Skin and the Integumentary System

1. Skin and the Integumentary System Chapter 6

2. Aids for understanding • Cut- skin • Derm- skin • Epi- upon • Follic- small bag • Kerat- horn • Melan- black • Seb- grease

3. Clinical • Transdermal patch contains drug • Diffuses into the epidermis and enters the blood vessels of the dermis

4. Skin • Organ vital in maintaining homeostasis • Protective covering • helps regulate body temp. • retards water loss • houses sensory receptors • synthesizes biochemicals • excretes small quantities of waste

5. Epidermis • Lacks blood vessels • Stratum basale close to the dermis is nourished by dermal blood vessels • Farther cells move, poorer nutrient supply, cells die • Older cells harden in a process called keratinization forming stratum corneum

6. In healthy skin, production=loss • Rate of cell division increases where the skin is rubbed or pressed regularly (calluses, corns) • Melanocytes produce melanin • Absorbs UV radiation, preventing mutations in DNA of the skin

7. Skin Color • All have same # of melanocytes • Amt. produced determines darkness • Environmental factors • Sunlight • Sunlamps • X-rays • Physiological factors • Amt. of blood • Diet • Biochemical imbalance

9. ???????????????????????????????? • Explain how the epidermis is formed. • Distinguish between the stratum basale and the stratum corneum. • What is the function of melanin? • What factors influence skin color?

10. Dermis • Boundary is uneven • Dermal papillae extend between epidermal ridges and form fingerprints • Dermis binds epidermis to underlying tissues • Blood vessels supply nutrients to all skin cells • Nerve cell processes are scattered throughout • Contains hair follicles, sebaceous glands, and sweat glands

12. Clinical • Interference with blood flow may kill epidermal cells • Pressure ulcer may appear • Occur in the skin overlying bony projections • Frequently changing body position or massaging the skin to stimulate blood flow can prevent ulcers

13. Subcutaneous Layer (hypodermis) • Consists of loose connective and adipose tissues • Insulates • Contains major blood vessels

14. Accessory Organs of the Skin • Nails • Protective coverings on the ends of the fingers and toes • Consists of a nail plate that overlies a surface of skin called the nail bed • The whitish, half-moon shaped lunula at the base covers the most actively growing region • FYI: thumb nail grows slowest; the middle nail grows fastest!

15. Hair Follicles • Present on all surfaces except palms, soles, lips, nipples, and parts of the reproductive organs • Each hair develops from a follicle • Contains hair root • Composed of dead epidermal cells • Arrector pili muscle attaches to each hair follicle

16. Clinical • Just above base of follicle are stem cells that can give rise to hair and other epidermal cells • Manipulating these cells could someday treat baldness or extreme hairiness

17. Nerve Receptors • Pacinian corpuscle • Detects vibrations and heavy touch sensations and sends impulses to the brain • Meissner’s corpuscle • Detects light touch sensations and sends impulses to the brain

18. Sebaceous glands • Holocrine glands that secrete an oily mixture of fatty material and cellular debris called sebum through ducts into the hair follicles

19. Clinical • Acne vulgaris – disorder of the sebaceous glands • Overactive and inflamed glands become plugged and surrounded by small, red elevations containing blackheads or pimples

20. Sweat Glands • glands consist of a tiny tube that originates as a ball-shaped coil in the deeper dermis • Eccrine glands respond to body temp. • Common on forehead, neck, and back • Sweat carried away in a duct that opens to the outside (pore) • Sweat is mostly water, but contains salt and waste

21. Apocrine glands secrete sweat when a person is upset, frightened, or in pain • Ceruminous glands of the external ear canal secrete earwax • Mammary glands secret milk

22. Clinical • The avg. sq. in. of skin holds 650 sweat glands, 20 blood vessels, 60,000 melanocytes, and more than a thousand nerve endings.

23. Write a narrative essay of your journey through the skin. Pretend as though I know nothing about these structures. Be sure to “visit” Hypodermis Adipose tissue Blood vessels Dermis Nerves Hair Dermal papillae Arrector pilius sebaceous gland Sweat gland Pores Epidermis Stratum corneum Stratum basale melanocytes Journey Through The Skin

24. Regulation of Body Temperature • Even slight shifts can disrupt metabolic rates • 37°C (98.6°F) • How it works: • Body temp. rises • warmed blood reaches the brain • signal sent to muscles in the walls of dermal blood vessels to relax • heat escapes • Signal sent to sweat glands to release sweat

25. Clinical • Hypothermia – core body temp. falls below 95°F • Gradual loss of coordination • Stiffening muscles • Confusion • Fatigue • Slow, shallow breathing • At 87.8°F, the skin turns bluish-gray, weakness intensifies, and consciousness ebbs away

26. Hyperthermia – core body temp. exceeds 106°F • Skin becomes hot, dry, and flushed • Person becomes weak, dizzy, and nauseous • Headache • Rapid, irregular pulse

27. ???????????????????????????????? • Why is regulation of body temp. so important? • How does the body lose excess heat? • Which actions help the body conserve heat?

28. Healing of Wounds • Inflammation – normal response to injury or stress; red and painfully swollen • blood vessels dilate and become more permeable forcing fluids to the leave the blood vessels and enter damaged tissue • Injuries • Shallow break in skin – epithelial cells divide more rapidly • Deep – blood vessels break, escaping blood forms clot (blood clot + dried tissue fluid = scab), fibroblasts form new fibers

29. Phagocytic cells remove dead cells and other debris • Scab sloughs off • Scar may form • Large open wounds • Healing accompanied by granulation (new branch of a blood vessel and a cluster of collagen-secreting fibroblasts)

30. ???????????????????????????????? • Describe how inflammation helps a wound heal. • Distinguish between the activities necessary to heal a wound in the epidermis and those necessary to heal a wound in the dermis. • Explain the role of phagocytic cells in wound healing. • Define granulation.

31. Skin Cancer • the abnormal growth of skin cells — most often develops on skin exposed to the sun • There are three major types of skin cancer • basal cell carcinoma • squamous cell carcinoma • melanoma

32. basal cell carcinoma • most common form of nonmelanoma skin cancer • rarely fatal, but can cause extensive damage to surrounding tissue and bone if they're not removed • have a high recurrence rate • Most basal cell carcinomas are caused by long-term exposure to ultraviolet (UV) radiation from sunlight

33. squamous cell carcinoma • second most common form of nonmelanoma skin cancer following basal cell carcinoma • rarely causes further problems when caught and treated early • Untreated, squamous cell carcinoma can grow large or spread to other parts of your body, causing serious complications.

34. melanoma • the most serious type of skin cancer, develops in the cells that produce melanin • can also form in your eyes and, rarely, in internal organs, such as your intestines • The exact cause of all melanomas isn't clear, but exposure to ultraviolet (UV) radiation increases your risk; your genetic makeup may also play a role

35. How to identify? • http://www.mayoclinic.com/health/melanoma/DS00575&slide=2