Anatomy & Physiology Integumentary #2

Question

Which substance protects the skin against the harmful effects of ultraviolet (UV) radiation due to excessive exposure to the sun?

Answers

  1. Sebum
    • Rationale:

      The sebaceous glands of the integumentary system secrete sebum, an oily substance that helps keep skin from drying out. While sebum protects the skin from infection by bacteria and fungi, it does not play a role in protecting the skin from the harmful effects of UV radiation.

  2. Keratin
    • Rationale:

      Keratin is a protein in the epidermis that forms a protective layer on the outside of the skin that protects against dehydration. Keratin, however, does not protect the skin against the harmful effects of UV radiation.

  3. Melanin
    • Rationale:

      Melanin is a pigment that provides a natural defense mechanism against sunburn. It provides protection against skin damage from the sun’s harmful UV radiation.

  4. Ammonia
    • Rationale:

      Ammonia is a product of nitrogen breakdown of amino acids within the body. Ammonia can be excreted by sweat glands located in the skin; however, it does not play a role in protecting the skin from the harmful effects of UV radiation.

Overview

Melanin, a pigment produced by cells called melanocytes, gives human eyes, hair, and skin their color. In regard to the integumentary system, melanin plays a role in skin protection.

Explanation

Learning Outcomes

Within the skin’s outer (i.e., epidermal) layer are cells that contain the pigment melanin. Melanin protects the skin from the sun’s ultraviolet (UV) radiation. Excessive exposure to UV rays can cause sunburn which, over time, decreases the skin’s elasticity and increases the risk for skin cancer.

Test Taking Tip

Eliminate wrong answers. Consider each answer option and ask yourself, “Does this substance protect the skin from UV radiation?”

Video Rationale