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
