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PHYSCI 111A > Module 3 Lecture 1 > Flashcards

Module 3 Lecture 1 Flashcards

1
Q

___________ controls the vast majority of skeletal muscles

A

Spinal cord

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2
Q

_____________ controls neck and arm region

A

Cervical

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3
Q

_____________ controls the torso and leg

A

thoracic

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4
Q

________________ has pelvic control

A

lumbar and sacral

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5
Q

___________ controls and plans our movement

A

Motor cortex

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6
Q

______________ areas of the brain do not generate movements they smooth movements

A

coordinating areas

ex- basal ganglia, cerebellum, the visual system

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7
Q

_____________is how the brain organizes auditory information

A

auditory system

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8
Q

Consists of all the muscles and the neurons

that control them

A

motor system

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9
Q

• The motor control comes from

A

– The spinal cord (programs)

– The brain

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10
Q

• Somatic motor system

A

– Skeletal muscles (33 somites)
– Nervous system controls them
– Voluntary

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11
Q

It was widely accepted
that reflexes occurred as
isolated activity within a _________________

A

a reflex arc

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12
Q

Reflexes are ___________

A

integrative activities

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13
Q 
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ shared
the Nobel prize with
Edgar Adrian in 1932
for their discoveries
regarding the
functions of neurons
A

Sir Charles Scott Sherrington
(1857-1952)
The Sherrington’s law

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14
Q

The brain commands and control the _________________

A

motor programs in the spinal cord.

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15
Q

______________
– Muscles of the trunk
– To maintain posture

A

• Axial muscles

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16
Q

_____________
– Muscles of the shoulders, elbows, thighs, and knees
– Locomotion

A

• Proximal muscles

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17
Q

________________
– Muscles of the hands, feet, and digits
– Manipulations of objects

A

• Distal muscles

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18
Q

__________________Innervated by alpha motor neurons

Roots form mixed spinal nerves

A

skeletal muscles

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19
Q

How many spinal nerves are there

A

31 nerves

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20
Q

C1-8: _______________

A

spinal nerves

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21
Q

T1-12: ___________

A

thoracic nerves

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22
Q

L1-5:_________________

A

Lumbar nerves

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23
Q

S1-5:___________________

A

sacral nerves

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24
Q

1:_____________________

A

coccygeal

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25
Q

C3-T1

Innervate _______________

A

about

50 muscles

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26
Q

Motor neurons that innervate the proximal and distal muscles are found mainly

A

in the cervical and lumbar-sacral segment.

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27
Q

Neurons innervating the

axial muscle are medial to

A

to those innervating the

appendicular

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28
Q

Neurons innervating flexors are dorsal to

those

A

innervating extensors

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29
Q

Lower Motor Neurons

A
  • Alpha motor neurons

* Gamma motor neurons

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30
Q

• Typical motor neurons that innervate the muscle

cells

A

Alpha Motor Neurons

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31
Q

What are the three types of inputs to alpha motor neurons

A
  1. input from upper motor neurons in the brain
  2. sensory input from muscle spindles
  3. input from spinal neurons
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32
Q

Sir Charles Scott Sherrington

When a muscle is stretched, it __________

A

tends to contract

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33
Q

_____________ are traditional muscles

A

extrafusal

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34
Q

___________ are special sensory muscles

A

intrafusal

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35
Q

__________ a group of muscle fibers which are innervated by unique nerves

A

muscle spindle

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36
Q

______________ wrap around the

muscle fibers of the spindle in the middle

A

Group Ia sensory axons wrap

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37
Q

_____________ stops the muscle from over stretching. Over stretching prevents the cross bridge cycle from working

A

muscle spindle

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38
Q

over stretching prevents the

A

cross bridge cycle from working

39
Q

_______________ never stop firing because their function is to relay length information

A

1a motor neurons

40
Q

Muscle spindles provide protection against overstretching because of ___________________________

A

1a sensory neurons which innervate alpha neurons causing contraction

41
Q

What happens when you put weight on a muscle and the muscle lengthens

A

1A sensory neurons fire more than normal and they tell alpha motor neuron to control mechanism of firing

42
Q

what makes 1a axons fast firing

A

more myelination and wider diameter

43
Q 
Group Ia Axons
• Thickest myelin
• Enter via the \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
• Synapse with \_\_\_\_\_\_\_\_\_\_\_\_\_
– Lots of synapses
A

dorsal root

interneurons and alpha motor
neurons

44
Q

____________ gated channels on the 1A sensory motor neurons

A

stretch gated channels

-works when membrane is stretched open causing depolarization and action potentials

45
Q

give an example of muscle mechano receptors

A

the knee jerk reflex. When tapping the tendon, the muscle briefly stretches

46
Q

muscle spindles are inside the muscle and thus have specific

A

origin and insertion

47
Q

When alpha motor neurons innervate the
extrafusal muscles, the _________.
As a result, the spindle becomes _________
The Ia sensory, will ________________

A

muscle contracts

slack (not stretched)-

not send a signal anymore

48
Q

• Gamma MNs innervate___________________

A

specialized muscle fibers

within the spindle called intrafusal muscle fibers

49
Q

__________________are located at the two ends of the

spindle

A

Gamma MNs

50
Q 
Feedback Loop (Homeostasis)
• Control center:
– Set point:\_\_\_\_\_\_\_\_\_\_\_\_\_
• Receptor: \_\_\_\_\_\_\_\_\_\_
• Effector: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
A

a desired muscle length

Ia axons

alpha motor neurons and extrafusal fibers

51
Q

Gamma Loop
• The gamma MN activity influences ________________________ if we are outside the
set point

A

the alpha motor neuron activities

52
Q

• During most normal movements, alpha and

gamma motor neurons are

A

simultaneously

activated

53
Q

________ controls th homeostasis loop

A

cerebellum

54
Q

___________ when the muscle spindle is not parallel to extrafusal muscle. Brain is not sure about what is going on

A

hypotonia

55
Q

___________
– Fiber is 50-100 um wide
– Fiber is 2-6 cm long
– Muscle has 103 – 109 fibers
– Muscle is controlled by about 100 alpha motor
neurons
– Alpha motor neuron innervates about 100-1000
muscle fibers
– A muscle fiber is innervated by only one alpha
motor neuron

A

• Extrafusal

56
Q 
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
– Known as muscle spindles
– Embedded in the extrafusal fibers
– A spindle consists of 8-12 muscle fibers
– Sensory axon wraps around them
– Continuously monitors length of muscle
– Used for feedback control of movement
– Innervated by gamma motor neuron
A

Intrafusal

57
Q

When Do We Use the Ia Sensory?

A

always

58
Q

when are the 1a sensory so valuable

A
  • in extreme situations

- tight rope walking and extreme balance

59
Q

what is the formula for gain

A

contraction/ stretching

60
Q

Shared the Nobel prize with Cajal in 1906 in recognition

of their work on the structure of the nervous system

A

camillo Golgi

61
Q

Golgi tendon organs:

When the muscle contracts, the_____________ fire action potential

A

sensory 1b axons

62
Q

____________ is located in the tendon of the insertion muscle

A

Golgi tendon organ

63
Q

The Ib sensory neuron may protect the muscle from being _____________
However, its normal function is to ________________

A

overloaded.

regulate muscle tension within an optimal range.

64
Q

The 1b axons do not communicated directly with the alpha Motor neurons, it goes through ______________

A

an inhibitory neuron

65
Q

Scottish surgeon and artist Charles Bell

showing a man in the throes of tetanus caused by

A

bacteria in the inhibitory neurons

66
Q

activity of muscle spinal has nothing to do with the activity of

A

Golgi tendon

67
Q

muscle spindle located in __________ to extra fusal muscles

A

series

68
Q

Golgi tendon located in __________ to extra fusal muscle

A

parallel

69
Q

What are the three Inputs to Alpha Motor Neurons:

Interneurons

A
  1. Upper motor neurons in brain
  2. sensory input from muscle spindles
  3. input from spinal neurons
70
Q

Most of the innervation to the alpha motor

neurons comes from _______________

A

interneurons of the spinal

cord

71
Q

Spinal interneurons receive inputs from

(3 places)

A

– Primary sensory axons
– Descending axons from the brain
– Collaterals of lower motor neurons axons

72
Q

• Spinal neurons can form

A

– Inhibitory synapses

– Excitatory synapses

73
Q

Spinal neurons can form
–_____________ (reciprocal inhibition)
–____________ (flexor withdrawal reflex and
cross extensor reflex)

A

inhibitory

excitatory

74
Q

Flexor reflex

– Its speed depends on how ___________

A

painful the stimulus is

75
Q

flexor reflex:
– The direction of the reflex depends on the
______________

A

location of the stimulus

76
Q

flexor reflex:

– Slower than the ___________

A

stretch reflex

77
Q

flexor reflex
– Activated by Aδ nociceptive axons that enter the
spinal cord and branch profusely and enter
_______________

A

different segment of the spinal cord

78
Q

• Flexor reflex
– Nociceptive axons act on excitatory interneurons
that excite alpha motor neurons of ____________________

A

the flexors of the affected limb

79
Q

flexor reflex
– At the same time, they activate the inhibitory
interneurons that synapse on the ______________

A

alpha motor

neurons of the extensors

80
Q

___________ activates the same muscle intending to move

A

muscle tendon

81
Q

_________ activates the opposite muscle intended to move

A

Golgi tendon

82
Q

Aδ nociceptive axons __________

A

branch profusely

83
Q

reflexes are helpful in

A

motor skills

84
Q

• Root reflex: corner of the mouth

A

helpful for breast feeding

85
Q

• Babinski reflex is the

A

toe fanning of a baby

86
Q

The cross extensor reflex is the building block

for ____________

A

locomotion

87
Q

Local circuits within the spinal cord

A

– Central pattern generator
– Neurons with pacemaker properties
– Able to control the timing and coordination

88
Q

In bipeds, the movement of a single limb is a

cycle of _____________

A

two phases

89
Q

Phase I:____________
• Limb is extended in contact with the ground to propel
forward

A

stance phase

90
Q

Phase II: ___________

Limb is flexed to leave the ground and brought forward

A

swing phase

91
Q

Locomotion is accomplished by ___________

A

higher centers

in the brain

92
Q 
Decerebrate prep: spinal
cord and brain stem
isolated by cut at “a”
Animal can still walk on a
treadmill

Spinal prep: cut at “b”
isolates hind limb spinal
segments yet animal can
still walk on a treadmil

Deafferented prep: yet
animal can still walk on a
treadmil

A

Conclusion

In conclusion, locomotion
– Is not dependent on sensory input
– Not dependent entirely on higher centers in the
brain
– It is dependent on spinal cord neurons that exhibit
a central pattern generator rhythm

93
Q

_________

  • work on their own
  • have their own action potentials
A

central pattern generators

94
Q

compare cpg vs reflex

A

CPG: does not rely on sensory information as much
Reflex: rely on sensory information

PHYSCI 111A (20 decks)

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