8.4 Electrical Signals And Neural Pathways

Question 1

uneven distribution of charge means that the cell membrane is

Answer 1

polarized

Question 2

in an unsimulated (or resting) cell, the uneven charge distibution is called

Answer 2

resting membrane potential

Question 3

a small voltage difference

Answer 3

potential

Question 4

3 main factors generating the resting membrane potential

Answer 4

(1) a higher concentration of K+ immediately inside the cell membrane
(2) a higher concentration of Na+ immediately outside the membrane
(3) grater permeability of the cell membrance to K+ than Na+

Question 5

protein embedded in the cell membrane

Answer 5

ion channels

Question 6

always open

Answer 6

leak channels

Question 7

closed until opened by specific signals

Answer 7

Gated channels

Question 8

opened by neurotransmitters or other chemicals

Answer 8

Chemically gated channels

Question 9

opened by a change in membrane potential

Answer 9

Voltage-gated channels

Question 10

point of equilibrium at which the tendency for K+ to move down its concentration gradient out of the cell is balanced by the negative charge within the cell

Answer 10

restin membrane potential

Question 11

required to maintain the greater concentration of Na+ outside the cell membrane and K+ inside

Answer 11

sodium-potassium pump

Question 12

the resting membrane potential changes in response ti stimuli that activate gated ion channels

Answer 12

excitable celle

Question 13

channels responsible for the action potential

Answer 13

voltage gated Na+ and K+ channels

Question 14

movement of Na+ which causes the inside of the cell membrane to become positive

Answer 14

local current

Question 15

a change in which the inside of the cell is positive

Answer 15

depolarization

Question 16

Depolarization results in

Answer 16

a local potential

Question 17

causes voltage-gated Na+ channels to open

Answer 17

threshold depolarization

Question 18

depolarization and repolarization constitue an

Answer 18

action potential

Question 19

condition when the charge on the cell membrane briefly becomes more negative than the resting membrane potential

Answer 19

hyperpolarization

Question 20

If threshold is reached, an action potential occurs; if the threshold is not reached, no action potential occurs

Answer 20

all-or-non fashion

Question 21

type of action potential conduction wherein the action potential is conducted along the entire axon cell membrane

Answer 21

continuous conduction

Question 22

wherein action potentials “jump” from one node of Ranvier to the next along the length of the axon

Answer 22

saltatory conduction

Question 23

a junction where the axon of one neuron interacts with another neuron or with cells of an effector organ, such as a muscle or gland

Answer 23

synapse

Question 24

end of the axon forms a

Answer 24

presynaptic terminal

Question 25

membrane of the dendrite or effector cell

Answer 25

postsynaptic memberane

Question 26

space separating the presynaptic and postsynaptic membranse

Answer 26

synaptic cleft

Question 27

chemical substances

Answer 27

neurotransmitter

Question 28

where neurotransmitters are stored in the presynaptic terminal

Answer 28

synaptic vesicles

Question 29

In which the inside of the postsynaptic cell tends to become more negative and an action potential is inhibited from occurring

Answer 29

hyperpolarized

Question 30

are repidly broken down by enzymes within the synaptic cleft or are transported back into the presynaptic terminal

Answer 30

Neurotranmitter substances

Question 31

enzyme that breaks down acetylcholine

Answer 31

acetylcholinesterase

Question 32

an involuntary reaction inr esponse to a stimulus applied to the periphery and transmitted to the CNS

Answer 32

Reflex

Question 33

the neuronal pathway by which a reflex occurs

Answer 33

reflex arc

Question 34

basic functional unit of the nervous system because it is the smallest, simplest pathway capable of receiving a stimulus and yielding a response

Answer 34

reflex arc

Question 35

5 baisc components in a relfex arc

Answer 35

(1) sensory receptor
(2) sensory neuron
(3) interneurons
(4) motor neurons
(5) effector organ

Question 36

neurons located between and communicating with two other neurons

Answer 36

interneurons

Question 37

two or more neurons synapse with the same neuron

Answer 37

converging pathway

Question 38

the axon from one neuron divides and snapses with more than one other neuron

Answer 38

diverging pathway

Question 39

occurs when the local potentials originate from different locations on the postsynaptic neuron

Answer 39

Spatial summation

Question 40

occurs when local potentials overlap in time

Answer 40

Temporal summation