Integumentary System

• This body system connects to the other systems in many ways!! See handout pg 45.

• This system consists of the skin and its accessory organs, hair, nails, and cutaneous glands.

Functions of the Integumentary System

1. Resistance to trauma and infection(epidermal cells have lots of KERATIN (protein) strong!

2. Barrier to liquids3. Vitamin D synthesis4. Sensation5.Thermoregulation6. Social functions

Layers of the skinEpidermis: is the top five layers of skin, and contains five different types of cells1A. Dead cells (keratinocytes)1B. Living Keratinocytes :most of the epidermal cells, they produce keratin and use UV light to convert a steroid to pre-vitamin D Stratum Corneum2. Dendritic cells (Langerhans cells): microphages that fight toxins, microbes, and other pathogens that penetrate the skin, (Immune alarm) Stratum Spinosum

3. Tactile cells (Merkel cells) are receptors for touch Stratum Basale

4. Stem Cells: they go through mitosis to produce keratinocytes Stratum Basale5. Melanocytes : produce melanin that reacts to sun light to increase sun burn protection Stratum Basale•See table 6.1 on page 194

2nd layer of skin: Dermis

• Dermis: lies below epidermis, has large amounts of fibrous connective tissue.

• Composed mainly of collagen, elastic, and reticular fibers.

• The connective tissue in this layer contains: blood vessels, sweat glands, hair follicles, nail roots, sebaceous glands, smooth muscles,(Piloerector), pressure receptors and nerve endings

•

3rd Layer of the Skin: Hypodermis

• The hypodermis is often called the superficial fascia

• The fascia contains large amounts of adipose • ( subcutaneous fat), connective tissue, blood

vessels• Adipose tissue pads the body, is a thermal

insulation and energy store and is the preferred injection site due to it vascular rate

• Connective tissue binds the skin to the underlying tissues

Skin Color• Skin color is determined by amount of • melanin produced by melanocytes.• There are basically 2 colors:• Eumelanin= Brown Black• Pheomelanin= Red/Yellow (sulfur containing)

• Other factors are hemoglobin (red/pink hues) and • carotene (yellow/orange…in veggies)

Skin Color : can indicate disease or disorders

• 1. Cyanosis—blueness due to O2 deficiency• 2. Erythem—abnormal redness, blush, sunburn• 3. Pallor---- ash, pale, too little blood flow, dermal

collagen shows through• 4. Albanism—lack of melanin..genetic recessive• 5. Jaundice– yellowing of skin due to high levels of

billirubin, hemoglobin break down product• 6. Bronzing—golden brown, Addison Disease, lack of

glucocorticoid hormone.• 7. Hematoma—bruising, purplish, clotted blood showing

through.

Types of Skin Markings

• Friction Ridges: markings on fingertips, form during fetal development

• Flexion Lines: Lines on digits, palms, wrists, elbows

• Freckles: flat melanized patches of skin that vary with heredity and sun exposure

• Moles: same as freckle but elevated• Hemangiomas: birth marks caused by begnin

tumors of dermal blood capillaries

Accessories of the skin: Hair, Nails, and CutaneousGlands

• Hair and Nails are composed of mostly dead keratinized cells.

• Skin (stratum corneum has soft keritin)• Hair and Nails made of more compact, hard

keritin, cross linked between keritin moelcules.

Cross section of a hair

Structures of hair

Basis of hair color and texture

• See page 199

• Hair grows from the hair matrix just above the hair bulb.

• The hair bulb is near vascular connective tissue which provides hair with it’s nutrients.

Nail structure

• What are the Accessory Structures: Nails?– Nail body• Dense mass of keratinized cells

– Nail bed– Nail root– Cuticle (eponychium)– Lunula

Glands of the skin

• The skin has 5 types of Glands• 1. Merocrine Sweat Glands• 2. Apocrine Sweat Glands• 3. Sebaceous Glands• 4. Ceruminous glands• 5. Mammary Glands

Sweat Glands• Merocrine (eccrine)• Most numerous• Produces watery 99%

perspiration for cooling• 3-4X106 all over• Palms, soles, forehead• pH 4-6• Tubular gland with

twisted coil• Narrow lumen, opens at

pore on skin

• Apocrine• Occur in groin, anal,

axilla, beard area.• Produces thicker soln.

with fatty acids• Are scent glands

• Large lumen, opens to hair follicle

Sebaceous Glands

• Produce an oily secretion called SEBUM• Flask shaped, located higher up in dermis• Short ducts opening to hair follicles• Keeps skin and hair from becoming dry• (brushing hair spreads this)• Lanolin in moisturizers is sheep sebum

Ceruminous Glands• Found only in external ear canal• Secretion combines with sebum &dead

epithelial cells to make ear wax CERUMEN

• Waterproofs the ear canal and is anti-bacterial

Mammary Glands• Milk producing glands in female breasts• Are modified apocrine glands which produce

richer secretions

• For summary see chart 6.2 on page 203

Skin Disorderssee chart 6.3

• What are the Effects of UV Radiation?–Beneficial effect

– Activates synthesis of vitamin D3

– Harmful effects• Sun burn• Wrinkles, premature aging• Malignant melanoma• Basal cell carcinoma

Skin Cancer

• Cancer: rapid mitotic division of cells caused by a trigger environmental, genetic

• Skin cancer: is caused by exposure to UV rays. There are three types named for tissue affected

• 1. Basal carcinoma:• most common, • easiest to remove. • Appears as a red shiny bump that enlarges with

depressed center

• 2. Squamous Cell Carcinoma• found usually on scalp, ears, lip, back of

hands. • Has red scaly appearance with concave

center. • High survival rate with early detection, • will metastasize to lymph nodes highly lethal

• 3. Malignant melanoma• most deadly • arises in melanocytes in moles. • Fast to metastasize • lethal without immediate treatment

Recognizing Malignant Melanoma

• A= Asymmetry• B= Border irregularity• C= Color (brown, black, tan, red, purple)• D= Diameter (6mm)

Burns and Healing

• Burns: Leading cause in accidental death, death results from fluid loss and the toxic effect of eschar

• First degree: found in only epidermis, epidermis turns red, edema and pain, heals in a few days

• Second degree: or partial-thickness burns due to damage only in top of dermis layers, has blisters can scar and takes about 2 weeks to heal

• Third degree: or total thickness burns, turns black, skin can only grow from sides of damaged area so grafts are needed, debridement must occur in 24 hours, then toxic

Healing and Repair on injury to skin

What are the Four Stages in Skin Healing?

1. Inflammation• Blood flow increases• Phagocytes attracted

2. Scab formation3. Cell division and migration4. Scar formation

Bleeding occurs at the site of injury immediately after the injury, and mast cells in the region trigger an inflammatory response.

After several hours, a scab has formed and cells of the stratum germinativum are migrating along the edges of the wound. Phagocytic cells are removing debris,

and more of these cells are arriving with the enhanced circulation

in the area. Clotting around the edgesof the affected area partially isolates

the region.

One week after the injury, the scab has been undermined by epidermal cells migrating over the meshwork produced by fibroblast activity. Phagocytic activity around the site has almost ended, and the fibrin clot is disintegrating.

After several weeks, the scab has been shed, and the epidermis is complete. A shallow depression marks the injury site, but fibroblasts in the dermis continue to create scar tissue that will gradually elevate the overlying epidermis