Chapter 12

Question 1

Central Nervous system

Answer 1

brain and spinal cord

Question 2

Peripheral nervous system

Answer 2

nerves and ganglia

Question 3

Sensory nervous system

Answer 3

Afferent = arrives to CNS. detects stimuli and transmits info from receptors to cns. Has somatic and visceral sensory. somatic is consciously perceived by receptors and visceral is not consciously perceived

Question 4

Motor Nervous system

Answer 4

initiates and transmits info from cns to effectors. Somatic is motor output voluntarily controlled and autonomic is not.

Question 5

Neuron

Answer 5

sends and receives signals; processes info.

Question 6

synapse

Answer 6

where neurons “connect” to another neuron or effector. Chemical or electrical

Question 7

chemical synapse

Answer 7

more common and precise and selective. use neurotransmitters and are composed of a presynaptic neuron (produces signal) and postsynaptic neuron (signal receiver). knob almost touches; gap called synaptic cleft.

Question 8

Neurotransmitters

Answer 8

chemicals in the synaptic knob. Are released through vesicles and diffuse across cleft binding to another neuron.

Question 9

synaptic delay

Answer 9

time between neurotransmitter release and binding

Question 10

electrical synapse

Answer 10

rare: neurons are physically toughing and have gap junctions

Question 11

pumps

Answer 11

type of transport protein that move substances against concentration gradient and require energy.

Question 12

channels

Answer 12

move substances down concentration gradient

Question 13

leak channels

Answer 13

channels that are open for continuous diffusion

Question 14

chemically gated channels

Answer 14

normally closed; open in response to binding of a neurotransmitter. Allow a specific type of ion to diffuse when open

Question 15

voltage gated channels

Answer 15

normally closed, open in response to changes in electrical charge across membrane.

Question 16

3 stages of voltage-gated na channels

Answer 16

have an activation gate and inactivation gate.
stage 1: resting state. inactivation gate open, activation closed. entry of Na is prevented
stage 2: activation state. inactivation open, activation open; na moves through
stage 3: inactivation state: activation and inactivation closed; Na entry is prevented.
stage 4: resting stage reestablished

Question 17

distribution of leak channels

Answer 17

K and Na leak channels are present throughout entire neuron. more K present; easier to go through. Helps maintain resting membrane potential

Question 18

receptive segment

Answer 18

includes dendrites and cell body. Chemically gated channels are here, but few voltage-gated.

Question 19

initial segment

Answer 19

composed of axon hillock (top of axon). contains voltage gated Na and K channels

Question 20

conductive segment

Answer 20

length of axon and its branches. contains voltage gated Na and K channels

Question 21

Transmissive segment

Answer 21

includes synaptic knobs. contains voltage gated Ca channels and pumps

Question 22

events of an action potential (6)

Answer 22

1. unstimulated axon has resting potential of -70mv
2. graded potentials reach axon hillock and are added together
3. depolarization occurs when the threshold of -55mv is reached; voltage gated Na channels open until membrane reaches +30mv
4. repolarization occurs due to closure of Na channels and opening of K channels to move potassium out of cell. Happens until -90mv
5. hyperpolarization occurs due to K channels being open to long. They reach -90 instead of -70mv.
6. Voltage gated K is closed and plasma membrane is returned to normal by Na/K pumps

Question 23

4 steps of releasing a neurotransmitter

Answer 23

1. action potential reaches synaptic knob
2. voltage gated Ca channels open and Ca binds to proteins of synaptic vesicles containing neurotransmitters
3. Synaptic vesicles merge with plasma membrane and neurotransmitter is released by exocytosis.
4. Neurotransmitter crosses synaptic cleft and attaches to receptors on a muscle, neuron, or gland.

Question 24

Somatic nervous system

Answer 24

part of the motor output. voluntary part of the nervous system in control of skeletal muscles

Question 25

Autonomic nervous system

Answer 25

part of motor output for involuntary muscles

Question 26

sympathetic nervous system

Answer 26

part of autonomic motor output that initiates the fight or flight response.

Question 27

parasympathetic nervous system

Answer 27

part of autonomic system that conserves energy.

Question 28

what causes voltage?

Answer 28

positively charged ions

Question 29

resting membrane potential

Answer 29

-70mv

Question 30

polarized neuron

Answer 30

positive on outside, negative on inside

Question 31

sodium potassium pump

Answer 31

for every 2 K it pumps in, it pumps 3 Na out

Question 32

graded potential

Answer 32

a potential that does not reach -55 mv and does not stimulate voltage gated channels

Question 33

conduction velocity

Answer 33

how fast an action potential travels. myelin sheaths conduct action potential faster.

Question 34

saltatory conduction

Answer 34

when action potential jumps between myelin sheaths.

Question 35

excitatory neurotransmitter

Answer 35

depolarizes the neuron making the inside more positive and more likely to send a signal to other neurons.

Question 36

inhibitory neurotransmitter

Answer 36

hyperpolarizes the neuron by making it more negative on the inside (either takes K+ out of cell by opening chemically gated K channels or opens Cl- channels to bring Cl- into cell); prohibits signal from moving.