INSPIRATION:a)The act of drawing air into the lungs.b)Rib cages move forward and upward.c) Contraction of external intercostals muscles and relaxations and internal intercostals muscles occur.d) Increase in volume of the thoracic cavity.e)Diaphragm contracts and becomes flattened.f)Increase in volume of the thoracic cavity.g) Air pressure in lungs is less than atmospheric pressure.EXPIRATION.a)Expulsion of air from the lungs.b)Rib cages move downward and inward.c)Relaxations of external intercostals muscles and Contraction of internal intercostals muscles occure) Diaphragm relaxes and becomes original dome-shaped.f) The decrease in the volume of the thoracic cavity.g) Air pressure in lungs is higher than atmospheric pressure.