Chapter 4 - Muscle Tissue
Muscle tissue is composed of cells that maintain the contractile function of connective tissue. Three types of muscle tissue are recognized based on their structure, function, and location:
- Skeletal muscle cells - striated, voluntary control
- Cardiac muscle cells - striated, involuntary control
- Smooth muscle cells - nonstriated, involuntary control
In all types of muscle, contraction is caused by the movement of myosin filaments along actin filaments .
The terms muscle fiber and muscle cell are synonymous.
Skeletal Muscle
Skeletal muscle fibers , also known as myofibers, are long, cylindrical cells that are quite large, often spanning the entire length of a muscle.
A sarcomere is the fundamental contractile unit of striated muscle fibers.
Cardiac Muscle
Cardiac muscle cells has branching fibers, a single, centrally located nucleus, show the same striations as skeletal muscle, and are under involuntary control.
Cardiac muscle cells are joined by specialized structures known as intercalated discs . These discs are unique to cardiac tissue and help maintain strong mechanical connections and pass electrical impulses between cells.
Smooth Muscle
Smooth muscle cells are spindle-shaped (fusiform), have a single, centrally located nucleus, lack striations, and are under involuntary control.
