MEDICAL PHYSIOLOGY

Detailed explanation-1: -Pulmonary ventilation is commonly referred to as breathing. It is the process of air flowing into the lungs during inspiration (inhalation) and out of the lungs during expiration (exhalation). Air flows because of pressure differences between the atmosphere and the gases inside the lungs.

Detailed explanation-2: -Pulmonary ventilation comprises two major steps: inspiration and expiration. Inspiration is the process that causes air to enter the lungs, and expiration is the process that causes air to leave the lungs (Figure 3). A respiratory cycle is one sequence of inspiration and expiration.

Detailed explanation-3: -Exhalation is a passive process because of the elastic properties of the lungs. During forced exhalation, internal intercostal muscles which lower the rib cage and decrease thoracic volume while the abdominal muscles push up on the diaphragm which causes the thoracic cavity to contract.

Detailed explanation-4: -Ventilation is the movement of air into and out of the lungs, and perfusion is the flow of blood in the pulmonary capillaries.