Functions of the Skin

-Protection

-regulation of body temp

-excretion

-synthesis of Vitamin D

-Houses sensory receptors

Layers of the Skin

-epidermis

-dermis

-hypodermis (or subcutaneous tissue)

Epidermis

Dermis

Hypodermis or subcutaneous tissue

The layer of tissue under the skin

-composed of mainly adipose tissue

Hypodermis functions

-anchoring the skin to underlying organs

-shock absorption

-provides insulation

Facts about the Epidermis

1. made out of layers called strata

2. made of stratified squamous epithelium and lacks blood vessels

What happens to older cells in the epidermis?

what is Melanin and where is it located.

Located in the Epidermis.

It is a pigment produced by special cells in the epidermis, it gives color to the skin.

What is the function of Melanin

What is the Dermis Composed of

dense connective tissue

collagen fibers

elastic fibers

What do the collagen fibers in the Dermis cause

for the dermis to be tough

What do the elastic fibers in the dermis cause

giving the skin its ability to stretch and recoil

(elasticity)

Blood vessels

muscle fibers

sweat and oil glands

hair

receptors

3 pigments of the skin and their color

Melanin- brown/black

carotene-orange/yellow

hemoglobin-red

What are the accessory organs of the skin

(appendages)

Hair

Nails

Glands

-sebaceous glands

-Sweat glands

What does each hair develop from

Hair shaft

What is hair color determined by

arrector pili

Nails

-modification of the epidermis, dead material composed of mainly keratin

-they protect the ends of fingers and toes

3 types of Glands in the integumentary

Sebaceous

Sudoriferous

and

Ceruminous

Sebaceous glands

-exocrine glands the produce sebum

-ducts usually empty into a hair follicle

Sebum

Sebum function

Sudoriferous Glands

Sweat glands

2 types are--

Apocrine

Eccrine

Apocrine glands

-empty secretion into hair follicle

-located in axillary and genital regions

-active at puberty

-milky sweat due to proteins and fats

-odorless

--body odor is due to bacterial decomposition

-function is unknown

Eccrine glands

-Occur all over the body

-secrete sweat onto skin surface directly

-Cleary, watery perspiration

-activated with increase in body temp.

-Functions to cool the body

Ceruminous glands

-produce cerumen

-found in external auditory canal (ear)

-keeps foreign particles and insects out of auditory canal

Normal body temperature

Varies around 98.6

-Brain increases flow of blood to the skin so heat can be lost by radiation

-also increases perspiration

What happens if body temp is too low?

-Brain reduces blood flow to skin and diverts blood to internal organs

-slows perspiration

-starts shivering to generate heat

Effects of Skin aging

-wrinkles

-drying of skin, hair and nails

-thinning of skin, hair and nails

-loss of skin elasticity

-graying of hair

-uneven pigmentation

Acne

Infectious

chronic skin disorder characterized by plugged hair follicles that often form pimples due to infection by certain bacteria

Athletes Foot

Infectious

slightly contagious infection that is caused by a fungus growing on the skin, especially between and under the toes, where moisture persists

Boils

Infectious

acute, painful staphylococcus infections of hair follicles and their sebaceous glands as well as the surrounding dermis and subcutaneous tissue

fever blisters

Infectious

cold sores, are clusters of luid filled vesicles that occur on the lips or oral membranes, they are caused by a herpes simplex virus and are transmitted by oral or respiratory exposure

Impetigo

Infectious

highly contagious skin infection caused by bacteria, it typically occurs in children and is characterized by a fluid filled pustules that rupture, forming yellow crust over the infected area.

Warts

Infectious

small skin tumors that have a normal skin color, caused by a virus infection that stimulates excessive growth of epithelial cells

Alopecia

Noninfectious

loss of hair, most common in males who have inherited male pattern baldness, but it may result from noninherited causes such as poor nutrition, sensitivity to drugs and eczema

Bedsores

Noninfectious

result from a chronic deficiency of blood circulation in the dermis and subcutaneous layers. Bedsores form over bones that are subjected to prolonged pressure against a bed or cast.

Blisters

noninfectious

fluid filled pockets form when an abrasion, burn or injury cases the epidermis to separate from the underlying dermis

Burns

Noninfectious

damage to the skin caused by heat, chemicals or radiation

1st degree- involes only the epidermis

2nd degree- produces damage to the epidermis and the outer portion of the dermis.

3rd degree- destroys the epidermis, dermis glands, hair follicles and nerve endings

Calluses and corns

Noninfectious

thickend areas of skin that result from chronic pressure

Cancers

Noninfectious

result from excessive cell divsion by cells that have lost control of the process

Dandruff

Noninfectious

excessive shedding of dead epidermal cells from the scalp as a result of excessive cell production

Eczema

Noninfectious

inflammation producing redness, itching, scaling, and sometimes cracking of the skin

Hives

Noninfectious

red, itchy bumps or wheals that usually result from an allergic reaction to certain foods, drugs or pollens

Moles

Noninfectious

slow growing skin tumors that are usally brown or black in color

Psoriasis

Noninfectious

chronic dermatitis that is charcterized by reddish, raised patches of skin that are covered with whitish scales

conelike projections of the dermis that fit into recesses of the epidermis

possess blood vessels and touch receptors

form fingerprints and toe prints

Hypodermis function

attaches skin to underlying tissues and organs

site for subcutaneous injections

site of white blood cell action

Heat insulator

Fat Storage

Conserve body heat and retards penetration of external heat

2 Parts of Hair

Shaft and Root

Structure of the Nail

Body

Root

Lunula