8. Muscles - Marco Narici Flashcards

1
Q

What 2 types of cells are in the nervous system? Describe each one

A
  1. Neurones = transmits electrical impulses
  2. Supporting cells =
    In CNS - glial cells, oligodendroctyes and microglia
    In peripheral nerve - Schwann cells
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2
Q

Nerve cell structure

  1. Also known as?
  2. What 3 things does it consists of?
A
  1. Neurone

2. Cell body, dendrites and axon

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3
Q

Neurone structure

  1. What does the cell body contain?
  2. What do the dendrites do?
  3. What does the axon do?
  4. Which 2 ways can an axon end?
A
  1. Cell organelles
  2. Conducts nerve impulses towards the cell body
  3. Conducts nerve impulses away from the cell body
  4. Terminates as a swelling which synapses with the next neurone
    Ends as a motor end plate on a skeletal muscle cell
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4
Q

Neurone

  1. Why do neurones have large nucleus and nucleolus?
  2. Size of nerve cell body?
  3. What 2 things are there a lot of for protein synthesis?
  4. What 3 features do all neurones have?
A
  1. High metabolic requirements
  2. Large
  3. RER and ribosomes
  4. Dendrites, soma and axons
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5
Q

Structure of a spinal nerve

  1. What will be the function of the neurones?
  2. What type of nerves are all spinal nerves?
  3. What are the 3 coverings?
A
  1. Some will have sensory function and some will have motor function
  2. Mixed nerves
  3. Epineurium
    Perineurium
    Endoneurium
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6
Q

Spinal nerve

  1. Describe the epineurium
  2. Describe the perineurium
  3. Cells that form the inner surface of the perineurium are joined by what?
  4. What is a bundle of nerve fibres also known as?
  5. Describe the endoneurium
A
  1. Dense layer of fibrous tissue
  2. Layers of flattened cells separated by layers of collagen; surrounds a bundle of nerve fibres
  3. Tight junctions
  4. Fascicle
  5. Thin layer of tissue surrounding individual axons and myelin sheath
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7
Q

Myelin

  1. What is it made out of?
  2. It can be formed from the cell membrane of what in the CNS?
  3. It can also be formed from the cell membrane of what in peripheral nerves?
  4. What is the node of Ranvier?
  5. What is found here?
  6. It is also the anatomical basis of what?
  7. In the CNS, all axons are what?
  8. Is this the case in peripheral nerves?
A
  1. Lipid
  2. Oligodendroctyes
  3. Schwann cells
  4. The gap between the myelin covering formed by adjacent Schwann cells
  5. Majority of the sodium ion channels
  6. Saltatory conduction
  7. Myelinated
  8. No, some axons are non-myelinated (but are embraced by supporting cells)
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8
Q

Muscle types

  1. Describe skeletal muscles in 3 ways
  2. Describe cardiac muscle in 3 ways
  3. Describe non-striated/smooth muscle in 3 ways
A
  1. Striated / rapid & strong contractions / usually voluntary nervous control
  2. Striated / contracts rhythmically / involuntary
  3. Contractions slow and sustained / involuntary / can be single unit or multi-unit
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9
Q

Skeletal muscle

  1. A single skeletal muscle is made up of what?
  2. Within this, what is there?
  3. Each muscle fibre contains what?
  4. What does this contain?
A
  1. Multiple fascicles
  2. Multiple skeletal muscle fibres
  3. Multiple myofibrils
  4. Myofilaments made of action, myosin and other proteins
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10
Q

Striated muscle contraction

  1. How is striated muscle shortened?
  2. What 2 things become shorter?
  3. What stays the same?
  4. What is shortening dependent on?
  5. Equation for force generated?
  6. Equation for velocity if contraction?
A
  1. Thick filaments pulling thin filaments towards the centre of the sarcomeres
  2. H zone and I band
  3. A band
  4. Calcium-dependent
  5. F = number of sarcomere in parallel
  6. V= number of sarcomere in series
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11
Q

Muscle fibre arrangement

What are the 2 ways skeletal muscle fibres can be arranged?

A

Parallel-fibres muscles

Pennate-fibred muscles

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12
Q
  1. Parallel-fibred muscles: fibre length? Relevance to function?
  2. Pennate fibred muscles: fibre length? Fibre number? Relevance to function?
A
  1. Longer fibres
    Capable of greater shortening velocity
  2. Shorter fibres but more fibres
    Stronger but slower contracting
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13
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 motor unit
  4. Define Henneman’s size principle
A
  1. Several muscle fibres
  2. One motor neurone only
  3. An alpha motor neurone in the spinal cord and all the muscle fibres it innervates
  4. The degree of contraction of a whole muscle relies on recruiting motor units from smallest to largest
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14
Q

What are the 3 muscle fibre types? What is each one also known as?

A
  1. Slow oxidative fiber = SO = type 1
  2. Fast oxidative glycolytic fiber = FOG = type 2a
  3. Fast glycolytic fiber = FG = type 2x
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15
Q

Slow oxidative fiber = SO = type 1

  1. Twitch type?
  2. Metabolic type?
  3. Myosin ATPase activity?
  4. Source of ATP?
  5. Glycogen content?
  6. Fibre diameter?
  7. Resistance to fatigue?
  8. Functional role?
A
  1. Twitch type? Slow
  2. Metabolic type? Slow oxidative
  3. Myosin ATPase activity? Low
  4. Source of ATP? Oxidative phosphorylation
  5. Glycogen content? Low
  6. Fibre diameter? Low
  7. Resistance to fatigue? High
  8. Functional role? Posture/ endurance
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16
Q

Fast oxidative glycolytic fiber = FOG = type 2a

  1. Twitch type?
  2. Metabolic type?
  3. Myosin ATPase activity?
  4. Source of ATP?
  5. Glycogen content?
  6. Fibre diameter?
  7. Resistance to fatigue?
  8. Functional role?
A
  1. Twitch type? Fast
  2. Metabolic type? Fast oxidative-glycolytic
  3. Myosin ATPase activity? High
  4. Source of ATP?oxidative phosphorylation and glycolysis
  5. Glycogen content? Moderate
  6. Fibre diameter? Moderate
  7. Resistance to fatigue? Moderate
  8. Functional role? Medium endurance
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17
Q

Fast glycolytic fiber = FG = type 2x

  1. Twitch type?
  2. Metabolic type?
  3. Myosin ATPase activity?
  4. Source of ATP?
  5. Glycogen content?
  6. Fibre diameter?
  7. Resistance to fatigue?
  8. Functional role?
A
  1. Twitch type? Fast
  2. Metabolic type? Fast glycolytic
  3. Myosin ATPase activity? High
  4. Source of ATP? Glycolysis
  5. Glycogen content? High
  6. Fibre diameter? High
  7. Resistance to fatigue? Low
  8. Functional role? Rapid powerful movements
18
Q

Neurotransmitter

  1. What happens to it in a presynaptic neurone?
  2. What happens to it when a presynaptic neurone is stimulated?
A
  1. Synthesised and stored

2. Released

19
Q
  1. What is between the presynaptic cell and the post synaptic cell?
  2. What 2 types of synapses can there be? What takes place here?
  3. What 2 types of transmittor receptors can there be?
  4. What ion is predominantly inside the cell?
  5. What 2 ions are predominantly outside the cell?
A
  1. Synaptic cleft
  2. Axo-dendritic + axo-axonic
    Neurotransmission
  3. G-protein linked + gated channels
  4. Potassium
  5. Sodium and chloride
20
Q
  1. What is the name of the equation that works out the equilibrium potential for any ion?
  2. What is the name of the equation that works out the membrane potential?
  3. What is the resting membrane potential in neurones?
A
  1. Nernst equation
  2. Goldman equation
  3. Electronegative
21
Q

What are the 2 types of postsynaptic potentials and what kind of nerve do you have to stimulate in each one?
Which one represents depolarisation of a postsynaptic cell and which one represents hyperpolarisation?

A
  1. EPSP = excitatory post synaptic potential
    Stimulate excitatory nerve
    Depolarisation of post synaptic cell
  2. IPSP = inhibitory post synaptic potential
    Stimulate inhibitory nerve
    Hyperpolarisation of post synaptic cell
22
Q
  1. Explain temporal summation
  2. Explain spatial summation
  3. What do these summations determine?
A
  1. 4 separate incoming action potentials - first there will be 2 separate EPSPs/IPSPs and then when 2 action potentials get close enough there will be “summated” EPSPs/IPSPs
  2. 2 separate inputs - separated EPSPs/IPSPs when inputs fire separately but when they fire together you get a combined (summated) EPSP/IPSP
  3. Likelihood of an AP being set up in post synaptic cell
23
Q

ACh release at NMJ

  1. Is dependent on what happening to the motor neurone?
  2. What ion influx is there and through what?
  3. What do the ions promote?
  4. What is activated by ACh? How many ACh molecules per each one?
  5. This leads to an influx of what ions in the muscle fibre membrane? What does this result in?
  6. Release of several vesicles of ACh (when the motor neurone is activated) causes what?
A
  1. Depolarisation of the presynaptic membrane
  2. Calcium ions / voltage dependent calcium channels
  3. Fusion of ACh vesicles with presynaptic membrane
  4. nAChR’s = nicotinic ACh receptor - 2 molecules per receptor
  5. Sodium ions - depolarisation of muscle fibre membrane
  6. EPP = end plate potential
24
Q

Drugs used at the NMJ to induce paralysis

  1. Which drugs antagonise the action of ACh on nAChRs?
  2. Which activate nAChRs for a long time?
  3. Which increase ACh in the synapse, reversing the effects of competitive muscle relaxants? What kind of side effects do they cause?
A
  1. Competitive muscle relaxants
  2. Depolarising muscle relaxants
  3. Anticholinesterases
    Muscarinic side effects
25
Q
  1. What can 2 action potentials close together cause?
  2. What can 4 action potentials close together cause?
  3. What can 8 action potentials very close together cause?
  4. In skeletal muscle, why is wave summation and tetanic contraction possible?
A
  1. Wave summation
  2. Unfused tetanus
  3. Fused tetanus
  4. The twitch contraction lasts longer than the action potential
26
Q
  1. What are thick filaments made of?

2. What are thin filaments made of?

A
  1. Myosin

2. Actin

27
Q

Myosin = thick filaments

Which part interacts with the thin filaments?

A

Head

28
Q

Actin = thin filaments

  1. What are the other 2 things that the thin filaments is made up of?
  2. Which one prevents the myosin head binding to the actin?
A
  1. Troponin and tropomyosin

2. Tropomyosin

29
Q

Calcium ions in contraction

  1. In striated muscle, what do the calcium ions bind to?
  2. What does this cause?
  3. What is moved out of the way?
  4. If other conditions are correct (eg. ATP levels high enough) what takes place?
  5. What is this process known as?
A
  1. Troponin C
  2. Conformation change in the troponin complex
  3. Moves tropomyosin out of myosin binding sites
  4. Contraction
  5. Actin-linked regulation of muscle contraction
30
Q

Calcium ions

  1. In skeletal muscle, what does sarcoplasmic reticulum do when the muscle is relaxed and when it is depolarised?
  2. In cardiac muscle, apart from the SR, where else of the calcium ions come from?
  3. In smooth muscle, where do almost all calcium ions come from?
A
  1. Muscle relaxed = SR acts as calcium store
    Muscle depolarised = SR releases calcium ions
  2. From the extracellular fluid via calcium channels
  3. Extracellular fluid
31
Q

T-tubules

  1. What do T tubules allow?
  2. What do T tubules come close to in striated muscle?
  3. When the membrane on the T tubule is depolarised, what does this do to SR?
  4. Because of this, ions can be released where they are needed. What are the 2 places they are needed?
A
  1. Changes in membrane potential to be communicated right to the middle of the muscle fibre
  2. SR
  3. Calcium release
  4. Junction of the A bands and the I bands
32
Q

The cross bridge cycle of contraction

  1. What do myosin heads hydrolyse in order to become reorientated and energised?
  2. Myosin heads then bind to actin, forming what?
  3. Myosin heads then rotate toward what?
  4. As the myosin head binds to ATP, what happens?
  5. Contraction will continue if what 2 things are available?
A
  1. ATP
  2. Crossbridges
  3. The centre of the sarcomere
  4. The cross ridges detach from actin
  5. ATP and calcium ions
33
Q

What are the 3 type of nerve fibres? Which of these are myelinated and which are non-myelinated?

A

A / B / C
A and B myelinated
C unmyelinated

34
Q

Nerves fibre types: As you go from A-C…

  1. Diameter
  2. Conduction velocity
A
  1. Decreases

2. Decreases

35
Q

What are the 3 type of cutaneous receptors?

A
  1. Pain and temperature
  2. Touch
  3. Deep pressure
36
Q

Adaptation of receptors

  1. What are the 2 types of adaptations?
  2. What does the CNS use to judge the amplitude of the stimulus?
  3. The receptor for a painful stimuli (for example) would display which type of adaptation so that there is a continuous message that the stimulus is still there?
A
  1. Slow adaptation and rapid adaptation
  2. Frequency of APs coming in via a given type of fibre
  3. Slow adaptation
37
Q

What 5 types of sensory receptors are there?

A
Pain
Touch
Deep pressure
Tendon
Muscle spindle
38
Q

Muscle and tendon proprioceptors

  1. Muscle spindles are used to detect changes in what?
  2. What are the main muscle fibres outside known as?
  3. What are the small muscle fibres inside known as?
  4. Golgi tendon organs are used to detect changes in what?
A
  1. Muscle length
  2. Extrafusal muscle fibres
  3. Intrafusal muscle fibres
  4. Tendon tension
39
Q

Spinal cord

  1. White matter contains axons of what?
  2. Grey matter contains what?
  3. What is in the ventral and lateral horns?
  4. What is in the dorsal horn?
A
  1. Axons of neurones ascending to/descending from higher centres in CNS
  2. Cell bodies of many kinds of neurones
  3. Cell bodies of motor neurones
  4. Cell bodies of sensory neurones and interneurones
40
Q
  1. How do sensory neurones enter the dorsal horn?

2. How do motor neurones leave the ventral and lateral horn?

A
  1. Via the dorsal root of the spinal nerve

2. Via the ventral root of the spinal nerve