Question

Which of the following statements concerning alveoli would be correct?SELECT ALL THAT APPLY!!

a.Pulmonary surfactant of the alveoli is secreted by Type II alveolar cells.

b.When intra-alveolar pressure becomes greater than atmospheric pressure expiration will occur.

c.The walls of the alveoli are very thin and are surrounded by a network of capillaries so that air and blood are separated by only a very thin respiratory membrane.

d.Alveoli are the site of gas exchange in the lungs.e.The wall of the alveoli is composed primarily of simple squamous epithelium.

Answer 1

a.Pulmonary surfactant of the alveoli is secreted by Type II alveolar cells.

b.When intra-alveolar pressure becomes greater than atmospheric pressure expiration will occur.

c.The walls of the alveoli are very thin and are surrounded by a network of capillaries so that air and blood are separated by only a very thin respiratory membrane.

d.Alveoli are the site of gas exchange in the lungs.

e.The wall of the alveoli is composed primarily of simple squamous epithelium.

Explanation: All of the option given are correct.

There two types of alveolar cells in the lung.

Type I alveolar cells line the alveoli and it constitue about 95 % of the total epithelium. They helps in gaseous exchange of the gases.

Type II alveolar cell has two functions :

- They act as stem cell that undergo regeneration to replace injured alveolar epithelium.

- They secrete the surfactant that lines the alveoli and helps to reduce the surface tension.

When intraalveolar pressure increases above atmospheric pressure, expiration occurs while if intraalveolar pressure gets below the atmospheric pressure, inspiration occurs.