Well Aisha siso... √ during inhalation...ribs r pulled up n diaphragm become straight. volume of chest cavity increases n pressure inside chest cavity decreases..air rushes to the lungs..(lower pressure)√during exhalation ribs come down n diaphragm becomes convex. volume inside chest cavity decreases n pressure inside chest cavity increases. air is forced out of lungs..hope I made u clear..

1.Breathing: The process of breathing involves inhalation and exhalation.#Inhalation: The process in which oxygen rich air is taken in through the nose is called as inhalation. During this process the size of the chest is increased because of the downward movement of diaphragm. This causes the air from the external environment to rush into the lungs, so that it can fill the extra spaces.#Exhalation: In this process the carbon dioxide rich air comes out of the body. This process takes place when the cavity of the chest becomes narrower and there is an upward movement of diaphragm. As a result a pressure gets created inside the lung which causes the air inside the lungs to rush outside as there is lack of space inside. 2.Cellular respiration: When the oxygenated air enters inside our body it goes to the blood stream. This process is involved in the release of energy. The released energy is used for other metabolic activities. In this process carbon dioxide is released as a by-product..is this answer u want ..LUNGS :The lungs are a pair of spongy, air-filled organs located on either side of the chest (thorax). The trachea (windpipe) conducts inhaled air into the lungs through its tubular branches, called bronchi. The bronchi then divide into smaller and smaller branches (bronchioles), finally becoming microscopic.