The blood must keep moving round the body to keep the rate of diffusion high explains why

red blood cells and diffusion.

Explanation:

this process involves red blood cells and diffusion. Red Blood cells (RBCs) are a type of blood cell whose role is to transport oxygen from the lungs to the peripheral tissues of the body. Oxygen diffuses from the alveoli of the lungs in to the RBC's, where it binds to hemoglobin.

Diffusion is a very important process within the human body and is essential to the transport of molecules within a number of organs including the lungs, kidneys, stomach and eyes. The lungs process millions of tiny air sacs that are called alveoli, each of which are in close contact with capillaries.

away from the curb

explanation:

the wheels would then hit the curb if it started to rolling, decreasing the chance of an accident.