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