4.2c Video

Melanin

• Primary pigment for skin color and UV protection; deposited in granules in the epidermis; produced by melanocytes in the basal layer.

Melanin Types and Variation

• Types exist: yellow, reddish brown, and black.

• Skin color results from the mix and amount of these melanin types.

UV-Driven Melanin Production

• UV exposure damages skin, triggering melanocytes to upregulate melanin.

• Negative feedback promotes protection; tanning is a visible outcome of this protective response.

Other Pigments Affecting Skin Color

• Keratin-derived color: keratin has an orangish/yellow tint; dietary carotene-rich foods can tint skin.

• Hemoglobin: oxygenated blood near the skin contributes a red tint; increased blood flow (heat, stress, embarrassment) enhances redness; helps with cooling via heat transfer and sweating.

Other Variations in Skin Color and Conditions

• Erythema: redness due to increased blood flow or inflammation.

• Pallor: paleness when blood flow to skin decreases.

• Jaundice: yellowing from bile pigments, often indicating liver issues.

• Bruises/Hematomas: dark blue/black coloration from blood that has leaked outside vessels and clotted.