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BIOL 319 > Lab 8: Introduction to the Nervous System > Flashcards

Lab 8: Introduction to the Nervous System Flashcards

1
Q

are reflexes inborn or learned

A

can be either

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2
Q

describe the difference between sensory neurons and motor neurons

A
  • sensory neurons: receptors that detect changes in the environment and send this information to the central nervous system
  • motor neurons: send the information from the central nervous system to the effectors that produce a response
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3
Q

what is involved in a motor response

A

series of action potentials that produce a muscle contraction

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4
Q

define reflexes

A
  • response reaction
  • can be inborn or learned
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5
Q

define learned reflexes

A

result from repetition

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6
Q

example of a learned reflex

A

those needed to drive a car where, with practice, the activity is mostly automatic and subconscious

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7
Q

define inborn reflexes

A
  • rapid, predictable, involuntary, and unlearned motor response to a stimulus
  • part of all our neural pathways
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8
Q

examples of inborn relfexes

A
  • keep us breathing
  • maintain posture
  • controlling the viscera
  • avoiding pain
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9
Q

how fast are inborn reflexes to pain

A

can be so rapid that a response in generated before you perceive the pain

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10
Q

what are many of the inborn reflexes regulated by

A

the spinal cord and brain stem

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11
Q

define myotatic reflex

A
  • inborn reflex
  • tapping on the tendon under the kneecap produces the knee-jerk reflex
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12
Q

what are the 5 parts of all reflex arcs

A
  1. the receptor that senses the stimulus and initiates the signal
  2. a sensory neuron that carries afferent nerve impulses to the central nervous system
  3. an integration center where the signal is processed
  4. the motor neuron that carries efferent signals to the effector from the integration center
  5. the effector such as a muscle or a gland which generates a response to the signal
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13
Q

define monosynaptic reflex

A

a single synapse between a motor and sensory neuron serves as the integration center

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14
Q

define polysynaptic reflex

A

the integration center will include a few synapses and interneurons

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15
Q

where is the integration center for most reflexes

A

in the central nervous system

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16
Q

define somatic reflex

A

activates skeletal muscle

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17
Q

define autonomic reflex

A

controls visceral effectors such as smooth muscle, cardiac muscle, or a gland

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18
Q

do spinal reflexes involve higher brain centers for the arc to function

A

no

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19
Q

what does distorted, exaggerated, or absent reflexes indicate

A

damage to the nervous system

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20
Q

what do stretch and tendon reflexes do

A

help coordinate smooth movements of skeletal muscle groups

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21
Q

what do muscle spindles in skeletal muscle do

A

convey information about muscle length or amount of stretch for proper regulation of reflexes

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22
Q

what do Golgi tendon organs do

A

convey information about tendon tension for proper regulation of reflexes

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23
Q

define propriceptors

A
  • receptors that supply information to the central nervous system about the body’s position in space and how much a muscle has or hasn’t moved its insertion
  • ex: muscle spindles, Golgi tendon organs
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24
Q

how is the myotatic reflex produced

A

single synapses between sensory axons and motor neurons

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25
Q

where is the essential circuitry for the myotatic reflex confined to

A

the spinal cord

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26
Q

how many neurons are employed during the myotatic reflex

A

4

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27
Q

describe the process of the myotatic reflex

A
  • striking the patellar ligament stretches the quadriceps muscle
  • stimulates sensory muscle spindle receptors
  • triggers an impulse in a sensory axon
  • sensory axon synapses directly with a motor neuron
  • motor neuron conducts the impulse to the quadriceps
  • triggers contraction in extrafusal fibers of the stretched muscle
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28
Q

where is the cell body of the sensory axon stimulated during the myotatic reflex located

A

in the dorsal root ganglion in the lumbar region of the spinal cord

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29
Q

what does the sensory nerve axon stimulated during the myotatic neurons synapse with

A

both the motor neuron and an inhibitory interneuron in the spinal cord

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30
Q

describe the inhibitory interneuron of the myotatic reflex

A
  • synapses with the sensory neuron to receive information
  • synapses with a motor neuron that conducts impulses to the antagonistic muscle (hamstrings)
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31
Q

define reciprocal inhibition

A
  • inhibitory interneuron conducts with a motor neuron that conducts impulses in the antagonistic muscle to inhibit contraction
  • allows for the contraction of the stretched muscle without impedance form the basal muscle tone of the opposing muscle
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32
Q

define ipsilateral

A

involving motor activity on the same side of the body

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33
Q

all stretch reflexes are ______ and ______ in the contracting portion of the pathway

A
  • ipsilateral
  • monosynaptic
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34
Q

what is one thing that makes the inhibitory portion of the reflex pathway different from the contracting portion of the reflex pathway

A
  • inhibitory portion is polysynaptic
  • contracting portion is monosynaptic
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35
Q

what is the patellar knee-jerk reflex tested to determine

A

if motor and sensory connections between the spinal cord and the thigh muscles are functioning

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36
Q

what different damage could be indicated by an exaggerated reflex vs an absent reflex

A
  • exaggerated reflex could indicate damage in the brain or spinal cord
  • absent reflex would indicate damage of peripheral nerves
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37
Q

define stretch reflex

A

stimulates muscle contraction when muscle length is increased or the muscle is stretched

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38
Q

define tendon reflex

A
  • polysynaptic
  • causes muscles to relax in circumstances of high tendon tension
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39
Q

what happens to the timing of more complex reflexes

A
  • longer delay between stimulus reception and the more complex response
  • requires additional cells
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40
Q

how many neurons are in the “direct light” or pupillary reflex and what do they connect

A
  • 4 neurons
  • connect the retina to the midbrain and then convey information back to the pupillary sphincter muscles
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41
Q

define consensual light reflex

A

as the pupillary sphincter of one eye constricts due to increased light, the pupillary sphincter on the other eye will also constrict

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42
Q

define miosis

A
  • pupillary constriction
  • from Greek meiosis = diminution
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43
Q

define mydriasis

A

pupillary dilation

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44
Q

how are superficial reflexes stimulated

A

gentle stroking of the skin in specific location

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45
Q

what are superficial reflexes used to test

A

spinal-cord level reflex arcs and upper motor pathways

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46
Q

how is the plantar reflex elicited

A

running a blunt object down the lateral aspect of the sole of the foot

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47
Q

what happens as a response to the plantar reflex

A

the toes should flex

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48
Q

what does the plantar reflex indiretly indicate

A

the functionality of the corticospinal tracts

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49
Q

what does the plantar reflex directly indicate

A

spinal cord integrity from L4 to S2

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50
Q

describe Babinski’s sign

A
  • abnormal reflex displayed when the corticospinal tract or primary motor cortex is impaired
  • the great toe dorsiflexes and the other toes laterally fan out
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51
Q

what abnormal reflex do infants display

A

Babinski’s sign

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52
Q

why do infants display Babinski’s sign until they are 1 year old

A

the nervous system is not yet completely myelinated

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53
Q

how are the abdominal reflexes elicited

A

by stroking the lateral skin of the abdomen on any side of the umbilicus

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54
Q

describe the effects of the abdominal reflexes

A

produces an abdomen contraction which moves the umbilicus into the direction of the stimulus

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55
Q

what does testing the abdominal reflexes indicate

A

spinal cord integrity from T8 to T12

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56
Q

what does an absence of abdominal reflexes indicate

A

corticospinal tract lesion

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57
Q

which are more complicated: voluntary reactions to a cue OR reflexes

A

voluntary reactions to a cue

58
Q

what do voluntary reactions to a cue require in contrast to reflexes

A

voluntary reactions require brain functions rather than relying exclusively on neuronal circuitry of the spinal cord in the case of relfexes

59
Q

define simple reaction time

A

only one stimulus and one corresponding response

60
Q

where does the major in reaction time occur

A

at the synapses between the different neurons involved

61
Q

what is the mean reaction time for college-aged individuals for light (photonic) stimuli

A

190 ms

62
Q

what is the mean reaction time for college-aged individuals for sound stimuli

A

150 ms

63
Q

what is the mean reaction time for college-aged individuals for touch stimuli

A

155 ms

64
Q

how long does it take an auditory stimulus to reach the brain

A

8-10 ms

65
Q

how long does it take a visual stimulus to reach the brain

A

20-40 ms

66
Q

list factors that may affect an individual’s reaction time

A
  • age
  • arousal
  • distraction
  • gender
  • practice
  • errors
  • fatigue
  • drugs
  • warnings
67
Q

what is the effect (positive or negative) of age on reaction time

A

can be either positive or negative

68
Q

what is the effect (positive or negative) of arousal on reaction time

A

can be either positive or negative

69
Q

what is the effect (positive or negative) of distraction on reaction time

A

positive

70
Q

what is the effect (positive or negative) of gender on reaction time

A

can be either positive or negative

71
Q

what is the effect (positive or negative) of practice on reaction time

A

negative

72
Q

what is the effect (positive or negative) of errors on reaction time

A

positive

73
Q

what is the effect (positive or negative) of fatigue on reaction time

A

positive

74
Q

what is the effect (positive or negative) of drugs on reaction time

A

can be either positive or negative

75
Q

what is the effect (positive or negative) of warnings on reaction time

A

negative

76
Q

describe how age effects reaction time

A
  • reaction time shortens from infancy to 20s
  • reaction time increases slowly from 20s to 50/60s
  • reaction time lengthens faster as a person gets into their 70s and beyond
77
Q

describe how arousal effects reaction time

A
  • reaction time is fastest with an intermediate level or arousal
  • reaction time deteriorates when the subject is either too relaxed or too tense
78
Q

describe how distraction effects reaction time

A

distractions increase reaction time significantly, especially in younger individuals

79
Q

describe how practice effects reaction time

A

practice at a task decreases reaction time

80
Q

describe how errors effect reaction time

A

when a volunteer makes an error, subsequent reaction times are slower due to the subject being more cautious

81
Q

describe how fatigue effects reaction time

A
  • reaction time due to fatigue deteriorates more in complicated tasks than simple tasks
  • mental fatigue, especially sleepiness, has the greatest effect
82
Q

describe how drugs effect reaction time

A
  • stimulants tend to decrease reaction times to a point (too much will increase)
  • depressants increase reaction times
83
Q

describe how warnings effect reaction time

A

reaction times are faster when the subject has been warned that a stimulus will arrive soon

84
Q

what are the two groups of nerves in the peripheral nervous system

A
  • cranial nerves
  • spinal nerves
85
Q

how are nerves in the peripheral nervous system categorized into either cranial or spinal nerves

A

based on the part of the CNS with which they communicate

86
Q

how are nerves classified

A
  • sensory
  • motor
  • sensory and motor
87
Q

describe why motor neurons also have a small sensory somponents

A

due to proprioception (the sense of self-movement, force, and body position)

88
Q

define epineurium

A

outer covering of a whole nerve

89
Q

define perineurium

A
  • beneath epineurium
  • separates axons into bundles called fascicles
90
Q

define endoneurium

A
  • beneath perineurium
  • surrounds each axon inside a fascicle to separate it from neighboring axons
91
Q

what is the myelin sheath composed of in axons in nerves of the PNS

A

schwann cells

92
Q

what are the two types of cells in the nervous system

A
  • neurons
  • glial cells
93
Q

what is the overall function of glial cells

A
  • supportive role in protecting and maintaining nerve tissue
  • protect, support, and anchor neurons in place
94
Q

define neuron

A
  • communication cells of the nervous system
  • capable of propagating and transmitting electrical impulses
95
Q

define neuroglia

A

network composed of glial cells

96
Q

what is the function of glial cells in the CNS

A

production and circulation of cerebrospinal fluid that circulates in the ventricles in the brain and in the central canal of the spinal cord

97
Q

what is the function of glial cells in both the CNS and PNS

A

isolate and support neurons with myelin to increase conduction velocity

98
Q

what are the four types of glial cells in the CNS

A
  • astrocytes
  • microglia
  • ependymal cells
  • oligodendrocytes
99
Q

what are the two types of glial cells in the PNS

A
  • satellite cells
  • shwann cells
100
Q

what are the most abundant and versatile glial cells

A

astrocytes

101
Q

function of astrocytes

A
  • making exchanges between capillaries and neurons
  • helping to determine capillary permeability
  • guiding the migration of young neurons
  • synapse formation
102
Q

what part of an astrocyte is in contact with blood vessels and the neuronal surfaces

A

perivascular feet

103
Q

describe the structure of microglia

A
  • small
  • oval-shaped
  • relatively long “thorny” processes
104
Q

function of microglia

A
  • thorny processes touch nearby neurons to monitor their health
  • if they sense that certain neurons are injured, they migrate towards them
105
Q

where are ependymal cells located

A
  • CNS
  • lining the central cavities of the brain and the spinal cord
106
Q

function of ependymal cells

A

cilia help to circulate cerebrospinal fluid that cushions the brain and spinal cord

107
Q

function of oligodendrocytes

A

-wrap around thicker neuron fibers in the CNS to produce insulating myelin sheaths

108
Q

where are satellite cells found

A
  • in the PNS
  • surrounding neuron cell bodies
109
Q

function of satellite cells

A
  • thought to have many of the same functions in the PNS as astrocytes in the CNS
  • exchanges between capillaries, guiding young neurons, synapse formation
110
Q

function of schwann cells

A
  • surround and form myelin sheaths around larger nerve fibers in the PNS
  • vital to regeneration of damaged peripheral nerve fibers
  • increase speed of transmission or nerve impulses
111
Q

what are the most abundant cell type in the nervous system

A

glial cells

112
Q

what are the 3 main parts of neurons

A
  • dendrites
  • cell body (soma)
  • axon
113
Q

define dendrites

A
  • main receptors or input regions of neurons
  • provide enormous surface area for receiving signals from other neurons
114
Q

where do dendrites convey messages to

A

towards the cell body (soma)

115
Q

what signals are the messages conveyed by dendrites to the cell body

A
  • NOT action potentials
  • graded potentials
116
Q

define cell body (soma)

A

part of neuron that surrounds the nucleus and contains organelles

117
Q

define Nissl bodies

A

rough endoplasmic reticulum granules in the cell body of neurons that stains darkly in histological sections

118
Q

where are most neuron somas located

A

in the CNS

119
Q

what are clusters of somas in the CNS termed

A

nuclei

120
Q

what are clusters of somas in the PNS termed

A

ganglia

121
Q

how many axons are in a single neuron

A

one

122
Q

where do axons convey messages to

A

from the cell body to other neurons

123
Q

define the initial segment of the axon

A

the first part of the axon of a neuron that extends from the axon hillock

124
Q

define axon hillock

A

area of the neuron where the cell body and axon connect

125
Q

define collateral branches of the axon

A

initial divisions of the axon

126
Q

define telodendria

A

further divisions of the collateral branches of the axon

127
Q

define synaptic terminal

A
  • distal tip of each telodendrion
  • has synaptic vesicles containing neurotransmitters
128
Q

which nerve fibers are usually protected by a myelin sheath

A

usually those that are long or large in diameter

129
Q

what does the myelin in the myelin sheath do

A
  • protects and electrically insulates fibers
  • increases to speed of transmission of nerve impulses
130
Q

are dendrites ever myelinated

A

no

131
Q

define multipolar neurons

A

neurons with more than two dendrites

132
Q

what percent of neurons in the nervous system are multipolar

A

99%

133
Q

when do chemically (ligand)-gated ion channels open

A

when the appropriate neurotransmitter binds to the receptor, allowing simultaneous movement of Na and K

134
Q

when do voltage-gated ion channels open

A

in response to changes in membrane voltage

135
Q

define membrane ion channels

A
  • large proteins
  • selectively allow certain ions to pass through the membrane
136
Q

define gated channel proteins

A

have a “gate” that opens and closes in order to allow an ion to pass

137
Q

when do mechanically gated channels open

A

open in response to physical deformation of the receptor

138
Q

describe ion movement chemically

A

move from an area of higher concentration to an area of lower concentration

139
Q

describe ion movement electriaclly

A

move toward an area of opposite electrical charge

140
Q

describe the voltage decay in a bare plasma membrane of an axon

A

voltage decays because current leak across the membrane

141
Q

describe the voltage decay in an unmyelinated axon

A
  • voltage-gated Na and K channels regenerate action potential at each point along teh axon so voltage does not decay
  • conduction is slow because movements of ions and gates of channel protein takes time and must occur before voltage regeneration occurs
142
Q

describe voltage decay in a myelinated axon

A
  • myelin keeps current in axons and voltage does not decay much
  • action potentials are generated only in teh nodes of Ranvier and appear to jump rapidly from node to node

BIOL 319 (15 decks)

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