action potentials

Question 1

Concentration of ions differs on opposite sides of the membrane.
T/F

Answer 1

T

Question 2

Resting membrane potentials (RPM) are Positive (inside relative to the outside).
T/F

Answer 2

F. they are NEGATIVE

Question 3

graded potentials

Answer 3

Non-Excitable cells respond to stimulation with a proportional change in membrane potential

Question 4

Hyperpolarize VS

Depolarize

Answer 4

Hyperpolarize: create a more negative membrane potential
Depolarize: create a more positive membrane potential

Question 5

Ohm’s Law:

Answer 5

Ohm’s Law: V= I x R or I = V x g
Voltage (V) –
Current (I) – the rate of flow of electrical charge between two points
Resistance (R) – hindrance to charge flow
Conductance (g) – allowance to charge flow (1/R)

Question 6

Insulator VS Conductor

Answer 6

Insulator – substance with high electrical resistance

Conductor – substance with low electrical resistance

Question 7

Electrical vs chemical gradient

Answer 7

Electrical gradient: A difference in electrical charge across a membrane
Ions flow along their electrical gradient toward an area of opposite charge.
Chemical gradient: A difference in ion concentration across a membrane
Ions flow along their chemical gradient from an area of high concentration to an area of low concentration.

Question 8

what is nernst equation ?

Answer 8

used to calculate equilibrium potential
E=(RT/zF)ln(Xout/Xin)
R- gas constant
T-temp in K
z-valence
F-faraday's constant 
Xout- concentraton outside cell

Question 9

Typical Ion Concentrations for Mammalian Neurons

Answer 9

K+: IN: 145 OUT:5
Na+: IN:5-15 OUT:145
Cl- IN:4-30 OUT:110
Ca2+: IN .0001 OUT 1-2

Question 10

Equilibrium Potential for Important Ions in a Neuron

Answer 10

K+: -80 TO -90 mV
Cl-: -60 to -70
Na=: 55 to 60
Ca2+: 100 to 130

Question 11

Leakage/Passive channels

Answer 11

Leakage/Passive channels – Always open, allow passive diffusion of specific ions

Question 12

Chemically/ligand gated channels

Answer 12

Chemically/ligand gated channels – open with binding of a specific neurotransmitter

Question 13

Mechanically gated channels

Answer 13

Mechanically gated channels – open and close in response to physical deformation of receptors

Question 14

Voltage-gated channels

Answer 14

Voltage-gated channels – open and close in response to changes in membrane potential

Question 15

What determines duration of a graded potential

Answer 15

Duration is directly proportional to the duration of the triggering event

Question 16

graded potentials Initiated by

Answer 16

Initiated by ion flow through gated channels
or
activation of voltage gated channels

Question 17

when can graded potential produce an action potential

Answer 17

Graded Potentials That Reach Threshold Can Induce Action Potentials

Question 18

spatial vs temporal summation

Answer 18

multiple excitatory neurons at once
temporal
excitatory neurons come back to back

creating AP

Question 19

normakalemia

Answer 19

When serum K+ is in normal range (normokalemia):

a stimulus that depolarizes the cell by ≥15mV elicits an action potential.

Question 20

hyperkalemia

Answer 20

When serum K+ is high (hyperkalemia):

The Vm is depolarized

Vm is closer to threshold

a previously subthreshold stimulus now elicits an action potential.

Question 21

hypokalemia

Answer 21

When serum K+ is low (hypokalemia):

The Vm is hyperpolarized.

Vm is farther from threshold.

a previously suprathreshold stimulus now fails to elicit an action potential.

Question 22

Hyperpolarizing involving Cl- flow is an example of graded potential T/F

Answer 22

True

Question 23

types of gated ion channels involved in AP vs Gated

Answer 23

AP:Voltage gated

gated : mechanically, chemically, or voltage gated

Question 24

where do graded potentials occur

Answer 24

dendrites and cell body

Question 25

where do AP occur

Answer 25

trigger zone through axon

Question 26

Contiguous Conduction

Answer 26

Depolarization spreads from one area to adjacent areas.

Occurs in unmyelinated fibers.

Question 27

Action Potentials Vary by Cell Type
cardiac?
skeletal muscle?
motor neuron ?

Answer 27

200 msec
5 msec
2msec

Question 28

Goldman’s equations is a measure of

Answer 28

resting Membrane potential depending on distribution and permeability of Na+, K+ and Cl- ions.