Ch 37: Neurons, Synapses, Signaling

Question 1

neurons

Answer 1

nerve cells that transfer information

Question 2

most of a neuron’s organelles are in the ________

Answer 2

cell body

Question 3

dendrites

Answer 3

highly branched extensions that receive signals from other neurons

Question 4

axon

Answer 4

longer than dendrites; transmits signals to other cells

Question 5

synapse

Answer 5

junction where branched ends of axons transmits signals to other cells

Question 6

neurotransmitters

Answer 6

at synapse; chemical messenger that passes information from transmitting neuron to receiving cell

Question 7

glial cells

Answer 7

supporting cells required by neurons of vertebrates and most invertebrates

Question 8

3 stages of nervous system processing information

Answer 8

sensory input, integration, output

Question 9

sensory neurons

Answer 9

transmit information from sensors that detect external and internal stimuli

Question 10

interneurons

Answer 10

integrate the information sent to the brain and connect neurons; neither sensory or nor motor

Question 11

neurons that extend out of the processing centers

Answer 11

can tigger muscles or gland activity ex. motor neurons

Question 12

motor neurons

Answer 12

transmit signals to muscle cells

Question 13

central nervous systems CNS

Answer 13

neurons that carry out integration are organized in CNS

Question 14

peripheral nervous system PNS

Answer 14

neurons that carry info in and out of the CNS

Question 15

nerves

Answer 15

PNS neurons bundled together

Question 16

membrane potential

Answer 16

potential energy; inside of cell is negative relative to outside

Question 17

resting potential

Answer 17

membrane potential of a neuron not sending signals

Question 18

signals

Answer 18

changes in membrane potential; transmitting and processing info

Question 19

where is the concentration of K+ highest?

Answer 19

inside the cell

Question 20

where is the concentration of Na+ highest?

Answer 20

outside the cell

Question 21

sodium-potassium pumps

Answer 21

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

Question 22

ion channels are selectively permeable

Answer 22

allowing only certain ions to pass through

Question 23

a resting neuron has many open potassium channels

Answer 23

allowing K+ to flow out

Question 24

major source of membrane potential

Answer 24

resting buildup of negative charge within the neuron

Question 25

gated ion channels

Answer 25

open or close in response to stimuli; in neurons; causing changes in membrane potential

Question 26

depolarization

Answer 26

triggered by opening gated ion channels; reduction in magnitude of the membrane potential; ex. gated Na+ channels open and Na+ diffuses into the cell

Question 27

action potential

Answer 27

depolarization shifts the membrane potential sufficiently, resulting in massive change in membrane voltage

Question 28

threshold

Answer 28

particular value that depolarization increases the membrane potential to causing action potential

Question 29

T or F: there are big and small action potentials

Answer 29

F: action potentials are all or none

Question 30

Stages of action potential

Answer 30

1. resting potential 2. stimulus depolarizes the membrane 3. rising phase 4. falling phase 5. undershoot 6. refractory period

Question 31

stage 1 of action potential

Answer 31

At Resting Potential: most voltage-gated sodium (Na+) channels and potassium (K+) channels are closed

Question 32

stage 2 of action potential

Answer 32

when stimulus depolarizes the membrane, some gated Na+ channels open first and Na+ flows INTO the cell

Question 33

stage 3 of action potential

Answer 33

Rising Phase: the threshold is crossed, and the membrane potential increases as all gates Na+ channels are open

Question 34

stage 4 of action potential

Answer 34

Falling Phase: voltage-gated Na+ channels become inactivated ; voltage-gated K+ channels open and K+ flows OUT of the cell

Question 35

stage 5 of action potential

Answer 35

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

Question 36

stage 6 of action potential (not really a stage, after action potential)

Answer 36

Refractory Period: result of temporary inactivation of Na+ channels; the interval between the start of an action potential and the end of the refractory period is only 1-2 msec

Question 37

T or F: after an action potential, a second action potential can be created

Answer 37

F: after an action potential, a second action potential canNOT be created

Question 38

action potentials travel only toward _________

Answer 38

synaptic terminals

Question 39

inactivated Na+ channels behind the zone of depolarization prevent the action potential from ______________

Answer 39

traveling backward

Question 40

consequence of the refractory period

Answer 40

action potentials can only move in one direction

Question 41

the speed of an action potential increases with ______________

Answer 41

the axon's diameter

Question 42

myelin sheath

Answer 42

insulate axons in vertebrates; enables fast conduction of action potentials; produced by glia: oligodendrocytes in the CNS and Schwann cells in the PNS

Question 43

oligodendrocytes

Answer 43

glia in the CNS that produces myelin sheath

Question 44

Schwann cell

Answer 44

glia in PNS that produces myelin sheath

Question 45

nodes of Ranvier

Answer 45

gaps in the myelin sheath where voltage-gates Na+ channels are found; where action potentials are formed

Question 46

saltatory conduction

Answer 46

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

Question 47

chemical synapses

Answer 47

chemical neurotransmitter carries information from the presynaptic neuron to the post synaptic cell

Question 48

presynaptic neuron

Answer 48

synthesizes and packages the neurotransmitter in synaptic vesicles located in the synaptic terminal

Question 49

neurons communicate with other cells at ____________

Answer 49

synapses

Question 50

the arrival of the action potential causes __________

Answer 50

the release of the neurotransmitter

Question 51

the neurotransmitter diffuses across the __________ and is received by the postsynaptic cell

Answer 51

synaptic cleft

Question 52

the neurotransmitter diffuses across the synaptic cleft and is received by the ______________

Answer 52

postsynaptic cell

Question 53

stages of chemical neurotransmitter carrying info

Answer 53

1. presynaptic neuron synthesizes and packages neurotransmitter in synaptic vesicles located at synaptic terminal 2. arrival of action potential causes the release of the neurotransmitter 3. neurotransmitter diffuses across the synaptic cleft and is received by the postsynaptic cell

Question 54

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

Answer 54

ligand-gated ion channels

Question 55

postsynaptic potential

Answer 55

generated when neurotransmitter binds to ligand-gated ion channels causes ion channels to open example of neurotransmitters: Acetylcholine