... ensures that the correct level of gas exchange is maintained according to the body's demands. These nerve cells send a rhythmic pattern of impulses to the diaphragm and the intercostals, the muscles of respiration. When intense respiratory effort is required, the accessory muscles of respiration are used. The most important is the sternocleidomastoid. Contraction of these muscles in addition to the diaphragm and the intercostals muscles ensures the maximum increase in the capacity of the thoracic cavity. The rhythm is supplemented by stretch receptors situated in the lungs. These stretch receptors inhibit nerve impulses when the lungs are inflated, and stimulate nerve impulses when they are deflated (Fitness Complete, 2002 p3). The Hering- Breuer reflex prevents over inflation of the lungs. Stretch receptors situated in the thoracic wall generate nerve inhibitory impulses when the lungs have inflated. They travel via the vagus nerves to the respiratory centre. Automatic and rhythmic discharge of ...

See this essay or coursework document in full right now