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A&P 1 > Exam 3: Chapter 12 Nervous Tissue > Flashcards

Exam 3: Chapter 12 Nervous Tissue Flashcards

1
Q

The nervous system detects _______ changes.

A

environmental changes

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2
Q

These environmental chanegs impact the body and works in tandem with what other system?

A

endocrine

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3
Q

What is hte nervous system responsible for?

A

-responsible for all our behaviors, memories, and movement

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4
Q

How does the nervous system accomplish everything it is responsible for?

A

able to accomplish this because of the excitable characteristics of nervous tissue which allow for the generation of nerve impulses

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5
Q

What are the two divisions of the nervous system?

A

central nervous system and the peripheral nervous system

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6
Q

What are the three fundamnetal steps of the nervous tissue?

A

sensory, interpretation, motor response occurs

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7
Q

what is happening in the sensory step?

A

detecting internal and external stimuli

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8
Q

What are the two functional divisions of the nervous system?

A

sensory (afferent) divisions and motor (efferent) division

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9
Q

Which fibers are used in the afferent division?

A

somativ afferent fibers and visceral afferent fibers

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10
Q

What does the somatic afferent fibers function to do?

A

convey impulses from skin, skeletal musces, and joints

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11
Q

What do the visceral afferent fibers to do?

A

convey impulses from visceral organs

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12
Q

What does the motor (efferent) division function do?

A

transmits impulses from the CNS to the effector organs

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13
Q

What are the two motor systems within the peripheral nervous system?

A

somatic (voluntary) motor system and the autonomic (involuntary) motor system (ANS)

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14
Q

What is the function of the voluntary motor system?

A

conscious control of skeletal muscles

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15
Q

What is the function of the autonomic (involuntary) motor system>

A

control visceral motor nerve fibers regulate smooth muscle, cardiac muscle, and glands

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16
Q

What are the two functional subdivisions of the autonomic motor system?

A

sympathetic and parasympathetic

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17
Q

What are neurons?

A

functional units of the nervous system, fomring complex processing networks within the brain and spinal cord that bring all regions of the body under the CNS control

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18
Q

Neuroglia are?

A

smaller than neurons, however, they greatly outnumber nuerons. They act to support and maintains the neuronal networks

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19
Q

What are the special characteristics of neurons?

A

long-lived cells
amitotic
high metabolic rate
plasma membrane functions in electrical signaling and cell to cell interactions during development

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20
Q

What does amitotic mean?

A

cannot divide

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21
Q

What does the high metabolic rate depend on?

A

depends on continuus supply of oxygen and glucose

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22
Q

What does the plamsa membrane function in doing for neurons?

A

electrical signaling and cell to cell interactions during developments

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23
Q

Most neurons contain…

A

dnedrites
cell body
axon
axon terminals

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24
Q

there are several types of neurons, what are some of the differences?

A

some lack dendrites
some lack axons
synapses that connect an axon to another axon or a dendrite to another dendrite

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25
Q

What do dendrites look like?

A

short, tapering, and diffused branches

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26
Q

Dendrites are what part of the of the neruon/

A

receptive, input region of the nueruon

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27
Q

What do the dendrites do?

A

convey electrical signals toward the cell body as graded potentials

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28
Q

The cell body is the ________ center of a neuron

A

biosynthetic

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29
Q

What does the cell body look like?

A
  • a spherical nucleus with nucleolus
  • well-developed Golgi -apparatus
  • Rough ER
  • contains the axon hillock
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30
Q

What is the Rough ER of a neuron called?

A

Nissil bodies

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31
Q

What is the axon hillock?

A

cone-shaped area from whcih axon arises

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32
Q

Axons conduct impulses _____ from the cell body toward another _____ or _____ _____?

A

away, toward, neuron or effectory cell

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33
Q

What is the initial segment?

A

beginning of the axon

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34
Q

What is the trigger zone?

A

junction between the axon hillock and the initial segment

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35
Q

Axons contain numerous _____ ______.

A

terminal branches

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36
Q

What are the terminal branches known as?

A

telodendria

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37
Q

axons contain knoblike ___ ________

A

axon terminals

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38
Q

axon terminals are the?

A

secretory region of the neuron that releases neurotransmitters to excite or inhibit other cells

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39
Q

what are the spaces in between Schwann cells?

A

nodes of Ranvier

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40
Q

What are the types of axon movement?

A

slow axon transport, and fast axon transport

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41
Q

Slow axonal transport functions in

A
  • supplying new axoplasm to developing or regenerating axons

- replenishes axoplasm in growing and mature axons

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42
Q

Fast axonal transport has two types of axonal transport, what are they?

A

anterograde (forward) and retrograde (backward)

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43
Q

Anterograde (forward) transport is what

A

the direction that moves organelles and synaptic vesicles from the cell body to the axon terminal

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44
Q

Retrograde (backward) transport is

A

the direction that moves membrane vesicsles and other cellular materials from the axon terminals to the cell body to be degraded or recycled

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45
Q

What are the 3 types of fucntional classifications of neurons

A

sensory (afferent)

  • interneurons (association neruons)
  • motor neurons (efferent)
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46
Q

What are sensory (afferent) neurons function?

A

transmits impulses from sensroy receptors Toward the CNS

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47
Q

What are the functions of internuerons (association neurons)?

A

shuttle signals through CNS pathways

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48
Q

Internuerons are most entirely within what division of the nervous system?

A

CNS

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49
Q

Moro neurons (efferent) carry…

A

impulses from CNS to efferent cells and organs

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50
Q

What are neuroglia?

A

support cells that dont generate or conduct nerve impulses

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51
Q

how do neuroglia support neurons?

A

forming the blood brain barrier (BBB)

  • forms myelin sheaths (nerve insulation) around neuronal axons
  • making cerebral spinal fluid that circulates around the brain and spinal cord
  • participates in phagocytosis
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52
Q

What are teh different types of neuroglia cells?

A

astrocytes, microglia, satellite, Schwann cells,

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53
Q

what are astrocytes?

A

most abundant and maintian chemical environement

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54
Q

microglia function to

A

migrate to injured tissue and phagocytize

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55
Q

satellite cells function to

A

maintian the chemical envirnement in the CNS

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56
Q

Schwann cells are

A

vital to regeneration of damaged PNS nerve fibers

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57
Q

What is myelination?

A

process of forming myelin sheath which insulates and increases nerve impulse speed

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58
Q

Myelin sheaths are a ______-_____ sheath

A

protein-lipid

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59
Q

Myelin sheaths are large in ______

A

diameter

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60
Q

In the CNS, what are the myelin sheaths made by?

A

oligodendrocytes

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61
Q

in the PNS, what cells form the myelin sheaths?

A

Schwann cells

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62
Q

Myelin sheaths in the PNS are made by…

A

schwann cells wraping many times around the axon

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63
Q

the myelin sheath is _____ layers of the schwann cell _______

A

concentric, membrane

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64
Q

Neruolemma is the

A

peripheral bulge of schwann cell cytoplasm

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65
Q

What is the process for Schwann cells forming the myelin sheath

A
  1. schwann cell envelops an axon
  2. schwann cell rotate aroudn axon wrapping its plasma membrane loosely around in its successive layers
  3. schwann cell cytoplasm is forced from between membranes. The tiht memrbane wrappings surrounding the axon from the myelin sheath
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66
Q

What are the nodes of ranvier?

A

Gaps in the myelin sheath

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67
Q

For every schwann cell that wraps around a portion of the axon, there are _____ nodes of ranvier formed

A

Two

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68
Q

When does myelin increase?

A

Increases from birth to maturity

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69
Q

What is multiple sclerosis?

A

Destruction of myelin sheaths

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70
Q

Why is an infnats response to stimuli niether rapid or as corrdinated as an adult?

A

Because mylein sheaths are still forming

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71
Q

Thin nerve fibers are_____

A

Unmyelinated

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72
Q

One ______ ______ may ___________ enclose ____ or more unmyelinated axons

A

Schwann cell, incompletely, 15

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73
Q

How are the myelin sheaths formed in the CNS?

A

Fomred by processes of oligodendroytes, not the whole cells

74
Q

In the myelin sheaths of the CNS what are still present?

A

Nodes of ranvier

75
Q

What is not present in the myelin sheaths of the CNS?

A

Neurolemma

76
Q

The thinnest fibers are __________.

A

unmyelinated

77
Q

What is gray matter?

A

Mostly neruon cell bodies with unmyeoinated fibers and houses the densdrite portions of neurons

78
Q

What is white matter?

A

Dense collections of myelinated axons from many neuorns

79
Q

Cell body clusters are called what in the CNS and what in the PNS?

A

CNS-> nuclie

PNS -> ganglia

80
Q

Axons and dendrite bundles are called what in the CNS and what in the PNS?

A

Tracts in the CNS an

Nerves in the PNS

81
Q

The cell bodies lose their mitotic function at?

A

Birth

82
Q

The cell bodies can only be repaired through ________ after injury

A

Regneration

83
Q

The regeneration of neurons depends largely upon …?

A

The Schwann cells in the PNS

84
Q

Regeneration essentially doesn’t happen at all in the?

Why does this occur?

A

CNS;

Becuaes the astrocytes form scar tissue when they neurons are injured

85
Q

When an axon is injured, the _________ aids in the regeneration

A

Neuronlemma

86
Q

How does the neurolemma assist in the regneration of the axon?

A

By formaing a regeneration tube that guides and stimulates regrowth of the axon

87
Q

What is demyelination?

A

Loss/destrution of sheaths

88
Q

What causes demyelination?

A

May result from disease, radiation, chemotherapy

89
Q

What can be a result of demyelination?

A

May cause nerve deteriation

90
Q

What is the neruolemma?

A

Outermost layer of nerve fibers in the PNS

91
Q

How is the neurolemma different from the axon or myelin sheath?

A

It doesn’t degenerate after a nerve has been cut or crushed.

92
Q

The neurolemma forms what in the nerve regeneration process?

A

The regenration tube

93
Q

In the CNS, axons are myleinated by __________ which is why they lack _________.

A

Oligodendrocytes, neurolemma

94
Q

Wrapping of Schwann cells allows for …?

A

More readily conducting impulses

95
Q

Like muscle fibers, nerve fibers are ________ _________.

A

Electrically excitable

96
Q

What are the two types of electrical signals used for communication?

A

Graded potentials and action potentials

97
Q

Graded potentials are?

A

Used for short distance communication ONLY

Has varying degrees of impusle

98
Q

Action potentials allows for?

A

Communication over long distances within the body

99
Q

The impulse of action potentials are always…?

A

The same regardless of impulse

100
Q

In the neurons, the RMP is about _____

A

-70mV

101
Q

How is the resting membrane potential generated?

A

Differences in ionic makeup of intercellular fluid and extracellular fluid

Differential permeability of the plasma membrane

102
Q

The differences in the ionic make up of ICE and ECF is referring to..?

A

ICF having a lower concentration of Na+ and Cl- than ECF

ICF having higher concentation of K+

103
Q

The differential in permeability of the plasma membrane refers to?

A

Membrane Freely permeable to Cl-

Large negatively charged proteins (A-) that always remain in the cytosol

Leakage channels favor a gradient where more K+ leaks out than Na+ leaks in

The memrbane is 75x more permeable to K+

104
Q

What are the types of membrane channels?

A

Passive (leak) channels

Active (gated) channels

105
Q

Passive channels are always_____

A

Open

106
Q

Active channels may be…

A

Closed but are capable of opening

107
Q

For active channels, open means ________ and closed means _______ and is incapable of ______.

A

Activated, inactive, opening

108
Q

What are some examples of membrane channels?

A

Chemical gated,

Voltage gated

Mechanical gated

109
Q

When do graded potentials occur?

A

When a stimulus causes gated ion channels to open

110
Q

What is this graded potential also known as?

A

Receptor potentials, generator potential, postsynaptic potential

111
Q

The magnitude of graded potentials are…?

A

Variable with stimulus strength

112
Q

When does the magnitude decrease?

A

Magnitude will decrease with distance as ions flow and diffuse through leakage channels

113
Q

Graded potentials travel only

A

Short distances

114
Q

When the cell is having a depolarizing graded potential occur the

A

Cell becomes more positive

115
Q

Hyperpolarized graded potentials are when the cell becomes

A

More negative

116
Q

Graded potentials can ______ or ______ each other out

A

Summate or cancel

117
Q

Wehre do graded potentials occur?

A

In dendrites and cell bodies

Don’t travel to axons

118
Q

What are action potentials (AP)?

t

A

Signal which travels the length of the neuron

119
Q

The action potential is where the membrane potential…?

A

Reverses and then eventually is restored to its resting state

120
Q

What is the amplitude of the action potential?

A

About –100 mV

121
Q

If a neuron receives a threshold stimuuls, this means?

A

A full strength nerve impulse is produced

122
Q

When the neruon recevies a threshold stimulus and the full strength nerve impulse is produced it will…?

A

Spread down the axon of the neuron to the axon terminals

123
Q

If a stimulus is not strong enough (subthreshold), no nerve impulse will resul

A

duh

124
Q

WHAT HAPPENS DURING AN ACTION POTENTIAL?

A
  1. Sodium ions arrive at the axon hillock
  2. Threshold voltage is reached
  3. Voltage-regulated Na+ (fast) gates open and slow voltage gated K+ gates open
  4. Propogation of signal (sending down neuron)
  5. Na+ gated close (inactive) above 0mV
  6. K+ gates are finally fully open
  7. K+ gates close more slowly than Na+ gates
125
Q

What is causing the action potential?

A

Permiablility changes in the plasma membrane

126
Q

All action potentials are _____ and are _______ of stimulus ________.

A

Alike, independent, intensity

127
Q

What is a strong stimuli?

A

Generate AP more often than weaker stimuli but it will not cause a larger impulse

128
Q

CNS determines stimulus intensity by…

A

The frequency of impulses

129
Q

What is the absolute refractory period?

A

STUDY THE IMAGE ON NOTES
- The time when a cell cnt generate an AP no matter the stimulus. This is the time where opening of Na+ channels to resetting.

130
Q

What does the relative refractory period ensure?

A

That an AP is all or nothing and enforces one-way transmission or nerve impulses

131
Q

The relative refractory period follows the?

A

Absolute refactory period

132
Q

What may generate another AP after the refractory period?

A

An exceptionally strong stimulus

133
Q

What is happening in the relative refractory period?

A

The membrane can respond only to a larger-than-normal stimulus

134
Q

At the relative refractory period, what is happeining to the cell?

A

Na+ channels have returned to their resting state
SOme K+ channels are still open

Repolarization is occuring

135
Q

Threshold for AP generation is _________.

A

Elevated because of hyperpolarization

136
Q

Conduction velocities of neurons vary _____.

A

Widely

137
Q

What are the things that affect conduction velocity?

A

Axon diameter, effect of myelin

138
Q

What is the effect of axon diameter?

A

Larger diameter fibers have less resistance to local current flow and have faster impulse

139
Q

What is the effect of myelin on conduction velocity

A

Continous conduction in unmyelinated axons is slower than saltatory conduction in myelinated axons

Myelin sheath prevents leakage ions

140
Q

What is the differece of conduction velocity with myelination?

A

Saltatory conduction

141
Q

What happens in saltatory conduction?

A

About 30x faster

Voltage gated Na+ channels are located at nodes

APs appear to “jump” from node to node

142
Q

What are the classification of fibers?

A

Group A, B, and C

143
Q

What are group A fibers?

A

Large diameter fibers

Fast fibers (120m/s or 268mph)

Myelinated somatic sensory and motor fibers

144
Q

What are group B fibers?

A

Intermediate diameter

Medium speed (18m/sec; 40 mph)

Lightly myelinated visceral sensory and ANS fibers

145
Q

What are group C fibers?

A

Smallest diameter

Slowest (1m/sec, 2mph)

Unmyelinated sensroy ANS motor fibers

146
Q

The presynaptic neuron converts ______ ______ into ______ ________.

A

Electrical signal (nerve impulse), chemical signal (released neurotransmitter)

147
Q

Post syaptic neuron reeives the _________ _______ and generates an _______ _________.

A

Chemical signal, electrical signal

148
Q

The time needed for these processes at a chemical synpase produces a _________ _______ of about ______.

A

Synaptic delay; 0.5msec

149
Q

The synaptic delay is known as the?

A

Rate limiting step of neural transmission

150
Q

Within a few msec, the neurotransmitter is ______.

A

Terminated

151
Q

What are the types of termination done to a neurotransmitters?

A

Degradation, reuptake, diffusion

152
Q

Degradation is done by?

A

Enzymes

153
Q

Reuptake is done by?

A

Astrocytes or axon terminal

154
Q

Diffusion is done at?

A

Away from the synaptic cleft

155
Q

Postsynaptic potential Strength is determined by…?

A

Amount of neurotransmitter released

Time the neurotransmitter is released in the area

156
Q

What are the types of postsynaptic potentials?

A

EPSPs and IPSPs

157
Q

What are EPSPs?

A

Excitatory postsynaptic potentials

Local depolarization of postsynaptic membrane that brings the neuron closer to AP threshold

158
Q

What do EPSPs allow for?

A

Neurotransmitter binding opens ligand channels allowing outflow of K+ and influx of Na+

159
Q

What are IPSP?

A

Inhibitory postsynaptic potentials

This is local hyperpolarization of postsynaptic membrane and arises the neruon away from AP threshold

160
Q

What does IPSPs do?

A

Neurotransmitter binding opens K+ and Cl- channels which allows for K+ outflow and Cl- inlux

161
Q

A single EPSP cannot…?

A

Induce an action potential

162
Q

Howeer, EPSPs can ________ to reach ________.

A

Summate, threshold

163
Q

IPSPs can also _______ with EPSPs _______ ____ each other

A

Summate, cancel out

164
Q

What are the types of summation?

A

Temporal summation and spatial summation

165
Q

What is temporal summation?

A

One or more presynaptic neruons transmit impulses in rapid fire order

166
Q

What is spatial summation?

A

Postsynaptic neuron is stimulated by a large number of terminals at the same time

167
Q

Most neurons make _____ or more neurotransmitters.

A

Two

168
Q

Neurotransmitters are released at different ________ ______.

A

Stimulation frequencies

169
Q

____ or _____ neurotransmitters have been identified.

A

50 or more

170
Q

Neurotransmitters are classified by ______ ________ and by _______.

A

Chemical structure and by function

171
Q

Neurotransmitters may be ________ or ________ depending on ________ on the postsynaptic neuron.

A

Excitatory or inhibitory, receptor

172
Q

Neurotransmitter effects can be modified many ways by?

A

Synthesis can be stimulated or inhibited

Release can be blocked or enhaned

Removal can be stimulated or blocked

Receptor site can be blocked or activated

173
Q

What is the agonist?

A

Chemical that enhances or stimulates the effects at. A given receptor

174
Q

What is the antagonist?

A

Chemical that blocks or dimisnihes the effects at a given receptor

175
Q

What are the two types of actions of neurotransmitters?

A

Direct and indirect

176
Q

What does direct action of neurotransmitters do?

A

The neurotransmitter binds to channel linked receptor and opens channels
Promotes rapid responses

177
Q

What does indirect action neurotransmitters do?

A

Neurotransmitters binds to a G-protein linked receptor

Promotes long lasting effects

178
Q

Neurons porcess information when changes occur at the _______ _____ through _______ and ______ _______ of _____ and _____.

A

Trigger zone through spatial and temporal summation IPSPs and EPSPs

179
Q

Integration is the…?

A

Process accomplished by the post-synaptic neuron when it combines all excitiatory and inhibitory inputs and responds accoridingly

180
Q

These integration processes occurs over and over as interneurons are activated..?

A

In higher parts of the brain

A&P 1 (3 decks)

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