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CRLS > Muscle Control > Flashcards

Muscle Control Flashcards

1
Q

What are the subdivisions of the nervous system?

A
  • Topographical subdivisions
  • Functional subdivisions
  • Directional subdivisions
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2
Q

What is included in the topographical subdivisions?

A
  • central NS - brain and spinal cord
  • peripheral NS - cranial and spinal nerves
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3
Q

What’s included in functional subdivisions?

A
  • somatic (voluntary)
  • visceral (involuntary) also includes the sympathetic and parasympathetic subdivisions
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4
Q

What’s included in the directional subdivisions?

A
  • Afferent = towards brain and spinal cord
  • Efferent = away from the brain and spinal cord
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5
Q

what is a neuron?

A
  • A type of nerve cell that transmits information quickly
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6
Q

What do dendrites do?

A

-Synapse with other neurones to receive information

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7
Q

What does and axon do?

A
  • axon rapidly conduct action potential to distant site
  • myelination enhances conduction speed
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8
Q

What is a motor neuron?

A
  • Efferent nerve cell transmitting information from CNS to muscle to elicit contraction
  • they are excitatory
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9
Q

Complete the sentence … each skeletal muscle fibre is innervated by …

A
  • one motor neurone
  • but each neurone can innervate few or many fibres
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10
Q

Skeletal muscle requires innervation from what to contract?

A
  • motor neurons
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11
Q

The pattern of muscle contraction (strength, speed, duration) is determined by what?

A
  • the pattern of activity in motor neurons
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12
Q

what is a motor unit?

A
  • A motor neurone plus all the muscle fibres it innervates
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13
Q

Ratio of neurone to muscle fibres depends on what?

A
  • the muscle function
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14
Q

If a muscle has fine control and low force what size motor unit would it have?

A
  • small motor unit
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15
Q

If a muscle has less control and a large force what size motor unit would it have

A
  • large motor units
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16
Q

What can muscle force be controlled by?

A
  • number of motor units recruited
  • altering pattern of activity within a motor unit
17
Q

What is a neuromuscular junction?

A
  • A specialised chemical synapse between motor neurone and muscle
18
Q

Synaptic vesicles contain what neurotransmitter? and what does it do?

A
  • acetylcholine which enforces one-way messaging
19
Q

why is the sarcolemma folded at the neuromuscular junction

A
  • to increase surface area
20
Q

How do we ensure that there is only one action potential per nerve?

A
  • Acetylcholinesterase rapidly degrades Ach left in the cleft
21
Q

How can you detect muscle action potentials?

A
  • electromyography can be used to detect electrical activity in muscles
22
Q

What is the function of T-tubules?

A
  • T-tubules conduct an action potential deep into the muscle fibre
  • T-tubules surrounded by sarcoplasmic reticulum
23
Q

What is the function of the sarcoplasmic reticulum?

A
  • Store of calcium ions
24
Q

What are coupled receptors?

A
  • voltage-sensitive proteins in the T-tubules which are linked to calcium channels in the sarcoplasmic reticulum
25
Q

What is the name for the calcium ion channels in the sarcoplasmic reticulum?

A
  • Ryanodine receptors
26
Q

What causes Ryanodine receptors to open?

A
  • when an action potential arrives at a ryanodine receptor, it causes a change in shape of the voltage sensor meaning that protein channels open and calcium ions move from the sarcoplasmic reticulum into the cytosol
27
Q

What happens after muscle control?

A

calcium ions in the cytosol are pumped back into the sarcoplasmic reticulum ( the pump required ATP). This stops contraction.

28
Q

Increasing the frequency of nerve impulses means what?

A
  • contraction force doesn’t have time to fully subside before a new action potential arrives
  • greater force can be developed
  • more stretching of elastic components in muscle
29
Q

If action potentials are frequent enough muscles will undergo what?

A
  • tetanic contraction
30
Q

What is tetanic contraction?

A
  • Sustained, constant high force
  • useful
  • normal contraction type for most skeletal muscles
31
Q

How does depolarisation of the postsynaptic membrane result in muscle contraction?

A
  • The sarcolemma has thin, tube-like
    extensions into the cell (T-tubules),
    surrounding Z-discs of myofibrils
  • T-tubules conduct AP deep into muscle fibre
  • Sarcoplasmic reticulum expanded and well-developed near to T-tubules
  • AP travel in T-tubule stimulates Ca2+ release
    from SR

CRLS (10 decks)

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