The integumentary system forms the body's outer protective layer. It consists of the skin, hair, and nails. The digestive system includes the tube running from the mouth through the trunk and several accessory organs. In this system, food is broken down into essential nutrients, nutrients are absorbed, and solid wastes are eliminated. The circulation system transports nutrients, gases, and chemicals to all prats of the body.
Blood is circulated through blood vessels by pumping action of the heart.
The lymphatic system, part of the circulatory systems, collects fluid from tissue and returns it to the blood. Both sytems also fight disease. The respiratory system takes oxygen into the body and eliminates carbon dioxide and water. The excretoty system removes cellular wastes from the blood. Waste leaves the body through the urinary system, a part of the excretory system.