Muscle tissue

Muscle tissue

Muscle tissues are highly specialized tissues which contract to produce movement. Because muscle cells are elongated to provide a long axis for contraction, they are called muscle fibers. There are three types of muscle tissue known as skeletal muscle, cardiac muscle, and smooth muscle.

Figure 7 shows what the different muscle tissue types look like:

Figure 7

Skeletal muscle

Skeletal muscle cells are packaged by connective tissue into organs called skeletal muscles. Skeletal muscles can be consciously controlled, and are thus known as voluntary muscles.

When skeletal muscles contract, they pull on the bones or skin. Gross body movements and changes in facial expression are the result of skeletal muscle contractions.

The cells of skeletal muscles are long and cylindrical, with obvious stripes called striations.

Cardiac muscle

Cardiac muscle is only found in the heart. As it contracts, the heart pumps and forces blood through the blood vessels. Like skeletal muscle, cardiac muscle has striations.

Cardiac muscle is not controlled consciously, and is therefore known as involuntary muscle.