The circulatory system is a network of blood vessels that transport blood throughout the body. Blood is pumped by the heart through arteries, which carry oxygenated blood away from the heart to the rest of the body. Blood then returns to the heart through veins, which carry deoxygenated blood back to the heart.
The lymphatic system is a network of vessels that transport lymph, a clear fluid that contains white blood cells. Lymph is collected from tissues and organs and returned to the bloodstream.
The respiratory system is a network of airways that transport air into and out of the lungs. Oxygen is absorbed from the air into the bloodstream, and carbon dioxide is removed from the bloodstream into the air.
The digestive system is a network of organs that break down food and absorb nutrients from food. Nutrients are absorbed into the bloodstream and transported throughout the body.
