Anatomy & Physiology for Health Professions: An Interactive Journey

1. Anatomy &Physiologyfor Health Professions:An Interactive Journey Bruce J. Colbert Jeff Ankney Karen Lee Chapter 7The Integumentary System:The Protective Covering

2. Introduction • The integumentary system protects the body from environmental damage. • The skin forms a protective barrier shielding the body from the elements and pathogens, as well as performing several other vital functions. • Skin is essential to well-being, helps to regulate body temperature, and contains many accessory organs such as nail, hair, and glands.

3. Learning Objectives • Discuss the functions of the integumentary system • List and describe the layers of the skin • Explain the healing process of skin • Describe the structure and growth of hair and nails • Explain how the body regulates temperature through the integumentary system • Discuss various common diseases of the integumentary system

4. Apocrine Glands Carotene Corium Eccrine Glands Epidermis Epithelial Tissue Keratin Keratinization Lesion Lunala Melanin (APP oh crin) (CARE eh teen) (CORE ee um) (EKK rin) (ep ih DER miss) (ep ih THEE lee al) (KAIR ah tin) (KAIR ah tin eye ZAY shun) (LEE zhun) (LOO nyoo lah) (MELL an in) Pronunciation Guide Click on the megaphone icon before each item to hear the pronunciation.

5. Melanocytes Pustule Sebaceous gland Sebum Squamous cells Stratum corneum Subcutaneous fascia (mell AN oh sights) (PUS tyool) (see BAY shuss) (SEE bum) (SKWAY muss sells) (STRAY tum core NEE um) (sub cue TAY nee us FAY she ah) Pronunciation Guide (cont’d) Click on the megaphone icon before each item to hear the pronunciation.

6. System Overview • The integumentary system is comprised of the skin and its accessory components including hair, nails, and associated glands. • The integumentary system performs several vital functions: • Protection from pathogens • Balances fluid levels • Stores fatty tissue for energy supply • Produces vitamin D (with help from the sun) • Provides sensory input • Helps to regulate body temperature

7. The Skin • The skin is the largest organ, weighing approximately 20 pounds and covering an area about 20.83 square feet on an adult. • A cross section of skin reveals three layers: • Epidermis • Dermis • Subcutaneous Fascia

8. Figure 7-1 The three layers of the skin.

9. Epidermis • The epidermis is the layer of skin that we see on the outside. It is made up of five or six even smaller layers of tissue. • There are no blood vessels or nerve endings in this layer. • The cells on the surface of the epidermis are constantly shedding, being replaced with new cells that grow and arise from the deeper region called the stratum basale every 2–4 weeks.

10. Outermost Layer of the Epidermis • The outermost layer is a layer of dead cells, called the stratum corneum, which are flat, scaly, keratinized epithelial cells. • You slough off 500 million cells every day, or about 1½ pounds of dead skin a year, allowing for rapid repair in case of injuries.

11. Skin Color • Specialized cells called melanocytes are located deep in the epidermis and are responsible for skin color. • Melanocytes produce melanin, a substance that causes skin color.

12. Skin Color (cont’d) • Everyone contains the same amount of melanocytes, but the variation in skin color is the result of the amount of melanin produced and how it is distributed. • Carotene, another form of pigment, gives a yellowish hue to skin while a pinkish hue is derived from the hemoglobin in the blood.

13. Affects of Disease on Skin Color • Color of skin can indicate disease. • When liver disease occurs, the body can’t breakdown bilirubin. The buildup of bilirubin gives the skin a deeper, yellow color. • A malfunctioning adrenal gland can cause the skin to turn bronze due to excessive melanin.

14. Affects of Disease on Skin Color (cont’d) • Excessive bruising could indicate skin, blood, or circulatory problems. • Cyanosis, or a blue coloring, results from a drop in oxygenation.

15. Dermis • The layer below, or inferior, to the epidermis is the thicker dermis layer. • This layer contains the following: • Capillaries • Collagenous/elastic fibers • Involuntary muscles • Nerve endings • Lymph vessels • Hair follicles • Sudoriferous glands (sweat) • Sebaceous glands (oil)

16. The Dermal Layer • Small “fingers” of tissue project from the surface of the dermis and anchor this layer to the epidermal layer. • Finger and toe prints arise from this layer. • Nerve fibers allow you to sense what is happening in your environment.

17. The Dermal Layer (cont’d) • Vasodilation of capillaries in this layer cause blushing. • Collagen and elastic fibers allow for the elasticity of skin, preventing the tearing of skin with movement. They allow skin to return to normal shape during periods of rest. Older people lose some of this elasticity, leading to wrinkles.

18. Sudiferous Glands • There are two main types of sudiferous, or sweat, glands. • Apocrine sweat glands secrete at the hair follicles in the groin and anal region as well as the armpits. These glands become active around puberty and are believed to act as sexual attractants. • Eccrine glands are found in greater numbers on your palms, feet, forehead, and upper lip and are important in the regulation of temperature.

19. Sudiferous Glands (cont’d) • The body has 3 million sweat glands. • Sweat has no odor, but bacteria degrades the substances in the sweat over time into chemicals that give off strong smells commonly known as body odors.

20. Sebaceous Glands • Sebaceous glands play an important role by secreting oil, or sebum. • Sebum keeps the skin from drying out and (due to its acidic nature) helps destroy some pathogens on the skin’s surface.

21. Figure 7-2 Sweat and sebaceous glands.

22. More Bothersome Than Amazing Fact of Life • When sebaceous glands within the skin become blocked, sebum stagnates and is exposed to air, drying out. The sebum turns black creating the infamous blackhead. If it becomes infected, it becomes a pimple. Squeezing blackheads can cause craters at the site. It is best to keep the area clean and let nature take its course.

23. More Bothersome Than Amazing Fact of Life (cont’d) • When cleaning your skin, washing too frequently using water that is too hot, soap that is too harsh, or aggressive drying can dry out and damage your skin, as well as removing the anti-bacterial layer of sebum. Moderation is the key.

24. Subcutaneous Fascia • The innermost layer of the skin is the subcutaneous fascia, or hypodermis. • The subcutaneous fascia is composed of elastic and fibrous connective tissue and fatty tissue. • Lipocytes, or fat cells, produce the fat needed to provide padding to protect the deeper tissues of the body and act as insulation for temperature regulation. • Fascia attaches to the muscles of the body.

25. How Skin Heals • Everyone has skin injuries from time to time. • If skin is punctured and the wound damages blood vessels, the wound fills with blood. Blood contains substances that cause clotting. The top part of the clot exposed to air hardens to form a scab, nature’s band-aid, forming a barrier and preventing pathogens from entering.

26. How Skin Heals (cont’d) • Next, white blood cells enter and destroy any pathogens, while fibroblasts come and begin pulling the edges of the wound together. The basale layer hyperproduces cells for repair of the wound.

27. Skin Healing • If the wound is deep, a scar, composed of collagen fibers, develops. Scars don’t contain any accessory organs or nerve endings. Stitches, adhesive strips (butterflies), or special glue reduce scarring. • Note, the wound ideally starts to heal from the inside out. This aids in preventing pathogens from becoming trapped between a healed surface and the deeper layer of skin where they could develop into a pocket of infection.

28. Figure 7-3 Wound repair.

29. Click here to view an animation on the topic of Wound Repair. Back to Directory

30. Burns to the Skin • Burns can be caused by heat, chemicals, electricity, or radiation. • Two factors affect assessments of damage: • Depth • Amount of area damaged

31. First Degree Burns • The depth of a burn relates to the layer or layers of skin affected by the burn. • First degree burns damage only the outer layer, or epidermis. • Symptoms include redness and pain, but no blister. • Pain subsides in 2–3 days and there is no scarring. • Complete healing takes about 1 week.

32. Second Degree Burns • Second degree burns involve the entire depth of the epidermis and a portion of the dermis. • Symptoms include redness, pain, and blistering. • The extent of blistering is dependent on the depth of the burn. • Blistering extends after the initial burn. • Blisters heal within 10–14 days if there are no complications, with deeper second degree burns taking 1–3½ months. • Scarring in second degree burns is common.

33. Third Degree Burns • Third degree burns affect all three layers of the skin. • The surface of the burn has a leathery feel and will range in color from black, brown, tan, red, or white. • The victim feels no pain because the pain receptors are destroyed. • Also destroyed are sweat and sebaceous glands, hair follicles, and blood vessels.

34. Fourth Degree Burns • Fourth degree burns are the worst burns. • These burns penetrate the bone and cause bone damage.

35. Amount of Area Damaged • The rule of nines is used to estimate extent of area damaged by burns. • The body is divided into the following regions, each given a percentage of body surface area value: • Head and neck – 9% • Each upper limb – 9% (2 x 9 = 18%) • Front of trunk – 18% • Back of trunk and buttocks – 18% • Front of legs – 18% • Back of legs – 18% • Perineum (including anus and urogenital region) – 1%

36. Figure 7-4 Assessing the degree of the burn.

37. Clinical Concerns • The clinical concerns for burn victims relate to the functions of the skin already discussed, including: • Bacterial infections • Fluid loss • Heat loss

38. Burn Treatment • Severe burns require healing steps at an intensity level the body can’t manage on its own. • Damaged skin must be removed as soon as possible and skin grafting must be started. • Autografting is using the patient’s own skin, while heterografting is required if the patient suffered a large area of burn and has little healthy skin to graft.

39. Burn Treatment (cont’d) • Grafting requires many trips to the OR because large areas can’t be done all at once and often the grafts don’t “take.” • It is possible to grow sheets of skin tissue in the laboratory from patient cells or utilization of synthetic materials.

40. Clinical Application: Medicine Delivery via the Skin • A variety of medications can be delivered via the integumentary system. Medicines can be applied to adhesive patches that are placed on the skin where it is slowly absorbed into the blood stream. These are called transdermal patches. Nicotine, nitroglycerin, and birth control are all medications that can be delivered in this manner. A more rapid absorption method would be sublingually (under the tongue).

41. Clinical Application: Medicine Delivery via the Skin (cont’d) • If medications can’t be taken by mouth or the digestive system destroys the medication, a hypodermic injection using a syringe and needle allows medication to be directly delivered subcutaneously (under the skin) or intracutaneously (into the skin). Other routes include intramuscular, intraspinal, and intravascular.

42. Nails • Specialized epithelial cells originating from the nail root form your nails. • As these cells grow out and over the nail bed, they become keratinized forming a substance similar to the horns on a bull. • The cuticle is a fold of tissue that covers the nail root.

43. Nails (cont’d) • The portion that we see is called the nail body. • Nails normally grow 1 mm every week. • The pink color of the nail comes from the vascularization of the tissue under the nails, while the white half-moon shaped area, or lunula is a result of the thicker layer of cells at the base.

44. Figure 7-5 Structure of the fingernail.

45. Clinical Application: Assessing Peripheral Perfusion • The pink color of the nail is clinically significant in assessing perfusion (blood flow) to the extremities and is a determinate of oxygenation. If you pinch one of your fingers, the pink color should return within 5 seconds (usually within 3 seconds) if you have good perfusion. Longer return to normal pink color indicates a problem.

46. Clinical Application: Assessing Peripheral Perfusion (cont’d) • Diabetes can cause reduced blood flow to the extremities. This is called peripheral vascular disease (PVD). Blood clots or vascular spasm can decrease blood flow, as can hypothermia, making peripheral refill slower. • Reduced levels of oxygen can cause a blue color to nail beds.

47. Hair • Body hair is normal and serves important purposes. • Hair helps to regulate body temperature and functions as a sensor to help detect things on your skin such as bugs or cobwebs. • Eyelashes help to protect our eyes from foreign objects while hair in the nose helps filter out particulate matter.

48. Anatomy of a Hair • Visible hair is composed of fibrous protein called keratin. • The hair you see is called the shaft with the root extending down into the dermis to the follicle.

49. Anatomy of a Hair (cont’d) • The follicle is formed by epithelial cells with a rich source of blood provided by the dermal blood vessels. • Cells divide and grow in the base of the follicle, older cells are pushed away and die, so the shaft of the hair is comprised of dead cells.

50. Hair Anatomy • Shaving or cutting hair doesn’t make it grow quicker or thicker. • There is a sebaceous gland associated with each hair follicle, secreting sebum that coats the hair follicle and works its way to the skin’s surface to prevent drying of the hair, acting as an anti-bacterial, and lubricating the hair shaft. • Sebum production decreases with age, explaining why older people have drier skin and more brittle hair.