Respiratory System Functions

Respiratory System Functions

The functions of the respiratory system include the intake of oxygen and the removal of CO₂. Cells need oxygen to break down nutrients to release energy and produce adenosine triphosphate. CO₂ results from this process and it must be excreted. The respiratory system includes tubes that filter incoming air while transporting it into and out of the lungs. Gases are exchanged in microscopic air sacs. Respiratory organs entrap incoming air particles, control temperature and water (H₂O) content in the air, produce vocal sounds, regulate blood pH, and are essential for the sense of smell.

Respiration is the process of gas exchange between the atmosphere and cells. Four major events are involved in respiration, with the first two handled by the respiratory system and the last two handled by the cardiovascular or circulatory system:

■■ Movement of air into and out of the lungs called pulmonary ventilation or breathing, involving inward movement or inspiration and outward movement or expiration, in which gases are changed and refreshed continuously.

■■ Gas exchange between air in the lungs and the blood or external respiration; oxygen diffuses from the lungs to the blood, whereas CO2 diffuses from the blood to the lungs.

■■ Gas transport in blood between the lungs and body cells, accomplished by the cardiovascular system, using blood as the transporting fluid; ­oxygen is transported from the lungs to the body’s tissue cells, whereas CO2 is transported from the tissue cells to the lungs.

■■ Gas exchange between the blood and the cells or internal respiration; oxygen diffuses from the blood to the body’s tissue cells, whereas CO2 dif-fuses from the tissue cells to the blood.

All four processes must occur for the respiratory system to obtain oxygen and eliminate CO 2. Both sys-tems are closely linked, and if either fails, the cells of the body die from lack of oxygen. The process of using oxygen and CO2 at the cellular level is called cellular respiration. It is the basis of all chemical reactions in the body that produce energy. Cellular respiration is a circulatory function, not a respiratory function.