HBS 1.2

skeletal muscle structures

muscle tissue(muscle cells or fibers), connective tissues, nerves, blood vessels

skeletal muscles

are attached to the skeletal system, allows us to move

skeletal muscles functions

produce skeletal movement, maintain body position, support soft tissues, guard body openings, maintain body temperature

3 layers of connective tissue in a musc

epimysium, perimysium, endomysium

Epimysium

• exterior collagen layer

• connected to deep fascia

• separates muscle from surrounding tissues

Perimysium

• surrounds muscle fiber bundles (fascicles)

• contains blood vessel and nerve supply to fascicles

Endomysium

• surround individual muscle cells (muscle fibers)

• contains capillaries and nerve fibers contacting muscle cells

• contains satellite cells (stem cells) that repair damage

Endomysium, perimysium, and epimysium come together:

• at ends of muscles

• to form connective tissue attachment to bone matrix

• tendon (bundle) or aponeurosis

What are skeletal muscle cells called?

Fibers

Skeletal muscle fibers

• are very long

• develop through fusion of mesodermal cells (myoblasts)

• become very large

• contain hundreds of nuclei

Sarcolemma

• the cell membrane of a muscle cell

• surrounds the sarcoplasm (cytoplasm of muscle fiber)

• a change in the transmembrane potential begins contractions

Myofibrils

• lengthwise subdivisions within muscle fiber

• made up of bundles of protein filaments (myofilaments)

• myofilaments are responsible for muscle contraction

What are the 2 types of myofilaments?

• Thin filaments (made of the protein acting)

• Thick filaments (made of the protein myosin)