Bio 4.1 Race and Hypodermis Structure/Accessory

Melanin

• Main pigment responsible for skin color.

• Produced by melanocytes in the stratum basale.

• More melanin → darker skin.

• Less melanin → lighter skin.

• Helps protect the skin from UV radiation.

• Carotene

• Yellow-orange pigment obtained from the diet.

• Stored in the skin and fatty tissues.

• Can give the skin a yellowish or orange tint.

Hemoglobin

• Pigment in red blood cells.

• Blood flow through the dermis can give the skin a pink or reddish color.

• More noticeable in lighter-colored skin.

Hair follicles

• Tube-like structures located in the dermis.

• Surround and support the hair root.

• Produce and hold hair.

• Help protect the skin and provide some insulation.

 Hair

• Made mostly of dead, keratinized cells.

• Helps protect the skin and reduce heat loss.

 Nails

• Plates of hard, keratinized cells.

• Protect the ends of fingers and toes.

• Help with grasping and scratching.

• Sebaceous glands

• Produce sebum (oil).

• Usually empty into hair follicles.

• Lubricate and help protect the skin and hair.

• Sweat glands

• Produce sweat.

• Help regulate body temperature.

• Also help remove small amounts of waste.

• Eccrine (merocrine) sweat glands

• Found throughout most of the body.

• Produce watery sweat for cooling.

• Apocrine sweat glands

• Found mainly in the armpits and groin.

• Become active at puberty.

• Produce a thicker secretion that can contribute to body odor

• Ceruminous glands

• Modified sweat glands found in the external ear canal.

• Produce cerumen (earwax).

• Help protect the ear canal.