Block 3

Question 1

injection of a negative current into a neuron

Answer 1

hyperpolarization

Question 2

injection of a positive current into a neuron

Answer 2

depolarization

Question 3

region of instability in the current/voltage relationship

Answer 3

action potential

Question 4

basis of neural signaling

Answer 4

abrupt depolarization

Question 5

What happens during rapid depolarization?

Answer 5

takes the membrane potential past zero, approaches the sodium equilibrium potential but does not quite get there

Question 6

What happens during rapid hyperpolarization?

Answer 6

takes the membrane potential farther way from zero, approaches the potassium equilibrium potential but does not quite get there

Question 7

slightly depolarizing stimulus that is necessary to produce an action potential in an axon

Answer 7

threshold

Question 8

___ mV of charge brings neuron to just above resting potential

Answer 8

10

Question 9

the overall concentrations of K, Na, Cl on the outside and inside of the axon do not dramatically change, so vM must fluctuate because the ____ of the ion change (movement of ions in vs. movement of ions out)

Answer 9

relative contributions

Question 10

the ability of ions to move across the membrane

Answer 10

conductance

Question 11

two ions currents that drive the entire action potential

Answer 11

sodium and potassium

Question 12

a positive electrical signal causes ___ conductance to increase, so it enters the axon fast

Answer 12

sodium

Question 13

conductance dependent upon an initial electrical signal

Answer 13

voltage dependent

Question 14

charge on the inside of an axon

Answer 14

voltage

Question 15

Voltage and conductance relationship depends upon the opening and closing of channels for what ions?

Answer 15

sodium and potassium

Question 16

What kind of gate is the first sodium gate inside the membrane? (blocked by amino acids when at rest, unblocked during depolarization, and on a timer so the gate can only stay open for a millisecond)

Answer 16

voltage and time sensitive gate

Question 17

second sodium gate on cytoplasmic side of membrane blocks channel; this gate produces the refractory period by closing the gate regardless of the state of other gate and timer

Answer 17

inactivation gate

Question 18

this delays opening the potassium channel for 1 msc, allowing for the Na conductance to depolarize the entire axon

Answer 18

delay mechanism

Question 19

prevents sodium and potassium channels from being interchangeable

Answer 19

selectivity filter

Question 20

channels exist at ___, which are gaps in myelin sheathing where the axon is exposed

Answer 20

nodes of Ranvier

Question 21

the movement of action potential down the axon

Answer 21

propogation

Question 22

the electrically excitable domain

Answer 22

presynaptic terminal

Question 23

__ entry into the terminal facilitates the fusion of vesicles to the plasma membrane, and release of neurotransmitters

Answer 23

Calcium

Question 24

presynaptic communication depends on __ and __

Answer 24

calcium and sodium

Question 25

__ is responsible for endocytosis and replenishment of the free pool of vesicles

Answer 25

calcium

Question 26

Where does threshold usually occur?

Answer 26

axon hillock