Question

System

•Two phases of breathing:

•__________: the process of taking in air

•__________: the process of blowing out air

fill in blanks

Answer 1

The two phases of breathing are:

• Inhalation or inspiration: the process of taking in air.

Explanation: The process by which atmospheric gases enters lungs is called inhalation or inspiration. It is hence, the simple process of breathing in. It is a vital part of breathing mechanisms in all aerobic organisms. In humans, inhalation of air allows oxygen to enter the lungs and subsequently the blood stream.

In human, inhalation of air starts with the contraction of internal intercostal muscles (muscles associated with rib cage) and contraction of the diaphragm. This processes expands the lung, and increases its volume. Consequently, the pressure in the lung decreases. Thus, atmospheric air rushes in the alveoli of the lungs through the external and internal nares, pharynx and trachea. This is how air is taken in the lungs via inhalation or the process of inspiration.

• Exhalation or expiration: the process of blowing out air.

Explanation: The process by which the air from the lungs moves out of the body through the airways in to the external atmosphere is called exhalation or expiration. It is the simple process of breathing out. By this process excess carbon dioxide produced in the body as a result of cellular respiration is removed from the bloodstream and subsequently out of the body.

In human, exhalation of air starts with the relaxation of internal intercostal muscles and diaphragm. Relaxation of these muscles causes the decrease in volume of the lung. As a result, the pressure inside the lung increases and the excess air rushes out of the lung through the airways. Thus, the process of blowing out air from the body occurs via exhalation or the process of expiration.