Respiratory System

The lower respiratory tract begins below the pharynx.

Henry’s law states that the amount of gas that will dissolve in water is proportional to its partial pressure. If its pp. increases by 50% (i.e. by 1.5 times), then 50% more gas will dissolve.

Muscular activity would have increased the rate of oxygen consumption and carbon dioxide production by cells. A higher breathing rate is required to take in the needed oxygen and to excrete the produced carbon dioxide. It is increased CO₂ rather than decreased O₂ that stimulates respiratory rate.

Contracting the diaphragm will increase the volume of the chest and lungs above the diaphragm. As volume has increased, the pressure will decrease. Choice C is wrong as the amount of gas has changed (it is not fixed).

As the diaphragm contracts, the lungs expand and their volume increases. All these things are inconsistent with increased air pressure in the lungs.

This is external respiration as it is an exchange that occurs with the atmosphere outside the body.

All these structures form the thin (0.5 μm) respiratory membrane.

Vital capacity = expiratory reserve volume + tidal volume + inspiratory reserve capacity. So VC is the largest (RV is ~1.2 L).

The larynx is the tube that surrounds the vocal apparatus. It consists of the epiglottis, thyroid cartilage and cricoid cartilage and is located at the top of the trachea.

The pleura surrounds each lung. There is an outer (parietal) layer and an inner layer, the visceral pleura.