Answer:
The correct statements are: A and D.
Step-by-step explanation:
a. Both the alveolar wall and capillary wall contribute to the respiratory membrane.
The respiratory membrane is a more or less homogeneous surface composed of a set of structures that gases must cross between the alveolus and the pulmonary capillary. When blood reaches the lungs it has a high CO2 content and a low O2 content. O2 passes by diffusion through the alveolar walls and capillaries into the blood. There it is transported by hemoglobin, which will take it to the cells of the body where, by the same diffusion process, it will pass inside them for later use.
d. The alveoli have a simple squamous epithelium to allow for diffusion of oxygen and carbon dioxide across the respiratory membrane.
The function of the lungs is to carry out the gas exchange with the blood, for this the alveoli are in close contact with the capillaries. The simple flat squamous epithelium lines the alveoli of the lungs, they are flattened and irregular cells in a single cell layer that allow the easy diffusion of water, gases and other substances. In the alveoli there is the passage of oxygen from the air to the blood and the passage of carbon dioxide from the blood to the air.