L4: Integumentary Pt. 2 Flashcards
What does sebum coat?
The surface of hairs.
What does sebum help prevent hairs from doing?
Drying and becoming brittle.
What does sebum prevent from evaporating excessively?
Water from the skin.
What effect does sebum have on the skin?
Keeps the skin soft and pliable.
What does sebum inhibit the growth of?
Some (but not all) bacteria.
During childhood, how are sebaceous glands described?
Relatively small and inactive.
At puberty, what stimulates sebaceous glands to grow in size and increase their production of sebum?
Androgens from the testes, ovaries, and adrenal glands.
What is acne?
An inflammation of sebaceous glands that usually begins at puberty.
When does acne usually begin?
At puberty.
What stimulates sebaceous glands at puberty, leading to acne?
Androgens.
In what type of follicles does acne occur predominantly?
Sebaceous follicles that have been colonized by bacteria.
What kind of bacteria thrive in the lipid-rich sebum of sebaceous follicles?
Some bacteria that contribute to acne.
What may the infection in acne cause to form?
A cyst or sac of connective tissue cells.
What can cystic acne do to the epidermis?
Permanently scar it.
What is the condition called when acne leads to a cyst or sac of connective tissue cells?
Cystic acne.
What does the treatment of acne consist of?
Gently washing affected areas once or twice daily with mild soap, topical antibiotics, topical drugs, and oral antibiotics.
What are examples of topical antibiotics used for acne treatment?
Clindamycin and erythromycin.
What are examples of topical drugs used for acne treatment?
Benzoyl peroxide and tretinoin.
What are examples of oral antibiotics used for acne treatment?
Tetracycline, minocycline, erythromycin, and isotretinoin.
Contrary to popular belief, what foods do not cause or worsen acne?
Chocolate or fried foods.
How many sudoriferous glands are there in the body?
Three million to four million.
What do the cells of sudoriferous glands release?
Sweat, or perspiration.
Where do sudoriferous glands release sweat?
Into hair follicles or onto the skin surface through pores.
What are the two main types of sweat glands?
Eccrine and apocrine.
What are eccrine sweat glands?
Simple, coiled tubular glands that are much more common than apocrine sweat glands.
Where are eccrine sweat glands distributed?
Throughout the skin of most regions of the body, especially the forehead, palms, and soles.
Where are eccrine sweat glands not present?
Margins of the lips, nail beds of fingers and toes, glans penis, glans clitoris, labia minora, or eardrums.
Where is the secretory portion of eccrine sweat glands located?
Mostly in the reticular dermis (sometimes in the upper subcutaneous tissue).
How does the excretory duct of eccrine sweat glands function?
It projects through the dermis and epidermis and ends as a pore at the surface of the epidermis.
How much sweat do eccrine sweat glands produce per day?
About 600 mL.
What does eccrine sweat primarily consist of?
Water, with small amounts of ions (mostly Na+ and Cl−), urea, uric acid, ammonia, amino acids, glucose, and lactic acid.
What is the main function of eccrine sweat glands?
To help regulate body temperature through evaporation.
What is the homeostatic regulation of body temperature called?
Thermoregulation.
What is the role of eccrine sweat glands in thermoregulation called?
Thermoregulatory sweating.
During thermoregulatory sweating, where does sweat first form?
On the forehead and scalp, then extends to the rest of the body, forming last on the palms and soles.
What is insensible perspiration?
Sweat that evaporates from the skin before it is perceived as moisture.
What is sensible perspiration?
Sweat that is excreted in larger amounts and is seen as moisture on the skin.
What small role do eccrine sweat glands play besides thermoregulation?
Eliminating wastes such as urea, uric acid, and ammonia.
What plays a bigger role in excretion of waste products than eccrine sweat glands?
The kidneys.
What type of sweating occurs in response to emotional stress like fear or embarrassment?
Emotional sweating or a cold sweat.
During emotional sweating, where does sweat first occur?
On the palms, soles, and axillae, then spreads to other areas of the body.
What type of sweat glands are also active during emotional sweating?
Apocrine sweat glands.
What are apocrine sweat glands?
Coiled tubular glands with larger ducts and lumens than eccrine glands.
Where are apocrine sweat glands found?
In the skin of the axilla (armpit), groin, areolae of the breasts, and bearded regions of the face in adult males.
How was it previously thought that apocrine sweat glands released their secretions?
By pinching off a portion of the cell (apocrine manner).
How do apocrine sweat glands actually release their secretions?
Via exocytosis, like eccrine glands.
Where is the secretory portion of apocrine sweat glands located?
In the reticular dermis or upper subcutaneous tissue.
Where does the excretory duct of apocrine sweat glands open?
Into hair follicles.
Compared to eccrine sweat, how does apocrine sweat appear?
Milky or yellowish in color.
What additional components does apocrine sweat contain compared to eccrine sweat?
Lipids and proteins.
What causes apocrine sweat to develop a musky odor?
Interaction with bacteria on the surface of the skin.
What is the musky odor of apocrine sweat commonly referred to as?
Body odor.
When do eccrine sweat glands start functioning?
Soon after birth.
When do apocrine sweat glands start functioning?
At puberty.
What types of sweating are apocrine sweat glands active in?
Emotional sweating and sweating during sexual activities.
What type of sweating are apocrine sweat glands not active in?
Thermoregulatory sweating.
Do apocrine sweat glands play a role in thermoregulation?
No.
What are the modified sweat glands in the external ear called?
Ceruminous glands.
What do ceruminous glands produce?
A waxy lubricating secretion.
Where do the secretory portions of ceruminous glands lie?
In the subcutaneous layer, deep to sebaceous glands.
Where do the excretory ducts of ceruminous glands open?
Either directly onto the surface of the external acoustic meatus (ear canal) or into ducts of sebaceous glands.
What is the combined secretion of ceruminous and sebaceous glands called?
Cerumen, or earwax.
What color is cerumen?
Yellowish.
What does cerumen, along with hairs in the external acoustic meatus, provide?
A sticky barrier that impedes the entrance of foreign bodies and insects.
What are the other functions of cerumen?
Waterproofing the meatus and preventing bacteria and fungi from entering cells.
Where are sebaceous glands largely distributed?
Largely in lips, glans penis, labia minora, and tarsal glands; small in trunk and limbs; absent in palms, palmar surfaces of the digits, soles, and plantar surfaces of the toes.
Where are eccrine sweat glands distributed?
Throughout skin of most regions of body, especially skin of forehead, palms, and soles.
Where are apocrine sweat glands distributed?
Skin of axillae, groin, areolae, bearded regions of face, clitoris, and labia minora.
Where are ceruminous glands distributed?
External acoustic meatus.
Where is the secretory portion of sebaceous glands located?
Dermis.
Where is the secretory portion of eccrine sweat glands located?
Mostly in reticular dermis (sometimes in upper subcutaneous tissue).
Where is the secretory portion of apocrine sweat glands located?
Mostly in reticular dermis and superficial subcutaneous tissue.
Where is the secretory portion of ceruminous glands located?
Subcutaneous tissue.
Where do the excretory ducts of sebaceous glands terminate?
Mostly connected to hair follicle.
Where do the excretory ducts of eccrine sweat glands terminate?
Surface of epidermis.
Where do the excretory ducts of apocrine sweat glands terminate?
Hair follicles.
Where do the excretory ducts of ceruminous glands terminate?
Surface of external acoustic meatus canal or into ducts of sebaceous glands.
What do sebaceous glands secrete?
Sebum (mixture of triglycerides, cholesterol, proteins, and inorganic salts).
What do eccrine sweat glands secrete?
Perspiration, which consists of water, ions (Na+, Cl−), urea, uric acid, ammonia, amino acids, glucose, and lactic acid.
What do apocrine sweat glands secrete?
Perspiration, which consists of same components as eccrine sweat glands plus lipids and proteins.
What do ceruminous glands secrete?
Cerumen, a waxy material.
What is the function of sebaceous glands?
Prevent hairs from drying out, prevent water loss from skin, keep skin soft, inhibit growth of some bacteria.
What is the function of eccrine sweat glands?
Regulation of body temperature, waste removal; stimulated during emotional stress.
What is the function of apocrine sweat glands?
Stimulated during emotional stress and sexual excitement.
What is the function of ceruminous glands?
Impede entrance of foreign bodies and insects into external acoustic meatus, waterproof meatus, prevent microbes from entering cells.
When do sebaceous glands become active?
Relatively inactive during childhood; activated during puberty.
When do eccrine sweat glands become active?
Soon after birth.
When do apocrine sweat glands become active?
Puberty.
When do ceruminous glands become active?
Soon after birth.
arise by transformation of superficial cells of the nail matrix
Nails
Some people produce an abnormally large amount of cerumen in the external auditory canal. If it accumulates until it becomes impacted (firmly wedged), sound waves may be prevented from reaching the tympanic membrane (eardrum).
Impacted Cerumen
Treatments for impacted cerumen include ____ to dissolve the wax and removal of wax with a blunt instrument by trained medical personnel
periodic ear irrigation with enzymes
is the portion that is not visible
Nail root
is the stratum corneum of the epidermis
Eponychium
is the crescent-shaped white area of the nail plate
Lunule of the nail
is the skin below the nail plate
Nail bed
is the visible portion of the nail
Nail plate
extends past the finger or toe
Free edge
secures nail to the fingertip
Hyponychium
is the epithelium proximal to the nail root. It contains dividing cells, which produce new nail cells
Nail matrix
are plates of tightly packed, hard, dead, keratinized epi dermal cells that form a clear, solid covering over the dorsal surfaces of the distal portions of the digits.
Nails
Each nail consists of
a nail plate, a free edge, and a nail root
is the visible portion of the nail. It is comparable to the stratum corneum of the epidermis of the skin, with the exception that its flattened, keratinized cells fill with a harder type of keratin and the cells are not shed.
nail plate
Below the nail plate is a region of
epithelium and a deeper layer of dermis
Most of the nail plate appears ___ because of blood flowing through the capillaries in the underlying dermis.
pink
is the part of the nail plate that may extend past the distal end of the digit. The free edge is white because there are no underlying capil laries.
Free edge
is the portion of the nail that is buried in a fold of skin.
Nail root
The whitish, crescent- shaped area of the proximal end of the nail plate is called the
lunule of the nail
It is usually most prominent on the thumb. The whitish appearance of the lunule of the nail is due to the thick opaque layer of partially keratinized matrix cells in this region
lunule of the nail
Beneath the free edge is a thickened region of stratum cor neum called the ___. It is the junction between the free edge and skin of the fingertip and secures the nail to the fingertip.
Hyponychium
is the skin below the nail plate that extends from the lunula to the hyponychium
nail bed
The epidermis of the nail bed lacks a
stratum granulosum
is a narrow band of epidermis that extends from and adheres to the margin (lateral border) of the nail wall.
Eponychium or cuticle
It occupies the proximal border of the nail and consists of stra tum corneum
Eponychium or cuticle
It is a small torn piece of skin at the side or base of a fingernail or toenail, usually caused by dryness of the eponychium.
hangnail
The portion of the epithelium proximal to the nail root is the
Nail matrix
The superficial nail matrix cells divide ____ to produce new nail cells.
mitotically
The growth rate of nails is determined by the rate of mitosis in matrix cells, which is influenced by factors such as
a person’s age, health, and nutritional status.
Nail growth also varies according to
the season, the time of day, and environmental temperature.
The average growth in the length of fingernails is about ___ mm (0.04 in.) per week.
1
The growth rate is somewhat slower in
toenails
T or F: The longer the digit the faster the nail grows.
t
Nails have a variety of functions:
- They protect the distal end of the digits. 2. They provide support and counterpressure to the palmar surface of the fingers to enhance touch perception and manipulation. 3. They allow us to grasp and manipulate small objects, and they can be used to scratch and groom the body in various ways.
Two major types of skin are recognized on the basis of certain structural and functional properties:
thin (hairy) skin and thick (hairless) skin
The great est contributor to epidermal thickness is the increased number of layers in the ___. This arises in response to the greater mechanical stress in regions of thick skin
stratum corneum
Distribution of the Thin Skin
All parts of body except areas such as palms, palmar surfaces of digits, soles, and plantar surfaces of toes.
Distribution of the Thick Skin
Areas such as palms, palmar surfaces of digits, soles, and plantar surfaces of toes.
Epidermal Thickness of Thin Skin
0.10–0.15 mm (0.004–0.006 in.).
Epidermal Thickness of Thick Skin
0.6–4.5 mm (0.024–0.18 in.), due mostly to a thicker stratum corneum.
Epidermal strata of Thin Skin
Stratum lucidum essentially lacking; thinner strata spinosum and corneum.
Epidermal strata of Thick Skin
Stratum lucidum present; thicker strata spinosum and corneum
Epidermal ridges of Thin Skin
Lacking due to poorly developed, fewer, and less well organized dermal papillae.
Epidermal ridges of Thick SKin
Present due to well developed and more numerous dermal papillae organized in parallel rows.
Hair follicles and arrector muscles of the hair in Thin Skin
Present
Hair follicles and arrector muscles of the hair in Thick Skin
Absent
Sebaceous glands in Thin Skin
Present
Sebaceous glands in Thick Skin
Absent
Sudoriferous glands in Thin Skin
Fewer
Sudoriferous glands in Thick Skin
More numerous
Sensory receptors in Thin Skin
Sparser
Sensory receptors in Thick Skin
Denser
The numerous functions of the integumentary system (mainly the skin) include
thermoregulation, storage of blood (blood reservoir), protection, cutaneous sensations,excretion and absorption, and synthesis of vitamin D.
the homeostatic regulation of body temperature
Thermoregulation
The skin contributes to thermoregulation in two ways:
by liberating sweat at its surface and by adjusting the flow of blood in the dermis.
How does liberating sweat at its surface and adjusting the flow of blood in the dermis contribute to thermoregulation at high environmental temperature?
In response to high environmental temperature or heat produced by exercise, sweat production from eccrine sweat glands increases; the evaporation of sweat from the skin surface helps lower body temperature. In addition, blood vessels in the dermis of the skin dilate (become wider); consequently, more blood flows through the dermis, which increases the amount of heat loss from the body
How does liberating sweat at its surface and adjusting the flow of blood in the dermis contribute to thermoregulation at low environmental temperature?
In response to low environmental temperature, production of sweat from eccrine sweat glands is decreased, which helps conserve heat. Also, the blood vessels in the dermis of the skin constrict (become narrower), which decreases blood flow through the skin and reduces heatloss from the body. And, skeletal muscle contractions generate body heat.
The dermis houses an extensive network of blood vessels that carry 8–10% of the total blood flow in a resting adult. For this reason, the skin acts as a
Blood reservoir
Functions of the skin wherein Keratin protects underlying tissues from microbes, abrasion, heat, and chemicals, and the tightly interlocked keratinocytes resist invasion by microbes.
Protection
For the protection of the skin, it released by lamellar granules inhibit evaporation of water from the skin surface, thus guarding against dehydration; they also retard entry of water across the skin surface during showers and swims.
Lipids
For the protection of the skin, it keeps skin and hairs from drying out and contains bactericidal chemicals (substances that kill bacteria).
oily sebum from the sebaceous glands
retards the growth of some microbes
acidic pH of perspiration
The pigment ___ helps shield against the damaging effects of ultraviolet light
melanin
Two types of cells carry out protective functions that are immunological in nature
Dendritic cells of the epidermis and macrophages in the dermis
alert the immune system to the presence of potentially harmful microbial invaders by recognizing and processing them
Dendritic cells of the epidermis
phagocytize bacteria and viruses that manage to bypass the dendritic cells
Macrophages in the dermis
are sensations that arise in the skin, including tactile sensations— touch, pressure, vibration, and tickling— as well as thermal sensations such as warmth and coolness.
Cutaneous sensations
Another cutaneous sensation, ___, usually is an indi cation of impending or actual tissue damage.
pain
There is a wide variety of nerve endings and receptors distributed throughout the skin, including the
nonencapsulated sensory corpuscles in the epidermis, the tactile corpuscles in the dermis, lamellar corpuscles in the dermis and subcutaneous tissue, and hair root plexuses around each hair follicle
the elimination of substances from the body
Excretion
the passage of materials from the external environment into body cells
Absorption
Despite the almost waterproof nature of the stratum corneum, about ___ mL of water evaporates through it daily.
400
A sedentary person loses an additional ___ mL per day as sweat; a physically active person loses much more.
200
Besides removing water and heat from the body, ___ also is the vehicle for excretion of small amounts of salts, carbon dioxide, and two organic molecules that result from the breakdown of proteins— ammonia and urea
Sweat
The absorption of water- soluble substances through the skin is negligible, but certain lipid- soluble materials do pene trate the skin. These include
fat- soluble vitamins (A, D, E, and K), certain drugs, and the gases oxygen and carbon dioxide.
Toxic materials that can be absorbed through the skin include
organic solvents such as acetone (in some nail polish removers); salts of heavy metals such as lead, mercury, and arsenic; and the substances in poison ivy and poison oak
Since topical (applied to the skin) steroids, such as cortisone, are lipid- soluble, they move easily into the ___ of the dermis. Here, they exert their anti- inflammatory properties by inhibiting histamine production by mast cells
papillary region
T or F: Certain drugs that are absorbed by the skin may be administered by applying adhesive patches to the skin.
t
requires activation of a precursor mol ecule in the skin by ultraviolet (UV) rays in sunlight
Synthesis of vitamin D
the most active form of vitamin D. It is a hormone that aids in the absorption of calcium from foods in the gastrointestinal tract into the blood.
calcitriol
Only a small amount of exposure to ___ (about 10 to 15 minutes at least twice a week) is required for vitamin D synthesis.
UV light
People who avoid sun exposure and individuals who live in colder, northern climates may require vitamin D supplements to avoid
vitamin D deficiency
Most cells of the immune system have vitamin D receptors, and the cells activate vitamin D in response to an infection, especially a respiratory infection, such as
influenza
is believed to enhance phagocytic activity, increase the production of antimicrobial substances in phagocytes, reg ulate immune functions, and help reduce inflammation.
Vitamin D
Most drugs are either absorbed into the body through the ___ system or injected into ___ or muscle
digestive; subcutaneous tissue
enables a drug contained within an adhesive skin patch to pass across the epidermis and into the blood vessels of the dermis. The drug is released continuously at a controlled rate over a period of one to several days.
transdermal (transcutaneous) drug administration
This method is especially useful for drugs that are quickly eliminated from the body because such drugs, if taken in other forms, would have to be taken quite fre quently.
transdermal (transcutaneous) drug administration
Because the major barrier to penetration is the stra tum corneum, transdermal absorption is most rapid in regions where this layer is thin, such as the
scrotum, face, and scalp
A kind of transdermal administration drug that is used for prevention of angina pectoris (chest pain associated with heart disease)
nitroglycerin
A kind of transdermal administration drug that is used for motion sickness
scopolamine
A kind of transdermal administration drug that is used for estrogen- replacement therapy during menopause
estradiol
A kind of transdermal administration drug that is used for in contraceptive patches
ethinyl estradiol and norelgestromin
A kind of transdermal administration drug that is used to help people stop smoking
nicotine
A kind of transdermal administration drug that is used to relieve severe pain in cancer patients
fentanyl
sets in motion a sequence of events that repairs the skin to its normal (or near- normal) structure and function.
Skin damage
Two kinds of wound- healing processes can occur, depending on the depth of the injury. These are:
Epidermal wound healing and deep wound healing
occurs following wounds that affect only the epidermis
Epidermal wound healing
occurs following wounds that penetrate the dermis
Deep wound healing
Even though the central portion of an epidermal wound may extend to the dermis, the edges of the wound usually involve only slight damage to superficial epidermal cells.
Epidermal wound healing
Common types of epidermal wounds include
abrasions and minor burns
An epidermal wound wherein a portion of skin has been scraped away
abrasions
In response to an epidermal injury, epidermal stem cells of the epidermis surrounding the wound break contact with the basement membrane. The cells then enlarge and migrate across the wound (Figure 5.6a). The cells appear to migrate as a sheet until advancing cells from opposite sides of the wound meet. When epidermal cells encounter one another, they stop migrating due to a cellular response called contact inhibition. Migration of the epidermal cells stops completely when each is finally in contact with other epidermal cells on all sides.
Epidermal wound healing
When epidermal cells encounter one another, they stop migrating due to a cellular response called
contact inhibition
As the basal epidermal cells migrate, a hormone called ___ stimulates basal stem cells to divide and replace the ones that have moved into the wound. The relocated basal epidermal cells divide to build new strata, thus thickening the new epidermis
epidermal growth factor
occurs when an injury extends to the dermis and subcutaneous tissue. Because multiple tissue layers must be repaired, the healing process is more complex than in epidermal wound healing. In addition, because scar tissue is formed, the healed tissue loses some of its normal function.
Deep wound healing
Deep wound healing occurs in four phases:
an inflammatory phase, a migra tory phase, a proliferative phase, and a maturation phase.
A phase wherein a blood clot forms in the wound and loosely unites the wound edges
Inflammatory phase
a vascular and cellular response that helps eliminate microbes, foreign material, and dying tissue in preparation for repair
Inflammation
The vasodilation and increased permeability of blood vessels associated with inflammation enhance delivery of helpful cells. These include
neutrophils, monocytes, and mesenchymal cells
phagocytic white blood cells
neutrophils
develop into macrophages that phagocytize microbes
monocytes
develop into fibroblasts
mesenchymal cells
The three phases that follow do the work of repairing the wound.
a migratory phase, a proliferative phase, and a maturation phase.
the clot becomes a scab, and epithelial cells migrate beneath the scab to bridge the wound. Fibroblasts migrate along fibrin threads and begin synthe sizing scar tissue (collagen fibers and glycoproteins), and damaged blood vessels begin to regrow.
migratory phase
During migratory phase, the tissue filling the wound is called
granulation tissue
is characterized by extensive growth of epithelial cells beneath the scab, deposition by fibroblasts of collagen fibers in random patterns, and continued growth of blood vessels.
proliferative phase
the scab sloughs off once the epidermis has been restored to nor mal thickness. Collagen fibers become more organized, fibro blasts decrease in number, and blood vessels are restored to normal
maturation phase
The process of scar tissue formation is called
fibrosis
Sometimes, so much scar tissue is formed during deep wound healing that a raised scar— one that is elevated above the nor mal epidermal surface— results. If such a scar remains within the boundaries of the original wound, it is a
hypertrophic scar
If it extends beyond the boundaries into normal sur rounding tissues, it is a
keloid scar (cheloid scar)
T or F: Scar tissue differs from normal skin in that its collagen fibers are more densely arranged, it has decreased elasticity, it has fewer blood vessels, and it may or may not contain the same number of hairs, skin glands, or sensory structures as undamaged skin.
t
T or F: Because of the arrangement of collagen fibers and the scarcity of blood vessels, scars usually are darker in color than normal skin.
FALSE (lighter)
In an ___, the injury is restricted to the epidermis; in a ___, the injury extends deep into the dermis.
epidermal wound; deep wound
The epidermis is derived from the ___, which covers the surface of the embryo.
ectoderm
Initially, at about the ___ after fertilization, the epidermis consists of only a single layer of ectodermal cells
fourth week
At the beginning of the seventh week the single layer, called the ___, divides and forms a superficial protected layer of flattened cells called the ___
basal layer; periderm
The peridermal cells are continuously sloughed off, and by the fifth month of development secretions from sebaceous glands mix with them and hairs to form a fatty substance called
vernix caseosa
This substance covers and protects the skin of the fetus from the constant exposure to the amniotic fluid in which it is bathed. In addition, it facilitates the birth of the fetus because of its slippery nature and protects the skin from being damaged by the nails.
vernix caseosa
By about 11 weeks, the basal layer forms an ___ of cells.
intermediate layer
Proliferation of the basal cells eventually forms all layers of the ___, which are present at birth
epidermis
form along with the epidermal layers.
Epidermal ridges
By about the eleventh week, cells from the ectoderm migrate into the dermis and differentiate into
melanoblasts
Melanoblasts soon enter the epidermis and differentiate into
melanocytes
Later in the first trimester of pregnancy, ___, which arise from red bone mar row, invade the epidermis.
dendritic cells
appear in the epidermis in the fourth to sixth months; their origin is unknown.
Tactile epithelial cells
arises from mesoderm located deep to the surface ectoderm.
dermis
The mesoderm gives rise to a loosely organized embryonic connective tissue called
mesenchyme
By 11 weeks, the mesenchymal cells differentiate into ___and begin to form collagen and elastic fibers.
fibroblasts
As the epidermal ridges form, parts of the papillary dermis project into the epidermis and develop into the ___, which contain capillary loops, corpuscles of touch, and free nerve endings
dermal papillae
develop at about 12 weeks as downgrowths of the basal layer of the epidermis into the reticular dermis.
Hair follicles
The downgrowths are called
hair buds
As the hair buds penetrate deeper into the dermis, their distal ends become club- shaped and are called
hair bulbs
Invaginations of the hair bulbs, called ___ of the hair, fill with mesoderm in which blood vessels and nerve endings develop
papillae
Cells in the center of a hair bulb develop into the ___, which forms the ___, and the peripheral cells of the hair bulb form the ___; mesenchyme in the surrounding dermis develops into the ___ and ___
matrix; hair; epithelial root sheath; dermal root sheath; arrector muscle of the hair
By the fifth month, the hair follicles produce delicate fetal hair called ___. It is produced first on the head and then on other parts of the body, and is usually shed prior to birth.
lanugo
Most -___ develop as outgrowths from the sides of hair follicles at about four months and remain connected to the follicles
sebaceous glands
Most ___ are derived from downgrowths (buds) of the stratum basale of the epidermis into the dermis
sudoriferous glands
As the buds penetrate into the dermis, the proximal portion forms the duct of the ___ and the distal portion coils and forms the ___ of the gland
sweat glands; secretory portion
appear at about five months on the palms and soles and a little later in other regions.
Sweat glands
are developed at about 10 weeks.
Nails
Nails consist of a thick layer of epithelium called the
primary nail field
The nail itself is ___ and grows dis tally from its base. It is not until the ninth month that the nails actually reach the tips of the digits.
keratinized epithelium
The epidermis develops from ___, and the dermis develops from ___
ectoderm; mesoderm
Most of the age- related changes begin at about age ___ and occur in the proteins in the dermis
40
During the aging of the integumentary system, ___ fibers in the dermis begin to decrease in number, stiffen, break apart, and disorganize into a shapeless, matted tangle
collagen
lose some of their elasticity, thicken into clumps, and fray, an effect that is greatly accelerated in the skin of smokers.
Elastic fibers
produce both collagen and elastic fibers, decrease in number during the aging of the integumentary system
Fibroblasts
the skin forms the characteristic crevices and furrows known as
wrinkles
dwindle in number and become less efficient phagocytes, thus decreasing the skin’s immune responsiveness
dendritic cells
decreased size of ___ leads to dry and broken skin that is more susceptible to infection
sebaceous glands
Production of ___ diminishes, which probably contributes to the increased inci dence of heat stroke in the elderly.
sweat
There is a decrease in the number of functioning ___, resulting in gray hair and atypical skin pigmentation.
melanocytes
Hair loss increases with aging as hair follicles stop producing hairs. About 25% of males begin to show signs of hair loss by age 30 and about two- thirds have significant hair loss by age 60. Both males and females develop ___.
pattern baldness
An increase in the size of some melanocytes produces
pigmented blotching (age spots)
Walls of blood vessels in the dermis become thicker and less permeable, and ___ is lost.
subcutaneous adipose tissue
___ (especially the dermis) is thinner than young skin, and the migration of cells from the basal layer to the epidermal surface slows considerably.
Aged skin
With the onset of old age, skin heals poorly and becomes more susceptible to pathological conditions such as
skin cancers and pressure sores
is a skin condition that affects mostly light- skinned adults between the ages of 30 and 60. It is characterized by redness, tiny pimples, and noticeable blood vessels, usually in the central area of the face.
rosacea
Growth of ___ and ___ slows during the second and third decades of life. The nails also may become more brittle with age, often due to dehydration or repeated use of cuticle remover or nail polish.
nails; hair
Several cosmetic anti- aging treatments are available to diminish the effects of aging or sun- damaged skin. These include the following:
topical products, Microdermabrasion, chemical peel, laser resurfacing, dermal fillers, fat transplantation, Botulinum toxin (Botox), Radio frequency nonsurgical facelift, and facelift, browlift, or necklift
bleach the skin to tone down blotches and blemishes (hydroquinone) or decrease fine wrinkles and roughness (retinoic acid)
topical products
the use of tiny crystals under pressure to remove and vacuum the skin’s surface cells to improve skin texture and reduce blemishes
Microdermabrasion
the application of a mild acid (such as gly colic acid) to the skin to remove surface cells to improve skin texture and reduce blemishes
Chemical peel
the use of a laser to clear up blood vessels near the skin surface, even out blotches and blemishes, and decrease fine wrinkles. An example is the IPL Photofacial®
Laser resurfacing
injections of human collagen (Cosmo derm®), hyaluronic acid (Restylane® and Juvaderm®), calcium hydroxylapatite (Radiesse®), or poly-L- lactic acid (Sculptra®) that plumps up the skin to smooth out wrinkles and fill in furrows, such as those around the nose and mouth and between the eyebrows
Dermal fillers
fat from one part of the body is injected into another location such as around the eyes
Fat transplantation
a diluted version of a toxin that is injected into the skin to paralyze skeletal muscles that cause the skin to wrinkle.
Botulinum toxin or Botox®
the use of radio fre quency emissions to tighten the deeper layers of the skin of the jowls, neck, and sagging eyebrows and eyelids
radio frequency nonsurgical facelift
invasive surgery in which loose skin and fat are removed surgically and the underly ing connective tissue and muscle are tightened.
Facelift, browlift, or necklift
There are two forms of ultraviolet radiation that affect the health of the skin
UVA and UVB
Longer wavelength ____ rays make up nearly 95% of the ultraviolet radiation that reaches the earth. They are not absorbed by the ozone layer. They penetrate the furthest into the skin, where they are absorbed by melanocytes and thus are involved in sun tanning. It also depress the immune system.
Ultraviolet A (UVA)
Shorter wavelength ___ rays are partially absorbed by the ozone layer and do not penetrate the skin as deeply as UVA rays. It cause sunburn and are responsible for most of the tissue damage (production of oxygen free radicals which disrupt collagen and elastic fibers) that results in wrinkling and aging of the skin and cataract formation.
Ultraviolet B (UVB)
are thought to cause skin cancer.
Both UVA and UVB rays
Long- term overexposure to sunlight results in
dilated blood vessels, age spots, freckles, and changes in skin texture
Exposure to ultraviolet radiation (either natural sunlight or the artificial light of a tanning booth) may also produce ___, a heightened reaction of the skin after consumption of certain medications or contact with certain substances
photosensitivity
characterized by redness, itching, blistering, peeling, hives, and even shock.
photosensitivity
Among the medications or sub stances that may cause a photosensitivity reaction are
certain antibiotics (tetracycline), nonsteroidal anti- inflammatory drugs (ibuprofen or naproxen), certain herbal supplements (St. John’s wort), some birth control pills, some high blood pressure medications, some antihistamines, and certain artificial sweeteners, perfumes, aftershaves, lotions, detergents, and medicated cosmetics.
topically applied sub stances, contain a color additive (dihydroxyacetone) that produces a tanned appearance by interacting with proteins in the skin
Self-tanning lotions (sunless tanners)
are topically applied preparations that contain various chemical agents (such as benzophenone or one of its derivatives) that absorb UVB rays but let most of the UVA rays pass through
Sunscreens
are topically applied preparations that contain sub stances such as zinc oxide that reflect and scatter both UVB and UVA rays.
Sunblocks
Both sunscreens and sunblocks are graded according to a ___ rating, which measures the level of protec tion they supposedly provide against UV rays. The higher the rating, presumably the greater the degree of protection.
sun protection factor (SPF)
Some studies suggest that ___ increase the incidence of skin cancer because of the false sense of security they provide.
Sunscreens
As a precaution ary measure, individuals who plan to spend a significant amount of time in the sun should use a sunscreen or a sunblock with an SPF of
15 or higher
Excessive exposure to ultraviolet radiation from the sun or tanning beds causes virtually all of the one million cases of
Skin cancer
There are three common forms of skin cancer
Basal cell carcinomas, Squamous cell carcinomas, and Malignant melanomas
account for about 78% of all skin cancers. The tumors arise from cells in the stratum basale of the epidermis and rarely metastasize.
Basal cell carcinomas
account for about 20% of all skin cancers, arise from the stratum spinosum of the epider mis, and they have a variable tendency to metastasize
Squamous cell carcinomas
Basal and squamous cell carcinomas are together known as
nonmelanoma skin cancers
arise from melanocytes and account for about 2% of all skin cancers. The estimated life time risk of developing melanoma is now 1 in 75, double the risk only 20 years ago. It can metastasize rapidly and can kill a person within months of diagnosis.
Malignant melanomas
The early warning signs of malignant mel anoma are identified by the acronym
ABCDE
malignant melanomas tend to lack symmetry. This means that they have irregular shapes, such as two very different looking halves
Asymmetry
malignant melanomas have irregular— notched, indented, scalloped, or indistinct— borders
Border
malignant melanomas have uneven coloration and may contain several colors
Color
ordinary moles typically are smaller than 6 mm (0.25 in.), about the size of a pencil eraser
Diameter
malignant melano mas change in size, shape, and color.
Evolving
Once a malignant mel anoma has the characteristics A, B, and C, it is usually larger than ___ mm.
6
Among the risk factors for skin cancer are the following:
Skin type, sun exposure, family history, age, and immunological status
Individuals with light- colored skin who never tan but always burn are at high risk.
Skin type
People who live in areas with many days of sunlight per year and at high altitudes (where ultraviolet light is more intense) have a higher risk of developing skin cancer. Likewise, people who engage in outdoor occupations and those who have suffered three or more severe sunburns have a higher risk.
Sun exposure
Skin cancer rates are higher in some families than in others.
Family History
Older people are more prone to skin cancer owing to longer total exposure to sunlight
Age
Immunosuppressed individuals have a higher incidence of skin cancer.
Immunological status
tissue damage caused by excessive heat, electric ity, radioactivity, or corrosive chemicals that denature (break down) proteins in the skin. It destroy some of the skin’s important contributions to homeostasis— protection against microbial invasion and dehydration, and thermoregulation.
Burns
provide barriers that protect all internal organs from damaging agents in external environment
Skin and Hair
regulate body temperature, needed for proper functioning of other body systems
Sweat glands and skin blood vessels
Skin helps activate vitamin D, needed for proper absorption of dietary calcium and phosphorus to build and maintain bones
Skeletal system
Skin helps provide calcium ions, needed for muscle contraction
Muscular system
Nerve endings in skin and subcutaneous tissue provide input to brain for touch, pressure, thermal, and pain sensations
Nervous system
Keratinocytes in skin help activate vitamin D to calcitriol, a hormone that aids absorption of dietary calcium and phosphorus
Endocrine system
Local chemical changes in dermis cause widening and nar rowing of skin blood vessels, which help adjust blood flow to skin
Cardiovascular system
Skin is first line of defense in immunity, providing mechan ical barriers and chemical secretions that discourage pene tration and growth of microbes
Lymphoid (Lymphatic) system and immunity
Dendritic cells in epidermis participate in immune responses by recognizing and processing foreign antigens
Lymphoid (Lymphatic) system and immunity
Macrophages in dermis phagocytize microbes that pene trate skin surface
Lymphoid (Lymphatic) system and immunity
Hairs in nose filter dust particles from inhaled air
Respiratory system
Stimulation of pain nerve endings in skin may alter breath ing rate
Respiratory system
Skin helps activate vitamin D to the hormone calcitriol, which promotes absorption of dietary calcium and phos phorus in small intestine
Digestive system
Kidney cells receive partially activated vitamin D hormone from skin and convert it to calcitriol
Urinary system
Some waste products are excreted from body in sweat, con tributing to excretion by urinary system
Urinary system
Nerve endings in skin and subcutaneous tissue respond to erotic stimuli, thereby contributing to sexual pleasure
Genital (Reproductive) systems
Suckling of a baby stimulates nerve endings in skin, leading to milk ejection
Genital (Reproductive) systems
Mammary glands (modified sweat glands) produce milk
Genital (Reproductive) systems
Skin stretches during pregnancy as fetus enlarges
Genital (Reproductive) systems
Burns are graded according to their severity
first-degree burn, second-degree burn, and third-degree burn
involves only the epidermis. It is characterized by mild pain and erythema (redness) but no blisters. Skin functions remain intact. Immediate flushing with cold water may lessen the pain and damage. Healing will occur in 3 to 6 days and may be accompanied by flaking or peeling.
first-degree burn
An example of first-degree burn
mild sunburn
destroys the epidermis and part of the dermis. Some skin functions are lost. Redness, blister formation, edema, and pain result. In a blister the epidermis separates from the dermis due to the accumulation of tissue fluid between them. Associated structures, such as hair follicles, sebaceous glands, and sweat glands, usually are not injured. If there is no infection, it heals without skin grafting in about 3 to 4 weeks, but scarring may result.
Second-degree burn
First- and second- degree burns are collectively referred to as
partial-thickness burns
destroys the epi dermis, dermis, and subcutaneous tissue. Most skin functions are lost. Such burns vary in appearance from marble- white to mahogany colored to charred, dry wounds. There is marked edema, and the burned region is numb because sensory nerve endings have been destroyed. Regener ation occurs slowly, and much granulation tissue forms before being covered by epithelium. Skin grafting may be required to promote healing and to minimize scarring.
third-degree burn or full-thickness burn
The injury to the skin tissues directly in contact with the damaging agent is the ___ of a burn
local effect
The systemic effects of a major burn are a greater threat to life. The systemic effects of a burn may include
(1) a large loss of water, blood plasma, and blood plasma proteins, which causes shock; (2) bacterial infection; (3) reduced circulation of blood;
(4) decreased production of urine; and (5) diminished immune responses.
The seriousness of a burn is determined by its
depth and extent of area involved as well as the person’s age and general health
According to the ___ classifi cation of burn injury, a major burn includes third- degree burns over 10% of body surface area; or second- degree burns over 25% of body surface area; or any third- degree burns on the face, hands, feet, or perineum
American Burn Association’s
When the burn area exceeds ___%, more than half the victims die.
70
A quick means for estimat ing the surface area affected by a burn in an adult is the
rule of nines
What is stated in the rule of nines?
- Count 9% if both the anterior and posterior surfaces of the head and neck are affected. 2. Count 9% for both the anterior and posterior surfaces of each upper limb (total of 18% for both upper limbs). 3. Count four times nine, or 36%, for both the anterior and posterior surfaces of the trunk, including the buttocks. 4. Count 9% for the anterior and 9% for the posterior surfaces of each lower limb as far up as the buttocks (total of 36% for both lower limbs). 5. Count 1% for the perineum
Excessive exposure to ultraviolet radiation from the sun or tanning beds accounts for almost all cases of
skin cancer
tissue damage caused by agents that destroy the proteins in the skin.
burn
In severely burned patients with full- thickness or deep partial- thickness burns where there is not sufficient autograft, a tissue engineered product called ___ is available
Integra® Dermal Regener ation Template (DRT)
It is designed to promote organized regeneration of the dermis while providing a protec tive barrier against fluid and heat loss and microbes.
Integra® Dermal Regener ation Template (DRT)
Integra® DRT consists of two layers, just like human skin.
matrix layer and the silicone layer
The bottom layer, called the ___, is composed of bovine (cow) ten don collagen and the carbohydrate glycosaminoglycan (GAG). It mimics the dermis, functions as an extracellular layer, and induces the body’s own dermal cells to migrate into the area and regenerate a new dermis.
matrix layer
The outer layer, called the ___, consists of a thin layer of silicone that mimics the epidermis. Its role is to close the wound, control fluid loss, and serve as a protective barrier. Once the dermis has regenerated sufficiently (about three weeks), it is removed and a thin sheet of the patient’s own epidermal cells is applied
silicone layer
are caused by a constant deficiency of blood flow to tissues
pressure ulcers (decubitus ulcers or bedsores)
Typically the affected tissue overlies a bony projection that has been subjected to prolonged pressure against an object such as a bed, cast, or splint. If the pressure is relieved in a few hours, redness occurs but no lasting tissue damage results.
pressure ulcers (decubitus ulcers or bedsores)
____ of the affected area may indicate superficial damage; a reddish- blue discoloration may indicate deep tissue damage.
blistering
Prolonged pressure causes ____. Small breaks in the epidermis become infected, and the sensitive subcutaneous layer and deeper tissues are damaged. Eventually, the tissue dies.
tissue ulceration
occur most often in bedridden patients.
pressure ulcers (decubitus ulcers or bedsores)
a shedding of epithelium caused by a constant deficiency of blood flow to tissues
pressure ulcers (decubitus ulcers or bedsores)
An area where skin has been scraped away.
abrasion
A collection of serous fluid within the epidermis or between the epidermis and dermis, due to short- term but severe friction.
Blister
refers to a large blister.
bulla
An area of hardened and thickened skin that is usually seen in palms and soles and is due to persistent pressure and friction.
Callus
A lesion, usually in an oral mucous membrane, caused by type 1 herpes simplex virus (HSV) transmitted by oral or respira tory routes. The virus remains dormant until triggered by factors such as ultraviolet light, hormonal changes, and emotional stress. Also called a fever blister
Cold sore
A collection of sebaceous material and dead cells in the hair follicle and excretory duct of the seba ceous gland. Usually found over the face, chest, and back, and more commonly during adolescence.
Comedo
Also called as blackhead
Comedo
Inflammation of the skin characterized by redness, itching, and swelling and caused by exposure of the skin to chemicals that bring about an allergic reaction, such as poison ivy toxin
Contact dermatitis
Condition in which tissue deep to the skin is damaged, but the epidermis is not broken.
Contusion
A painful conical thickening of the stratum corneum of the epidermis found principally over toe joints and between the toes, often caused by friction or pressure. It may be hard or soft, depending on their location. Hard corns are usually found over toe joints, and soft corns are usually found between the fourth and fifth toes.
Corn
A sac with a distinct connective tissue wall, containing a fluid or other material.
Cyst
An inflammation of the skin characterized by patches of red, blistering, dry, extremely itchy skin. It occurs mostly in skin creases in the wrists, backs of the knees, and fronts of the elbows. It typically begins in infancy and many children outgrow the condition. The cause is unknown but is linked to genetics and allergies
eczema
Local destruction of skin and subcutaneous tissue on exposed surfaces as a result of extreme cold. In mild cases, the skin is blue and swollen and there is slight pain. In severe cases there is considerable swelling, some bleeding, no pain, and blistering. If untreated, gangrene may develop. Frostbite is treated by rapid rewarming.
Frostbite
Localized benign tumor of the skin and subcutaneous tissue that results from an abnormal increase in the number of blood vessels
hemangioma
One type of hemangioma that is a flat, pink, red, or purple lesion present at birth, usually at the nape of the neck.
portwine stain
Reddened elevated patches of skin that are often itchy. Most commonly caused by infections, physical trauma, medications, emotional stress, food additives, and certain food allergies.
Hives
Also called as urticaria
Hives
An elevated, irregular darkened area of excess scar tissue caused by collagen formation during healing. It extends beyond the original injury and is tender and frequently painful. It occurs in the dermis and underlying subcuta neous tissue, usually after trauma, surgery, a burn, or severe acne; more common in people of African descent.
Keloid
Formation of a hardened growth of epidermal tissue, such as solar keratosis, a premalignant lesion of the sun- exposed skin of the face and hands
Keratosis
An irregular tear of the skin.
laceration
Contagious arthropods that include two basic forms, head lice and pubic lice
lice
are tiny, jumping arthropods that suck blood from the scalp. They lay eggs, called nits, and their saliva causes itching that may lead to complications.
Head lice
are tiny arthropods that do not jump; they look like miniature crabs.
Pubic lice
A small, round skin elevation less than 1 cm in diameter. One example is a pimple
papule
Itching, one of the most common dermatological disorders. It may be caused by skin dis orders (infections), systemic disorders (cancer, kidney failure), psy chogenic factors (emotional stress), or allergic reactions.
Pruritus
A fungal infection character ized by scaling, itching, and sometimes painful lesions that may appear on any part of the body; also known as ringworm.
tinea corporis
Fungi thrive in warm, moist places such as skin folds of the groin, where it is known as ____ (jock itch) or between the toes, where it is called ____ (athlete′s foot).
tinea cruris; tinea pedis
In reference to a medication, applied to the skin surface rather than ingested or injected.
topical
Mass produced by uncontrolled growth of epithelial skin cells; caused by a papillomavirus. Most warts are noncancerous.
Wart
