Levels and Sacromeres (CH 10 LAB)

skeletal muscle (skeletal muscle level)

epimysium (skeletal muscle level)

• dense irregular connective tissue surrounding entire muscle; may blend with fascia 

muscle fascicle (skeletal muscle level)

muscle fiber (skeletal muscle level)

muscle fascicle (muscle fascicle level)

endomysium (muscle fascicle level)

• fine areolar connective tissue surrounding each muscle fiber

perimysium (muscle fascicle level)

• fibrous connective tissue surrounding fascicles 

  • Fascicles are groups of muscle fibers

muscle fiber (muscle fascicle level)

muscle fiber (skeletal view)

myofibril (skeletal and fascicle view)

filament (fascicle view)

myofibril (muscle fascicle/muscle fiber)

muscle fiber (muscle fascicle/muscle fiber)

sarcolemma (muscle fascicle/muscle fiber)

muscle fiber plasma membrane

sarcoplasm (muscle fascicle/muscle fiber)

muscle fiber cytoplasm

sarcoplasmic reticulum (muscle fascicle/muscle fiber)

• stores Ca2+ and wraps around the myofibrils

transverse(T) tubules (muscle fascicle/muscle fiber)

• conducts muscle action potentials toward the center of the muscle fibers

Glycosomes

glycogen storage

I band

• lighter regions encasing Z discs

  • In contraction: shorten

Z disc

• zig zagged region

  • In contraction: pulled towards M line

H band

• smaller region within A band

  • disappear

M line

• line of protein (myomesin) that bisects H zone vertically

A band

• larger dark region

  • In contraction: move closer to each other

Thick filament

myosin

Thin filament

actin