Question

Basement membrane is composed of
A. Hyaluronic acid and glycoproteins
B. Only mucopolysaccharides
C. Endodermal cells
D. Epidermal cells

Answer 1

Hint:- The basement membrane is a thin, fibrous, and pliable membrane that is present in a sheet-like pattern in the extracellular matrix. It separates the epithelium (such as skin, respiratory tract, etc.), mesothelium (such as the pleural cavity, pericardial cavity, etc.), and endothelium (such as blood vessels, lymph vessels, etc.) from the underlying layer of connective tissues.

Complete step-by-step solution:-
The basement membrane provides support to cells and tissues and also provides a platform for complex signalling processes. It attaches the epithelium to its connective tissues through cell-matrix adhesion with the help of substrate adhesion molecules. It protects the tissues from invading malignant cells. The basement membrane is also a platform for the development of new blood vessels.
Under an electron microscope, the basement membrane has two layers namely, the basal lamina and the reticular lamina. The connective tissue layer present underneath the epithelial layers attaches to the basal lamina with the help of collagen VII anchoring fibrils and fibrillin microfibrils. These two layers form the basement membrane, which is composed of two major components - hyaluronic acid and glycoproteins, along with some other proteins such as collagen I, II, and III, fibronectin, proteoglycans, elastin, etc.
Thus the correct option is (A) Hyaluronic acid and glycoproteins.

Additional information:- Some diseases are associated with the condition in which the basement membrane does not work properly. The causes of such defects could be genetic, injuries, etc. Some common diseases associated with the basement membrane are Alport syndrome (genetic defect), Goodpasture’s syndrome (an autoimmune disease), etc.

Note:- Some examples of the basement membranes are the basement membrane present in the glomerulus of the kidney, and between the alveoli and pulmonary capillaries present in the lungs where oxygen and carbon dioxide exchange occurs.