Ch. 5

What do you know about your skin?:What is the branch of medicine that

specializes in skin disorders?Dermatology

• About what percent of body weight does the skin make up?

15-20 percentWhat is the skin most susceptible to?

infection, disease, injury

Ravaged

Scarred

But Repairable!

What is skin?Its an organMade of cutaneous membrane. Superficial

epidermis made of stratified squamous epithelium and dense connective tissue.

Length of replacement? Youth: 28-30 days, Elderly 45-50 days

Is skin the same thing as the integumentary system?No.Skin is a cutaneous membraneIntegumentary system includes sweat and oil

glands, hair, and nails. Integument= covering

What is the jobs of the skin?Pg. 95

Regulates heat loss.Excretory functions for urea, salts, and

water. Water RetentionManufactures proteinsSynthesizes vitamin DIntegrate with the nervous system for

touch sensation

What are the three layers of the skin?*

What is the job of the epidermis?

Keratinizes: becomes hard for protection

Avascular: only the lowest level of the epidermis is close enough to capillaries to gain nutrients. That means: the skin you see is all dead! Shedding skin doesn’t hurt!!!

Contains Melanin: pigment produced by melanocytes.

Layers of EpidermisStratum Basale – deepest, only epidermal cells

Stratum Spinosum-make Keratinocytes

Stratum Granulosum-fuse cells together

Stratum Lucidum – only on hands/feet

Stratum Corneum – top layer, filled with keratin

Granulosum

Spinosum

Lucidum

Basale

Corneum

What is the job of the dermis?Its leather. Protective, strong,

living, and houses many other tissues.

Sweat Glands: maintain body temp. Excrete waste.

Hair follicles/bulbs: for warmthNerves: pain, pressure, temperatureBlood vessels: maintain body temp

2 Regions of DermisPapillary layer – contain capillaries for nutrients for epidermispain and touch receptorsRegulates temperature

2 Regions of DermisReticular Layer – deepest skin layerBlood vessels, sweat and oil glands, and deep pressure receptors

Thick collagen strengthens skin

Skin ColorMelanin (yellow, reddish brown, or black)

CaroteneOxygen bound to hemoglobin in dermal blood vesselsPoorly oxygenated blood causes cyanosis in Caucasians

What do Melanocytes do?Produces pigment to protect the cells DNA.

What is an appendage of the skin?Append= to hang onThese are things that “hang on” or are attached to the skin.

Appendages include: Glands, Hair, and Nails

All appendages are part of the epidermis

What is the job of hair and hair follicles?Guards the head and eyes as well as respiratory tract from particles & impact.

Head Hair retains body heat. All other body hair is a vestigial feature.

Hair Follicles grow hair

What are the parts of the hair follicle?Pg. 96

Root of hair is enclosed in the hair follicle (The hair bulb matrix= zone of growth which contains melanin).

Hair grows up the shaft to the surface of the skin.

The bulk of hair is dead. There are 3 layers to hair: 1) Medulla, 2) Cortex, 3) Cuticle (Protection against abrasion, Damage=Split Ends)

What makes hair look different?

The amount of melanin secreted The shape of the hair is regulated by the shape of the hair follicle which changes the shape of the hair shaft.Round Hair (straight shaft)= Straight and Coarse

Oval Hair= Wavy and SmoothCurley Hair (hooked shaft)= Flat

What are the parts of the nail?

Used for protectionThe root of the nail is embedded in the skin. Grows from the nail matrix. The cells heavily keratinized, die.

Extends along the nail bed. Lunula – moon shaped beginning of nail Fig4.7 pg. 102 Lun= moon

What do the cutaneous glands do?Exocrine glands that secrete onto the surface of the skin. Sebaceous & Sweat

Sebaceous Glands- Produce oil all over the body. Sebum used for softening, water retention, killing bacteria. Increases when testosterone is produced= Oily skin.

Sweat Glands- helps maintain homeostasis

What are the two types of sweat glands?Eccrine Glands: Cover Body, Contain H2O, Salt, Vit. C, Wastes, Lactic Acid

pH 4-6: antibacterial

Sweat pores are not easily visible, Contain nerve endings for regulation

And the Other One? Apocrine glands- auxiliary and genital areas. Ducts empty into hair follicles.

Milky-yellowish in color, odorless. Body odor occurs when bacteria eat it. *Thought to be used in excreting pheromones*

Pheromones And Mates

Why do you not have wrinkles when your young?

Collagen fibers: Strong and keep the skin hydrated (attract H2O).

Elastic fibers: Keep skin elastic. Like all elastic, it is less so with time.

Loose fat in the hypodermis. = sagging

Decrease in subcutaneous tissue, causes dryness, cold sensitivity, and bruising in the elderly.

What happens when the epidermis and dermis separate?A blisterCaused by friction or burns.

What causes goose bumps?Smooth muscles called Arrector pili that attach to hair follicles contract.

What is the job of the hypodermis?Anchors the skinShock absorberInsulates from temperature change

Gives shape to fatty areas of the body Fat Lab

Time

Brace Yourself

Problems of the skinBedsores or Decubitus Ulcers- Caused by

pinching off of the blood supply to the skin. Occurs over bony areas of the body. See figure 4.4 on Pg. 98

AlopeciaFancy word for baldingBy age 50, 1/3 of your hair follicles may be

lostSevere alopecia can happen to anyone at any

age and is not thought to be genetic. ALL BODY HAIR is lost!!!

Infections and Allergies of SkinAthlete’s foot (tinea pedis) – fungus

More DiseasesBoils and carbuncles – inflammation of hair follicles and sebaceous glands

And another DiseaseCold sores – herpes simplex virus – activated by emotional upset, fever or UV radiation

Infections and Allergies of SkinContact Dermatitis – itching, redness, and swelling caused by exposure to chemicals (poison ivy)

Still more DiseaseImpetigo – pink, water-filled, raised lesions that develop a yellow crust and rupture – caused by staphylococcus

Infections and Allergies of SkinPsoriasis – chronic condition of reddened epidermal lesions covered with dry scales – triggered by trauma, infection, hormones, stress

VitaligoThree possible causes

Autoimmune attackMalfunctioning nervesSelf destructive cells

Some treatments such as creams are effective in early stages.

Can effect anyone.

What are the problems with smoking and sun on the epidermis?

Leathery skinCold sore (herpes outbreak)Depressed immune systemAll from DNA damage.

Review Burns and Skin CancerWhat are the ABCD’s of Skin Cancer?What are the 3deg. Of Burn?

Skin Cancer

LinkBurns

Skin CancerSquamous Cell Basal Cell

Administering MedicationsTransdermal - skin patches for nicotine, motion sickness, birth control – slow absorption

Subcutaneous – insulin – moderate absorption

Intramuscular – vaccines – rapid absorption

Developmental Aspects5th month – fetus covered with downy hair (lanugo) that is shed by birth

Adolescence – skin and hair become more oily as sebaceous glands are activated (acne)

Developmental AspectsAging – hair thinning and baldness – males

Gray hair – decreasing amount of melanin deposited – caused by anxiety, protein-deficiency, chemotherapy, excessive vitamin A, genetics