Question

Lotions applied during winter season moisturize the skin very quickly. What could be the reason for this?

A.The oils in the lotion enter the skin cells by means of phagocytosis.
B.The oils in the lotion enter the skin cells with the help of carrier proteins.
C.The oils in the lotion enter the skin cells by means of facilitated diffusion.
D.The oils in the lotion enter the skin cells by means of simple diffusion.

Answer 1

The right answer is D.

The absorption of molecules at the level of the skin is carried out by passive diffusion for the molecules of low molecular weight (lower than 400 Da), the skin being covered with a lipoprotein film rich in water by its stratum corneum, rendering it little-permeable.

This absorption may be variable according to factors related to the skin such as stratum corneum's thickness, the state of hydration, the presence of cutaneous lesions or individual variations.

External factors may also modulate percutaneous absorption such as contact time, iontophoresis or the presence of specific adjuvants.