Compartments & Solutes Flashcards
Which cation is most abundant in plasma?
Sodium
Which cation is most abundant intracellularly?
Potassium
Is calcium a more abundant intracellularly of extracellularly?
Higher concentrations in the plasma than outside the cells
How is the internally high concentration of potassium neutralize?
Anions
What are the anions present intracellularly?
Phosphate ins
Proteins (net negative charge)
What is an isotonic concentration?
No osmotic effect
Between blood and intracellular compartment
What is diffusion?
The spontaneous movement of a solute down a concentration gradient until solute molecules reach an equilibrium
What is osmosis?
Movements of water through a water potential gradient across a partially permeable membrane (High water potential to low)
What is water potential?
Water potential is the tendency of water to move out of a system
What is osmolarity?
Solute concentration
What is the final state of osmosis?
Intracellular osmolarity = Outside osmolarity
Equal concentrations, no net volume change or diffusion
What is tonicity?
Measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a semi-permeable cell membrane
Which two factors influence tonicity?
Cell membrane permeability and solution composition
What are hypertonic solutions?
The osmolarity of the extracellular impermeant solutes greater than those inside the cells
Water moves to the region of lower water potential by osmosis, thereby the cell undergoes crenation
What are hypotonic solutions?
The osmolarity of the extracellular impermeant solutes are less than those inside the cell. The direction of osmosis and the net movement of water will be from the solution o to the cell
Cell swells and lysis
What is an isotonic solution?
The osmolarity of the extracellular impermeant solutes identical to those inside the cell
Cell volume, therefore, remains the cells
How do cells regulate cell volume?
Impermeant solute concentration greater intracellularly
Cells do not burst due to ATPase potassium-Sodium pump
Results in membrane permeability to Na, sodium actively pumped out
No net movement of sodium ions across the membrane
The intracellular osmolarity of the impermeant solutes negates the extracellular osmolarity of the impermeant solutes
The high concentration of protein within the cell
Which molecules can pass through the phospholipid bilayer into the cell?
Oxygen, nitrogen and carbon dioxide Hydrophobic molecules (steroids) undergo passive diffusion
How do hydrophilic molecules enter into the cell?
Active transport via carrier proteins and ion channels
How is ATP supplied to active transport?
ATP hydrolysis, ATP is supplied by creatine kinase via creatine phosphate
What conditions are used to preserve transplanted organs?
4 degrees celsius, perfused with cold solutions with the arteriole supply
Which is associated with hypothermic conditions?
Ischaemia
What happens to ATPase Na-K during ischemia?
The function is inhibited, low oxygen availability , ATP supplied is limited
Sodium and chloride will subsequently enter the cell and sodium permeability increases, along their respective electrochemical and concnetration gradients, wate rwill enter the cell as potassium exists, Cell swell, bleb and necrosis
What is the University of Wisconsin solution (UW)?
Organ is perfused with the solution, reduces hypothermic cell swelling and enhances cell preservation
Lack of sodium, cl; prevents influx of extracellular impermeant solutes
Presence of colloid (starch)
