Electrophysiology II

Question 0

What is a level of depolarization which when exceeded always results in an action potential?

Answer 0

Threshold

Question 1

What are voltage changes common to excitable cells?

Answer 1

Action potentials

Question 2

Action potentials are always what?

Answer 2

All or nothing

Question 3

What gates in Na+ (and sometimes Ca+) channels open upon depolarization?

Answer 3

M (activation) gates

Question 4

What gates in Na+ (and sometimes Ca2+) channels close upon depolarization?

Answer 4

H (inactivation) gates

Question 5

K+ channels with what type of gates open upon depolarization?

Answer 5

N(activation) gates

Question 6

The following gates are characteristic of what: M open, n open, h close?

Answer 6

Depolarization

Question 7

The following gates are characteristic of what: m close, n close, h open?

Answer 7

Repolarization

Question 8

What are the orders in gates from fastest to slowest?

Answer 8

M,h,n

Question 9

Positive feedback interaction of depolarizing activation of m gates and the resulting depolarization of inward Ina is known as what?

Answer 9

Hodgkin cycle

Question 10

What is the period of which h gates are closed and it’s not possible to generate another action potential?

Answer 10

Absolute refractory period

Question 11

What occurs because because the resulting depolarization closes h gates on muscle Na channels keeping them in the equivalent of an absolute refractory period?

Answer 11

Hyperkalemic periodic paralysis

Question 12

What is the period in which n gates are open and it takes an increased stimulus current to generate another action potential?

Answer 12

Relative refractory period

Question 13

What is the term referring to action potentials that are recorded extracellularly and are recoded together simultaneously?

Answer 13

Compound action potentials

Question 14

What are the 2 kinds of local circuit currents?

Answer 14

Resistive current and capacitive current

Question 15

What current flows by actual movement of ions through channels and inward IR depolarization?

Answer 15

Resistive current

Question 16

What current flows because of charge displacement across the lipid bilayer of the membrane and outward Ic depolarizes?

Answer 16

Capacitive current

Question 17

What is determined by stimulating a periphery nerve and recording the compound action potential at a known distance?

Answer 17

Conduction velocity

Question 18

Conduction velocity is proportional to what?

Answer 18

Fiber diameter

Question 19

What is the general conduction velocity in unmyelinated fibers?

Answer 19

2m/s

Question 20

Conduction is characterized by what?

Answer 20

Inflow of resistive current, out flow of capacitive current

Question 21

What type of fibers propagate action potentials by saltatory conduction?

Answer 21

Myelinated fibers

Question 22

The myelin decrease capacitance of what region preventing out flow of capacitive current?

Answer 22

Intermodal region

Question 23

The area in a myelinated axon where the axon membrane is exposed and the capacitive current can flow out is known as what?

Answer 23

Node of Ranvier

Question 24

What is the conduction velocity of myelinated fibers?

Answer 24

Between 5 and 120 m/s

Question 25

The resistive current of the excited node produces enough capacitive current to bring the next two nodes to threshold is known as what?

Answer 25

Safety factor

Question 26

What fiber type has a velocity of 120 m/s, found in spindle afferents for proprioception and alpha motor neuron efferents?

Answer 26

Large myelinated

Question 27

What fiber type travels 15-70m/s, has touch/ pressure afferents and gamma motor neuron efferents?

Answer 27

Intermediate myelinated fibers

Question 28

What type of fibers travel at 1 m/s, have pain/temperature afferents and autonomic efferents?

Answer 28

Small unmyelinated

Question 29

Demyelination results in what?

Answer 29

Capacitive current leaking out and a block of propagation