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 per 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 Function 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

Hair Produced by hair bulb Consists of hard keratinized epithelial cells Melanocytes provide pigment for hair color Figure 4.7c

Hair Anatomy Central medulla Cortex surrounds medulla Cuticle on outside of cortex Most heavily keratinized Figure 4.7b

Associated Hair Structures Hair follicle Dermal and epidermal sheath surround hair root Arrector pilli Smooth muscle Sebaceous gland Sweat gland Figure 4.7a

Nails Appendages of the Skin 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