The Integumentary System Chapter 5

Standards and Objectives CLE Identify structures of the integumentary system and show the relationship between these structures and their functions. Identify the structures of the skin and explain their role in protecting the body and maintaining homeostasis. CLE Investigate physiological mechanisms that allow the integumentary system to function. Explain the physiological processes involved in healing the skin and disorders of the skin. Construct a labeled model of the skin with descriptions of its functions.

Facts about the Integumentary System 1. Your skin is considered the largest organ in the human body. 2. Your skin is made up of three major layers - epidermis, dermis, and hypodermis (also called the subcutaneous tissue). 3. Your skin protects your inside organs while keeping infections out and prevents you from getting sick. 4. Your skin loses about 30,000 to 40,000 dead skin cells from the surface almost every minute and about strands of hair per day, even though you do not see it happening. 5. Your skin sheds a layer of these dead cells every 24 hours and renews itself about every 28 days. 6. Your skin swells when it absorbs water. 7. Your skin contains a protein called keratin which is also found in hair and nails 8. Your skin is the thinnest on the eyelid. 9. Goose bumps are actually little pimples that help retain a layer of warm air over our body. 10. About 32 million bacteria call every inch of your skin home.

CLE Identify structures of the integumentary system and show the relationship between these structures and their functions. Identify the structures of the skin and explain their role in protecting the body and maintaining homeostasis.

Skin Structure Epidermis: (epi – above) superficial epithelium Dermis: underlying area of connective tissues Hypodermis: AKA subcutaneous layer –loose connective tissue that separates the dermis from the deep fascia around other organs such as muscles or bones ◦ Fascia: connective tissue fibers, primarily collagenous, that form sheets or bands beneath the skin to attach, stabilize, enclose, and separate muscles and other internal organs ◦ Collagenous: made of strong, insoluble protein fibers that are common in connective tissues

Skin Functions Protection Excretion of wastes Temperature regulation Synthesis of compounds ◦ Melanin ◦ Keratin ◦ Calcitrol Storage of chemical compounds ◦ Lipids Sensations

The Skin Figure 5-1 Components of the Integumentary System

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Changes in skin appearance can help diagnose diseases Jaundice: the liver is unable to excrete bile, so a yellowish pigment accumulates in body fluids, and in advanced stages, the skin and whites of the eyes turn yellow Some tumors affecting the pituitary gland result in secretion of large amounts of melanocyte-stimulating hormone (MSH), causing a darkening of the skin, as it the individual has an extremely dark bronze tan. Addison disease: the pituitary gland secretes large quantities of adrenocorticotropic hormone (ACTH), which is similar to MSH Vitiligo: Melanocytes are lost due to immune defense malfunctions, where antibodies attack normal melanocytes, causing light spots on primarily dark-skinned individuals Skin cancers and melanomas

CLE Investigate physiological mechanisms that allow the integumentary system to function. Explain the physiological processes involved in healing the skin and disorders of the skin. Construct a labeled model of the skin with descriptions of its functions.

Skin Cancer Basal Cell Carcinoma ◦ Most common, least malignant skin cancer ◦ Usually occurs on face ◦ Rx – surgical removal or radiation Squamous Cell Carcinoma ◦ Mostly scalp and lower lip ◦ Grows rapidly and metastasizes to lymph nodes ◦ Rx – surgical removal or radiation ◦ Prognosis good with early diagnosis

Skin Cancer Melanoma ◦ Occurs in melanocytes ◦ Metastasizes to other areas quickly ◦ Appears as brown or black irregular patch that occurs ◦ Suddenly ◦ A change in an existing wart or mole may indicate ◦ Melanoma ◦ Rx – surgical removal of melanoma and surrounding area ◦ and chemotherapy

Basal Cell Carcinoma Human Anatomy, 3rd edition Prentice Hall, © 2001

Squamous Cell Carcinoma Human Anatomy, 3rd edition Prentice Hall, © 2001

Melanoma Human Anatomy, 3rd edition Prentice Hall, © 2001

Dermal Blood Supply and Innervation Cutaneous plexus: supplies the skin, hair follicles, sweat glands, and other structures in the dermis with blood, nutrients, and oxygen Papillary plexus: provides blood to capillary loops that follow the contours of the epidermis-dermis boundary ◦ Trauma to the skin often results in a contusion (bruise), Innervation : Nerve fibers in the skin control blood flow, adjust gland secretion rates, and monitor sensory receptors in the dermis and deeper layers of the epidermis

Dermal Circulation

Section 5.6: Hypodermis AKA Subcutaneous Layer Consists of areolar and adipose tissues and is quite elastic Is a fatty layer that: ◦ provides extra insulation ◦ helps reduce heat loss ◦ serves as an energy reserve and a shock absorber for rough activities.

Section 5.10 – Regeneration of Skin Bleeding occurs when damage extends through the epidermis into the dermis. Blood clot (scab) forms at the surface, temporarily restoring the integrity of the epidermis and restricting entry of additional microorganisms into the damaged area. Over time, deeper portions of the clot dissolve, and the number of capillaries decline. Fibroblast activity leads to the appearance of collagen fibers and typical ground substance. Formation of an inflexible, fibrous, noncellular scar tissue completes the repair process, but does not restore the tissue to its original condition.

Disorders of the Skin ACNE VULGARIS ◦ Common and chronic disorder of sebaceous glands ◦ Sebum plugs pores; area fills with leukocytes ◦ Also – blackheads, cysts, pimples and scarring

Disorders of the Skin ACNE VULGARIS

Disorders of the Skin ATHLETE’S FOOT ◦ Contagious fungal infection ◦ Usually contracted in public baths and showers ◦ Rx – antifungal agents

Disorders of the Skin DERMATITIS ◦ Non-specific inflammation of skin ◦ Can be rash – reaction to soap, plants, etc. ◦ Can be emotional – stress can cause skin blotches

Disorders of the Skin ECZEMA ◦ Acute or chronic, inflammatory skin disease ◦ Dry, red, itchy and scaly ◦ Rx – remove or avoid causative agent, hydrocortisone to help alleviate the symptoms

Disorders of the Skin WARTS (VERRUCAE) ◦ Caused by virus ◦ Some disappear spontaneously, others removed with liquid nitrogen, chemicals or laser

Disorders of the Skin IMPETIGO ◦ Acute, inflammatory and contagious ◦ Seen in babies and young children ◦ Caused by staphylococcus or streptococcus ◦ Characterized by the appearance of vesicles which rupture and develop distinct yellow crusts

Disorders of the Skin PSORIASIS ◦ Chronic inflammatory skin disease characterized by dry reddish patches which are covered with silvery-white scales ◦ Affects the skin surface over elbows, knees, shins, scalp and lower back ◦ Cause – unknown ◦ Onsets triggered by stress, trauma or infection

Disorders of the Skin RINGWORM ◦ Highly contagious fungal infection ◦ Can be contracted from infected animals ◦ Raised, itchy circular patches with crusts ◦ Skin, scalp or underneath nails ◦ Rx – griseofulvin (drug)

Disorders of the Skin BOILS (CARBUNCLES) ◦ Painful, bacterial infection of hair follicle or sebaceous glands ◦ Caused by staphylococcus organism ◦ Rx – antibiotics, excision and drainage of affected area

Disorders of the Skin SHINGLES (HERPES ZOSTER) ◦ Viral infection of nerve endings ◦ Can be caused by dormant chicken pox virus ◦ Chest or abdomen, accompanied by severe pain ◦ Rx – medication for pain and itching

Disorders of the Skin HERPES SIMPLEX I ◦ Viral and contagious  Spread by kissing, eating/drinking after infected person, sharing lipstick, etc. ◦ Symptom includes Fever blister or cold sore

Disorders of the Skin SCABIES ◦ Communicable, severe itching ◦ Contracted from infected living or nonliving things ◦ Mite burrows in skin, lays eggs, eggs hatch

Burns A simple, moderately severe sunburn damages the blood vessels extensively. How extensively? Studies have shown that it can take four to fifteen months for them to return to their normal condition. Consider that the next time you’re feeling too lazy to apply sunscreen before heading outside. Caused by radiation, sun, boiling water, chemicals, fire or electricity

RULE OF NINES – Measures percent of body burned. Body divided into 11 areas; each is 9% of body surface.

FIRST DEGREE BURNS ◦ Superficial ◦ Skin red and dry ◦ Involves only epidermis ◦ Rx – cold water ◦ Healing within one week

SECOND DEGREE BURNS ◦ Epidermis and dermis ◦ Pain, swelling, redness and blistering ◦ Skin may be exposed to infection ◦ Rx – pain medication, dry sterile dressing ◦ Healing within 2 weeks

THIRD DEGREE BURNS ◦ Epidermis, dermis and subcutaneous layers ◦ Symptoms – loss of skin, blackened skin ◦ May be life threatening