Answer and Explanation:
The cell is a basic functional and structural unit of life. All living organisms are made up of cells. The human body contains approximately 100 trillion cells in our blood, skin, nerves, muscles, bones, and brain. Humans have 200 diverse forms of cells that come in different sizes and shapes. Each cell performs a specific function in the human body. There are four main types of cells: nerve cells, muscle cells, epithelial cells, and connective tissue cells. Nerve cells are specific for communication. These cells send signals from the brain to glands and muscles that control functions. Nerve cells receive sensory information is from the skin, the ears, and the eyes and send this information to the brain. Epithelial cells cover the interior of hollow body organs such as digestive organs or blood vessels. Muscle cells are specific for contraction. The body cannot move without muscles. Connective tissue cells protect against foreign invaders and also provide strength to the body.