Hsf: Sodium And Potassium Channels

Front 1

Action Potentials (def)

Back 1

-Transient changes in the membrane potential of cells

Front 2

Nerve (def)

Back 2

a bundle of individual nerve fibers

Front 3

Myelinated Nerves

Back 3

-Axons tightly wrapped by glial cells
-Propagate Action potentials much more rapidly than unmyelinated fibers

Front 4

Unmyelinated Nerves

Back 4

-Axons loosely associated with glial cells

Front 5

Resting Potential of nerve cells

Back 5

~-60mV
-due to presence of some K+ selective channels
-small permeability to Na+

Front 6

The resting potential will be set by the relative amounts of ___ and ___ permeability which can be computed by Goldman-Hodgkin-Katz equation

Back 6

-Na+
-K+

Front 7

What causes depolarization?

Back 7

-An increase in P(Na) associated with the opening of the Na+ channel proteins

Front 8

What does Goldman-Hodgkin-Katz say about depolarization?

Back 8

-An increase in P(Na) will depolarize the membrane potential and the overshoot of the action potential will approach V(Na) when P(Na)>>P(K)

Front 9

The ____ ion permeability begins to increase slowly during the rising phase while ____ begins to decrease

Back 9

-K+
-P(Na)=permeability of Na+

Front 10

These two events (_____, ______) produce a repolarization of Vm.

Back 10

P(Na) decrease, P(K) increase

Front 11

Relative Refractory Period (def)

Back 11

-If too little time is allowed before the second stimulation, it will be impossible to generate the second action potential.
-P(Na) is near normal
-P(K)= somewhat higher than at rest

Front 12

Absolute Refractory Period (def)

Back 12

-P(K)=very high; P(Na)=very low compared to first action potential

Front 13

Depolarization overshoot approaches what?

Back 13

-V(Na)

Front 14

"Patch Clamp" Technique (more specific type of "Voltage" Clamp)

Back 14

-expt done by Ehren Neher (Nobel Prize winner)
-glass pipette pressed against cell membrane inside an ion channel
-Current through channel recorded

Front 15

Two Factors for Getting Membrane Voltage under control

Back 15

-Time
-Voltage

Front 16

Probability of Channel Openings Depends on....(2)

Back 16

-Time
-Voltage

Front 17

Both the kinetics and the steady-state probability of channel opening depend on ______ _______.

Back 17

Membrane Voltage

Front 18

"Voltage-Gated" ion channels (def)

Back 18

-Large, glycoproteins floating in the lipid bilayer membrane
-Must have a region that detects membrane voltage

Front 19

Voltage part of "Voltage-Gated" ion channels

Back 19

-Controls the protein conformation to provide closed, open, and inactivated states

Front 20

Open Conformation of "Voltage-Gated" Ion Channels

Back 20

-Allows ions and water to pass through the aqueous pore
-Controls ion selectivity
-Some modulated by phosphorylation