anatomy & physiology for health professions: an interactive journey

Anatomy & Physiology for Health Professions:An Interactive Journey, 1eBruce J. Colbert, Jeff Ankney, and Karen Lee

Copyright ©2007 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458

All rights reserved.

Anatomy &Physiologyfor Health Professions:An Interactive Journey

Chapter 7

The Integumentary System:The Protective Covering

Bruce J. ColbertJeff AnkneyKaren Lee




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.




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




Pronunciation Guide

Apocrine GlandsCaroteneCoriumEccrine GlandsEpidermisEpithelial TissueKeratinKeratinizationLesionLunalaMelanin

(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)

Click on the megaphone icon before each item to hear the pronunciation.




Pronunciation Guide (cont’d)

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)

Click on the megaphone icon before each item to hear the pronunciation.




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




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




Figure 7-1 The three layers of the skin.




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.




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.




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.




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.




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.




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.




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)




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.




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.




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.




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.




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.




Figure 7-2 Sweat and sebaceous glands.




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.




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.




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.




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.




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.




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.




Figure 7-3 Wound repair.




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

Back to Directory




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




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.




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.




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.




Fourth Degree Burns

• Fourth degree burns are the worst burns.• These burns penetrate the bone and cause

bone damage.




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%




Figure 7-4 Assessing the degree of the burn.




Clinical Concerns

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




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.




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.




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).




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.




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.




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.




Figure 7-5 Structure of the fingernail.




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.




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.




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.




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.




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.




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.




Figure 7-6 Diagram of a hair follicle.




Hair Color and Texture• Your hair color is dependent on the amount and

type of melanin you produce.• The more melanin, the darker your hair.• White hair occurs in the absence of melanin.• Red hair is the result of hair that has melanin with

iron in it.• Flat hair shafts produce curly hair, while round

hair shafts produce straight hair.• The life span of hair is dependent on location, with

eyelashes lasting 3–4 months while the hair on your head lasts 3–4 years (unless you’re a teacher – we pull our hair out before then!).




Applied Science:Forensics and Hair

• An interesting sidelight concerning hair is its ability to tell a pathologist if an individual ingested certain drugs or other substances such as lead or arsenic! Trace amounts of ingested substances can become part of the hair’s composition. As a result, analysis of a hair sample can reveal what and how long ago something was ingested. The longer the length of hair, the longer the record of what was consumed by that individual.




Temperature Regulation• The integumentary system plays a major role in

the regulation of the body’s temperature.• Part of the regulation of temperature is

accomplished by changes in the size of the blood vessels. Vasodilation exposes heated blood to external cooling air. Vasoconstriction keeps cooling of blood to a minimum when it’s cold outside.




Temperature Regulation (cont’d)

• Sweat glands excrete water onto the skin’s surface, allowing cooling through evaporation. This requires adequate hydration to continue to produce sweat. By the time you feel thirsty you’re already dehydrating. You can potentially secrete 12 liters of sweat in a 24 hour period.




Shivering• Shivering causes muscle activity that produces

heat to warm you when you’re cold.• Hairs on your skin stand erect when arrector pili

muscles contract; this is known as goose bumps. These hairs create a dead space insulating you from cooler surroundings, like a goose down jacket.




Figure 7-7 Integumentary regulation of body temperature.




Diseases of the Skin

• There are whole sections of medical libraries dedicated to diseases of the skin.

• A lesion is a single infected patch of skin.• In addition to lesions there are many common

pathological conditions of the integumentary system.




Figure 7-8 Various types of skin lesions.




Table 7-1 Common Pathological Conditions of the Integumentary System




Table 7-1 (continued) Common Pathological Conditions of the Integumentary System




Snapshots from the Journey• Your skin is your largest organ; it acts as a

barrier to infection and injury; helps to keep you from drying out; stores fat; synthesizes and excretes vitamin D; regulates body temperature; provides a minor excretory function in the elimination of water, salts, and urea; and provides sensory input.

• The skin is composed of 3 layers, constantly recreating itself. Glands secrete oil to moisturize, waterproof, and control body temperature.




Snapshots from the Journey (cont’d)

• Burns are assessed by depth of burn and area covered.

• Nails are protective devices composed of dead material.

• Hair (also dead material) aids in controlling body temperature.




Case Study

A 27-year-old female presents to her doctor’s office with complaints of red, itching, and oozing skin for the past 2 days. Physical exam and history reveal a well-nourished, white female who is otherwise in good health, has no known allergies, normal vital signs, pupils are normal and reactive, has good reflexes, normal breath sounds, liquid filled vesicles, and scabbing on both legs from the top of her sock lines to the bottom of her shorts, and new vesicles have formed around her eyes. The patient states that she returned from a primitive camping and hiking vacation in Virginia two days ago. Based on the case study information, what do you think the diagnosis is? What caused the vesicles to begin to form around her eyes?




End of ChapterReview Questions

1. The substance that is mainly responsible for skin color is:a. Melanin

b. Pigmentin

c. Carrots

d. Luna





2. Whether you have naturally curly or straight hair is dependent on the shape of youra. Hair follicle

b. Hair shaft

c. Sebum

d. Melanin





3. The fibrous protein that makes up your hair and nails is called and filled your epidermal cells is called:a. Carotene

b. Myelin

c. Keratin

d. Dermasene





4. In a cold environment, in order to maintain a core body temperature, peripheral blood vessels will:a. Vasodilate

b. Venospasm

c. Shiver

d. Vasoconstrict





5. The hair on your scalp can last:a. 3 to 4 months

b. Until your 40s

c. 3 to 4 years

d. Until you have kids





6. The three main layers of skin are the _______, ________, and ________ .

7. The two main types of sweat glands are the ______ and the _______ glands.

8. Sebaceous glands secrete an oily substance called __________ .

9. For some individuals, melanin locates in small patches called _________ .

10. Yellow jaundice, a condition associated with liver disease, occurs as a result of the build-up of _________.





11. Discuss three functions of the integumentary system.

12. Discuss the functions of sebum.

13. Why is there an increased production of melanin when there is an increased sun exposure?

14. How does the integumentary system assist in the regulation of body temperature?

anatomy & physiology for health professions: an interactive journey

Documents