chapter 6 the integumentary system and body membranes
TRANSCRIPT
Chapter 6The Integumentary System and
Body Membranes
ObjectivesO Classify, compare the structure of, and give
examples of each type of body membraneO Describe the structure and function of the
epidermis and dermisO List and briefly describe each accessory organ of
the skinO List and discuss the three primary functions of the
integumentary systemO List and describe major skin disorders and
infectionsO Classify burns and describe how to estimate the
extent of a burn injury2
Classification of Body Membranes
O Classification of body membranes O Epithelial membranes—composed of
epithelial tissue and an underlying layer of connective tissue
O Connective tissue membranes—composed exclusively of various types of connective tissue
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Classification of Body Membranes
O Epithelial membranesO Cutaneous membrane—the skinO Serous membranes—simple
squamous epithelium on a connective tissue basement membraneO Parietal—line walls of body cavitiesO Visceral—cover organs found in body
cavities
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Classification of Body Membranes
O ExamplesO Pleura—parietal and visceral layers
line walls of thoracic cavity and cover the lungs
O Peritoneum—parietal and visceral layers line walls of abdominal cavity and cover the organs in that cavity
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Classification of Body Membranes
O DiseasesO Pleurisy—inflammation of the serous
membranes that line the chest cavity and cover the lungs
O Peritonitis—inflammation of the serous membranes in the abdominal cavity that line the walls and cover the abdominal organs
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Classification of Body Membranes
O Mucous membranesO Line body surfaces that open directly
to the exteriorO Produce mucus, a thick secretion that
keeps the membranes soft and moist
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Classification of Body Membranes
O Connective tissue membranesO Do not contain epithelial componentsO Produce a lubricant called synovial
fluidO Examples
O The synovial membranes in the spaces between joints and in the lining of the bursal sacs
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The SkinO Structure—two primary layers called
epidermis and dermisO Epidermis
O Outermost and thinnest primary layer of skin
O Composed of several layers of stratified squamous epithelium
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The SkinOStructure
O EpidermisO Stratum germinativum—innermost (deepest) layer of
cells that continually reproduce; new cells move toward the surface
O Sometimes called the pigment layerO Pigment cells called melanocytes, which produce the
brown pigment melanin
O As cells approach the surface, they are filled with a tough, waterproof protein called keratin and eventually flake off
O Stratum corneum—outermost layer of keratin-filled cells12
The SkinOStructure
O EpidermisO Skin color changes
O Pink flush indicates increased blood volume or increased blood oxygen
O Cyanosis—bluish gray color indicates decreased blood oxygen level
O Vitiligo—patchy light skin areas resulting from acquired loss of epidermal melanocytes (Figure 6-4)
O Increased skin pigmentation caused by hormonal changes in pregnant women
O Freckles—small, flat macules—common normal skin pigment variation
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The SkinO Dermal-epidermal junction—
specialized area of contact between the epidermis and dermis; sometimes described as “spot welds”O Provide support for epidermisO Weakened or destroyed junctions can
cause blisters
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The SkinOStructure
O DermisO Deeper and thicker of the two primary skin layers
and composed largely of connective tissueO Upper area of dermis characterized by parallel rows
of peglike dermal papillaeO Thick skin has parallel friction ridges and no hairs O Thin skin has irregular, shallow grooves and hair O Deeper area of dermis is filled with network of
tough collagenous and stretchable elastic fibers
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The SkinO Structure
O DermisO Number of elastic fibers decreases with
age and contributes to wrinkle formation
O Striae—“stretch marks”; elongated marks caused by overstretching of skin
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The SkinO Structure
O DermisO Dermis also contains nerve endings,
muscle fibers, hair follicles, sweat and sebaceous glands, and many blood vessels
O Birthmarks—malformation of dermal blood vessels
O Strawberry hemangiomaO Port-wine stainO Stork bite
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The SkinO Appendages of the skin
O Hair O Soft hair of fetus and newborn called
lanugoO Hair growth requires epidermal tubelike
structure called hair follicleO Hair growth begins from hair papilla
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The SkinO Appendages of the skin
O HairO Hair root lies hidden in follicle; visible
part of hair called shaftO Alopecia (Figure 6-8)—hair lossO Arrector pili—specialized smooth
muscle that produces “goose pimples” and causes hair to stand up straight
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The SkinOAppendages of the skin
OReceptors OSpecialized nerve endings—make it
possible for skin to act as a sense organOMeissner (tactile) corpuscle—capable of
detecting light touchOLamellar (Pacini) corpuscle—capable of
detecting pressure24
The SkinONails
O Produced by epidermal cells over terminal ends of fingers and toes
O Visible part called nail bodyO Root lies in a groove and is hidden by cuticleO Crescent-shaped area nearest root called
lunulaO Nail bed may change color with change in
blood flow25
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The SkinO Nails
O Normal variations in nail structureO Longitudinal ridges in light-skinned
individualsO Pigmented bands in dark-skinned
individuals
O Abnormal variations in nail structureO Onycholysis—separation of nail from
nail bedO Pitting—common in psoriasis
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The Skin
OSkin glands—two main typesOSweat, or sudoriferous
OSebaceous 29
The SkinO Skin glands
O Sweat, or sudoriferous, glandsO Eccrine sweat gland
O Most numerous, important, and widespread of the sweat glands
O Produce perspiration or sweat, which flows out through pores on skin surface
O Function throughout life and assist in body heat regulation
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The SkinO Skin glands
O Sweat or sudoriferous glandsO Apocrine sweat glands
O Found primarily in axilla and around genitalia
O Secrete a thicker, milky secretion quite different from eccrine perspiration
O Breakdown of secretion by skin bacteria produces odor
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The SkinO Skin glands
O Sebaceous glandsO Secrete oil or sebum for hair and skinO Secretion increases during adolescenceO Amount of secretion regulated by sex
hormonesO Sebum in sebaceous gland ducts may
darken to form a blackheadO Acne vulgaris—inflammation of
sebaceous gland ducts
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Functions of the Skin OProtection—first line of defense
O Against infection by microbesO Against ultraviolet rays from sunO Against harmful chemicalsO Against cuts and tearsO Bruising can cause discoloration as blood
released from damaged vessels breaks down O Skin grafts may be needed to replace skin
destroyed by disease or trauma 34
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Functions of the SkinO Temperature regulation
O Skin can release almost 3000 calories of body heat per day
O Mechanisms of temperature regulationO Regulation of sweat secretionO Regulation of flow of blood close to the
body surface
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Functions of the SkinO Sense organ activity
O Receptors serve as receivers for the body, keeping it informed of changes in its environment
O Skin can detect sensations of light touch, pressure, pain, heat, and color
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Disorders of the Skin (Dermatoses)
OSkin lesions—any measurable variation from the normal structure O Elevated lesions—cast a shadow outside
their edgesO Papule—small, firm raised lesionO Plaque—large raised lesionO Vesicle—blisterO Pustule—pus-filled lesionO Crust—scabO Wheal (hive)—raised, firm lesion with a light center
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Disorders of the Skin (Dermatoses)
O Flat lesions—do not cast a shadowO Macule—flat, discolored region
O Depressed lesions cast a shadow within their edgesO Excoriation—missing epidermis, as in a scratch O Ulcer—craterlike lesionO Fissure—deep crack or break
O Some lesions are produced by scrapes and cuts—the skin can repair itself
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Burns O Treatment and recovery or survival depend on
total area involved and severity or depth of the burn
O Classification of burns O First-degree (partial-thickness) burns—only
surface layers of epidermis involvedO Second-degree (partial-thickness) burns—involve
deep epidermal layers; always cause injury to upper layers of the dermis
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BurnsO Classification of burns
O Third-degree (full-thickness) burns—characterized by complete destruction of the epidermis and dermisO May involve underlying muscle and bone (fourth
degree)O Lesion is insensitive to pain because of destruction
of nerve endings immediately after injury—intense pain is experienced soon thereafter
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BurnsOEstimating body surface area using the “rule of nines” in adultsOBody divided into 11 areas of 9% each
OAdditional 1% of body surface area around genitals 46
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Skin Infections O Impetigo—highly contagious
staphylococcal or streptococcal infectionOTinea—fungal infection (mycosis) of the
skin; several forms occurOWarts—benign neoplasm caused by
papillomavirusOBoils—furuncles; staphylococcal
infection in hair folliclesOScabies—parasitic infection
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Vascular and Inflammatory Skin
Disorders ODecubitus ulcers (bedsores) develop when pressure slows down blood flow to local areas of the skin
OUrticaria or hives—red lesions caused by fluid loss from blood vessels
OScleroderma—disorder of vessels and connective tissue characterized by hardening of the skin; two types: localized and systemic 50
Vascular and Inflammatory Skin
DisordersO Psoriasis—chronic inflammatory
condition accompanied by scaly plaques
O Eczema—common inflammatory condition characterized by papules, vesicles, and crusts; not a disease itself but a symptom of an underlying condition
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Skin Cancer O Three common types
O Squamous cell carcinoma—the most common type, characterized by hard, raised tumors
O Basal cell carcinoma—characterized by papules with a central crater; rarely spreads
O Melanoma—malignancy in a nevus (mole); the most serious type
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Skin CancerO The most important causative factor
in common skin cancers is exposure to sunlight
O Kaposi sarcoma, characterized by purple lesions, is associated with AIDS and other immune deficiencies
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