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BPK 142 Lecture Flashcards > Lecture 8 Neural Control of Movement > Flashcards

Lecture 8 Neural Control of Movement Flashcards

1
Q

Name the 2 organs part of the central nervous system

A
  • brain

- spinal cord

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2
Q

Explain the structure of the brain in relation to new regions and older primitive regions

A
  • newer/ more sophisticated regions are piled on top of older regions
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3
Q

spinal cord

  • explain shape and what it is made of
  • start and end point
  • average length and diameter
  • what protects it(4)?
A
  • long cylinder of nervous tissue
  • brain stem to second lumbar vertebrae
  • 45cm long and 2cm in diameter
  • vertebral column, associated ligaments and muscles, spinal meninges, and cerebrospinal fluid
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4
Q

What makes up the peripheral nervous system (2)? Give an example of each

A
  • 12 pairs of cranial nerves (olfactory nerve 1)

- 31 pairs of spinal nerves (cervical spinal nerves)

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5
Q

Explain the function of the afferent division

A
  • conveys information from the sensors in the periphery to the CNS
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6
Q

Explain the function of the efferent division; list the 2 systems of the efferent division and explain their difference

A
  • conveys information from CNS to periphery
  • somatic (motor) nervous system: nerve fibers innervate skeletal muscles
  • autonomic (visceral) nervous sytem: - nerve fibers innervate smooth muscles, cardiac muscle, and glands (sympathetic division and parasympathetic division)
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7
Q

explain the difference between the sympathetic and parasympathetic division

A
  • sympathetic: responsible for fight or flight response (danger)
  • parasympathetic: rest and digest response
  • depending on the scenario (sleeping or on the run from danger), the activity of one division dominates over the other
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8
Q

Define: neuroglia/ glia AND:

  • how many cells in the CNS are glia? estimated how many in the brain vs neurons?
  • how much volume do they occupy in the brain?
  • how do they differ from neurons?
A
  • cells within the CNS that support neurons both physically and metabolically
  • comprise 90% of cells within CNS; 1 trillion neuroglia vs 100 billion neurons
  • occupy half the volume of the brain
  • non excitable
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9
Q

List the 4 main types of glial cells

A
  • ependymal cells
  • astrocytes
  • microglia (modified immune cells)
  • oligodendrocytes
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10
Q

Function of: ependymal cells (2)

A
  • create barriers between compartments

- source of neural stem cells

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11
Q

Function of: astrocytes (5)

A
  • take up K+, and neurotransmitters
  • secrete neurotrophic factors
  • help form blood- brain barrier
  • provide substrates for ATP production
  • source of neural stem cells
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12
Q

Function of: oligodendrocytes

A
  • form myelin sheaths
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13
Q

Function of: microglia (modified immune cells)

A
  • act as scavengers
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14
Q

Give a few examples of how the sympathetic system changes the body?

A
  • increase heart rate
  • increase blood pressure
  • increase sweating
  • increase blood glucose
  • decrease skin blood flow
  • decrease digestive blood flow
  • dilate coronary arteries
  • dilate bronchioles
  • dilate pupil
  • decrease respiratory secretions
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15
Q

what is a neuon? What is its function? How do they differ from neuroglia/ glia?

A
  • nerve cell specialised to transmit electrical signals

- excitable

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16
Q

Name all the parts on a neuron (7)

A
  • cell body (soma)
  • cell membrane
  • axon
  • dendrite
  • myelin sheath
  • Nodes of Ranvier
  • synapse
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17
Q

Explain the function of the cell body (soma)

A
  • contains the nucleus
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18
Q

Explain the function of the axon

A
  • long fiber that conducts impulses away from the cell body
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19
Q

Explain the function of dendrites

A
  • short projections from the cell body that transmit impulses/info toward the cell body
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20
Q

Explain the function of the myelin sheath and describe its general structure

A
  • acts as insulation; allows info to transfer faster

- a discontinuous sheath around the axon. It is primarily composed of lipids and proteins.

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21
Q

Explain the function of the Nodes of Ranvier and describe its structure

A
  • where saltatory conduction occurs (ions/action potentials are exchanged across axon membrane)
  • spaces between the segments of myelin sheath
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22
Q

Explain the function of the synapse

A
  • the connection of an axon of one nerve to the cell body or dendrites of another nerve/ the region where a neuron meets its target cell
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23
Q

describe multiple sclerosis

A
  • autoimmune disease
  • body attacks myelin sheath within CNS
  • can impact bladder function, cause spasms, and vision problems
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24
Q

List the 3 functional classes of neurons

A
  • afferent neurons
  • efferent neurons
  • interneurons
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25
Q

explain the function of afferent nuerons

A
  • carry impulses from sensory receptors into spinal cord or brain
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26
Q

explain the function of efferent neurons

A
  • transmit impulses from the CNS out to the effector organs-muscles (motor neurons) and glands
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27
Q

explain the function of interneurons

  • where are they?
  • what % of nerve cells are interneurons?
A
  • allow different nerves to be connected (afferent → efferent, etc)
  • all within CNS
  • 99% of all nerve cells
28
Q

What is a nerve trunk and its relation to spinal nerves

- contains what?

A
  • each spinal nerve is actually a nerve trunk (same thanggg)

- contains hundreds of individual afferent and efferent nerve fibers that are bound by connective tissue sheaths

29
Q

How is nervous information relayed from a neuron to its target cell/ another neuron?

A
  • across the synaptic cleft by a chemical transmitter substance
30
Q

explain how transmitter substances can be:

  • excitatory or inhibitory
  • additive in nature
A
  • the substance either allows or does not allow the action potential to happen
  • impact of the different transmitter substances add up
31
Q

explain the 2 different types of transmitter substance summation

A
  • spatial: multiple inputs from different regions add together
  • temporal: same input occurs over a short period of time ot add up and cause an action potential
32
Q

Describe the neuromuscular junction and the chemical transmitter at it

A
  • nerve to muscle synapse

- acetylcholine

33
Q

define the spinal cord

A
  • 2 way conduction pathway to and from brain
34
Q

Where is the spinal cord enlarged (2)? Why are they enlarged here?

A
  • Cervical enlargement: extends from the C4 through T1 segments of the spinal cord
  • Lumbosacral enlargement: extends from the T11 through L1 segments of the spinal cord
  • limb innervation
35
Q

what is the plexus?

A
  • network of converging and diverging nerve fibers or blood vessels
36
Q

What 2 components make up the brain and spinal cord? Describe them briefly.

A
  • Gray matter: nerve cell bodies

- White matter: interconnecting tracts of nerve fibers (axons)

37
Q

Describe the resting membrane potential

A
  • a potential difference (voltage) exists between the inside and outside of the nerve fibre due to the selective permeability of the nerve cell membrane.
  • a high concentration of positive sodium ions on the outside of the nerve membrane causes it to be electrically positive, while the inside of the nerve is electrically negative
38
Q

Describe how an action potential happens

A
  • an appropriate stimulus suddenly causes sodium ions to rush inside the nerve resulting in a reverse of polarity. information and the action potential spreads along the entire length of the nerve fibre.
39
Q

Spinal nerve structure:

  • how many pairs are attached to the spinal cord
  • how many of each type? (cervical, thoracic, etc)
A
  • 31 pairs attached to spinal cord

- 8 cervical, 12 thoracic, 5 lumbar, 5 sacral. 1 coccygeal

40
Q

What 2 roots does each spinal nerve have? Describe both and their location

A

1 dorsal root and 1 ventral root

  • dorsal: contains afferent (sensory) fibres that carry info from periphery to spinal cord and brain. Is located outside the spinal cord in the spinal ganglia
  • ventral: contains efferent (motor) fibres that carry info to the skeletal muscle. Is located in the gray horns of the spinal cord
41
Q

Define ganglion

A
  • collection of nerve cell bodies located outside of the CNS
42
Q

What is a transection spinal cord injury? What is the result?

A
  • a complete cut of the spinal cord

- results in the loss of all sensation and voluntary movement inferior to the point of damage

43
Q

If transection were to happen at the following places, what would the result be?

  • transection superior to C5
  • transection superior to C4
  • transection below the cervical segment
A
  • superior to C5: quadriplegia
  • above C4: possible respiratory failure
  • below cervical segment: paraplegia
44
Q

Explain common causes to spinal cord injuries (4)

A
  • falls
  • car crashes
  • violence
  • recreational activities
45
Q

How can fractures, dislocations, and atherosclerosis be harmful to the spinal cord?

A
  • cause a deficiency of blood supply (ischemia) to spinal cord; impacts function and leads to muscle weakness and paralysis
46
Q

Fill in the blank: when the brain/ spinal cord is damaged, in most cases the _____ do not ______

A
  • injured axons

- recover

47
Q

Define proprioceptors

A
  • receptor that conducts sensory info to CNS from muscles, tendons, ligaments, and joints (especially info about movement and position)
48
Q

Define a muscle spindle, the structure and the distrubution throughout the muscle

A
  • stretch receptors within a muscle that detects changes in length of the muscle and sends info to CNS
  • several modified muscle fibers (4-10mm) in length, contained in a capsule with a sensory nerve spiraling around its centre
  • density varies with the degree of control required by a given muscle
49
Q

Explain the layout of muscle spindle fibres (intrafusal fibers) in relation to regular fibers (extrafusal fibers)

A
  • spindle fibres lie parallel to regular fibers
50
Q

When the degree of muscle stretch increaes, how does the muscle spindle respond?

A
  • the frequency of impulse transmission up the afferent neuron to the spinal cord progressively increases
51
Q

What are the 3 ways that muscle spindles can activate the alpha motor neurons to cause the muscle to contract

A
  • tonic stretch (concerned with final length of muscle fibre)
  • phasic stretch (spindle responds to velocity of the change of length)
  • gamma system (gamma efferent fibres innervate the intrafusal fibres; - activated when alpha motor neurons are activated (coactivation)
52
Q

Describe the function (2) of the gamma system and when they are activated

A
  • maintains spindle at peak operation at all muscle lengths and maintains spindle sensitivity (by keeping muscle spindles taut to allow continued firing of alpha neurons)
53
Q

What are the 5 functional components of the reflex arc

A
  • receptor
  • afferent (sensory) neuron
  • integrating centre (spinal cord)
  • efferent (motor) neuron (both alpha and gamma)
  • effector (muscle contraction)
54
Q

Describe the stretch reflex

A

Muscle spindle senses stretch, initiates signal down sensory (afferent) neuron, integrated in spinal cord, stimulating both alpha (extrafusal) and gamma (intrafusal) efferent motor neuron stimulation and muscle contraction.

55
Q

Golgi tendon organ:

  • define
  • location
  • length and diameter
  • layout
A
  • proprioceptive receptor that senses change in muscle tension
  • surrounded by tendon fibers near the junction of the muscle and tendon fibers.
  • they are approximately one millimeter long and 0.1 millimeters in diameter.
  • they are in series with the muscle fibers rather than in parallel as are muscle spindles.
56
Q

Describe 2 function of the Golgi tendon organ

A
  • regulates muscle tension within an optimal range (ex: maintaining a steady grip on an object)
  • protects muscle and its connective tissue harness from damage due to excessive loads (excessive tension or stretch causes the GTO to send info to the CNS so the contracted muscle relaxes (reflex inhibition)
57
Q

What is the function of the joint receptors?

A
  • Supply information to the CNS concerning joint angle, acceleration of the joint, pressure, pain, etc
58
Q

What are the main centers employed in learning new motor skills (2)?

A
  • cerebral cortex and cerebellum
59
Q

describe the cerebrum and its two hemispheres

A
  • the most anterior and largest part of the brain
  • right hemisphere: receives sensations from and controls movement of left side of body
  • left hemisphere: receives sensations from and controls movements on the right side of the body
60
Q

describe the cerebral cortex and its function

A
  • 3-4mm thick outer layer of gray matter of the cerebrum

- responsible for sensation, thought, reasoning, memory, and voluntary muscle movement

61
Q

describe the primary motor cortext’s location, its function,
- Where do primary motor neurons cross over in?

A
  • rear frontal lobe of the cerebral cortex
  • movement in specific areas of the body (depending on which part is stimulated)
  • cross over in pyramids of medulla
62
Q

What does the corticospinal system do?

A
  • assists in performance of fine, discrete, and voluntary movements of hands and fingers
63
Q

What is the premotor cortex? where are they located?

A
  • one of the 3 higher areas that command the primary motor cortex
  • lateral surface of each cerebral hemisphere in front of the primary motor cortex
64
Q

What is the extrapyramidal tract? What is it primarily concerned with?

A
  • multi neuronal pathways used to send impulses from the premotor area down to the lower motor neurons of the spinal cord.
  • involves many other brain regions
  • concerned with posture and coordination of large muscle groups
65
Q

Where is the cerebellum located and what is its function (2)?

A
  • behind the brainstem and under the occipital lobes of the cerebral hemispheres
  • monitors and coordinates other areas of the brain involved in motor control by means of intricate feedback circuits
  • (elaboration of above) It receives signals concerning motor output from the cerebral cortex and sensory information from receptors in muscles, tendons, joints and skin, as well as from visual, auditory and vestibular end organs.
  • evaluation centre for postural adjustments, locomotion, maintenance of equilibrium, perceptions of speed of body movement, and general motor coordination
66
Q

If damage is done to the cerebellum, what are the results?

A
  • Damage to the cerebellum results in impaired motor control. Individuals with severe cerebellar damage cannot start or stop movements quickly or easily. They cannot easily combine the movements of several joints into a single, smooth, coordinated motion.

BPK 142 Lecture Flashcards (13 decks)

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