Skin Color

• Due to:1. Pigment composition (melanin, carotene, and

hemoglobin) and concentration (how much)2. Dermal blood supply

• Skin Color:– Skin comes in different colors!! – Distribution of skin color is not random!– Darker skinned people live near the equator (need

more protection from the sun)– Lighter skinned people live near the poles

Skin Color - Pigments

• Melanin– Color Yellow reddish brown black– No matter how dark or light skinned a person is,

they have about the same number of melanocytes!!

Albinism• Mutant gene that makes melanin is inherited

•

Vitiligo

•

Jaundice• Most often seen in newborns

• Caused by blood incompatibility or immature liver

•

• Cured by: •

Skin Color - Pigments• Carotene = Orange-yellow pigment• Located: • 1)• 2)• 3)

• Can be converted to vitamin A– Required for:• Normal maintenance of epithelia• Synthesis of photoreceptor for pigments in the eye

Skin Color – Pigments• Blood contains pigment hemoglobin– Binds and transports oxygen– When oxygen is bound – When oxygen isn’t bound

• Most apparent in lightly pigmented individuals– Lots of blood flow (inflammation) bright red– When circulation is reduced pale– Sustained reduction in circulation very dark red (blue/purple)– Because Caucasian skin contains only small amounts

of melanin, the epidermis is nearly transparent and allows hemoglobin’s color to show through

Epidermis and Vitamin D3

• Limited sun exposure is very beneficial!!

• Epidermal cells exposed to UV radiation– Vitamin D3 is converted into calcitriol which is

necessary for calcium and phosphorus absorption in the small intestine.

– An inadequate supply of calcitriol leads to impaired bone maintenance and growth.

The Hypodermis• Aka. Subcutaneous or superficial fascia• Composed of Adipose• Not really a part of the integument, but it is

important in stabilizing the position of the skin in relation to underlying tissue

• Reduces heat loss, acts as an energy reserve, shock absorber

• Men accumulate – neck, arms, lower back, stomach, and butt

• Women accumulate – breasts, butt, hips, and thighs.

Integument Appendages

• Sweat glands– Sudoriferous glands

• Oil glands– Sebaceous glands

• Hair• Nails

Sweat Glands - Sudoriferous• APOCRINE• Located axillary and groin regions• Ducts are larger than eccrine• Ducts empty into hair follicles• Is thicker than regular sweat – also

contains fat• Secretion odorless bacteria

decomposes the fat odor• Start to function at puberty• No role in temperature regulation

Sweat Glands - Ceruminous

• Modified sweat gland• Makes cerumen • Ear wax• Function– Traps foreign particles or small insects and keeps

them from reaching the eardrum

Sebaceous Glands (OIL)• Found everywhere except on

palms of hands and soles of feet.

• Large on face, neck, and upper chest

• Small everywhere else• Secretes sebum– lubricates the hair and skin– Prevents hair from becoming

brittle– Slows water loss– Bactericidal action

Hair• Seen almost everywhere on the body

• About 5 million!• Made up of hard keratin– Tougher and more durable– Individual cells don’t flake

Hair - Types• Vellus– “peach fuzz”– Short, fine, lightly colored– Located over much of the

body• Terminal– Thick, long, more deeply

pigmented, sometimes curly

– Located on head, eyebrows, and eyelashes, arm pits, groin