2.Describe the process of breathing??
Breathing consists of two phases. The first is inspiration and the second is expiration. During inspiration, the diaphragm and the intercostal muscles contract. The diaphragm moves downwards increasing the volume of the thoracic cavity and the intercostal muscles pull the ribs up expanding the rib cage and further increasing this volume. This increase of volume lowers the air pressure in the alveoli to below atmospheric pressure. Due to air always flowing from a region of high pressure to a region of low pressure, it rushes in through the respiratory tract and into the alveoli. This is called negative pressure breathing, changing the pressure inside the lungs relative to the pressure of the outside atmosphere. In contrast to inspiration, during expiration the diaphragm and the intercostal muscles relax. This returns the thoracic cavity top its original volume, increasing the air pressure in the lungs and forcing the air out.
3.Explain the process of gaseous exchange in the alveoli??
Carbon dioxide and water diffuses out of the body cells and into the blood plasma because the cytoplasm has a higher concentration of carbon dioxide and water compared with the blood. In the lungs, carbon dioxide and water diffuse out of the blood plasma and into the alveolus i.e. from a high to a low concentration. In the same way, oxygen diffuses from the alveolus into the blood and then from the blood into the body cells. In each case, oxygen is passing from a high to a low concentration.
4.Explain the functions of the following parts of the respiratory system?? Larynx: The larynx is a passageway for air between the pharynx and trachea. It filters bacteria, helps in voice production and warms and moistens the air. Cartilage Rings: To prevent the trachea from collapsing inwards when there is no air. Trachea: The trachea is a passageway for air between the larynx and the bronchi. The...