Outline - 2, BIO 2310, Skeletal Muscle Tissue

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IV. SKELETAL MUSCLE TISSUE

A. Gross Structure

1. Fascia (Connective Tissue)

Connective tissue grouping whole muscles, filling spaces, providing origins of muscles

2. Epimysium

Connective tissue around entire muscle

3. Fascicles

Cell bundles

4. Perimysium

Connective tissue around fascicles

5. Endomysium

Connective tissue around single muscle cell

6. Tendon

Muscle to bone (epimysium to periosteum)

7. Aponeurosis

Broad sheet like tendon

B. Microstructure

1. Myofiber

Muscle cell

a. Multinucleate, numerous mitochondria

b. No mitosis

c. Sarcolemma

Plasma membrane

d. Sarcoplasmic reticulum [terminal cisternae]

Calcium storage

e. Transverse (T) tubules

Sarcolemma to interior of cell

2. Myofibril (1u)

Attached to sarcolemma, responsible for contraction

a. I bands (isotropic)

b. A bands (anisotropic)

c. Z lines

d. Sarcomere

Functional unit of muscle contraction. Spans from one Z line to next.

3. Myofilaments

a. Thick (16nm)

1. Myosin

2. Cross bridges

3. ATP binding site

4. Actin binding site

b. Thin (6nm)

1. Actin

2. Tropomyosin

3. Troponin

Anchors tropomyosin to actin