physiology of ventilation  it contain Ventilation (V) refers to the flow of air into and out of the alveoli, while perfusion (Q) refers to the flow of blood to alveolar capillaries. Individual alveoli have variable degrees of ventilation and perfusion in different regions of the lungs

how air flow in and out of alveoli when  The diaphragm  which is the main muscle for breathing and dome-shaped wall of muscle does most of the breathing work by expanding and contracting the chest to draw air in and out of your lungs. When the diaphragm contracts, air is pulled into your airway through your nose or mouth.

 What is  physiology of inhalation and exhalation so Inspiration occurs when the diaphragm and the external intercostal muscles contract. Expiration occurs when the diaphragm and the intercostal muscles relax.