The Respiratory Membrane Consists Of
A. Alveolar Epithelium And Terminal Bronchioles Smooth Muscle
B. Alveolar Ducts And Pulmonary Capillaries
C. Alveolar Epithelium, Capillary Endothelium, And A Fused Basal Lamina
D. Capillary Endothelium, Alveolar Ducts, And A Fused Basal Lamina
The correct answer and explanation is :
The correct answer is C. Alveolar Epithelium, Capillary Endothelium, And A Fused Basal Lamina.
Explanation:
The respiratory membrane is the thin barrier that separates the air in the alveoli (the tiny air sacs in the lungs) from the blood in the pulmonary capillaries. This structure plays a critical role in gas exchange, allowing oxygen to move from the alveoli into the blood and carbon dioxide to move in the opposite direction.
The respiratory membrane consists of the following key components:
- Alveolar Epithelium: This is the inner lining of the alveoli. It is made up of a single layer of epithelial cells, predominantly type I alveolar cells (pneumocytes), which are very thin to facilitate efficient gas exchange. There are also type II alveolar cells, which secrete surfactant to reduce surface tension and prevent alveolar collapse.
- Capillary Endothelium: This is the thin lining of the blood vessels (capillaries) that surround the alveoli. The endothelial cells are extremely thin, which also aids in the efficient exchange of gases (oxygen and carbon dioxide).
- Fused Basal Lamina: Between the alveolar epithelium and capillary endothelium is the basal lamina, which is a thin extracellular matrix layer. In the respiratory membrane, the basal laminae of the alveolar epithelium and capillary endothelium are fused together, creating an extremely thin structure that facilitates rapid diffusion of gases.
These components together form the respiratory membrane, which is essential for the exchange of gases between the lungs and the bloodstream. The combined thinness of the alveolar epithelium, capillary endothelium, and fused basal lamina allows gases to diffuse across the membrane efficiently. This enables the body to take in oxygen and remove carbon dioxide during breathing.
In contrast, the other options do not describe the correct structure of the respiratory membrane. For instance, terminal bronchioles, pulmonary capillaries, and alveolar ducts are not directly involved in the respiratory membrane’s function.