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Human Physiology > Ch 12: Muscles > Flashcards

Ch 12: Muscles Flashcards

1
Q

Cardiac & skeletal muscles contain?

A
  • Striations
  • Muscle fiber
  • Nucleus
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2
Q

“How you interact with external environment” is due to?

A

Skeletal muscle

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3
Q

Smooth muscles is found where?

A

Where you have an interior & want muscle around it to contract it
- By uterus, bladder

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4
Q

What does smooth muscle lack?

A

Striations

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5
Q

Types of muscles

A
  1. Skeletal
  2. Cardiac
  3. Smooth
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6
Q

Skeletal muscle - Antagonistic muscles: Flexion

A

Triceps - muscle relaxes
Biceps - muscle contracts (flexor)

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7
Q

Skeletal muscle - Antagonistic muscles: Extension

A

Triceps - muscle contracts (extensor)
Biceps - muscle relaxes

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8
Q

Muscle contraction is energetically ___________?

A

Expensive

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9
Q

Muscle fiber

A

Muscle cell
- can be long, but NOT as long as neurons

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10
Q

Modified ER

A

Sarcoplasmic reticulum
- stores Ca2+

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11
Q

Cytoplasm

A

Sarcoplasm

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12
Q

Cell membrane

A

Sarcolemma

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13
Q

Striated (skeletal) muscle occupies how much of the adult human body by mass?

A

40-50%

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14
Q

At rest, skeletal muscle accounts for ____ of oxygen consumed?

A

25%, can triple during exercise

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15
Q

Sarco

A

Muscle

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16
Q

Ultrastructure of Muscle

A

A. Contractile proteins
B. Regulatory proteins

17
Q

Contractile proteins

A
  1. Myosin
  2. Actin
18
Q

Myosin

A

Part of thick filament
- approx. 250 individual myosin molecules join to form thick filament
- each single myosin molecule has 4 subunits: 2 heavy chains forming a tail, 2 lighter chains forming the head

19
Q

Actin

A

Part of the thin filament
- double helix of G-actin (globular) molecules
- each G-actin has binding site for myosin (convenient)
- strand of G-actin called F-actin (fibrous)

20
Q

Regulatory proteins

A

Both found on thin filament
1. Tropomyosin
2. Troponin

21
Q

Tropomyosin

A

Regulatory protein that covers the binding sites on F-actin (covers 7 actin molecules)

22
Q

Troponin

A

Regulatory protein (composed of 3 subunits) bound to tropomyosin & has a binding site for Ca2+

23
Q

Actin-Myosin Cross Bridge Cycle

A
  1. Increased intracellular Ca2+ levels, Ca2+ binds to troponin
  2. Troponin changes shape & pulls tropomyosin off binding sites
  3. Actin & myosin attach
  4. Pi is released
  5. Power strokes occurs, shortens sarcomere
  6. ADP is released
  7. Fresh ATP, if available, binds to myosin head
  8. Myosin detaches from actin
  9. ATP hydrolyzed, energy re-cocks myosin head
  10. If Ca2+ still present, myosin attaches to actin, cycle repeats
  11. If Ca2+ is removed, tropomyosin covers binding sites preventing actin-myosin cross bridge
24
Q

Skeletal muscle group composed of?

A

Fibers aka cells

25
Q

Why is skeletal muscle multi-nucleated?

A

Due to fusion of myoblasts during development
- cannot undergo mitosis

26
Q

Epimysium

A

Connective tissue

27
Q

Perimysium

A

Fascicle - bundle of muscle fibers

28
Q

Endomysium

A

muscle fiber (cell)

29
Q

Myofibril

A

Contains thin and thick filament

30
Q

T-tubule

A

Brings action potentials into interior of muscle fiber

31
Q

Terminal cisterna

A

Big place for storage
- lateral sacs
- regions of SR that are T-tubules

32
Q

Sarcomere

A

Functional unit of skeletal muscle
- Z line to Z line
- the contractile unit of striated muscles

33
Q

Each myosin head contains a binding site for?

A

Actin & ATPase site
- can only bind to ONE, NOT BOTH

34
Q

A flexible hinge allows the head to undergo _________

A

The powerstroke

35
Q

Actin attached to?

A

Z-line

36
Q

Actin helix

A

Backbone of thin filament

37
Q

Sliding filament theory

A

Force is generated as fixed-length filaments slide pass one another

Human Physiology (8 decks)

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