable membrane
Osmotic pressure
Amount of solutes required to prevent osmosis from happening
Hydrostatic pressure
The force exerted by a fluid against a wall
Hydrostatic pressure in capillaries (conditions to make the nutrients leave and be reabsorbed)
Hydrostatic pressure is higher then the opposing osmotic pressure produced by the circulating albumin. This forces nutrients out of the capillaries and into the surrounding tissues. Reabsorbed when the hydrostatic pressure is less than the osmotic pressure
Osmotic gradient
movies via osmosis: produced by the difference in concentration of all solutes on either side of a semi-permeable membrane
Oedema
excess water in interstitial tissue spaces, disruption of the filtration and osmotic forces of circulating fluids
What is albumin needed for
Needed to pull fluid back into the blood vessel via oncotic pressure
Insensible losses definition
losses that cannot be measured/ occurs unconsciously
