nervous system

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What is the nervous system?

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1

What is the nervous system?

includes all neural tissue in the body

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2

What are the two kinds of neural cells?

neurons and neuroglia

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3

What are neurons?

cells that send and receive signal

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4

What are neuroglia (glial cells)?

cells that support and protect neurons

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5

What are the two divisions of the nervous system?

CNS and PNS

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6

What composes the CNS?

brain and spinal cord

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7

What composes the PNS?

all neural tissues outside the CNS

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8

What are the divisions of the PNS?

afferent and efferent

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9

What is the afferent division?

bring sensory information to CNS from receptors in peripheral tissues

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10

What neurons are involved in the afferent division?

sensory neurons

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11

What is the efferent division?

carries motor commands from CNS to effector tissues like muscles and glands

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12

What neurons are involved in the efferent division?

motor neurons

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13

What are the two divisions of the efferent division?

somatic and autonomic

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14

S.A.M.E. stands for?

sensory (afferent) and motor (efferent)

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15

What is the somatic nervous system?

controls voluntary and involuntary skeletal muscle contractions

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16

What is the autonomic nervous system?

controls smooth muscle, cardiac muscle, and glandular secretions at the subconscious level

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17

What two divisions can the autonomic nervous system be divided into?

sympathetic (fight or flight) and parasympathetic (rest and digest)

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18

What does the cell body of a neuron contain?

nucleus and perikaryon

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19

What is the perikaryon?

cytoplasm of neuron that contains organelles

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20

What are the other structures of the neuron?

dendrites, axon, and telodendria (synaptic terminals)

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21

What is gray matter made up of?

neuron cell bodies

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22

What makes it gray?

nissl bodies

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23

What are nissl bodies?

clustered areas of ribosomes and rough ER

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24

In the CNS, what are the collections of neuron cell bodies?

nuclei and cerebral cortex (gray matter)

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25

In the PNS, what are the collections of neuron cell bodies called?

ganglia (gray matter)

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26

What are the collections of neuron axons called in the PNS?

nerves

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27

What are the two nerves in the PNS?

cranial nerves and spinal nerves

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28

What are cranial nerves?

connected to the brain/brainstem

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29

What are the spinal nerves?

connected to the spinal cord

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30

What are the collections of neuron axons in the CNS?

tracts (white matter of CNS)

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31

What makes white matter white?

myelin sheath

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32

What is the synapse?

site where a neuron communicates with another cell

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33

What two cells are involved in the synapse?

postsynaptic cell: receives message presynaptic cell: sends message

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34

What could presynaptic cells possibly be?

neurons

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35

What could postsynaptic cells possibly be?

neurons, muscle fibers, or gland cells

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36

What are neurotransmitters?

chemicals that when released communicate between presynaptic and postsynaptic cells

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37

Where are neurotransmitters produced?

cell body

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38

How are neurotransmitters transported and what is the type of transportation called?

vesicles and axoplasmic transport

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39

What are the types of axoplasmic transport?

anterograde and retrograde

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40

What is the difference between anterograde and retrograde?

anterograde: toward the synaptic knob retrograde: toward the cell body

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41

What are the four structural classifications of neurons?

anaxonic, bipolar, unipolar, and multipolar

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42

What are the differences between the different types of neurons?

anaxonic: found in brain bipolar: found in special sensory organs (sight, smell) unipolar: most sensory neurons of PNS multipolar: skeletal muscle motor neurons, common in CNS What are the three functional classifications of neurons?

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43

What are the three functional classifications of neurons?

motor, sensory, and interneurons

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44

What are the two types of sensory neurons?

somatic and visceral

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45

What are visceral sensory neurons?

monitor internal environment

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46

What are somatic sensory neurons?

monitor external environment

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47

Where are the cell bodies of sensory neurons found? Where are the dendrites and axons found?

cell bodies found in sensory ganglia and processes (dendrites and axons) extend from sensory receptors to CNS

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48

What are proprioceptors?

monitor joint and muscle position

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49

What are the motor neurons responsible for?

the somatic nervous system and autonomic nervous system

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50

Where are the cell bodies of motor neurons found? Where are their axons found?

cell bodies found in CNS (gray matter) and axons travel from CNS to periphery

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51

What are interneurons aka association neurons?

they are responsible for distributing sensory info and coordinating motor info

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52

Where are interneurons located?

brain, spinal cord, and some ganglia

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53

What are interoceptors?

internal organ sensation, blood pH and O2

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54

What are exteroceptors?

touch, temperature, taste, smell, hearing

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55

What are the three types of sensory receptors?

interoceptors, exteroceptors, proprioceptors

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56

What is neuroglia?

cells that support and protect neurons

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57

What are the functions of neuroglia?

preserve physical and biochemical structure of neural tissue and are essential to survival and function of neurons

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58

What are the four neuroglia cells in the CNS?

ependymal, oligodendrocytes, astrocytes, and microglia cells

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59

What are the two neuroglia cells in the PNS?

satellite and schwann cells

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60

What are ependymal cells?

they produce cerebrospinal fluid and monitor/circulate CSF

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61

Where are ependymal cells found?

line the ventricles and central canal

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62

What are astrocytes?

they maintain the blood-brain barrier by acting as gatekeepers for substances entering the CSF/interstitial fluid

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63

What is another function of astrocytes?

they provide structural framework for the neurons of the CNS

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64

Where are astrocytes found?

they cover the surface of all capillaries in the CNS

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65

What are oligodendrocytes?

extensions containing myelin which wrap around neuron axons in order to conduct action potentials much faster

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66

What do the unmyelinated axons and neuron cell bodies make up?

gray matter of CNS

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67

What color does the myelin make?

it makes the white matter of the CNS

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68

What is the difference between internodes and nodes?

axons are myelinated at internodes and axons are unmyelinated at nodes

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69

What are microglia?

they engulf, phagocytize cellular debris, waste products, and infective organisms

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70

Where are microglia found?

they are able to move through CNS

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71

What are satellite cells?

regulate the environment around neurons, very similar to astrocytes in the CNS

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72

Where are satellite cells found?

surround neuron cell bodies in ganglia of PNS

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73

What are schwann cells?

they myelinate sections of a single axon or surround sections of many unmyelinated axons

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74

What do the neurons of neuroglia perform?

they perform all communication, information processing, and control functions of the nervous system

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75

What is the resting potential for a neuron?

-70mV

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76

What are the relative ions outside and inside the cells of a neuron?

high number of Na+ outside cell and high number of K+ and negative proteins inside the cell

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77

What is the net charge inside the cells of the neuron?

net negative charge inside the cell

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78

What is the chemical gradient (direction) of the Na+ and K+ ions?

Na+ wants to rush in cell and K+ wants to rush out

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79

Which channels are passive channels?

Na+ and K+ channels are always open

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80

What helps maintain the resting potential of the cell if the Na+ and K+ channels are always open?

sodium/potassium pump (pump 3Na out of cell and 2K in cell)

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81

What are the three gated channels?

chemically-gate channels, voltage-gated channels, and mechanically-gated channels

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82

What are chemically-gated channels?

open or close when they bind specific chemicals (dendrites and cell body)

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83

What are voltage-gated channels?

open or close in response to changes in transmembrane potential (axon)

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84

What are mechanically-gated channels?

open or close in response to physical distortion

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85

What are graded potentials?

a local change in transmembrane potential that may or may not result in an action potential

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86

What causes graded potentials?

any stimulus that opens gated ion channels

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87

What do graded potentials cause?

they can cause depolarization (shift toward more +) or hyperpolarization (shift toward more -)

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88

What causes depolarization?

sodium channels opening

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89

What causes hyperpolarization?

potassium channels opening

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90

What are action potentials?

propagated changes in transmembrane potential that spread across an excitable membrane

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91

How do action potentials travel?

they are chain reactions that moves along entire length of axon

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92

What is the threshold voltage at the axon hillock?

-60mV

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93

What happens once the threshold is reached?

an action potential occurs

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94

What are the steps of the action potentials?

  1. local depolarization to diffusion of Na+ ions

  2. threshold is reached: opening of activation gates on voltage-gated sodium channels

  3. Na+ rushes into axon causing rapid depolarization

  4. at +30mV, Na+ inactivation gates on voltage-gated channels close and voltage-gated K+ channels open

  5. K+ rushes out of the axons causing rapid repolarization

  6. at -70mV, the voltage-gated K+ channels start closing (hyperpolarization)

  7. passive channels allow ions to diffuse and the sodium/potassium pump runs resulting in the shift back to resting potential

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95

How does neurons return to resting potential?

passive channels and the sodium/potassium pumps

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96

What is a refractory period?

period of time during an action potential when another action potential cannot or is unlikely to occur

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97

What are absolute refractory periods?

no action potential possible

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98

Why are action potentials not possible in the absolute refractory period?

voltage-gated Na+ channels are either open or are inactivated

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99

What are relative refractory periods?

action potentials are possible but requires larger stimulus

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100

Why are action potentials possible in relative refractory periods?

Na+ channels are in normal resting state but K+ channels are open, or membrane is hyperpolarized

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