Which surface of an epithelial cell lies closest to its blood supply

Basal surface is the surface of epithelial cell lies closest to its blood supply.

There are three surfaces in the epithelial cell.

1. apical

2. lateral

3. basal

1. Apical surface :  This is the surface which faces towards the cell and it is the exposed layer.

2. Lateral surface : This is the surface which is in between the adjacent cells.  

3. Basal surface :  It is divided into two lamina : Basal and Reticulate.

Basal lamina is made up of glycoproteins and collagen, this lamina remains separated from underlying connective tissue. Basal lamina is in attachment with Reticulate lamina.  Reticulate lamina is in contact with underlying connective tissues this arrangement forms a basal membrane for linking the epithelial surface with connective tissue layer or region of blood supply.

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.