4 - Membrane Transport Flashcards
What are the dominant ions in the ECF and ICF?
ECF - Na
ICF - K
How do you work out osmolality if you know the sodium and potassium concentration?
Double it, can assume same amount of Cl as other ions
What transport requires ATP and what doesnt?
No ATP: Osmosis, Diffusion
ATP: Phagocytosis, Pinocytosis, Active
Why is facilitated diffusion faster than normal?
Don’t have to worry about the thickness of the membrane
What are the main points of Fick’s law?
Diffusion is proportional to SA of barrier and inversely proportional to thickness.
Concentration gradient is driving force of net diffusion
Flux is 0 when no concentration gradient
Does Na+/K+ ATPase affect membrane potential?
No, swapping exact same charges
How do large molecules enter the cell?
Endocytosis, Phagocytosis, Pinocytosis
ACTIVE
What is the structure of an aquaporin and what is it’s function?
- 6 TM Alpha helices
- Narrow inner cavity with hydrophilic AA
- Centre of channel +vely charged residues to prevent entry of H+ ions
- Molecules go through single file really fast
- In tissues associated with movement of fluid
What does it mean having a high osmotic pressure?
High solute concentration, would take a lot of force to resist the water entering the solution
What is osmolality and what are the units?
When the concentration of a solution is expressed as the number of solute particles per kg of water
280-310 mOsm/kg normally
