Give suitable explanations for the following :
(a) Breathing through the nose is said to be healthier than through the mouth.
(b) Why does gaseous exchange continue in the lungs even during expiration?
(c) Why does a person feel breathlessness at higher altitudes?
(d) Why do you shiver and why do your teeth chatter when it is very cold in winter?
(a) Breathing through the nose is said to be healthier than through the mouth because the hair present in the nostrils prevent large dust particles from entering inside the respiratory system.
(b) Gaseous exchange continues in the lungs even during expiration because expiration is the result of reverse movements of the ribs and diaphragm. As a consequence of the movements of the ribs and the diaphragm, the thoracic cavity is diminished and the lungs are compressed, forcing the air out into the atmosphere.
(c) At higher altitudes, the oxygen content of the air is low. So, a person feels breathlessness at higher altitudes.
(d) In order to maintain the body temperature constant in very cold conditions in winter, heat production is increased by enhanced metabolic rate and increased muscular activity. Shivering and chattering of teeth involves a lot of muscular activity. That is why we shiver and our teeth chatter in winter in order to increase heat production in the body.
