Diffusion Potential, Resting Membrane Potential, Action Potential

Question 1

Refers to INTRACELLULAR charge

Answer 1

Resting Membrane Potential
ALL cells
-70 mV - large neurons
-90 mv - cardiac muscles

Question 2

Exhibited only by EXCITABLE cells (neurons, all muscle types)

Answer 2

Action Potential (AP)

rapid depolarization (upstroke) followed by repolarization

Question 3

Characteristics of TRUE AP

Answer 3

stereotypical size and shape
propagating (nondecremental manner)
all or none

Question 4

Cell membrane INTEGRAL proteins that permit passage of certain ions

Answer 4

ION CHANNELS

selective for specific ions
maybe OPEN or CLOSED

Question 5

Opened or closed by CHANGES in membrane potential

Answer 5

voltage gated channels

Question 6

Opened or closed by HORMONES, 2ND MESSENGERS, NEUROTRANSMITTERS

Answer 6

Ligand Gated Channels

Question 7

POTENTIAL DIFFERENCE generated across a membrane because of a concentration difference of an ion

Answer 7

DIFFUSION POTENTIAL

Question 8

Diffusion potential that exactly balances (opposes) the tendency for diffusion caused by concentration difference

Answer 8

Equilibrium Potential (Nernst Potential)

Question 9

Make the MP more positive

Answer 9

DEPOLARIZATION

Question 10

Make the MP more negative

Answer 10

HYPERPOLARIZATION

Question 11

positive charges flow INTO the cell –> DEPOlarization

Answer 11

Inward Current

Question 12

positive charges flow OUT the cell –>HYPERpolarization

Answer 12

Outward current

Question 13

MP where AP is INEVITABLE

Answer 13

THRESHOLD

net inward current > net outward current

Question 14

Occurs during an AP when MP > 0 mV

Answer 14

OVERSHOOT

Question 15

Occurs during an AP when MP < RMP

Answer 15

UNDERSHOOT (after hyperpolarization)

Question 16

Occurs during an AP when no new AP can be elicited no matter how large the stimulus

Answer 16

ABSOLUTE REFRACTORY PERIOD (ARP)

closed Na inactivation gates

Question 17

Occurs during an AP after ARP when a new AP can be elicited by required greater than usual Na inward current

Answer 17

Relative Refractory Period (RRP)

prolonged opening of K channels

Question 18

Occurs when cell membrane is DEPOLARIZED but NOT RAPIDLY ENOUGH thus causing Na inactivation gates to eventually close –> NO AP

Answer 18

ACCOMODATION

i.e. hyperkalemia

Question 19

Non propagated local potential d.t. local change in ionic conductance

Answer 19

Electrotonic Potential

Question 20

Local electrical charge in the generator/sensitive region of the receptor cell graded potential

Answer 20

Generator potential/Synaptic potential

Question 21

Principal inputs signal to which neuron responds

Conductance changes are triggered by neurotransmitters

Answer 21

Synaptic Potentials

Question 22

Conduction VELOCITY is INCREASED by

Answer 22

Fiber size
Nerve diameter - conduction velocity is MOST DEPENDENT
myelination