The Integumentary System Chapter 5 The Integumentary System

Intro to Integumentary The integumentary system contains the cutaneous membrane & accessory structures Cutaneous membrane (skin) composed of epidermis & dermis Hypodermis separates integument from deeper tissues

Functions of integumentary system: Protection Temperature maintenance Synthesis of nutrients Sensory reception Excretion & secretion

Intro Checkpoint List the general functions of the integumentary system.

5-1: The Epidermis Epidermis layers Thick skin (palms of hands, soles of feet) Thin skin (rest of body) Deepest layer of epidermis contains melanocytes Make melanin—brown pigment

Middle layer of epidermis produce keratin to toughen skin Surface layer of epidermis contains dead, keratinized cells

5-1 Checkpoint Dandruff is caused by excessive shedding of skin cells from the outer layer of skin in the scalp. Which epidermal layer produces dandruff? Will the sanding off of fingerprints permanently remove the fingerprints? Why or why not?

5-2: Factors In Skin Color The Role of Pigmentation Carotene—orange pigment Melanin—brown pigment Freckles—areas of more melanin Prevents skin damage from ultraviolet radiation Albinos lack melanin

The Role of Dermal Circulation Blood vessels in the dermis give skin a pink or flushed color Constricting blood vessels causes pale color Loss of oxygen causes cyanosis—blue color

5-2 Checkpoint Name the two pigments in the epidermis. Why does exposure to sunlight or sunlamps darken skin? Why does the skin appear red during exercise?

5-3: Sunlight & Skin Skin Cancers Basal cell carcinoma & squamous cell carcinomas rarely spread; are surgically removed Malignant melanomas are life-threatening Usually begins in a mole

Risk factors for skin cancer Caucasian, European ancestry Prolonged exposure to sunlight Preventing skin cancer Wear at least SPF 15 Avoid prolonged exposure, avoid mid-day sun

Use ABCD Rule for examining moles for skin cancer A. Asymmetry: mole should be uniform in shape B. Border: edges of mole should be definite C. Color: mole should be black, brown or tan, sometimes red or blue D. Diameter: mole should not be larger than 6 mm

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5-3 Checkpoint What are the most common types of skin cancer? How can skin cancer be prevented? What is the ABCD Rule for examining moles?

5-4: The Dermis The dermis nourishes the epidermis Contains elastic & collagen fibers Blood vessels, nerves, accessory organs and glands are found in the dermis

5-4 Checkpoint Describe the location of the dermis. Where are the capillaries that supply the epidermis located?

5-5: The Hypodermis The hypodermis (subcutaneous layer) connects the skin to underlying tissues Contains numerous adipose cells for insulation & energy storage

5-5 Checkpoint List the two terms for the tissue that connects the dermis to underlying tissues. Describe the hypodermis.

5-6: Hair Hair & Hair Follicles Hair is a nonliving structure produced in hair follicles Hair & Hair Follicles Hair is formed from repeated cell divisions Cells are pushed to the surface & die

The hair root anchors the hair shaft Hair shaft covered by cuticle—overlapping cells Hairs are shed & replaced by new hairs

Functions of Hair Protect from UV, prevent entry of foreign particles, sensitivity Arrector pili pull on hair follicles to make hair stand up (goose bumps) Hair color determined by amounts of melanin

5-6 Checkpoint Describe a typical strand of hair. What happens when the arrector pili muscle contracts? If a burn on the arm destroys the epidermis & deep dermis, will hair grow again in the affected area?

5-7: Sebaceous & Sweat Glands Sebaceous (Oil) Glands Secrete oil (sebum) into hair follicles or on skin Blocked sebaceous glands generate acne

Sweat Glands Apocrine glands—begin secretions at puberty Merocrine glands—most numerous type of sweat gland Release secretions onto skin to cool the body Excessive sweating can lead to dehydration

5-7 Checkpoint Identify two types of exocrine glands found in the skin. What are the functions of sebaceous secretions?

5-8: Nails Nails protect the tips of the fingers & toes Consist of a nail body (keratinized cells) over a nail bed The cuticle folds over the nail Blood vessels found under the nail bed

5-8 Checkpoint What substance makes nails hard? Where does nail growth occur?

5-9: Steps in Skin Repair Repair of Skin Injuries Bleeding occurs at injury site; forms a clot A scab forms over the injured epidermis New fibers replace damaged tissue May form scar tissue

Effects of Burns First-degree (superficial)—epidermis CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Effects of Burns First-degree (superficial)—epidermis Redness, swelling & pain

Second-degree (partial thickness)—epidermis & dermis CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Second-degree (partial thickness)—epidermis & dermis Similar to first-degree; blisters appear

Third-degree (full thickness)—entire thickness of skin CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Third-degree (full thickness)—entire thickness of skin No initial pain or swelling—nerve ends burned

5-9 Checkpoint Why can skin regenerate effectively even after considerable damage has occurred? What are the three types of burns, and what layers of the skin does each type affect?