chapter 37

Question 1

neurons

Answer 1

nerve cells that transfer information

Question 2

cell body

Answer 2

most of a neurons organelles are in this

Question 3

dendrites

Answer 3

highly branched extensions of neurons that receive signals from other neurons

Question 4

axon

Answer 4

a much longer extension that transmits signals to other cells

Question 5

synapse

Answer 5

axon transmits signals to other cells at a junction called this

Question 6

neurotransmitters

Answer 6

chemical messengers at synapse pass information from the transmitting neuron to receiving cell

Question 7

glial cells

Answer 7

neurons of vertebrates and most invertebrates require supporting cells called these

Question 8

motor neurons

Answer 8

transmit signals to muscle cells

Question 9

central nervous system (CNS)

Answer 9

neurons that carry out integration are organized in this system

Question 10

Peripheral nervous system (PNS)

Answer 10

the neurons that carry information out and in of the CNS are a part of this system

Question 11

nerves

Answer 11

PNS neurons bundled together

Question 12

inside the cell the charge is

Answer 12

negative

Question 13

membrane potential

Answer 13

the difference in negativity inside and positivity on the outside is a source of potential energy

Question 14

resting potential

Answer 14

the membrane potential of a neuron not sending signals

Question 15

sodium-potassium pumps

Answer 15

use the energy of ATP to maintain these K+ and Na+ gradients across the plasma membrane

Question 16

resting neuron has..

Answer 16

many open potassium channels (allowing K+ to flow out)

Question 17

gated ion channels

Answer 17

open and close in response to stimuli

Question 18

depolarization

Answer 18

a reduction in the magnitude of membrane potential

Question 19

action potential

Answer 19

if depolarization shifts the membrane potential sufficiently it resulted in a massive change in membrane voltage

Question 20

threshold

Answer 20

action potentials occur whenever a depolarization increases teh membrane potential to a particular value

Question 21

rising phase

Answer 21

threshold is crossed and the membrane potential increases as all gated Na+ channels are open

Question 22

falling phase

Answer 22

voltage-gated Na+ channels become inactivated. voltage gated K+ channels open and K+ flows out of cell

Question 23

undershoot

Answer 23

membrane permeability to K+ at first higher than at rest, and then voltage gated K+ channels close and resting potential is restored

Question 24

refractory period

Answer 24

after an action potential a second action potential cannot be fired. result in inactivated Na+ channels

Question 25

speed of an action potential is increased by

Answer 25

axons diameter

Question 26

myelin sheath

Answer 26

enables fast conduction of action potentials in vertebrates

Question 27

oligondentrocytes

Answer 27

what produces myelin sheaths in CNS. type of glial cells

Question 28

schwann cells

Answer 28

type of glial cell that produces myelin sheaths in the PNS

Question 29

nodes of ranvier

Answer 29

action potentials are formed here. gaps in myelin sheath where voltage gated Na+ channels are found

Question 30

saltatory conduction

Answer 30

action potentials in myelinated axons jump between the nodes of Ranvier in this process

Question 31

ligand-gated ion channels

Answer 31

many synaptic transmissions involve binding of neurotransmitters to these channels in the postsynaptic cell

Question 32

acetylcholine

Answer 32

is one of more than 100 known neurotransmitters