Membrane Physiology Review

Question 1

what are cells aurrounded by? composed of?

Answer 1

surrounded by plasma membrane composed of lipid bilayer

Question 2

why are some tails of the lipid bilayer bend? what does this do to the membrane?

Answer 2

due to saturated or unsaturated FAs, gives membrane fluidity

Question 3

what does the lipid bilayer do? (3)

Answer 3

1. forms basic membrane structure
2. prevent pasasge of most water-soluble substances
3. largely responsible for fluidity of plasma membrane

Question 4

give 6 peices besided lipid bilayer in plasma membrane

Answer 4

1. channels
2. carriers
3. receptors
4. docking-marker acceptors
5. enzymes
6. self-identity markers

Question 5

what are the 3 types of membranes?

Answer 5

1. permeable: all substances cross
2. impermeable: substance can’t cross
3. selectively permeable: some substance can and some substances can’t cross

Question 6

what is membrane permeability influenced by? (2)

Answer 6

1. relative solubility in lipid (uncharged or nonpolar readily permeates, charged or polar has low lipid solubility)
2. size of molecule

Question 7

if force is needed to produce movement across a membrane what are the two types?

Answer 7

active and passive

Question 8

what is diffusion?

Answer 8

the result of molecules richoceting off each other, a steady state of equilibrium with no net mvmt, slow (slower over distance)

Question 9

what are the kinds of forces that move substances acorss membranes?

Answer 9

gradients: chemical/concentration and electrical

Question 10

what are the types of carrier mediated transport?

Answer 10

1. facilitated diffusion (3 kinds)
2. active transport

Question 11

what are the 3 types of facilitated diffusion?

Answer 11

1. uniport: one substance, one direction
2. symport: 2 substances, same direction
3. antiport: 2 substances, opposite directions

Question 12

give example of uniport faciliated diffusion

Answer 12

glucose transporters

Question 13

give an example of symport faciliated diffusion

Answer 13

pull NaCl back in inloops of Henle

Question 14

give an example of antiport faciliated diffusion

Answer 14

H+ and Na+ in proximal convoluted tubules of kidneys

Question 15

what is membrane potential?

Answer 15

all cells have; slightly + outside and slightly - inside

Question 16

what can produce rapid, transient changes in membrane potential?

Answer 16

extiable tissues (nervous, muscle)

Question 17

what is resting membrane potential?

Answer 17

constant membrane potential in excitable cells at rest and non-excitable cells

Question 18

?what are 4 sources of membrane potential

Answer 18

1. Na+: more outside the cell
2. K+: more inside the cell
3. A- (large, negatively charged intracellular proteins) found only inside the cell
4. Cl-: more outside the cell, minor impact

Question 19

describe the Na+/K+ ATPase pump

Answer 19

a type of facilitaed diffusion;
1. 3 Na+ from inside the cell bind to a carrier
2. the energy released from ATP changes the carrier configuration to release 3 Na+
3. carrier then binds 2 K+ from outside the cell
4. carrier configuration changes again to bring K+ inside
both Na+ and K+ move against their concentration gradients (requires energy)