Download Muscles - CHOW

Muscles: A Closer Look
Types of Muscles
1. Skeletal Muscle
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Attached to bone – skeletal movements
Conscious and voluntary control
Basic unit  muscle fibre with many nuclei
Striated (transverse streaks)
Act independently of neighbouring muscle fibres
2. Smooth Muscle
• Walls of hollow internal organs (i.e. blood vessels,
gastrointerstrial tract, bladder & uterus)
• Involuntary control
• Non-striated (smooth) muscle cells – spindle shaped
• 1 central nuclei
3. Cardiac Muscle
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Only in walls of heart
Involuntary movement
1 central nuclei
Striated
Rectangular in shape
Types of Muscle Contraction
1. Concentric
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Muscle fibres shorten
2. Eccentric
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Muscle fibre lengthen
3. Isometric
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Muscle fibres do not
change in length
Contraction During Exercise
• Isotonic Exercise
– Controlled shortening & lengthening of muscles
– i.e. Chin-ups, push-ups & sit-ups
• Isometric Exercise
– Constant length throughout contraction
– No motion
– Against an immovable surface or object
• Isokinetic Exercise
– Involve machines to control speed of contractions
with range of a muscle’s motion
Isotonic Contraction
Isometric Contraction
Anatomy of a Skeletal Muscle
• Epimysium - outermost layer, surrounds entire muscle
• Perimysium - separated and surrounds the fascicles
(bundles) of muscle fibres
• Endomysium - surrounds each individual muscle fibre
– Beneath endomysium lies plasma membrane
(sarcolemma)
– contains muscle cell’s cytoplasm (sarcoplasm)
• Each fibre contains:
– Contractile machinery & cell organelles
– Each fibre has capillaries that supply nutrients &
eliminates waste
Anatomy of a Skeletal Muscle
• Bundles of Muscle fibres  Muscle Fibre 
Myofibrils  Myofilaments
• 2 types of myofilaments
1. Actin – thin filaments
2. Myosin – thick filaments