Topic 4: Circulatory and Respiratory Systems

CORE CONTENT:

Breathing, gaseous exchange, circulation and respiration

• oxygen is inhaled in a process called breathing

• in the lungs gases are exchanged (gaseous exchange) between the alveoli and the surrounding capillaries by the process of diffusion

• oxygenated blood is transported (circulation) from the lungs to the left side of the heart where it is pumped under high pressure to the body through the arteries [arteries transport oxygenated blood, except for the pulmonary arteries]

• arteries subdivide to form capillaries which are in close contact with the body cells. Here, gaseous exchange occurs and oxygen moves into the cells by the process of diffusion

• in the mitochondria of the cells, oxygen is combined with food in the process of respiration and energy is released for other body processes

• carbon dioxide (by-product of respiration), diffuses from the cells into the capillaries for excretion, and is transported (circulation) in the blood to the right side of the heart by veins [veins transport deoxygenated blood, except for the pulmonary veins]

• the heart pumps the deoxygenated blood (contains carbon dioxide), to the lungs where it is, where it diffuses into the air that is exhaled out of the body