Structures & Functions of the Integumentary System COURSE DESCRIPTION

Transcription

1 Structures & Functions of the Integumentary System COURSE DESCRIPTION The skin and its accessory organs (sweat glands, sebaceous glands, hair, and nails) are known as the integumentary system. This continuing educational course describes the structures, functions, diseases, and disorders of the integumentary system. Rev 2.0 March

2 COURSE TITLE: Structures & Functions of the Integumentary System Author: Francine L, Rogers, MPH, MS, BA, NCMA (NCCT), CMAA (NHA), CBC(NHA) Allied Health Instructor Smyrna, GA Number of Clock Hours Credit: 2.0 Course # P.A.C.E. Approved: _ Yes X No OBJECTIVES Upon completion of this continuing education course, the professional should be able to: 1. Describe the structures of the integumentary system. 2. Explain the functions of the integumentary system structures. 3. Describe the common diseases and disorders of the skin. 4. Identify types of skin lesions. 5. Identify medical terms related to the integumentary system. Disclaimer The writers for NCCT continuing education courses attempt to provide factual information based on literature review and current professional practice. However, NCCT does not guarantee that the information contained in the continuing education courses is free from all errors and omissions. 2

3 INTRODUCTION The skin and its accessory organs are known as the integumentary system and it is classified as both a body system and an organ. It is considered the largest organ of the human body. The integumentary system consists of skin, hair, nails, and glands. This continuing educational course describes the structures, functions, diseases, and disorders of the integumentary system. Following is a graphic depiction of the integumentary system. This work is in the public domain in the United States because it is a work prepared by an officer or employee of the United States Government as part of that person s official duties under the terms of Title 17, Chapter 1, Section 105 of the US Code. STRUCTURES AND FUNCTIONS SKIN The skin on an average person covers approximately 3,000 square inches (22 square feet) and makes up about 15% of the body weight. The skin is composed of three layers. From the outermost to innermost, the layers are the epidermis, dermis, and subcutis (subcutaneous fat layer). 3

4 Epidermis The epidermis is the outermost layer of the skin and it protects the body from the environment. The epidermis has five layers. Cells found in these layers can become malignant resulting in different types of skin cancer. Dermis Basal Cell Layer This is the innermost layer of the epidermis and it consists of basal cells and Merkel cells. Basal cells are constantly dividing with new cells pushing older cells up towards the surface of the skin where they are eventually shed. The basal cells layer also contains melanocytes, the cells which produce the skin coloring pigment melanin. Melanin protects the skin from damaging ultraviolet rays. Birthmarks, freckles, and age spots are patches of melanin. Merkel cells are associated with the sense of light touch, and discrimination of shapes and textures. Very rarely, Merkel cells can become cancerous causing an aggressive form of skin cancer. Squamous Cell Layer The squamous cell layer is right above the basal layer. This layer contains a type of squamous cell called a keratinocyte. Keratinocytes contain keratin, a tough protective protein that makes up most of the structure of the skin, hair, and nails. This layer is the thickest of the layers of the epidermis. Also in this layer are Langerhans cells which are involved in the immune response. Stratum Granulosum and the Stratum Lucidum Keratinocytes from the squamous cell layer are pushed up through the two thin layers called the stratum granulosum and stratum lucidum. As these cells get closer to the skin surface, they become bigger and flatter and fuse together. Eventually they die and become a tough durable layer that migrates to the surface of the skin. Stratum Corneum This is the outermost layer of the epidermis. It is sometimes called the horny layer as the cells are toughened like the cells in an animal s horn. This layer consists of many layers of dead keratinocytes that are constantly being shed. In young adults, complete cell turnover takes days; in elderly adults this process takes days. The dermis contains blood vessels, lymph vessels, hair follicles, nerves, collagen bundles, and sweat glands. It is held together by a protein called collagen which 4

5 contains fibroblasts and provides the skin with strength and resilience. The dermis also contains pain and touch receptors. The functions of the dermis are to regulate temperature and provide the epidermis with a blood supply. The dermis contains much of the body s water supply. Blood Vessels: Blood vessels supply nutrients and oxygen to the skin. These also take away cellular waste. Vitamin D produced in the skin is also transported to the rest of the body via the blood vessels. Lymph Vessels: Lymph vessels closely follow blood vessels. Lymph fluid contains infection-fighting cells that search for foreign microorganisms to destroy. These cells often move between the lymph vessels and blood vessels. Hair Follicles: Hair follicles are tube-like cavities that surround the root of the hair and provide nourishment to the hair. Sweat Glands: There are two types of sweat glands apocrine and eccrine. Sebaceous Glands: Sebaceous glands are also called oil glands. Nerve Endings: Receptors for pain and touch are located in the dermis layer. These receptors transmit sensations of pain, itch, pressure, and information about temperature to the brain. For example, when the body identifies itself as cold, involuntary contraction and relaxation of muscles (shivering) occurs, generating body heat. Collagen and Elastin: Collagen and elastin are proteins that give the skin strength and resilience. The dermis is divided into two sub-layers. The upper layer is the papillary layer and it consists of a thin arrangement of collagen. This layer supplies nutrients to the epidermis and regulates temperature. The lower layer is the reticular layer. It is thicker and denser than the papillary layer. This layer strengthens the skin and provides structure and elasticity. The reticular layer provides support for the hair follicles, sweat glands, and sebaceous glands. Subcutis The subcutis layer is also known as the subcutaneous or fat layer. This is the deepest layer of the skin. It consists of a network of collagen and fat cells. The subcutis helps conserve the body s heat and protects other organs from injury by acting as a shock absorber. Blood vessels, lymph vessels, and hair follicles cross through this area. This layer stores fat as an energy reserve for the body. The thickness of the subcutis layer varies from person to person, and throughout the body depending on the number of fat cells present. 5

6 HAIR Graphic courtesy of Wikimedia Commons. This file is licensed under the Creative Commons Attribution 3.0 Unported license. The surface of the human body is covered with millions of hairs that are most noticeable on the head, around the external genitalia, and under the arms. Very few areas of the body are devoid of hair. The functions of hair are to provide insulation of the body by trapping warm air around the skin and to protect the body from UV radiation. Eyebrows prevent sweat from getting into the eyes; nose and ear hairs filter dust and particles from the environment. Each hair has three major parts the follicle, root, and shaft. The hair follicle is located deep in the dermis. The follicle contains keratinocytes and melanocytes. Keratinocytes form the hair structure; melanocytes are pigment-producing cells. As new hair is produced in the follicle it is pushed up to the hair root which is just below the skin s surface. When the hair exits the skin, it is called the hair shaft. Each hair root and shaft has a medulla, cortex, and cuticle. The innermost portion is the medulla and it contains soft keratin and air. The cortex layer is between the medulla and cuticle. The cortex contains hard keratin (from keratinocytes) and the majority of the pigment (from melanocytes) that gives hair its color. The outermost layer is the cuticle which is made of hard keratin. The cells of the cuticle overlap like scales. Attached to each hair follicle is an involuntary muscle called the arrector pili. These muscles are regulated by the nervous system and are triggered by cold temperatures or fright. When the arrector pili muscles contract, the skin dimples form and are commonly called goose bumps. No new hair follicles develop after birth. In the fetus, hair begins to develop in the 3 rd month. By the 5 th month, very fine hair called lanugo covers the fetus. Shortly thereafter the lanugo disappears from all areas except the scalp and eyebrows. Lanugo may appear later in life as part of certain disease processes. The remaining hair on the fetal scalp and eyebrows is known as terminal hair. It is coarser, and in puberty, it will appear in the armpit and genital regions. The fine short hair found over the body is called vellus hair. 6

7 NAILS A. Nail plate B. Lunula C. Root D. Sinus E. Matrix F. Nail bed G. Hyponychium H. Free margin/edge Graphic courtesy of Wikimedia Commons. This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. Nails are hard plates of keratinized cells that develop from the epidermis. Nails form a hard protective covering for the vulnerable tips of the fingers and toes and provide a useful tool for scratching or scraping. Nails consist of the lunula, body, bed, root, free margin/edge. The nail sinus is where the root is located under the surface of the skin posterior to the lunula. The lunula is the pale crescent-shaped area located at the base of the nail. The visible portion of the nail is the body; the free edge is what is not attached to the skin. The nail bed underlies the body of the nail. The eponychium, commonly called the cuticle, surrounds the proximal and lateral edges of the nail. It serves a protective function to prevent the nail body from infection. The portion of the nail visible under the free edge is called the hyponychium. GLANDS There are two types of glands in humans sweat glands and sebaceous glands. Sweat glands are also referred to as sudoriferous glands; sebaceous glands are also referred to as oil glands. Sweat Glands Sweat glands are divided into two types: eccrine (also called merocrine) and apocrine. Eccrine Glands: These glands are located over the entire body but are most abundant on the palms, soles, and forehead. The sweat produced by the eccrine glands is 99% water. The purpose of eccrine glands is body temperature regulation. Apocrine Glands: Apocrine glands develop in puberty. These glands are mainly present in the axillary and genital areas. Fluid produced from apocrine glands is thicker than that produced by the eccrine glands. The characteristic odor of 7

8 sweat comes from bacteria on the skin decomposing the organic substances in sweat. Apocrine glands produce sweat in response to stress and sexual activity. The function of secretions from apocrine glands is that of olfactory communication, i.e. scent glands. Sweat glands in two areas of the body are modified to produce other secretions ceruminous glands and mammary glands. Ceruminous Glands: Cerumen, commonly called earwax, is produced and secreted from modified apocrine sweat glands and sebaceous glands that surround the outer third of the ear canal. Cerumen is a yellowish-waxy substance that assists in cleaning and lubrication of the ear. It also provides some protection from bacteria and insects. Mammary Glands: Mammary glands are modified apocrine glands that produce milk in females. Development of mammary glands is controlled by ovarian hormones. Mammary glands consist of alveoli lined with milk-secreting cells that form groups known as lobules. Each lobule has a duct that drains into openings in the nipple. Sebaceous Glands Sebaceous glands secrete an oily substance called sebum. These glands are found throughout the body except on the palms and soles. Sebum protects and waterproofs hair and skin to keep them from being dry, brittle, and cracked. Substances in sebum also have antimicrobial properties and can protect the skin from infections with bacteria and fungus. Sebum itself is odorless but bacterial digestion of sebum on the skin can produce odors. DISEASES & DISORDERS OF THE INTEGUMENTARY SYSTEM ACNE Acne is a very common skin disorder. It occurs when increased levels of androgens (hormones found in both males and females) cause increased production of sebum into hair follicles. The sebum combines with dead skin cells and blocks the follicle. The blocked follicle is invaded by normal skin bacteria, resulting in the follicle bursting open. White blood cells from the surrounding tissue invade the ruptured follicle and a pimple is formed. ALOPECIA AREATA Alopecia areata is a medical condition where hair falls out in round patches on the scalp and elsewhere on the body. If all hair is lost on the head it is called alopecia totalis; if all hair is lost on the body it is called alopecia universalis. In some, hair grows back. In others, hair loss is permanent. Alopecia areata is an autoimmune disorder where the person s immune system attacks the hair follicles, causing hair loss. Many types of prescription drugs can also reduce the ability to sweat properly. 8

9 ANHIDROSIS Anhidrosis, sometimes called hypohidrosis, is the inability to sweat normally. Depending on the severity, this can result in serious problems as the body becomes unable to cool itself, resulting in heat exhaustion or heat stroke. Anhidrosis can be caused by nerve damage from many types of illnesses such as diabetes, Parkinson s disease, Sjögren s syndrome, and more; or by skin damage from burns and clogged sweat ducts. The most common cause of anhidrosis is clogged sweat ducts. BIRTHMARKS Two types of birthmarks can be present at the time of birth vascular birthmarks and pigmented birthmarks. Vascular birthmarks are usually red and are made up of blood vessels that have not formed correctly. Vascular birthmarks can be hemangiomas and port wine stains. Both are caused by malformed blood vessels just under the surface of the skin. The presence of vascular birthmarks is almost always a cosmetic concern. Laser treatment can be used to minimize their appearance. Pigmented birthmarks are marks that appear at birth or shortly thereafter. They are generally shades of brown or brownish-blueish in color. Common birthmarks are moles, café au late spots, or Mongolian spots. As with vascular birthmarks, the presence of pigmented birthmarks is generally only a cosmetic concern. BOILS A boil is a bacterial infection caused by Staphylococcus aureus. The infection begins in a hair follicle or sebaceous gland by the hair follicle. Typically boils are red swollen lumps that develop pus after a couple of days. The boil eventually bursts and the pus drains out. Boils most often occur on the face, neck, armpit, shoulders, and buttocks. If several boils appear close together, it is called a carbuncle. A boil that occurs on the eyelid is called a sty. BULLAE Bullae are large fluid-filled sacs similar to blisters. A blister is called a bulla when it is larger than 1 centimeter. Bullae have many causes including friction blisters on hands or feet, chickenpox, contact dermatitis, thermal burns, and more. There is a more serious autoimmune disorder called bullous pemphigoid that results in the development of bullae throughout the body. BURNS Burns are caused by exposure to heat, cold, electricity, chemicals, or radiation. There are four levels of burns. First degree burns affect only the epidermis. They cause pain, redness, and swelling. Second degree burns affect both the epidermis and dermis. In addition to the symptoms of first degree burns, second degree burns also cause blistering. Third degree burns affect the epidermis, dermis, and subcutis. Third degree burns result in charred skin that can be black or white. Third degree burns are painless 9

10 as the receptors for pain have been destroyed. Burns can extend through all layers of skin to the muscles and bones. These are fourth degree burns. Burns can be very serious as the burned areas are open to infection and loss of fluids. Third and fourth degree burns generally do not heal on their own and require removal of dead tissue and skin grafts. CANCER Skin Cancer Skin cancer is the most common form of cancer. Most skin cancer is caused by overexposure to ultraviolet light (sunlight) and it appears on areas of the body that are most exposed to sunlight. However, skin cancer can occur in areas of the skin not exposed to sunlight such as the mucous membranes and genitalia. Basal cell carcinoma (that arising from basal cells) is the most common (about 75%) and the least malignant form of skin cancer. Basal cell carcinoma rarely metastasizes to other parts of the body or becomes disfiguring. However, these skin lesions should be removed to assure no further growth occurs. Death rarely results from basal cell carcinoma. Squamous cell carcinoma is the second most common form of skin cancer and comprises about 20% of all diagnoses of skin cancer. It arises from squamous cells in the epidermis that are destined to become keratinocytes. Squamous cell carcinoma can metastasize to other organs and become disfiguring. Following removal of squamous cell carcinoma, it may be necessary to have skin grafts, especially if the lesions have grown for a period of time. The most serious form of skin cancer and all cancers in general is melanoma, sometimes called malignant melanoma. It results in the most deaths from skin cancer but only comprises about 5% of all skin cancer diagnoses. Melanoma arises from the melanocytes in the epidermis. If not recognized and removed early, it quickly becomes invasive, spreading throughout the body. Breast Cancer The ducts and lobules of the mammary glands are the most common locations of breast cancer. The four most common types of breast cancer follow. Ductal carcinoma in situ (DCIS): In this type of cancer, cancerous cells are found only in the milk ducts and have not invaded any other breast tissue. Invasive ductal carcinoma: This is the most common form of breast cancer accounting for 80% of breast cancer diagnoses. In this type of cancer, the malignant cells start in the mild ducts and invade the fatty tissue of the breast. Infiltrating lobular carcinoma: This cancer is also called invasive lobular carcinoma. It accounts for about 10% of all cases of invasive cancer. This cancer begins in the lobules and spreads to other tissues of the breast. 10

11 Lobular carcinoma in situ (LCIS): In this type of cancer, malignant cells are found only in the lobules of the breast. Some research suggests that this is not really a form of cancer but rather an indicator for the increased risk of developing breast cancer later. DECUBITUS ULCERS Decubitus ulcers are also known as pressure ulcers or bedsores. These lesions result when pressure is constantly put on a location of the body causing interruption of blood flow to that location. Without blood flow, the tissue dies and a lesion develops. Decubitus ulcers can become large and deep, even exposing the bone. They can lead to serious infections and death. The most common locations for decubitus ulcers are the hip, tailbone, ankles, elbows, and lower back. Persons most at risk for developing decubitus ulcers are those that remain in one position for long periods of time such as the elderly, bed bound patients, and patients who are in wheelchairs. DERMATITIS Dermatitis is a general term used to describe a swollen, red, itchy skin rash. There can be many causes of dermatitis including eczema, seborrhea, and contact with an irritant or allergen such as poison ivy. DIAPHORESIS Diaphoresis is excessive sweating or perspiration. It normally occurs with physical exertion, high environmental temperatures, strong emotions, menopause, and more. Diaphoresis is also associated with medical conditions such as but not limited to myocardial infarction, hyperthyroidism, and infections. If excessive sweating occurs and it is not related to any factors, it is termed hyperhidrosis. The terms diaphoresis and hyperhidrosis are sometimes used interchangeably. HERPES Herpes infections are caused by the herpes simplex virus (HSV). There are two types of HSV HSV 1 and HSV 2. HSV 1, sometimes called oral herpes, typically causes cold sores around the mouth and face. HSV 2, sometimes called genital herpes, causes lesions in the genital and buttocks areas. However, HSV 1 can cause genital herpes and HSV 2 can cause oral herpes. Herpes lesions are painful fluid-filled blisters. The blisters break open, ooze fluid, and form a crust. The lesions can last up to 10 days. The blisters may be accompanied by a fever, malaise, muscle aches, and swollen lymph nodes. In individuals with lowered immune system responses, HSV can cause more serious infections. After the initial exposure and outbreak, HSV has the ability to remain dormant in the individual. The virus can reactivate, usually during times of stress, illness, etc. and cause recurring outbreaks. 11

12 HIRSUTISM Hirsutism is the development of male-pattern hair growth in women. Women develop coarse pigmented hair on the face, chest, and back. The development of excess hair is related to high levels of androgens (male hormones) that can occur in conditions such as polycystic ovary syndrome, Cushing s disease, tumors, certain medications, and more. If androgen levels are sufficiently elevated, other male characteristics such as deepened voice, increased muscle mass, and decreased breast tissue occur. Sometimes there is no identifiable cause for hirsutism, and sometimes even normal androgen levels are present. IMPETIGO Impetigo is a highly infectious common skin infection seen frequently in pre-school or school aged children. It is caused by Streptococcus pyogenes (group A streptococcus) or Staphylococcus aureus bacteria. The common signs are red blisters or sores on the face, neck, and hands. Methicillin-resistant Staphylococcus aureus (MRSA) is becoming an important cause of impetigo, making it more difficult to treat. KELOID A keloid is the growth of excess scar tissue after a skin injury has healed. Keloids can be tender and itchy, and lumpy or ridged. They can be flesh color, red, or pink, and darken with exposure to the sun. Common skin injuries that may result in keloid formation include chickenpox, ear piercing, vaccination sites, acne, burns, and cuts from surgery or trauma. MILIARIA Miliaria is a common skin rash that occurs in conditions of increased heat and humidity. It is sometimes called heat rash or prickly heat. Miliaria is caused by blockage of the sweat ducts. The blockage results in sweat leaking into the epidermis or dermis. It is more common in infants and children whose sweat glands are not fully developed. MOLES The medical term for moles is nevi (singular nevus). Moles are usually brown or black growths on the skin. They can appear in clusters or alone. Some moles appear at birth; others develop in early childhood to early adulthood. It is normal for an adult to have moles. Any changes seen in a mole such as bleeding, rapid growth, change in color, etc. should be brought to the attention of a physician to assure it is not developing into skin cancer. SEBORRHEA Seborrhea, also called seborrheic dermatitis, is a common inflammatory skin condition. It causes flaky scales that are white to yellow in color, to develop on oily areas of the skin, especially the scalp, face, or inside the ear. In some cases, the skin may itch, and large areas of skin may become involved causing plaques. Plaques are areas on the skin where the color has changed. The cause of seborrhea is unknown. 12

13 ONYCHOCRYPTOSIS Onychocryptosis is the medical term for an ingrown toenail. Ingrown toenails occur when something alters the fit of the nail plate into the nail groove. The nail imbeds itself into the nail bed resulting in inflammation and pain. The common causes of ingrown toenails include trauma, ill-fitting shoes, and abnormal nail shape. ONYCHOMYCOSIS Onychomycosis is a fungal infection of the nails. It can occur in fingernails and toenails. The nails become thickened, brittle, and have a darkened color. The nail may even separate from the nail bed, a condition called onycholysis. Toenails get fungal infections more easily than fingernails as the warm moist environment is conducive to the growth of fungal organisms. Onychomycosis is difficult to treat and it often returns. PARASITIC INFESTATIONS The skin and hair are sites of several parasitic infestations. This includes ticks which imbed themselves into the skin and lice which attach to hair shafts. Lice are not known for spreading infections through the bites. However, ticks and other biting insects such as mosquitos can transmit diseases via their bites. For example, certain species of mosquitos transmit viral encephalitis, malaria, dengue, and yellow fever. Certain species of ticks can spread Lyme disease, Rocky Mountain Spotted Fever, babesiosis, and more. Painful skin lesions occur from the bites of these and other parasites such as chiggers, no see ums, fleas, etc. PARONYCHIA Paronychia is a common disorder of the perionychium, the epidermis bordering the nails. It can be acute or chronic, and it most frequently involves the fingernails. The infections are localized and superficial infections or abscesses can develop. Those at risk include individuals who bite their nails and those whose work places their hands in contact with water and irritants such as bakers, bartenders, and dishwashers. PSORIASIS Psoriasis is a common skin condition causing skin redness and irritation. Most people with psoriasis develop a thick, red skin with silver-white flaky patches called scales. The most commonly affected areas are the elbows, knees, and scalp. There are five types of psoriasis erythrodermic (intense skin redness over a large part of the body), guttate (small pink-red spots on the skin), inverse (redness and irritation in the armpits, groin, and in between overlapping skin), plaque (thick red patches covered by flaky silverwhite scales), and pustular (red irritated skin with white blisters). Plaque psoriasis is the most common type. Psoriasis is thought to be an autoimmune disorder where skin cells are not shed, but built up in layers on the skin. ROSACEA Rosacea is a little understood but common skin disorder affecting people over the age of 30. It causes redness on the nose, cheeks, chin, and forehead. Some people get 13

14 small bumps and pimples on the red areas. Affected areas of the skin can become coarser in texture and thickened. Attacks of rosacea can be triggered by hot baths, alcohol, stress, sun/wind exposure, exercise, and stress. RINGWORM Ringworm is a fungal infection of the skin. Almost all ringworm is called by a fungus in the Tinea species and the infection is often called tinea. The fungal infection causes a crusted rash that may itch. The rash often appears in a round ring-like pattern, hence the name ringworm. Athlete s foot and jock itch are two types of tinea infections. Tinea can also occur on the scalp, beard area, and skin throughout the body. SCABIES Scabies is a contagious itchy skin rash caused by the mite Sarcoptes scabiei. Female mites burrow into the skin making tunnels in which to lay eggs. Scabies is spread by close contact with someone who has the disease, and by sharing towels, bed sheets, personal belongings, and more. SKIN LESIONS Numerous terms are use to describe skin lesions. Some of the most common follow. Name Description Examples Crust Collection of dried serum and debris Impetigo, eczema Cyst Closed pockets of tissue filled with fluid, pus, or Sebaceous cysts other material Excortication Scratch, may be covered with dried blood Injury Fissure Linear crack from the epidermis to dermis Athlete s foot, dry skin Furuncle Infected inflamed pus-filled sore; boil Bacterial skin infections Macule Flat discolored area of the skin < 1 cm wide Freckle, vitiligo, rosacea Papule Solid, raised spot on the skin up to 0.5 cm wide Scabies, fungal infections Plaque Small flat scaly area of skin Psoriasis Pustule Small elevations on the skin containing fluid or Acne, folliculitis pus; can be either white or red Ulcer Sore accompanied by loss of tissue Decubitus ulcer, certain infections Vesicle Small serum-filled blister formed in or beneath the skin Contact dermatitis, herpes, chickenpox Wheal A rounded or flat-topped, pale red papule or plaque Hives, mosquito bite URTICARIA Urticaria is a raised red itchy skin rash commonly called hives. Urticaria is almost always caused by an allergic reaction. Allergies can be to foods, medications, insect stings, and more. VARICELLA ZOSTER Varicella zoster is two diseases caused by the varicella zoster virus (VZV): varicella (chickenpox) and zoster (shingles). Initial infection with VZV causes chickenpox, generally a mild, self-limited childhood infection with a characteristic red rash. Later in 14

15 life, the virus, which has remained dormant in nerve cells, can reactivate causing shingles, a painful rash in a prescribed area of innervation called a dermatome. Pain can remain after the rash has resolved. VITILIGO Vitiligo is the loss of skin color pigment resulting in patches of lighter color skin. It occurs in all races and ethnicities. Some people develop only a few patches; others lose large areas of skin color. While skin is most often affected, patches of hair can turn white, and the iris of the eye can lose color. WARTS Common warts are caused by the human papillomavirus (HPV). These warts are small rough growths most often appearing on the fingers or hands. Certain types of HPV (there are more than 100 types) cause genital warts. Warts are transmitted by touch. Most warts are harmless and go away on their own. However, some of the HPV types that cause genital warts are associated with the development of cancer of the cervix. MEDICAL TERMS COMBINING FORM COMBINED WITH MEDICAL TERM DEFINITION Derm/o epi-/-al Epidermal Pertaining to upon the skin Dermat/o -itis Dermatitis Inflammation of the skin Cutane/o sub-/ -ous Subcutaneous Pertaining to under the skin Hidr/o an-/-osis Anhidrosis No sweat Lip/o -cyte Lipocyte Fat cell Lip/o -oma Lipoma Fat mass Onych/o -ectomy Onychectomy Removal of a nail Melan/ -oma Melanoma Black tumor Seborrhea -rrhea Seborrhea Oily discharge REFERENCES Blesi, M., Wise, B., & Kelley-Arney, C. (2012). Medical Assisting: Administrative & Clinical Competencies (7 th ed). Clifton Park, NY: Delmar, Cengage Learning De Burgh, J. (2007). The Human Body: An Essential Guide to How the Body Works. San Diego, CA: Thunder Bay Press Fremgen, B.F., & Frucht, S. S. (2009). Medical Terminology: A Living Language (4 th ed). Upper Saddle River, NJ: Pearson Education, Inc Integumentary System. InnerBody. Accessed 7 December 2013 Layers of the Skin. National Institutes of Health. Accessed 9 December 2013 Marieb, E.N. (2009). Essentials of Human Anatomy and Physiology (9 th ed). San Francisco, CA: Pearson Education, Inc Skin (Integumentary System). University of Pennsylvania Health system. Accessed 26 March

16 QUESTIONS Structures and Functions of the Integumentary System # Directions: Before taking this test, read the instructions on how to complete the answer sheets correctly. If taking the test online, log in to your User Account on the NCCT website Select the response that best completes each sentence or answers each question from the information presented in the module. If you are having difficulty answering a question, go to and select Forms/Documents. Then select CE Updates and Revisions to see if course content and/or a test questions have been revised. If you do not have access to the internet, call Customer Service at The skin of an average person covers approximately how many square feet? a. 15 b. 22 c. 3,000 d. 5, Which of the following represents the layers of the skin from innermost to outermost? a. Dermis, epidermis, subcutis b. Epidermis, dermis, subcutis c. Epidermis, subcutis, dermis d. Subcutis, dermis, epidermis 3. Which of the following epidermal layers contain melanocytes? a. Basal cell b. Squamous cell c. Stratum granulosum/stratum lucidum d. Stratum corneum 4. Keratinocytes contain keratin, a tough protective protein that makes up most of the structure of the. a. hair b. nails c. skin d. All contain keratin 16

17 5. Which layer of the skin contains blood vessels? a. Dermis b. Epidermis c. Subcutis d. All layers contain blood vessels 6. What is the purpose of collagen and elastin? a. Distributes infection-fighting cells b. Provides nourishment to the skin c. Provides skin with strength and resilience d. Regulates temperature of the epidermis 7. Nerve receptors for pain and touch are found in which of the following layers of skin? a. Dermis b. Epidermis basal cell layer c. Epidermis stratum corneum d. Subcutis 8. Which layer of the skin contains stores of fat as an energy reserve for the body? a. Dermis b. Papillary layer of the dermis c. Reticular layer of the dermis d. Subcutis 9. One of the functions of hair is to. a. keep the skin from getting too warm b. prevent oil from accumulating on the skin c. protect the body from UV radiation d. supply nutrients to the body 10. Which type of hair covers most of the body of adults? a. Lanugo b. Terminal c. Sub-terminal d. Vellus 11. Which type of hair can appear in adults as part of certain disease processes? a. Lanugo b. Terminal c. Sub-terminal d. Vellus 17

18 12. Which portion of the hair exits the skin? a. Follicle b. Root c. Medulla d. Shaft 13. In what portion of the hair are the majority of the pigment-producing cells found? a. Cortex b. Cuticle c. Follicle d. Medulla 14. The pale crescent-shaped area located at the base of the nail is called the. a. body b. free edge c. lunula d. root 15. What is the medical term for the cuticle? a. Epidermis b. Eponychium c. Lanugo d. Lunula 16. Olfactory communication is the function of which of the following glands? a. Apocrine b. Ceruminous c. Eccrine d. Mammary 17. Which of the following glands function to regulate body temperature? a. Apocrine b. Ceruminous c. Eccrine d. Mammary 18. Secretions from which of the following glands have antimicrobial properties? a. Apocrine b. Eccrine c. Mammary d. Sebaceous 18

19 19. Which of the following is the cause of acne? a. Increased levels of androgens b. Increased production of sebum c. Blockage of hair follicles d. All can contribute to acne 20. Malformed blood vessels cause the development of. a. alopecia areata b. anhidrosis c. carbuncles d. hemangiomas 21. Which of the following is considered the most serious form of skin cancer? a. Basal cell carcinoma b. Melanoma c. Squamous cell carcinoma d. All can be serious forms of cancer 22. The most common type of breast cancer is. a. ductal carcinoma in situ b. infiltrating lobular carcinoma c. invasive ductal carcinoma d. lobular carcinoma in situ 23. Bed-bound people are at risk for developing. a. Boils b. Decubitus ulcers c. Dermatitis d. Diaphoresis 24. Which of the following can recur without reexposure to the infectious agent? a. Herpes b. Impetigo c. Rocky Mountain Spotted Fever d. Miliaria 25. Onychomycosis is caused by a/an. a. bacterial infection b. fungal infection c. mosquito bite d. tick bite 19

20 26. Which of the following is thought to be an autoimmune disorder? a. Psoriasis b. Ringworm c. Rosacea d. Scabies 27. A skin lesion described as a flat discolored area of the skin less than 1 cm wide is a/an. a. Excortication b. Furuncle c. Macule d. Papule 28. Which of the following can appear years after a chickenpox infection? a. Urticaria b. Varicella c. Vitiligo d. Zoster 29. Which of the following viruses is the cause of the common wart? a. HPV b. HSV c. VZV d. Warts are not caused by a virus *End of Test* 20