The Integumentary SystemThe Integumentary System

Chapter 5

Integumentary System Includes:Integumentary System Includes:

Skin (cutaneous membrane)Subcutaneous tissue below the skinAccessory Structures

◦Sweat glands◦Sebaceous or oil glands◦Hair◦Nails

Layers Of The SkinLayers Of The SkinEpidermis – outer

◦ composed of stratified squamous epithelium

Dermis – inner anchored to a

subcutaneous layer

• Hypodermis• subcutaneous fat

(adipose) layer –• energy storage

 

EpidermisEpidermis

• Composed of stratified squamous epithelium

• Avascular- as it has no blood supply of its own

• Oxygen and nutrients diffuse from the underlying dermis

Click here to copy the picture“skin, thick trichrome”

And paste it here.

Click here to copy the picture“skin, thin H&E”And paste it here.

First Layer of the EpidermisFirst Layer of the Epidermis

Stratum Basale• Deepest layer of the epidermis (closest to the dermis).

• Consists of a single layer of columnar or cuboidal cells • Renewal - takes about 3 to 4 weeks • Cells here undergo keratinization

• keratin- a tough protein, is deposited within the cell.

• keratin hardens and flattens the cells as they move outward and it waterproofs the skin.

Epidermal LayersEpidermal Layers• Stratum spinosum

• Consists of spiny prickle cells that interlock to support the skin.

• Stratum granulosum

• This thin middle layer, initiates keratinization (production of keratin).

• Stratum lucidum • This thick layer appears only in frequently

used areas such as palms of the hands and soles of the feet.

Final Epithelial LayerFinal Epithelial Layer

Stratum Corneum• Outermost layer • Thick with rows of dead cells.

• These cells contain soft keratin, which keeps the skin elastic and protects underlying cells from drying out.

• Act as barrier against microbe invasion.

Dermis- Dermis- Called "true skin, " is the layer beneath the epidermis. Its major components are:

• collagen (a protein that adds strength)

• reticular fibers (thin protein fibers that add support)

• elastic fibers (a protein that adds flexibility)

Click here to copy and paste the picture“skin, thick van Gieson elastin”

Skin ColorSkin Color Skin color results from the presence of :• Melanin- keeps excessive ultraviolet rays from

burning the skin. Exposure to sunlight causes the skin to produce more melanin, causing suntan, a temporary change in skin color. Melanin-rich cells continually move toward the surface, where they are sloughed.

• Carotene -yellow to orange pigment usually hidden by the effects of melanin. underlying blood reflected through skin.

• Pigmentation is not just under the control of light. Hormones produced by the pituitary and the adrenal glands also affect pigmentation. Diseases of these two endocrine organs often result in changes of pigmentation of the skin.

MelaninMelanin

Click here to copy and paste a picture of The integument showing melanocytes stained blue

Malfunctioning MelanocytesMalfunctioning Melanocytes• Albinism – melanocytes completely fail to

secrete melanin. Hair, skin, and iris are white.

• Freckles and moles are formed when melanin becomes concentrated in local areas.

• Malignant melanoma – a cancerous change in a mole that may metastasize (spread) rapidly and is most difficult to treat. Exposure to sunlight increases risk.

• Vitiligo – loss of pigment in certain areas of the skin producing white patches.

Vitiligo

Other Pigments in SkinOther Pigments in Skin

• Pinkish color – seen in fair-skinned persons because the vascular dermis is visible.

• Cyanosis – blue look to skin due to poorly oxygenated blood

• Blushing – caused by dilation of blood vessels

• Pale by fright – caused by restriction of vessels

Response to DiseaseResponse to Disease

• Jaundice – when bilirubin is deposited in skin because a diseased liver is unable to excrete this pigment

• Skin may appear bronzed due to the deposit of excess melanin when a person’s adrenal gland is functioning poorly.

• A bruise or contusion indicates that blood has escaped from the blood vessels and has clotted under the skin.

• Over eating carotene-rich vegetables such as carrots may cause skin to have a yellow tint.

Accessory Structures of the SkinAccessory Structures of the Skin

◦Hair -Most of the skin is haired although the hair in most areas is short, fine and only lightly pigmented.

◦ Truly hairless -the palms of hands ◦ soles of feet◦ sides of fingers and toes ◦ parts of the external genitalia.

Accessory Structures of the SkinAccessory Structures of the Skin

• The free part of each hair is called the shaft. • The root of each hair is anchored in a tubular

invagination of the epidermis, the hair follicle, extends down into the dermis.

• The hair that you groom daily is actually dead keratinized cells.

• Each has an associated bundle of smooth muscle, the arrector pili muscle. causes your hair stand up on its end.

Accessory Structures of the SkinAccessory Structures of the Skin

                                                  

Hair Color and TextureHair Color and Texture• Hair color is determined by the amount

and type of melanin present.• Melanocytes become less active with

age= Gray hair• Red hair results from a modified type of

melanin that contains iron.

• The shape of the hair shaft determines texture.

Alopecia is the term for hair loss.

Accessory Structures of the SkinAccessory Structures of the Skin

Nails◦Plates of stratified squamous epithelial cells with hard keratin

◦Protect distal ends of phalanges◦Nail growth occurs in the lunula◦Athlete's foot is a fungal infection that

develops in the moist areas between your toes and sometimes on other parts of your foot.

Exocrine GlandsExocrine Glands

• Sweat glands or sudoriferous glands - simple coiled tubular glands., divided into two principal types:

• eccrine and apocrine. • Apocrine glands - found mainly in the skin of the armpits,

anogenital areas and of the areola of the breasts. • They start secreting at puberty.

• Eccrine glands are the most common. • Their secretory portion can be located in the dermis or in the

hypodermis. • Produce sweat, a watery mixture of salts, antibodies and

metabolic wastes. • Sweat prevents overheating of the body & helps regulate body

temperature.

• Ceruminous glands- produce ear wax glands• Mammary glands Produce milk.• are modified apocrine sweat glands.

Physiology of the SkinPhysiology of the Skin• Protection - the epidermis provides a

barrier to fluid loss from the body. • Barrier Function - intact skin prevents

the entry of micro-organisms into the body. laceration - a torn ragged wound

• Antimicrobial proteins - they act by piercing holes in the outer membranes of micro-organisms.

• Resistance to wear and tear - continuous replacement of the outer epidermal cells that wear off.

Continued• Excretion- water, salt, and small amounts of

waste products such as urea.• Vitamin D -can be synthesized in skin exposed

to sunlight ( also be obtained from the diet)• Barrier- to ultraviolet light. The melanocytes

absorb UV radiation. • Skin exposed to sunlight- wrinkled and crease.

• Dried blood and tissue fluid will create a scab.

Cancer• Ultraviolet light causes mutations at

points on a DNA strand.• Three types of skin cancer

corresponding to three major types of skin cells:

• basal cells• squamous cells• melanocytes.• Cancer of melanocytes - malignant

melanoma - is the most lethal variety, but also the least common.

Skin cancer

Sensory The integumentary system is well-

supplied with receptors for touch, pain, temperature, vibration and pressure.

Sensory information is relayed to the central nervous system via sensory nerves

3 types of receptors for touch- Meissner corpuscle, Merkel disk, Krause end bulb.

2 types of receptors for pressure-Pacini corpuscles, and Ruffini endings.

Free nerve endings- sense pain, heat and cold (READ YOUR HANDOUT)

Burns-pg 76 in your textBurns-pg 76 in your text First-degree - red and very sensitive to touch, involve

minimal tissue damage Sun burn is a good example.

Second-degree - affect both the outer-layer (epidermis) and the under lying layer of skin (dermis) causing redness, pain, swelling and blisters.- often affect sweat glands, and hair follicles.

Burns Third-degree- affect the epidermis, dermis and hypodermis, causing charring of skin or a translucent white color. Usually result in extensive scarring.

Fourth degree- involves tissues down to the bone. Chances of survival –not good

Major concern with burns-fluid and heat loss and bacterial infection.

““Rule of nines”Rule of nines” You can estimate the body surface area on an

adult that has been burned by using multiples of 9.

Head = 9% Chest/Abdomen (front) = 18% Upper/mid/low back and buttocks = 18% Each arm = 9% Groin = 1% Each leg = 18% total (front = 9%, back = 9%) Major concern with burns-fluid and heat loss

and bacterial infection.