Question

SHORT DISCUSSION QUESTIONS

1. Distinguish between Type I and Type II alveolar cells by explaining the role played by each in the lungs.

2. The alveoli of the lungs have a significant amount of elastic tissue as well as pores in their walls. Explain the specific role of each of these (elastic tissue and pores) in alveoli.

3. Explain Boyle's law then use it to explain why air enters the lungs during inspiration.

Answer 1

1) Type 1 Alveolar cells are the simple squamous epithelium cells which are responsible for forming the thin interface through which gas diffusion occurs into the blood. Type 2 alveolar cells, are precursors of Type 1, and their function is to produce surfactant which maintains the surface tension of the lung, preventing total collapse.

2) The alveoli have both elastic tissue in their walls as well as pores. The presence of Elastic tissues allows the alveoli to stretch, and accommodate a larger volume of air inside them, whereas the pores in the walls increase the transfer of oxygen and carbon dioxide from the pulmonary capillaries.  

3) Boyle's law states that the pressure of a gas is inversely proportional to its volume at a constant temperature. During inspiration, due to diaphragm moving down, and the ribs moving outwards and upwards, the total volume of the Thoracic cavity increases, which leads to decrease in pressure, according to Boyle's law. Thus, this decreased pressure leads to air entry from outside the body into the lungs.