Skin Color Determinants Normal Skin Color Determinants Melanin

Skin Color Determinants

Normal Skin Color Determinants • Melanin • Yellow, brown or black pigments • Carotene • Orange-yellow pigment from some vegetables • Hemoglobin • Red coloring from blood cells in dermis capillaries • Oxygen • Content determines the extent of red coloring • The more oxygen, the more red the skin

Skin colors resulting from conditions • Cyanosis • Hemoglobin is poorly oxygenated, and the skin appears blue • Skin becomes cyanotic when a person has difficulty breathing or heart attack • Skin color can indicate emotions or disease • Redness or erythema • Red skin may indicate embarrassment, fever, hypertension, inflammation, or allergy

Skin colors cont’d • Pallor or blanching – looking pale – may be anger, fear, anemia, low blood pressure, or impaired blood flow • Jaundice – yellow cast – shows as a yellow skin tone – indicates liver** disorder in which excess bile pigments are absorbed into the blood • Black and blue marks – bruises – blood has escaped from the circulation and clotted in tissue spaces – also called hematomas**

SKIN APPENDAGES

Appendages of the Skin • Cutaneous glands are all exocrine glands that release their secretion to the skin surface via ducts • 2 groups • Sebaceous (oil) glands • Sweat glands

Sebaceous glands (oil glands) • Found everywhere except palms of hands and soles of the feet • Produce oil or sebum • Lubricant for skin • Kills bacteria • Most with ducts that empty into hair follicles

Sebaceous Glands cont’d • Glands are activated at puberty • Blocked sebum gland’s duct forms a whitehead, a blackhead forms if it oxidizes • Acne is an active infection of the sebaceous glands

Sweat glands • More than 2. 5 million person • Widely distributed in skin • Produce sweat • Two types • Eccrine • Apocrine

Eccrine (Merocrine) glands • Open via duct to pore on skin surface • More numerous and are found all over the body • Help regulate body temperature • If body temperature or external temperature is high, they secrete sweat

Apocrine glands • Ducts empty into hair follicles • Found mainly in the axillary (arm pit) and genital regions • Begin to function in puberty • Function minimally in thermoregulation • Responsible for odor in humans

Sweat and Its Function • Composition • Mostly water • Some metabolic waste • Fatty acids and proteins (apocrine only) • Function • Helps dissipate excess heat • Excretes waste products • Acidic nature inhibits bacteria growth • Odor is from associated bacteria

• Produced by hair bulb • Consists of hard keratinized epithelial cells • Melanocytes provide pigment for hair color Hair Figure 4. 7 c

Hair Anatomy • Central medulla • Cortex surrounds medulla • Cuticle on outside of cortex • Most heavily keratinized Figure 4. 7 b

Associated Hair Structures • Hair follicle • Dermal and epidermal sheath surround hair root • Arrector pilli • Smooth muscle • Sebaceous gland • Sweat gland Figure 4. 7 a

Appendages of the Skin Nails • Scale-like modifications of the epidermis • Heavily keratinized • Stratum basale extends beneath the nail bed • Responsible for growth • Lack of pigment makes them colorless

Nail Structures • • Free edge Body Root of nail Eponychium – proximal nail fold that projects onto the nail body Figure 4. 9