Chapter 1 Skeletal Muscle

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1

Three types of Muscle Tissue

  • Skeletal, Cardiac, Smooth
2

Skeletal muscle

voluntary, skeleton

3

Smooth muscle

involuntary, hollow organs

4

Cardiac Muscle

involuntary, heart

5

Anatomy: Entire Muscle

  • surrounded by epimysium
  • consists of many bundles (fasciculi)
6

Anatomy: Fasciculi

  • surrounded by perimysium
  • consists of individual muscle cells (muscle fibers)
7

Anatomy: Muscle Fiber

  • Surrounded by endomysium
  • consists of myofibrils divided into sarcomeres
8

Sarcolemma consists of?

plasmalemma and basemant membrane

9

Plasma (____ membrane)

outer

10

Function of Plasmalemma

  • fuses with tendon
  • conducts action potentials, accepts action potentials
  • maintains pH, transports nutrients
11

Satellite Cells is found?

in between plasmalemma and basement membranes

12

Function of Satellite Cells?

  • muscle growth and development
  • response to injury, immobilization, and training
13

Structure of Muscle Fibers: Sarcoplasm

  • cytoplasm of muscle cell
  • unique features: glycogen storage, myoglobin
    • (myoglobin carries oxygen from hemoglobin. higher affinity so O2 goes to myoglobin then mitochondria)
14

Structure of Muscle Fibers: Transverse Tubules (T-tubules)

  • extensions of plasmalemma that pass laterally through muscle fiber
  • carry action potential deep into muscle fiber
15

Structure of Muscle Fibers: Sarcoplasmic Reticulum (SR) - Ca2+ storage

  • Run parallel to the myofibrils and loop around them
16

Myofibrils

  • Muscle --> fasciculi --> muscle fiber --> myofibril
  • hundred to thousands per muscle fiber
  • made of the basic contractile units
17

Sarcomeres

  • basic contractile element of skeletal muscle
  • end to end for full myofibril length
  • Distinctive striped appearance (striations)
    • A-bands: dark stripes
    • I-bands: light stripes
    • H-zone: middle of A-band
    • M-line: middle of H-zone
  • Common boundary structure: Z-disk
18

Which is anisotropic/isotropic? A-band and I-band

  • A-band: anisotropic
  • I-band: isotropic
19

The thin filament is?

myosin

20

The thick filament is?

actin, troponin, tropomyosin

21

Sarcomere: Protein Filaments

  • used for muscle contraction
  • Actin (thin filaments)
  • Myosin (thick filaments)
22

Actin (thin filaments)

  • show up lighter under the microscope
  • I-band contains only actin filaments
  • Actually composed of three proteins
    • Actin: contains myosin-binding site
    • Tropomyosin: covers active site at rest
    • Troponin: anchored to actin, moves tropomyosin
  • Anchored at Z-disk
  • Equally spaced out by titin
23

Myosin (thick filaments)

  • show up darker under the microscope
  • A-band contains both actin and myosin filaments
  • H-zone contains only myosin filaments
  • Two intertwined filaments with globular heads
  • Globular heads
    • protrude 360 from thick filaments axis
    • will interact with actin filaments for contraction
  • stabilized by titin
24

Contractile proteins

actin and myosin

25

Regulatory proteins

troponin and tropomyosin

26

Structural protein

titin