4: Skin and Body Membranes
Which structure(s) are responsible for fingerprints?
The dermal papillae in the papillary layer of the dermis are responsible for fingerprints.
also called covering and lining membranes, include the cutaneous membrane (skin), the mucous membranes, and the serous membrane
The epithelial membranes
Tissue damage and cell death caused by intense heat, electricity, UV radiation (sunburn), or certain chemicals (such as acids), which denature proteins and cause cell death in the affected areas
burn
Pigment in the stratum corneum and subcutaneous tissue
carotene
represented by synovial membranes
connective tissue membranes,
Functions of body membranes
cover surfaces, line body cavities, and form protective (and often lubricating) sheets around organs
The skin appendages include:
cutaneous glands, hair and hair follicles, and nails
The _____________ is the most heavily keratinized region; it provides strength and helps keep the inner hair layers tightly compacted
cuticle
When hemoglobin is poorly oxygenated, both the blood and the skin of light-skinned people appear blue, a condition called ____________
cyanosis
As we age, the number of collagen and elastic fibers ____________, and the __________________________ loses fat. As a result, the skin loses its elasticity and begins to sag and wrinkle.
decreases, subcutaneous tissue
two types of sweat glands
eccrine and apocrine
The cutaneous glands are all __________________ glands that release their secretions to the skin surface via ducts.
exocrine
Sunburn without blistering is a
first degree burn
In _____________________- burns, only the superficial epidermis is damaged. The area becomes red and swollen. Except for temporary discomfort, they are not usually serious and generally heal in two to three days
first-degree
Papillary patterns are __________________ determined
genetically
Hair pigment is made by melanocytes in the __________, and varying amounts of different types of melanin
hair bulb
A ____________ is a flexible epithelial structure. The part of the hair enclosed in the hair follicle is called the ________, and the part projecting from the surface of the scalp or skin is called the _______
hair, root, shaft
Pigment in the dermal blood vessels
hemoglobin
Deep to the dermis is the subcutaneous tissue, or ____________________, which essentially is adipose (fat) tissue. It is not considered part of the skin, but it does anchor the skin to underlying organs and provides a site for nutrient storage.
hypodermis
The stratum basale of the epidermis extends beneath the nail as the __________________. Its thickened proximal area, called the ________________, is responsible for nail growth
nail bed, nail matrix
The borders of the nail are overlapped by folds of skin called __________________. The edge of the thick proximal nail fold is commonly called the cuticle
nail folds, cuticle
This latter epidermal layer is not present in all skin regions. It occurs only where the skin is hairless and extra thick, that is, on the palms of the hands and soles of the feet.
stratum lucidum
the ABCDE rule for recognizing melanoma:
(A) Asymmetry. Any two sides of the pigmented spot or mole do not match. (B) Border irregularity. The borders of the lesion are not smooth but exhibit indentations. (C) Color. The pigmented spot contains areas of different colors (black, brown, tan, and sometimes blue or red). (D) Diameter. The lesion is larger than 6 millimeters (mm) in diameter (the size of a pencil eraser). (E) Evolution. One or more of these characteristics (ABCD) is evolving, or changing.
What name is given to the rule for recognizing the signs of melanoma?
ABCDE rule.
Is the least malignant and most common skin cancer
Basal cell carcinoma
Why do no skin cancers develop from stratum corneum cells?
Because stratum corneum cells are dead and thus no longer are dividing.
give the skin its elasticity when we are young
Elastic fibers
What are the criteria for classifying burns as first-, second-, third-, or fourth-degree?
First-degree burns are red and swollen; only epidermis damaged. Second-degree burns damage the epidermis and the superficial part of the dermis; blisters appear, but epithelial regeneration can occur. Third-degree burns destroy the entire skin thickness and can extend into the subcutaneous tissue; the burn is gray and painless; must graft. Fourth-degree burns destroy all layers of the skin; appear charred; extend into deep tissues such as muscle or bone.
___________________ burns are also full-thickness burns, but they extend into deeper tissues such as bone, muscle, or tendons. These burns appear dry and leathery, and they require surgery and grafting to cover exposed tissue. In severe cases, amputation may be required to save the patient's life.
Fourth-degree
________________________________ is a cancer of melanocytes. It accounts for only about 5 percent of skin cancers, but it is often deadly
Malignant melanoma
What pigments determine skin color?
Melanin, carotene, and hemoglobin all contribute to skin color.
________________________________________ arises from the cells of the stratum spinosum. The lesions appear as scaly, reddened papules (small, rounded swellings) that gradually form shallow ulcers with firm, raised borders (Figure 4.11b). This variety of skin cancer appears most often on the scalp, ears, back of the hands, and lower lip, but can appear anywhere on the skin. It grows rapidly and metastasizes to adjacent lymph nodes if not removed. This epidermal cancer is also believed to be induced by UV exposure. If it is caught early and removed surgically or by radiation therapy, the chance of complete cure is good
Squamous cell carcinoma
Serves as a shock absorber and insulates the deeper tissues from extreme temperature changes occurring outside the body. It is also responsible for the curves that are more a part of a woman's anatomy than a man's.
Subcutaneous tissue
Are composed of loose areolar connective tissue and contain no epithelial cells at all
Synovial membranes
These membranes line the fibrous capsules surrounding joints , where they provide a smooth surface and secrete a lubricating fluid. They also line small sacs of connective tissue called bursae and the tube-like tendon sheaths
Synovial membranes
When the skin is burned and its cells are destroyed, two life-threatening problems result.
1. Without an intact boundary, the body loses its precious supply of fluids containing proteins and electrolytes as these seep from the burned surfaces 2. Infection
Is composed of a layer of simple squamous epithelium resting on a thin layer of areolar connective tissue
A serous membrane, or serosa,
When sebaceous gland ducts are blocked by sebum, acne appears on the skin surface. __________ is an active infection of the sebaceous glands. If the accumulated material oxidizes and dries, it darkens, forming a _____________________. If the material does not dry or darken, a _____________ forms.
Acne, blackhead, whitehead
Are largely confined to the axillary (armpit) and genital areas of the body. They are usually larger than eccrine glands, and their ducts empty into hair follicles.
Apocrine glands
Their secretion contains fatty acids and proteins, as well as all the substances present in eccrine sweat; consequently, it may have a milky or yellowish color. The secretion is odorless, but when bacteria that live on the skin use its proteins and fats as a source of nutrients for their growth, it can take on a musky, sometimes unpleasant odor.
Apocrine glands
begin to function during puberty under the influence of androgens
Apocrine glands
An itchy, red, peeling condition of the skin between the toes, resulting from an infection with the fungus Tinea pedis
Athlete's foot
Are caused by inflammation of hair follicles and surrounding tissues, commonly on the dorsal neck
Boils
How do secretions of apocrine glands differ from those of the eccrine sweat glands?
Both are dilute salt solutions containing vitamins and wastes. Apocrine secretion also contains proteins and fatty acids.
Are clusters of boils often caused by the bacterium Staphylococcus aureus.
Carbuncles
In which epidermal layer do cells begin to die?
Cells begin to die as they leave the stratum granulosum.
What change in aging skin accounts for wrinkles and cold intolerance in older adults?
Loss of subcutaneous fat.
Small fluid-filled blisters that itch and sting, caused by human herpesvirus 1 infection. The virus localizes in a cutaneous nerve, where it remains dormant until activated by emotional upset, fever, or UV radiation. Usually occur around the lips and in the oral mucosa of the mouth and nose
Cold sores (fever blisters)
are responsible for the toughness of the dermis; they also attract and bind water and thus help to keep the skin hydrated
Collagen fibers
Itching, redness, and swelling of the skin, progressing to blistering. It is caused by exposure of the skin to chemicals (such as those in poison ivy) that provoke allergic responses in sensitive individuals
Contact dermatitis
Pink, fluid-filled, raised lesions (commonly around the mouth and nose) that develop a yellow crust and eventually rupture (Figure 4.9b). Caused by highly contagious staphylococcus or streptococcus infections, impetigo is common in elementary school-aged children
Impetigo
You have just gotten a paper cut, but it doesn't bleed. Which layer(s) of the skin has/have the cut penetrated?
Just the epidermis.
What cell type is most abundant in the epidermis?
Keratinocytes are the most abundant cell type in the epidermis.
Where would you find a synovial membrane?
Lining a fibrous capsule surrounding a joint.
What are the two life-threatening consequences of a severe burn?
Loss of body fluids containing needed proteins and electrolytes, resulting in circulatory shock, and overwhelming infection.
____________, a pigment that ranges in color from yellow to brown to black, is produced by special spider-shaped cells called melanocytes, found chiefly in the _________________. Freckles and moles are seen where melanin is concentrated in one spot
Melanin, stratum basale
Seen here and there at the epidermal-dermal junction are ____________________________, which are associated with sensory nerve endings and serve as touch receptors called Merkel discs.
Merkel cells
When a factory worker caught his finger in a machine, the entire nail, plus the nail matrix and bed, was torn off. Will his nail grow back? Why or why not?
No, the nail won't regrow, because the growth region (nail matrix) is torn off.
A scalpel penetrates the left lung and enters the heart. Name the six serous membrane layers the blade passes through as it moves from the body surface into the heart.
Parietal pleura, visceral pleura, (lung), visceral pleura, parietal pleura, parietal pericardium, visceral pericardium, (heart).
important functions of the integumentary system
Protects deeper tissues, aids in body heat loss or heat retention, aids in excretion of urea and uric acid, synthesizes vitamin D
Characterized by reddened epidermal lesions covered with dry, silvery scales that itch, burn, crack, and sometimes bleed. A chronic condition, psoriasis is believed to be an autoimmune disorder in which the immune system attacks a person's own tissues, leading to the rapid overproduction of skin cells. Attacks are often triggered by trauma, infection, hormonal changes, or stress. When severe, psoriasis may be disfiguring.
Psoriasis
________________________ burns involve injury to the epidermis and the superficial part of the dermis. The skin is red, painful, and blistered. Because sufficient numbers of epithelial cells are still present, regrowth (regeneration) of the epithelium can occur. Ordinarily, no permanent scars result if care is taken to prevent infection
Second-degree
How do the body locations of serous and mucous membranes differ?
Serous membranes line ventral body cavities closed to the exterior. Mucous membranes line body cavities open to the exterior (respiratory, digestive, urinary, and reproductive organ cavities).
_____________________________ occur in pairs. The _________________ layer lines a specific portion of the wall of the ventral body cavity. It folds in on itself to form the visceral layer, which covers the outside of the organ(s) in that cavity.
Serous membranes, parietal, visceral,
This method divides the body into 11 areas, each accounting for 9 percent of the total body surface area, plus an additional area surrounding the genitals (the perineum) representing 1 percent of body surface area
The rule of nines
What is the source of the vernix caseosa that covers the skin of the newborn baby?
The sebaceous glands of the baby.
Which of the cutaneous gland types can make your hair limp and oily?
The sebaceous glands, which produce oily secretions.
Explain the relationships between the words skin, cutaneous membrane, integument, and integumentary system.
The skin is the epithelial membrane that covers the body surface. Cutaneous membrane is a synonym for skin, as is integument, which means "covering." The integumentary system is the skin and its derivatives (nails, hair, glands).
Which layer of the epidermis produces new epidermal cells?
The stratum basale.
Excess shedding of dead cells from the superficial layer of the skin of the scalp causes dandruff. What is the name of that skin layer?
The stratum corneum.
_____________________ burns destroy both the epidermis and the dermis and often extend into the subcutaneous tissue, reflecting their categorization as full thickness burns. Blisters are usually present, and the burned area appears blanched (gray-white) or blackened. Because the nerve endings in the area are destroyed, the burned area is not painful.
Third-degree
True or False: The dermis has a rich blood and nerve supply
True
What is the single most common risk factor for skin cancer?
UV radiation exposure (sun or tanning bed).
Sweat is _________ (pH from 4 to 6), a characteristic that inhibits the growth of certain bacteria, which are always present on the skin surface
acidic
The epithelium of mucosae is often
adapted for absorption or secretion
Small bands of smooth muscle cells—________________—connect each side of the hair follicle to the dermal tissue. When these muscles contract (as when we are cold or frightened), the hair is pulled upright, dimpling the skin surface with "goose bumps."
arrector pili
Like all other epithelial tissues, the epidermis is ________________; that is, it has no blood supply of its own
avascular
The ________________ are far more numerous and are found all over the body. They produce sweat, a clear secretion that is primarily water plus some salts (sodium chloride), vitamin C, traces of metabolic wastes (ammonia, urea, uric acid), and lactic acid (a chemical that accumulates during vigorous muscle activity)
eccrine glands
Scattered in the epidermis are _________________________________, which are important "sentries" that alert and activate immune system cells to a threat such as bacterial or viral invasion.
epidermal dendritic cells
The two major categories of body membranes—___________________________—are classified in part according to their ___________________
epithelial and connective tissue, tissue makeup.
include the cutaneous, mucous, and serous membranes
epithelial membranes
Two major groups of body membranes:
epithelial membranes and connective tissue membranes
Hair follicles are actually compound structures. The _________________________ is composed of epithelial tissue and forms the hair. The _________________ is actually dermal connective tissue. This dermal region supplies blood vessels to the epidermal portion and reinforces it. Its nipplelike hair papilla provides the blood supply to the matrix in the hair bulb
inner epithelial root sheath, outer fibrous sheath
Most cells of the epidermis are _____________________________, which produce keratin, the fibrous protein that makes the epidermis a tough protective layer in a process called keratinization. These keratinocytes are connected by __________________________ throughout the epidermis
keratinocytes (keratin cells), desmosomes
Pigment in epidermis
melanin
Three pigments contribute to skin color:
melanin, carotene, and hemoglobin
Lines all body cavities that open to the exterior body surface
mucus membrane
A __________________ is composed of epithelium (the type varies with the site) resting on a loose connective tissue membrane called a lamina propria
mucous membrane
In contrast to mucous membranes, which line ____________________________, serous membranes line body cavities ______________________________ (except for the dorsal body cavity and joint cavities).
open body cavities, that are closed to the exterior
The ______________ is the superficial dermal region. It is uneven and has peg-like projections from its superior surface, called dermal papillae, which indent the epidermis above
papillary layer
The connective tissue making up the dermis consists of two major regions—the ______________ and the _________________ areas, which are composed of ____________ and __________________________________________, respectively
papillary, reticular, areolar, dense irregular connective tissue
The serosa lining the abdominal cavity and covering its organs is the ______________________
peritoneum
The membranes surrounding the lungs are the __________________; those around the heart are the ________________
pleurae, pericardia
It contains dense irregular connective tissue, as well as blood vessels, sweat and oil glands, and deep pressure receptors called lamellar corpuscles
reticular layer
the deepest skin layer
reticular layer
The __________________, or oil glands, are found all over the skin, except on the palms of the hands and the soles of the feet
sebaceous glands
two groups of cutaneous glands
sebaceous glands and sweat glands.
The product of the sebaceous glands, a mixture of oily substances and fragmented cells
sebum
a lubricant that keeps the skin soft and moist and prevents the hair from becoming brittle
sebum
contains chemicals that kill bacteria, so it is important in preventing bacterial infection of the skin
sebum
In the body, the serous layers are separated not by air but by a scanty amount of thin, clear fluid, called _____________, which is secreted by both membranes
serous fluid
The lubricating _____________________ allows the organs to slide easily across the cavity walls and one another without friction as they carry out their routine functions
serous fluid
In the thorax, __________________________ isolate the lungs and heart from one another.
serous membranes
The epidermis is composed of ____________________________, whereas the dermis is mostly ______________________________________.
stratified squamous epithelium, dense (fibrous) connective tissue
The outer epidermis is made up of _____________________________ that is capable of becoming hard and tough. The underlying dermis is made up mostly of __________________________. The epidermis and dermis are firmly connected and the _______________ is fairly tear resistant.
stratified squamous epithelium, dense connective tissue, dermis
Stem cells in this layer are constantly dividing, and millions of new cells are produced daily; hence its alternate name, stratum germinativum
stratum basale
The deepest cell layer of the epidermis
stratum basale
This basal layer contains the most adequately nourished of the epidermal cells because nutrients diffusing from the dermis reach them first.
stratum basale
lies closest to the dermis and is connected to it along a wavy border that resembles corrugated cardboard
stratum basale
The epidermis is composed of up to five layers, or strata. From the inside out these are the:
stratum basale, spinosum, granulosum, lucidum, and corneum
The outermost layer, the ___________________________, is 20 to 30 cell layers thick, but it accounts for about three-quarters of the epidermal thickness. The shinglelike dead cell remnants, completely filled with keratin, are referred to as cornified, or horny, cells
stratum corneum
Stratum lucidum is located between
stratum granulosum and stratum corneum
Burns are classified according to their severity (depth) as first-degree (______________), second-degree (_________________________), third-degree (_________________________), or fourth-degree (_______________________________________)
superficial, superficial partial-thickness burns, full-thickness burns, full-thickness burns with deep-tissue involvement
The cutaneous membrane is composed of two layers:
the superficial epidermis and the underlying dermis
Like the epidermis, the dermis varies in
thickness
In ________________________ burns, regeneration is not possible, and skin grafting must be done to cover the underlying exposed tissues.
third-degree
