John Jay College for Criminal Justice defines tissue as “a collection of similar cells that group together to perform a specialized function.” Human tissue is generally divided into four groups: epithelial, connective, muscle, and nerve. However, the body is a system, and although human tissue is divided into categories based on its characteristics and functions, the different types of tissue commonly work together.
Epithelial human tissue is composed of tightly packed multi-sided cells that act as protection for the body’s interior and exterior. Some types of human tissue are wholly internal. However, one of the most recognizable epithelial tissues is a person’s outer layer of skin. Epithelial tissue also acts as lining, such as that found inside the mouth, lungs, and stomach.
This type of tissue is commonly referred to as protective tissue. In addition to covering the human body and lining various organs, epithelial tissue helps separate organs and keeps them in the right position. It makes up the endocrine system, which is responsible for the production of hormones, and the exocrine system, which is responsible for releasing items from the body such as sweat.
Connective tissue is used for structure and to support the body. This type of tissue contains both living elements, such as cells, and non-living elements, such as salts and gases. This category of human tissue includes body parts such as tendons, bones, and ligaments. Blood is also considered a connective tissue. This is partly because one of the primary roles of blood is transporting nutrients and other items throughout the body.
This tissue group is often noted for its fibrous characteristics. One of the most common fibers is collagen, which among other things adds strength to the tissue. This group of human tissue also provides a degree of protection by occupying space that would otherwise be void between organs and tissues.
Muscle tissue is the group to which humans’ muscles belong. This tissue group is generally characterized by its ability to contract. It is credited for allowing movement. This movement is not simply limited to the limbs and joints. Muscle tissue also allows food and blood to be transported throughout the body. This human tissue group is commonly divided into three subcategories: smooth muscle, cardiac muscle, and skeletal muscle.
Nerve tissue is used to control the human body. There are three primary components of this tissue group: the brain, nerves, and spinal cord. These three components work together because the nerves can generate and conduct electrical signals. The spinal cord acts as a route for the nerves to travel so electrical messages can flow to and from the brain, which is the control center of the body.