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Anatomy > ✅Muscle Tissue > Flashcards

✅Muscle Tissue Flashcards

1
Q

What are the functions of skeletal muscle?

A

-Produce skeletal movement
• Maintain posture and body position
• Support soft tissue
• Guard entrances and exits
• Maintain body temperature
• Store nutrient reserves

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2
Q

What are the 3 layers of connective tissue that muscles have?

A
  1. Epimysium
  2. Perimysium
  3. Endomysium
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3
Q

Describe Epimysium

A

– Exterior collagen layer
– Connected to deep fascia
– Separates muscle from surrounding tissues

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4
Q

Describe perimysium

A

-Surrounds muscle fibre bundles (fascicles)
– Contains blood vessel & nerve supply to fascicles

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5
Q

Describe endomysium

A

-Surrounds individual muscle cells (muscle fibres)
– Contains capillaries & nerve fibres contacting muscle cells
– Separates & electrically insulates muscle cells from each other

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6
Q

When do Endomysium, perimysium & epimysium come together?

A

-At ends of muscles
– To form connective tissue attachment to bone matrix
– i.e. tendon (bundle) or aponeurosis (sheet)

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7
Q

Muscles have extensive vascular systems that…

A
  • Supply large amounts of oxygen

* Supply nutrients
• Carry away wastes

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8
Q

Are skeletal muscles voluntary or involuntary?

A

Voluntary

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9
Q

What are skeletal muscle controlled by?

A

nerves of the central nervous system (brain + spinal cord)

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10
Q

Thick & thin myofilaments form alternating light & dark bands (striations) along the myofibril.

T or F

A

True

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11
Q

What is the sliding filament theory?

A

• Thin filaments of sarcomere slide toward M line, alongside thick filaments, H,I bands get smaller
• Zones of overlap get larger
• The width of A zone stays the same
• Z lines move closer together

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12
Q

What is myosin?

A

A complex protein

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13
Q

What is myosin structure?

A

A molecule with a head, a hinge and a tail

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14
Q

What to myosin head have in thick filaments?

A

An ATP binding site, the enzyme, ATPase

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15
Q

How are myosin proteins bound in thick filaments?

A

By the tail

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16
Q

What is actin?

A

Strands of globulin protein molecules

17
Q

What does actin consist of?

A

2 strands wound together to make a thin filament

18
Q

What does each actin have?

A

A myosin binding site

19
Q

What is wrapped around actin filaments?

A

Regulatory protein, tropomyosin

20
Q

What is bound to tropomyosin strands?

A

Calcium-binding protein, troponin

21
Q

What does the process of skeletal muscle contraction involve?

A
  • Neural stimulation of sarcolemma
    – Causes excitation–contraction coupling
  • Muscle fibre contraction
    – Interaction of thick and thin filaments
  • Tension (force) production
22
Q

What is a motor neuron and all of the muscle cells it stimulates called?

A

A motor unit

23
Q

How does a muscle contact?

A

• Muscle contraction is initiated by neural
stimulation which induces Calciumion (Ca2+) release
• (Ca2+) is released from the SR of the myofilament

24
Q

How is contraction initiated?

A

(Ca2+) binds to actin and initiates contraction by exposing myosin binding site

25
Q

What are the stages of the contractile cycle (skeletal muscle)

A
  1. Contraction Cycle Begins
  2. Active-Site Exposure
  3. Cross-Bridge Formation
  4. Myosin Head Pivoting
  5. Cross-Bridge Detachment
  6. Myosin Reactivation
26
Q

What happens at stage 1?

A

The arrival of calcium ions within the zone of overlap.

27
Q

What happens at stage 2?

A

Calcium ions bind to troponin, weakening the bond between actin and the troponin– tropomyosin complex. The troponin molecule then changes position, rolling the tropomyosin molecule away from the active sites on actin and allowing interaction with the energized myosin heads.

28
Q

What happens are stage 3?

A

Once the active sites are exposed, the energized myosin heads bind to them, forming cross-bridges.

29
Q

What happens at stage 4?

A

After cross-bridge formation, the energy that was stored in the resting state is released as the myosin head pivots toward the M line. This action is called the power stroke; when it occurs, the bound ADP and phosphate group are released.

30
Q

What happens at stage 5?

A

When another ATP binds to the myosin head, the link between the myosin head and the active site on the actin molecule is broken. The active site is now exposed and able to form another cross-bridge.

31
Q

What happens at stage 6?

A

Myosin reactivation occurs when the free myosin head splits ATP into ADP and P. The energy released is used to recock the myosin head.

Anatomy (20 decks)

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