Chapter 8: Skeletal Muscle Flashcards
Functions of skeletal muscle
- force generation for locomotion and breathing
- force generation for postural support
- heat production during cold stress
Human body contains over ____ skeletal muscles
600
- 40-50% of total body weight
Fascia
Separates individual muscles and holds them in position
Epimysium
surrounds entire muscle
Perimysium
Surrounds bundles of muscle fibers (fascicles)
Endomysium
surrounds individual muscle fibers
External lamina (basement membrane)
just below endomysium
sarcolemma
muscle cell membrane
Muscle cells (fibers)
- unique shape
- contain same organelles with other cells (mitochondria)
- multinucleated
- striated appearance
– stripes produced by alternating dark and light bands - each muscle fiber extends the entire length of the muscle
Above the sarcolemma and below the external lamina are a group of muscle precursor cells called
satellite cells
Satellite cells
- undifferentiated cells involved in muscle growth and repair
- can be activated to increase number of nuclei which allows for greater protein synthesis
- important for adaptations to strength training
If muscle cells are destroyed due to injury or disease they _____ be replaced by cell division
cannot
Myonuclear domain
the volume of cytoplasm surrounding each nucleus
- each nucleus can support the gene expression (protein synthesis) of a limited myonuclear domain
During growth, to maintain a constant ratio of cell volume per nucleus
nuclei from satellite cells are incorporated
hypertrophy
increased number of nuclei by activating satellite cells