Objective 48 & 49: Inhalation and exhalation

Objective 48: Delineate the role of muscles and lung elasticity in inhalation and exhalation

Objective 49: Contrast inspiration and exhalation

I never actually put too much thought into inhalation and exhalation. I knew that we had to breathe in oxygen to survive, and breathe out carbon dioxide to keep us healthy but I never really understood how hard the lungs really work. The textbook and chapter outline slides really helped me out when it came to trying to understand the differences between inspiration and exhalation, and the roles that muscles and lung elasticity play. I included bits and pieces of texts from chapter 21 pages 716-718 that aided me in understanding these topics better. The chart on page 717 was also helpful in understanding the sequence of events during inspiration and expiration. During inspiration, inspiratory muscles contract which causes the diaphragm to fall and the rib cages to rise. While the thoracic cavity volume increases, the lungs stretch and intrapulmonary volume increases. The pressure then drops, and air flows into the lungs down its pressure gradient until the intrapulmonary pressure is 0. During expiration, the inspiratory muscles relax and causes the thoracic cavity volume to decrease. The elastic lungs recoil passively and intrapulmonary volume decreases. This causes intrapulmonary pressure to rise and cause air to flow out of the lungs down its pressure gradient until intrapulmonary pressure is 0. So, all in all, this photo was exactly what i needed to understand these two objectives.

                                            (Inspiration)

This simple, yet detailed photo was helpful in informing me about the differences of inspiration and expiration.

I also found this video that actually showed the lungs during inhalation and exhalation. It shows the side and front view, and shows how the diaphragm contracts during inhalation and relaxes during exhalation. Being able to view an animation of the lungs and diaphragm during this process gave me an even greater understanding of the two process of breathing.