Fluid Compartments and Solutes Flashcards
What is the most plentiful cation in the plasma?
Sodium
What is the most plentiful cation inside cells?
Potassium
True or false: chlorine is found at much lower concentrations in plasma than in cells
False: chlorine is found at much higher concentrations in the plasma that inside cells
What is the main intracellular anion?
Organic phosphate
What can phosphorylation of proteins do?
Activate and inactivate them
How does the pH of cell compare with plasma?
Cell is slightly more acidic (0.3 pH units)
Since pH is logarithmic it means the cell has twice the concentration of protons
True or false: the osmolarity between the blood and intracellular compartment is identical
True: normally no significant osmotic effect
Exception-kidney
Define diffusion
Spontaneous movement of a solute down a concentration gradient until the solute molecules reach an equilibrium
Define osmosis
Movement of water down its own concentration gradient
It can change cell volume with consequences for cell function an survival
Define osmolarity
Measure of the concentration of all the solute particles in a solution
What is tonicity?
Defines the ‘strength’ of a solution as it affects the final cell volume
Depends on both cell membrane permeability and the solution composition
What happens in a hypertonic solution?
Osmolarity of impermeant solutes outside the cell are greater than those inside
Water mover out
Cell shrinks
What happens to a cell in hypotonic solutions?
Osmolarity of the impermeant solutes outside the cell is less than inside
Water moves in
Cell swells
What happens to a cell in isotonic solution?
Nothing
Cell volume unchanged
How are cell volumes maintained?
By actively pumping ions
E.g. in hypotonic solution
Na/K pump maintains the conc. of Na+ much lower inside cell
Makes membrane effectively impermeable to Na+
Intracellular and Extracellular osmolarity balance
(High conc of Na+ outside cell)
How does university of wisconsin solution enhance organ preservation?
Reduces cell swelling
- lack of Na+ or Cl- (no influx possible)
- presence of Extracellular impermeant solutes
- presence of macromolecular colloid (starch)
What is colloid osmotic pressure?
Osmotic pressure generated due to higher concentrations of plasma proteins inside the capillary that outside
Why is there a tendency to ‘push’ molecules through the capillary pores?
Flow of blood through the vessel generated a hydrostatic pressure inside vessel greater than than of the tissues
Under normal condition this pressure results in net leakage from the capillary
What is oedema?
Accumulation of fluids with tissues
Results due to an imbalance in the normal chuckle of fluid exchange
What do lymphatic capillaries do?
Collect interstitial fluids destined to return to blood circulation to combat loss of plasma fluids
They have low internal pressure which results in net flow of fluids inwards
How does lymph fluid return to circulation?
Via the lymphatic ducts in the subclavian region or via lymph nodes
At what point does oedema occur?
When leakage of plasma into interstitium exceeds lymphatic capacity
Why does oedema result from high blood pressure?
Increased pressure pushes more fluid out of vessels
What causes elephantiasis?
Parasitic worms block lymphatic vessels preventing drainage
