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2017 Marco Narici > MEQ Marco Narici > Flashcards

MEQ Marco Narici Flashcards

1
Q

Structure of a spinal nerve

What are the 3 coverings in peripheral nerves from the outside in?

A

Epineurium
Perineurium
Endoneurium

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2
Q

Structure of a spinal nerve

Epineurium
Structure?
What does it cover?

A

Dense layer of fibrous tissue

Covers nerve

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3
Q

Structure of a spinal nerve

Perineurium

Structure?
What does it cover?

A

Layers of flattened cells seperated by layers of collagen

Covers a fascicle of nerve fibres

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4
Q

Structure of a spinal nerve

Endoneurium
Structure?
What does it cover?

A

Thin layer of tissue

Covers individual axons and myelin sheath

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5
Q

Some neurones will have sensory function and some will have motor function.

What are all spinal nerves?

A

Mixed nerves

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6
Q

What are the 2 types of cells in the nervous system?

A

Neurones

Supporting cells

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7
Q

What do neurones do?

A

They are specialised for the transmission of electrical impulses

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8
Q

What supporting cells are in the CNS?

What supporting cells are in the PNS?

A

CNS: glial cells

PNS: schwann cells

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9
Q

What is a nerve cell also known as?

A

Neurone

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10
Q

Name 3 things that a neurone consists of and give one brief piece of information about each one

A

Cell body: contains organelles

Dendrites: conducts nerve impulse towards the cell body

Axon: conducts nerve impulse away from the cell body

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11
Q

Axon

What does it do?

What are its 2 possible outcomes?

A

Axons conduct the nerve impulse away from the cell body

They can:

  1. Terminate as a swelling which synapses with the next neurone
  2. Ends as a motor end plate on a skeletal muscle cell
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12
Q

What are the 3 muscle types?

A

Skeletal muscle

Cardiac muscle

Smooth muscle

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13
Q 
Skeletal muscle
Appearance?
Contractions?
Control?
Single unit/ multi unit?
A

Striated
Rapid, strong contractions
Voluntary nervous control (usually)
Multi-unit muscle

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14
Q 
Cardiac muscle
Appearance?
Contractions?
Control?
Single unit/ multi unit?
A

Striated
Contracts rythymically
Involuntary - by autonomic neurones
Single unit muscle (functional syncytium)

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15
Q 
Smooth muscle
Appearance?
Contractions?
Control?
Single unit/multi unit?
A

Non-striated / smooth
Slow, sustained contractions
Involuntary - autonomic neurones
Can be single unit or multi unit

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16
Q

What are the 3 muscle fibre types?

A

Slow twitch (Type 1)

Fast twitch (Type 2a)

Fast twitch (Type 2x)

17
Q

Slow twitch (Type 1) Muscle fibre

Metabolic type?
Source of ATP?
Resistance to fatigue?
Functional role?

A

Metabolic type: slow oxidative
Source of ATP: oxidative phosphorylation
Resistance to fatigue: high
Functional role: posture/endurance

18
Q

Fast twitch (Type 2a) Muscle Fibre

Metabolic type?
Source of ATP?
Resistance to fatigue?
Functional role?

A

Metabolic type: fast oxidative/glycolytic
Source of ATP: oxidative phosphorylation and glycolysis
Resistance to fatigue: moderate
Functional role: medium endurance

19
Q

Fast twitch (Type 2x) Muscle Fibre

Metabolic type?
Source of ATP?
Resistance to fatigue?
Functional role?

A

Metabolic type: fast glycolytic
Source of ATP: glycolysis
Resistance to fatigue: low
Functional role: rapid powerful movements

20
Q

ACh release at NMJ

  1. What is the first step that has to occur and where does it occur?
  2. Which ion influx is there and what does it come through?
  3. What do the ions promote?
  4. What is activated by ACh and how many molecules are required per receptor?
  5. What does this activation lead to?
A
  1. Depolarisation of the presynaptic membrane of the motor neurone
  2. Calcium ion influx through voltage dependent calcium channels
  3. Calcium ions promote fusion of the ACh vesicles with the presynaptic membrane
  4. Activation of nicotinic acetylcholine receptors (nAChR) - 2 molecules per receptor
  5. Depolarisation of the muscle fibre membrane via a net influx of Sodium ions
21
Q

What does the release of a single vesicle of ACh (at rest) result in?

A

Miniature end-plate potential

22
Q

What does the release of several vesicles of ACh (when the motor neurone is activated) result in?

A

End plate potential

23
Q

In skeletal muscle, why is wave summation and tetanic contraction possible?

A

Because the twitch contraction lasts longer than the action potential

24
Q

Nerve AP to muscle contraction

  1. ACh binds to nAChR, this elicits an end plate potential which then triggers what?
  2. The action potential propagates in which direction?
  3. This triggers calcium release from where?
  4. What does the calcium bind to and what does this expose?
  5. Which cycle begins leading to muscle fibre contraction?
A
  1. An action potential in the muscle cell
  2. Along the sarcolemma and down the T-tubules
  3. Calcium release from sarcoplasmic reticulum
  4. Calcium binds to troponin and exposes myosin binding sites
  5. Crossbridge cycle begins
25
Q

Once the crossbridge cycle begins, what are the 2 outcomes?

A
  1. Calcium is actively transported back into the sarcoplasmic reticulum after the action potential
  2. Tropomyosin blocks the myosin binding sites so the muscle fibre relaxes
26
Q

Sliding filament theory of muscle contraction

  1. How do the filaments move?
  2. What does this shorten?
  3. What is this mechanism dependent on?
A
  1. Thick filaments pull thin filaments towards the centre of the sarcomere
  2. Sarcomeres shorten
  3. Shortening is calcium dependent
27
Q

Explain the crossbridge cycle

A
  • myosin heads hydrolyse ATP
  • myosin heads bind to actin forming a crossbridge
  • myosin heads rotate towards the centre of the sarcomere
  • myosin heads bind ATP
  • crossbridges detach from actin
28
Q

Why is ATP needed in contraction?

A

To allow the cocking of the myosin head

29
Q

What are the 2 reasons ATP is needed for relaxation?

A
  1. When calcium ion concentrations fall, to help detach myosin from actin
  2. To pump calcium ions into SR or out of cell
30
Q

Motor units

  1. Each alpha motor neurone (in the spinal cord) can innervate what?
  2. A single muscle fibre receives innervation from what?
  3. Define a motor unit
  4. The degree of contraction of a whole muscle relies on what?
  5. What kind of movement would be at the lower end and what kind of movement would be at the upper end?
A
  1. Several muscle fibres
  2. One motor neurone
  3. Motor unit = an alpha motor neurone in the spinal cord and all of the muscle fibres it innervates
  4. Recruiting motor units from smallest to largest (Henneman’s size principle)
  5. Lower end = fine control of movement
    Upper end = forceful contraction
31
Q

What are the 3 types of motor units called?

A

1

2a

2b

32
Q

Motor unit type 1

Property?
Twitch speed?
Twitch force?
Fatigue?
Myoglobin?
A 
Property: slow oxidative
Twitch speed: slow
Twitch force: small
Fatigue: low
Myoglobin: high
33
Q

Motor unit type 2a

Property?
Twitch speed?
Twitch force?
Fatigue?
Myoglobin?
A 
Property: fast oxidative-glycolytic
Twitch speed: fast
Twitch force: intermediate
Fatigue: low
Myoglobin: high
34
Q

Motor unit type 2b

Property?
Twitch speed?
Twitch force?
Fatigue?
Myoglobin?
A 
Property: fast glycolytic
Twitch speed: fast
Twitch force: large
Fatigue: high
Myoglobin: low

2017 Marco Narici (1 decks)

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