Question

The pigment melanin which protects the body from harmful ultraviolet radiation is produced by
A. Dead epidermis
B. Living epidermis
C. Dermis
D. Subcutaneous layer
E. Epithelial

Answer 1

Melanocytes are the cells present deep within the epidermis which produces a pigment called melanin that is responsible for skin color. Exposure of skin to the sun stimulates melanocytes to produce more melanin to protect the skin from the damaging effects of ultraviolet radiation.

Complete answer:
Melanocytes are specialized cells that are capable of producing melanin located in the stratum basale of the skin's epidermis. Melanocytes are present within the middle layer of the eye, the inner ear, bones, and heart. Melanin is a dark pigment that is responsible for skin color. Melanin is first synthesized and contained in special organelles called melanosomes.

When exposed to sunlight these organelles release the melanin to nearby keratinocytes to induce pigmentation. Melanin serves as protection against UV radiation. The process of melanin production is called melanogenesis. This melanogenesis leads to a long-lasting pigmentation, which is in contrast to the pigmentation that originates from the oxidation of already-existing melanin.

The primary role of melanin is to protect the hypodermis from UV damage. This is why the melanocytes are found on the base of the epidermis. As melanin production dictates the skin color the melanogenesis in light-skinned people is much lower compared to dark-skinned people.

Therefore, the correct option is B.

Note: The dead layer of the epidermis refers to the topmost layer of dead keratinocytes which form a very thin layer of the granular cell layer. Melanin is not produced here. Beneath the epidermis is the dermis where ducts of sweat glands, blood vessels, and sebaceous glands are present. This is beneath the epidermis and no melanocytes are present in this layer. The subcutaneous layer is the hypodermis where the glands, muscles, and adipose tissue are present.