Lecture 3 & 4 - Memb/action Potentials

Question 0

Resting membrane potential that we will use for physiological purposes?

Answer 0

-90 mEv

Question 1

saltatory conductions occurs in which part of the neuron?

Answer 1

axon

Question 2

resting membrane potential eqn?

Answer 2

EMF = Eion = z(61.5) x log ([ion]outside/[ion]inside)

Question 3

Dendrites conduct what type of potentials?

Answer 3

Local potentials

Question 4

Cell bodies of neurons typically conduct __________ potentials, rather than ______ potentials?

Answer 4

Local

Action

Question 5

what type of protein channels are dendrites known for having ?

Answer 5

Ligand gated ion channels

Question 6

What is the plasma memb. of an axon called? and what protein channels does it contain?

Answer 6

Plasmolemma

Voltage gated ion channels

Question 7

•A diffusion potential is caused by ?

Answer 7

an ion concentration difference on either side of a membrane

Question 8

resting potentials always negative b/c ?

Answer 8

they are taken from INSIDE the cell

Question 9

•The Nernst potential is ?

Answer 9

the diffusion potential level across a membrane that exactly opposes the net diffusion of a
particular ion through the membrane;

Question 10

Eqn for the nernst potential?

what is it used for ?

Answer 10

E = 2.3 RT/F log Co/Ci
EMF = Eion = z(61.5) x log ([ion]outside/[ion]inside)
-z if Cl ion, + of K or Na ion.
measures the potential for one ion at a time.

Question 11

Diffusion potential =

Answer 11

the EMF electro motive force

Question 12

resting memb. potentials in nerves for
Na?
K?

Answer 12

+70 mV

-94 mV

Question 13

What does goldman equation get us?

What is the actual potential and why?

Answer 13

the calculated memb. potential on the inside of the cell of -86 mV
With the Na/K pump it takes our resting potential to -90.

Question 14

what are the 2 potentials to be balanced in the Nernst Eqn?

Answer 14

Osmolarity potential and Electric potential

Question 15

What is the difference in channels b/w action and local potentials?

Answer 15

Local have ligand gated and Action pot’s have ion gated.

Question 16

how many gates in K and Na ion gated channels? when open

Answer 16

K - 1 gate open from +30mV to -90mV
Na - 2, activation and inactivation gate
activation open from -70to -50 and stay open until -90 but
Inactivation closed from +35 to -90

Question 17

What is responsible for forming the selectivity filters on the K ion channels?

Answer 17

Carbonyl oxygens bound to the poor helix.

Question 18

larger diameters of axons =

Answer 18

less resistance and therefore faster action potential

Question 19

myelin sheaths act like ? to insulate and keep charges separate.

Answer 19

Capacitors

Question 20

Threshold .

Answer 20

is the point at which a local potential will elicit an action potential
typically -65 mV

Question 21

Direction of Action Potentials, 2 ways? and why more one than the other?

Answer 21

Orthodromic - normal direction , down axon away from soma
Antidromic - opposite direction.
Ortho more b/c of Refractory periods, and ion gated channels need a moment to reset.

Question 22

Do all axons contain schwann cells? what does this mean or not mean?

Answer 22

Yes they all have schwann cells, though it doesn’t mean that they all contain myleinated sheaths, B/c they don’t.

Question 23

•_________ is the principle lipid found in myelin sheaths.

Answer 23

Sphingomyelin

Question 24

Which are fastest neurons?

Answer 24

Large myelinated nerves