1.2 Phys gradients Flashcards
gradients
when a difference exists between two compartments with respect to the pressure, conc, or electrical potential of a given variable
3 types gradients?
Examples?
1) pressure= fluid moves from high pressure to low
2) concentration= K+ and Na+
3) electrical= membrane potentials
* **energy
Gradients are a source of? Cells spend a lot of ____ controlling gradients?
energy
**conc gradients of Na+ and K+
150 outside (ECF= Na); 140 inside (ICF=K+) *ocean banana*
membrane potential is another way of saying?
electrical gradient
membrane function and examples?
1) membrane dynamics= transport, translation, signal transduction
2) membrane potentials= graded, action, equilibrium, receptor
membrane structure?
bilayer lipid barrier
1) repels hydrophilic/lipophobic/polar/charges
2) admits hydrophobic/lipophilic/nonpolar/uncharged
communication across membrane (3)
1) membrane transport proteins= selectivity =specific
2) membrane translocation channels= selectivity; pass ions
3) signal transduction processes= INFO ONLY passes
hydrophobic affect with transport channels
nonpolar outside and polar inside
outer leaflet and inner leaflet of phospholipid bilayer
outer=sphingomyelin and phosphatidylcholine
inner= phosphotidylcholine, P serine, P inositol
amphipathic
having both hydrophilic and hydrophobic parts
determinants for what crosses?
!) polarity
2) lipid solubility
3) size
* charged molecules like to hang out with charged molecules and repel neutral
* neutral like neutral and repel charged
charged heads of lipid bilayer do not provide much of a barrier for?
neutral molecules
H2O is polar or non?
permeable bc of?
- polar/charged/hydrophilic/lipophobic
* aquaporins
what are aquaporins
membrane translocation proteins selective for WATER and bidirectional
- water cannot cross by itself, NEEDED
- amount depends on cell
description for charged molecules?
POLAR hydrophilic lipophobic CANNOT cross freely *ions, glucose, AA, neurotransmitter
description for UNcharged molecules? (aka neutral)
NONPOLAR hydrophobic lipophilic CAN cross freely *FA, cholesterol, steroid hormones, O2, CO2
increaseing concentration always increases?
rate of diffusion
passive transport process? (2)
hydro or lipophilic?
1) diffusion or simple diffusion =lipophilic
2) facilitated diffusion =hydrophilic
* no ATP energy required
active transport processes? (2)
1) primary active transport
2) secondary active
* ATP energy required
what transport processes are mediated transport?
1) facilitated (passive)
2) primary active transport (active)
3) secondary active transport (active)
influx vs efflux vs net flux
influx= into cell
efflux= exit cell
net flux= there is ALWAYS movement both directions, depends on what one is more
what is inversely related to diffusion rate?
thickness of diffusion barrier
what is directly related to diffusion rate?
surface area available for diffusion
diffusivity of solute= lipid solubility
concentration of solute
