Define the Rate and Depth of Breathing
Do you know what the normal rate of breathing in adults is and what are the factors on which it depends? Well, the normal rate of respiration in adults is 14 - 18 per minute. The rate and depth of breathing vary depending upon the health, physical activity and emotional state of the individual. The amount of air which enters or leaves the lungs varies in association with the changes in the depth of respiration.
In normal breathing, the intercostal muscles and the diaphragm are involved, but in deep breathing, accessoly muscles of respiration are involved. These muscles include sterno- mastoid, the pectoral is major (a skeletal muscle that adducts and rotates the arm) and the platysma (either of the two broad muscles located on the either side of the neck and innervated by the facial nerve, it extends from the lower jaw to clavicle and is involved in the movement of the mouth and jaw). Contraction of these muscles increases the capacity of the thoracic cavity. In this section, we have learnt about the mechanics of respiration. We have seen how the air passes in and then exhaled out. During this process, there is volume of air in the lungs, what we call pulmonary volumes.