Epidermal Variations

Hemoglobin

A red pigment from oxygen that carries oxygen in red blood cells

Function of hemoglobin

It binds oxygen and gives blood a bright red color.

Color of hemoglobin

Bright red

Melanin

A brown/black pigment produced by melanocytes.

Function of melanin

It protects the skin from UV damage and contributes to skin pigmentation.

Colors of melanin

Black, brown, tan, or yellow-brown.

Carotene

A yellow/orange pigment obtained from the diet.

Function of carotene

It serves as a vitamin A supplement, supports vision, immune function, and acts as an antioxidant.

Color of carotene

Yellow-orange

Nevus (mole)

Commonly called a mole; a harmless overgrowth of melanin-forming cells.

What is the risk of a nevus becoming malignant (cancerous) ?

Rarely may become malignant.

Why should a nevus be monitored?

It should be monitored for changes suggesting malignancy.

Freckles

Yellowish or brown spots representing specific areas of increased melanocyte activity.

How do freckles form?

They occur where melanocytes are more active, producing extra pigment in that small area.

Factors affecting freckles

Sun exposure and heredity/genetics.

Effect of sun exposure on freckles

More sunlight causes skin cells to produce more melanin, making freckles darker.

Effect of heredity/genetics on freckles

Genes influence the number and darkness of freckles.

Hemangioma

Skin discoloration caused by a benign blood vessel tumor.

What two types of hemangioma are there?

Capillary and Cavernous hemangiomas

Capillary hemangiomas

Benign small blood vessel tumors that are bright red or purple at birth and often disappear in childhood. They are also called strawberry birthmarks.

Cavernous hemangiomas

Benign tumors made of larger blood vessels in the dermis that can last a lifetime. They are also called port-wine stains.

What are friction ridges?

Folds and valleys of the dermis and epidermis on palms, soles, fingers and toes

What is the structure of skin ridge patterns?

They are complex patterns that consist of arches, whorls and loops of pals, soles, fingers and toes

Function of friction ridges

To increase friction on contact, which improves grip.

How are skin ridge patterns used in identification?

Each individual has a unique pattern of friction ridges, similar to fingerprints, which can be used for personal identification.

Thick skin

Found on palms and soles; contains all 5 strata (including lucidum)

Thin skin

Covers most of the body; contains 4 strata (no lucidum)

Glands of Thick Skin

Sweat glands; no hair follicles or sebaceous glands

Glands of Thin Skin

Sweat glands, hair follicles and sebaceous glands

Thickness of Thick Skin

From 0.4 to 0.6 mm thick

Thickness of Thin Skin

From 0.075 to 0.150 mm thick