Animal Tissues

Groups of cells with a common structure and function make up tissues , and different tissues make up organs which together make up organ systems.

Anumal tissues are classified into four main categories:

Epithelial tissue covers the outside of the body and lines organs and cavities within the body; the cells are closely joined.
Connective tissue bind and support other tissues, and contains sparsely packed cells scattered throughout an extracellular matrix.
Nervous tissue senses stimuli and transmits signals throughout the animal.
Muscle tissue is composed of long cells called muscle fibers capable of contracting in response to nerve signals. Humans have three types of muscle tissue.
- Skeletal muscle are attached to bones , have striated . unbranched fibers, and are involved in voluntary movement of the body.
- Cardiac muscle are located in the heart , have striated , branched fibers, and are involved in contraction of the heart.
- Smooth muscle are located in the digestive tract, arteries, and bladder , have unstriated , spindle-shaped cells, and are involved in contraction of internal organs other than the heart.