chapter 3

Question 1

what is the central nervous system (CNS)?

Answer 1

brain and spinal cord. coordinating center for information.

Question 2

what is the nervous system?

Answer 2

it is a elaborate communication system with more than 100 billion nerve cells in the brain.

Question 2

what is the peripheral nervous system (PNS)?

Answer 2

nerves that carry information from CNS to the body.

Question 3

within the PNS what is the somatic?

Answer 3

the skeletal muscles, bones, skin, and sensory information.

Question 4

within the PNS what is the automimic?

Answer 4

the control of the internal organs. like blood flow or heart rate (involuntary)

Question 5

what is the glial cell or the neuroglial cell?

Answer 5

nonconducting cells for structural support and metabolism of nerve cells.

Question 6

what does the neuron do?

Answer 6

conducts nerve impulses. its a functional unit of nerve.

Question 7

what is the dendrite part of the neuron?

Answer 7

cytoplasm projection that carries impulses toward the cell body.

Question 8

what is the axon part of the neuron?

Answer 8

cytoplasm extension that carries impulses away from cell body. one axon per neuron, may have many branches. larger diameter makes impulse travel faster.

Question 9

what is the myelin sheath part of the neuron?

Answer 9

insulated covering over the axon. prevents loss of ions.

Question 10

what is the Schwann cells in the neuron?

Answer 10

it produces myelin sheath.

Question 11

what is the nodes of Ranvier in the neuron?

Answer 11

it is the gaps between the myelin sheath sections on the axon. impulses jump between nodes which makes impulse faster.

Question 12

what is the neurilemma part of the neuron?

Answer 12

the delicate membrane surrounding PNS nerves. promotes regeneration of damaged nerves. CNS does not have this permanent damage.

Question 13

what is the sensory afferent neuron?

Answer 13

carries impulse to CNS.

Question 14

what is the ganglia or ganglion

Answer 14

clusters of nerve cell bodies outside of CNS which make up sensory receptors.

Question 15

what are the sensory receptors?

Answer 15

modified dendrites activated by environmental stimulus. gives info to neuron.

Question 16

what are the interneurons or association neurons?

Answer 16

they link neurons to other neurons.
~only in brain and spinal cord. intercept sensory information.
~connect sensory neurons to motor neurons.

Question 17

what are the motor neurons or efferent neurons?

Answer 17

carried impulse from CNS to effector.

Question 18

what is the effector?

Answer 18

cell or organ that responds to a stimulus like the muscles, organs, and glands.

Question 19

what is the reflex arch?

Answer 19

reflexes are involuntary.

Question 20

what is the reflex arc?

Answer 20

neural circuit through spinal cord. the simplest nerve.

Question 21

what are the 5 components with the reflex arch?

Answer 21

1. sensory receptor
2. sensory neuron
3. interneuron
4. motor neuron
5. effector (muscle)

Question 22

what is action potential and the steps associated?

Answer 22

the voltage difference across a nerve when it is excited.
1.nerve receives stimulus
2. sodium flows into cell and charge is reversed- depolarization
3.sodium channels close and potassium channels open. change outside cell becomes positive again- repolarization.
4. potassium gates are slow to close. outside of the cell becomes more positively charged then the resting membrane- hyperpolarization.
5. sodium- potassium pump restores resting membrane condition. refractory period 1-10ms.
6. membrane must return to resting potential before another action potential can occur.

Question 23

what is resting potential?

Answer 23

voltage difference across a nerve when it is excited.

Question 24

what does -70mv mean?

Answer 24

difference between number of positive charges on the inside relative to the outside of the membrane.

Question 25

what does -90mv mean?

Answer 25

even fewer positives on the inside.

Question 26

what is saltatory conduction?

Answer 26

action potential only at the nodes of ranvier. makes nerve impulse faster.

Question 27

what is the threshold level?

Answer 27

the minimum level of stimulus required to produce a response.

Question 28

what is the all-or-none response?

Answer 28

a nerve responds completely or not at all.

Question 29

change in the stimulus is due to the frequency of impulses sent. so what is the warm glass verses hot class analogy?

Answer 29

warm does not send impulses as frequently. each nerve has many individual neurons. the number of neurons that fire also cause the intensity of response to change.

Question 30

what is the synapse?

Answer 30

region between neurons or neurons and effectors.

Question 31

what is the presynaptic neuron?

Answer 31

neuron that takes impulse to the synapse.

Question 32

what is the post synapse?

Answer 32

neuron that carries impulse away from synapse.

Question 33

what are the neurotransmitters?

Answer 33

chemicals released by presynaptic neuron that binds to receptors of postsynaptic neuron. more synapses= slower transmission speed.

Question 34

what is acetylcholine?

Answer 34

makes post synaptic membrane more perkable to na+

Question 35

what is cholinesterase?

Answer 35

an enzyme that breaks down acetylcholine. once acetylcholine is broken down na+ channels close and neuron is in recovery phase.

Question 36

what is summation?

Answer 36

accumulation of neurotransmitters from 2 or more neurons.