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Medicine for Engineers Part 2 > Muscles > Flashcards

Muscles Flashcards

1
Q

Which are the three different types of muscle cells?

A

Muscle cells

  1. Skeletal muscle cells
  2. Cardiac muscle cells
  3. Smooth muscle cells
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2
Q

What are the functions of the skeletal muscles?

A

Skeletal muscles - 40-50% of total body weight

Voluntary

  • Mostly movements of bone & body parts (produce body movements)
  • Stabilizing body positions
  • Store and move subtances
  • Produce heat (shivering)
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3
Q

Explain the function of Cardiac muscle tissue.

A

Cardiac muscle tissue

Involuntary

  • Heart only
  • Develops pressure for arterial blood flow
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4
Q

What is the function of Smooth muscle tissue?

A

Smooth muscle tissue - grouped in walls of hollow organs

  • Sphincters regulate flow in tubes
  • Maintain diameter of tubes
  • Move material in GI tract and reproductive organs
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5
Q

The Skeletal muscle tissue is well supplied with?

A

Skeletal muscle tissue

  • Well-supplied with blood vessels and nerves
  • Terminal of a neuron on each side of the muscle fiber.
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6
Q

Explain the following terms associated with skeletal muscle histology:

  • Sarcolemma
  • Transverse tubules
  • Nuclei
  • Sarcoplasm
A

Muscle histology

  • Elongated cylindrical cells = muscle fibers
  • Plasma membrane = sarcolemma
  • Transverse tubules (T) tunnels from surface to center of each fiber
  • Multiple nuclei lie near surface of cell
  • Cytoplasm=Sarcoplasm
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7
Q

Explain the function of sarcoplasmic reticulum in skeletal muscle tissue.

A

Stores calcium ions.

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8
Q

Sarcoplasm contains … ( specific protein)?

A

Sarcoplasm contains Myoglobin

Red pigmented protein related to Hemoglobin that carries oxygen.

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9
Q

What are Myofibrils made of?

A

Myofibril consists of the proteins Actin (Thin filament) and Myosin (Thick filament).

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10
Q

Explain the mechanism of Sarcomeres.

A

Functional structure of Sarcomeres

  • Thick filaments (myosin) have moveable heads (like “heads” of golf clubs).
  • Thin filaments (actin) are anchored to Z discs.
    • Contain myosin binding sites for myosin head
    • Also contain tropomyosin & troponin
  • Tropomyosin blocks myosin binding site when muscle is at rest.
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11
Q

Explain structure of Myosin in Skeletal muscle fibers.

A

See picture.

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12
Q

Explain the structure of Thin filaments in Skeletal muscle fibers.

A

See Picture.

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13
Q

Explain function of Tropomyosin in Skeletal muscle cells.

A

Troposin (in Thin filaments) blocks myosin binding site when muscle is at rest.

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14
Q

Explain the Sliding Filament Mechanism in Skeletal muscle cells.

A

Sliding Filament Mechanism

  • During contraction Myosin heads Actin sites.
  • Myosins pull and slide Actin molecules (and Z discs) toward H-zone.
  • I-bands and H-zones become more narrow.
  • Sliding generates force and shortens sarcomeres and thus fibers.
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15
Q

Explain the Neuromuscular interaction of Skeletal muscle tissue.

A

Neuromuscular interaction

  • Nerve signal triggers muscle action potential
  • Delivered by a motor neuron
  • One neuron can trigger 1 or more fibers at the same time
  • The more precise movements needed, the fewer fibers are activated
  • Neuron plus triggered fibers = Motor unit
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16
Q

What is a Motor unit?

A

Motor Neuron plus triggered Skeletal muscle fibers.

17
Q

Explain the action of NMJ.

A

Neuromuscular Junction (NMJ)

  1. Release of Acetylcholine (ACh)
    • Diffuses across cleft
  2. Activation of ACh receptors
  3. Generation of Muscle Action Potential
    • Repeats with each neuronal action potential
  4. Breakdown of Ach (Acetylcholinestras)
18
Q

Explain Contraction Trigger associated with Skeletal muscle fibers.

A

Contraction Trigger

  • Muscle action potential -> Ca2+ release from Sarcoplasmic Reticulum (SR)
  • Ca2+ binds to troponin ->
  • Moves tropomyosin off actin sites ->
  • Myosin binds & starts cycle
19
Q

Explain Relaxation associated with Skeletal muscle tissue.

A

Relaxation

  • Breakdown of ACh to stop muscle action potentials
  • Ca2+ ions transported back into SR lowering the concentration ->
    • This takes ATP
  • Tropomyosin covers actin binding sites.
20
Q

What is Muscle Tone?

A

Muscle Tone

  • Even at rest some motor neuron activity occurs = Muscle Tone.
  • If nerves are cut fibers become flaccid (very limp)
21
Q

Explain the production of ATP for muscle contraction.

A

See picture.

22
Q

Explain Aerobic Cellular Respiration.

A

Aerobic Cellular Respiration

  • Production of ATP in mitochondria.
  • Requires oxygen and carbon substrate.
  • Produces CO2 and H20 and heat
23
Q

Explain muscular fatigue.

A

Fatigue

  • Inability to contract forcefully after prolonged activity
  • Limiting factors can include:
    • Ca2+
    • Creatine Phosphate
    • Oxygen
    • Build up of acid
    • Neuronal failure
24
Q

Explain oxygen use after exercise associated with skeletal muscles.

A

Oxygen use after Exercise

  • Convert lactic acid back to glucose in liver
  • Resynthesize creatine phosphate and ATP
  • Replace oxygen removed from myoglobin
25
Q

Explain different levels of contraction concerning skeletal muscles.

A

Myogram

26
Q

Explain the terms agonist-antagonist.

A

Skeletal muscles are generally arranged in opposing pairs (agonist - antagonist)

  • Flexors - Extensors; Abductors - Adductors.
27
Q

Superficial Skeletal Muscles

A

See picture.

28
Q

Muscles of the Head

A

Muscles of the Head

Facial expression = Precis movement

29
Q

Muscles of the Eyeball

A
30
Q

Muscles of Abdomen

A

Muscles of Abdomen

31
Q

Muscles of Forearm

A

Muscles of Forearm

32
Q

Two exampels of Muscular disorders and diseases.

A

Muscular disorders and disease

  • Quite rare…
  • Muscular dystrophy
  • Myasthenia gravis - (Ach receptors)
33
Q

What happens with the skeletal muscle tissue when we age?

A

Age

  • As with bone there is a slow progressive loss of skeletal muscle
  • Relative numbers of SO (slow twitch oxidative) fibers tends to increase.

Medicine for Engineers Part 2 (11 decks)

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