Explanation: The immune system is the body's defense against infectious organisms and other invaders. Through a series of steps called the immune response, the immune system attacks organisms and substances that invade body systems and cause disease. The immune system is made up of a network of cells, tissues, and organs that work together to protect the body.
The concave disc shape of red blood cells Maximizes the surface area of the cell , allowing for rapid movement of oxygen or carbon dioxide to and form the hemoglobin within the cell.
