4.11

melanin

Freckles are red or brown patches where melanin has accumulated in the skin.Repeated exposure to ultraviolet light stimulates melanocytes to release melanin, resulting in a tanned appearance. Age spots are accumulations of melanin in patches that do not fade in winter.A nevus is a benign overgrowth of melanocytes in a localized area.

This epidermal cell has a role in immunity and disease resistance.

Langerhans cells

exposure to ultraviolet (UV) light

Precursors to calcitriol are produced in the skin by UV light. Melanocytes are stimulated by UV light to produce more melanin, giving the skin a tanned appearance.Melanin provides protection for the DNA in the epidermal keratinocytes by absorbing UV light. Too much exposure to UV light can lead to skin cancer, and melanocytes are particularly susceptible to damage from UV light.

skin

Skin and its derivatives function in protection. Skin can serve as a sensory structure. Skin aids in the synthesis of Vitamin D. Skin aids in body temperature homeostasis.

carotene

The dermis and stratum corneum accumulate a yellow-orange pigment when you eat foods, such as egg yolk and carrots, that are rich in

arrector pili

The muscle associated with a hair follicle that causes the hair to stand on end when contracted is called the

apocrine glands

They have excretory ducts that open into hair follicles.They are found mainly in the groin and axillary regions.They are stimulated during emotional stress and sexual excitement. They do not function until puberty.

sebum

a mixture of triglycerides, cholesterol, proteins and inorganic salts.

Body odor begins to appear at puberty. This is due to

bacterial breakdown of the secretions of the apocrine sweat glands that become active at puberty

glands produces a waxy secretion that slows the entrance of foreign material into the external auditory canal and prevents microbes from entering cells?

ceruminous glands

Light-skinned people have a translucent epidermis that ranges in color from pink to red depending on the amount of oxygen being carried by ______, a pigment in red blood cells.

hemoglobin

excreted from the skin in sweat

lactic acid, salts, urea, water

What is the name of the pigment that absorbs ultraviolet light?

melanin

This structure acts to prevent water loss as well as inhibiting bacterial growth on the surface of the skin.

sebaceous glands

Constant exposure of skin to friction, a mechanical stress, stimulates the formation of a callus. Which one of these layers is thickened in a callus?

stratum corneum

plays an important role in thermoregulation?

sweat gland

The skin is often referred to as a blood reservoir. This is because the vessels in the dermis carry ___% of total blood flow in a resting adult.

10

vitamin D

Approximately 15 minutes of exposure to ultraviolet light every 3 days is all the exposure the body requires for vitamin D synthesis.he liver and kidneys have enzymes to produce calcitriol, the most active form of vitamin D Ultraviolet light in the skin produces an activated molecule that is a precursor to the most active form of vitamin D.Calcitriol is a hormone that increases the absorption of calcium in the digestive system.