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Functions of the Muscular System
- 1. movement of the body
- 2. maintenance of posture
- 3. respiration
- 4. production of body heat
- 5. communication
- 6. constriction of organs and vessels
- 7. contraction of the heart
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Contractility
ability of the muscle to shorten with force
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Excitability
capacity of muscles to respond to a stimulus (from our nerves)
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Extensibility & Elasticity
- Extensibility: muscle can be stretched to its normal resting length and beyond to a limited degree
- Elasticity: ability of muscle to recoil to original resting length
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Types of muscle tissue
Skeletal, smooth, & cardiac
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Skeletal muscle tissue
- -Voluntary
- -Responsible for locomotion, facial expressions, posture, respiratory movements, other types of body movement
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Smooth muscle tissue
- -walls of hollow organs, blood vessels, eye, glands skin
- -functions: propel urine, mix food in digestive tract, dilating/constricting pupils, regualting blood flow
- -autorhythmic in some locations
- -controlled involuntary by endocrine & autonomic nervous system
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Cardiac muscle tissue
- -Heart: major source of movement of blood
- -autorhythmic
- -controlled involuntarily by endocrine & autonomic nervous system
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Skeletal Muscle structure
- -composed of muscle cells (fibers), connective tissue, blood vessels, & nerves
- -fibers are long, cylindrical, multinucleated
- -tend to be smaller diameter in small muscles and larger in large muscles (1mm - 4cm in length)
- -develop from myoblasts; numbers remain constant
- -striated appearance due to light and dark banding
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Connective Tissue coverings of muscle
- Layers
- Epimysium: C.T. that surrounds a whole muscle (many fascicles)
- Perimysium: Denser C.T. surrounding a group of muscle fibers. Each group called a fasciculus
- Muscular fascia: C.T. sheet
- -external to epimysium
- -holds muscles together and separates them into function groups
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