Physiology: Membrane Transport Flashcards
what influences a cell’s ability to permeate the membrane
lipid solubility and particle size
what are the two types of driving forces for moving an ion across the membrane
passive and active
how is passive transport driven
diffusion down a conc. gradient and/or movment along an electrical gradient
what is Fick’s Law of Diffusion (5)
- size of conc. gradient
- membrane SA
- substance’s lipid solubility
- substance’s molecular weight
- diffusion distance
what creates an electrical gradient and where does the ion move
created by two areas with differing charges, ions move to that of opposite charge
what are the two types of ions specific channel proteins
leak or ligand gated
what is an electrochemical gradient
the net of an ions chemical and electrical gradient
what channels allow osmosis
aquaporins
omsolarity
conc. of osmotically active particles in a solution
tonicity
effect a solution has on cell vol.
3 types of tonicity and their effects
- isotonic = no effect
- hypotonic = water into cell and cell swells
- hypertonic = water out of cell and cell shrinks
what are the 3 mechanisms of passive transport
- osmosis
- diffusion
- electrical gradients
2 mechanisms for selective active transport
- carrier mediated transport
- vesicular transport
describe the process of carrier-mediated transport
substance binds to carrier - conformational change - substance transported
what are the 3 characteristics in carrier-mediated transport determining the kind and amount of material transferred
- specificity
- saturation
- competition
what are the two types of carrier-mediated transport
active and facilitated
describe active carrier-mediated transport
carrier expends energy transferring against concentration gradients
describe facilitated carrier-mediated transport
carrier facilitates movement from high to low concentration gradient
what are the two forms of active transport
primary and secondary
describe primary active transport
energy needed directly to move substance against conc. gradient
descrive secondary active transport
energy needed but not in ATP form used energy stored in ion conc gradient, coupled with ion transfer used as driving force
what type of transporter is Na/K ATPase and what is the movement of its ions
- primary active carrier-mediated transporter
- 3 Na+ out and 2 K+ in
what are the 3 role of Na/K ATPase
- helps establish Na+ and K+ gradients
- helps regulate cells vol by controlling solute concs inside the cell
- energy used to drive pump indirectly used by secondary active transporters
what are the 2 mechanisms of secondary active transport and how they work
- symport - both move in same direction
- antiport - each move in different directions
