Muscles
Functions
All body movementsMoves bonesPumps bloodMove food through digestive systemAir movement
Types of Muscle Tissue
1) Skeletal MusclesResponsible for voluntary
movementsSkeletal movementsStriated (alternating light and dark
bands)
Skeletal Muscle, cont’d
Muscle Fibers
Myofibrils
Actin (thin filaments)
& Myosin (thick filaments)
Skeletal Muscle
Types of Muscle Tissue
2) Smooth Muscle Involuntary Found in intestines and blood vessels Move food through intestines through
peristalsis
Types of Muscle Tissue
3) Cardiac Muscle Involuntary Striated w/centrally located nuclei Found in Heart Never gets tired
Muscle Contraction
Thin filaments (Actin) in the muscle fiber slide over the thick filaments (Myosin) to contract the muscle
Muscle fibers contracting Cardiac muscle contracting
Cardiac Muscle
How would you characterize this muscle? The nuclei are centrally located, striations are present, and there is branching of the muscle fibers. Several intercalated discs are indicated by the white arrow heads. In Virtual Microscopy, look in the upper left corner of the section to find longitudinally cut fibers.
Skeletal Muscle
How would you characterize this muscle? The nuclei are peripheral, striations are present, and there is no branching of the muscle fibers. Even when you cannot visualize striations, the peripherally placed nuclei allow you to differentiate skeletal muscle from both cardiac and smooth muscle.
Smooth Muscle
How would you characterize this muscle? The nuclei are centrally located, there are no striations, and the muscle fibers do not branch. Another good clue that this is smooth muscle is that when smooth muscle contracts, the nuclei take on a corkscrew appearance.
Muscle Tone
Skeletal muscles remain in a state of partial contraction
Responsible for keeping head upright, and your back and legs straight
Antagonistic Relationship
Skeletal muscles work in opposing pairs When one muscle contracts, the other
relaxes Example of antagonistic relationship: biceps/t
riceps
Interesting Facts
Muscles make up about 40% of a male’s weight and about 35% if you are female
The largest muscle in your body is the gluteus maximus
Muscular strength reaches its peak between the ages of 20 and 30
Cellulite
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