Skin Flashcards
skin is composed of two different regions
epidermis
dermis
stores fat
anchors the skin to the underlying structures (mostly muscles)
Hypodermis
isn’t really part of the skin but shares some of the skin’s protective functions.
Hypodermis
Acts as a shock absorber and an insulator preventing heat loss from the body; thickens noticeably when one gains weight
Hypodermis
The outermost protective shield of the body
Epidermis
Cells of the epidermis
Four types: Keratinocytes Melanocytes Merkel cells Langerhans’ cells
Produce keratin (the fibrous protein that helps give the epidermis its protective properties)
Keratinocytes
Synthesize the pigment melanin.
Forms a pigment shield that protects the keratinocyte nucleus from the damaging effects of UV radiation in sunlight
Melanocytes
Arise from bone marrow and migrate to the epidermis.
They’re macrophages that help activate our immune system.
Langerhans’ cells aka Epidermal Dendritic cells
Located at the epidermal-dermal junction.
Intimately associated with a disc-like sensory nerve ending.
The combo is called a Merkel disc and functions as a sensory receptor for touch
Merkel cells
Layers of the epidermis
From superficial to deep they are: stratum corneum stratum lucidium stratum granulosum stratum spinosum stratum basal
attached to the underlying dermis
Stratum Basale (Basal Layer)
several layers thick; prickly layer
Stratum Spinosum
(Granular Layer) – three to five cell layers thick.
Stratum Granulosum
(Clear Layer) – consists of a few rows of clear, flat, dead keratinocytes with indistinct boundaries.
Stratum Lucidum
(Horny Layer) – outermost layer is 20-30 cell layers thick and accounts for up to ¾ of the epidermal thickness.
Stratum Corneum
strong, flexible connective tissue.
Cells found are fibroblasts, macrophages, and occasional mast cells and white blood cells.
Semi-fluid matrix is heavily embedded with collagen,
elastin, and reticular fibers
Binds the entire body together like a body stocking.
It’s your “hide”.
Dermis
The major portions of hair follicles, as well as oil and sweat glands reside in
dermis
Under the epidermis and makes up the bulk of the skin
dermis
How many layers in the dermis and what are they
2; papillary and reticular
thin, superficial layer of dermis
Papillary
Contains free nerve endings and touch receptors called Meissner’s corpuscles
Papillary
On the palms of the hands and soles of the feet, papillae lie atop larger mounds called dermal ridges.
Papillary
Because sweat pores open along their crests, our fingertips leave identifying films of sweat called
fingerprints
is deeper, and accounts for most of the dermal thickness.
Contains elastin and collagen fibers (Collagen fibers give skin strength and resiliency, preventing most jabs and scrapes from penetrating the dermis).
Collagen binds water, keeping skin hydrated.
The elastin provides the stretch-recoil properties of skin
Reticular layer
Three pigments contribute to skin color
melanin, carotene, and hemoglobin
made in the skin.
Ranges in color from yellow to reddish-brown to black.
melanin
a yellow to orange pigment found in plant products such as carrots.
Accumulates in the stratum corneum and fatty tissue of the hypodermis.
Color is most obvious in the palms and soles
Carotene
may indicate embarrassment, fever, hypertension, inflammation, or allergy
Redness or erythema
during fear, anger, and certain other types of emotional stress. May also signify anemia or low blood pressure
Pallor or blanching
usually signifies a liver disorder
Jaundice or yellow cast
sign of Addison’s disease, hypofunction of the adrenal cortex
Bronzing
Black and blue marks – reveals where blood escaped from the circulation and clotted beneath the skin
hematomas
Appendages of the Skin
Nails
Sweat glands
Sebaceous (oil) glands
Hair follicles and hair
Distributed all over the entire skin surface except the nipples and parts of the external genitalia
Sweat (Sudoriferous) Glands
Two types of sweat glands
Eccrine sweat glands aka merocrine sweat glands
Role of Eccrine sweat glands aka merocrine sweat glands
prevent overheating
Location of Eccrine sweat glands aka merocrine sweat glands
abundant on the palms, soles of the feet, and forehead
Secretion of abundant on the palms, soles of the feet, and forehead
Sweat
Sweat gland mostly in the axillary and anogenital areas
Apocrine sweat glands
Secretion is odorless but when its organic molecules are decomposed by bacteria on the skin, it takes on a musky and generally unpleasant odor, the basis of body odor
Apocrine sweat glands
found in the lining of the external ear canal. Secretes a sticky, bitter substance called cerumen or earwax.
Ceruminous glands
secrete milk
Mammary glands
found all over the body except on the palms and soles
Secrete an oily substance called sebum
Sebaceous (Oil) Glands
secreted into a hair follicle or occasionally to a pore on the skin surface. Softens and lubricates the hair and skin, prevents hair from becoming brittle. Slows water loss from the skin when the external humidity is low. Has bactericidal (bacteria-killing) action.
Sebum
scale-like modification of the epidermis
nails
Forms a clear protective covering on the dorsal surface of the distal part of a finger or toe
Nail
Main function - sense insects on the skin before they sting us.
hair
shield the eyes, and nose hairs filter larger particles from the air we inhale
eyelash
guards the head against physical trauma, heat loss, and sunlight
hair
Chief regions of hair
shaft, which projects from the skin.
root, the part embedded in the skin
Hairs act as
sensitive touch receptors
Hair follicles contain a bundle of smooth muscle cells called
arrector pili muscle.
pulls the hair follicle into an upright position and dimples the skin surface to produce goose bumps in response to cold external temperatures or fear
Arrector pili muscle contraction
Hair can be classified as
vellus or terminal
most vulnerable organ system, exposed to bacteria, abrasion, temperature extremes, and harmful chemicals.
Integumentary System
Three types of barriers in the integumentary system
chemical, physical, and biological
these include skin secretions and melanin.
chemical barriers
provides a chemical pigment shield to prevent UV damage to the viable skin cells
Melanin
provided by the continuity of skin and the hardness of its keratinized cells
Physical/Mechanical Barriers
barrier that has the Langerhans’ cells of the epidermis, are active elements of the immune system.
The dermal macrophages are a second line of defense to get rid of viruses and bacteria
Biological barrier
Skin is richly supplied with ___ ___ ____ that are a part of the nervous system
cutaneous sensory receptors
alert us to bumps or contacts involving deep pressure
Pacinian receptors
report on wind blowing through our hair and a playful tug on a pigtail
Hair follicle receptors
sensed by bare nerve endings which wind throughout the skin
Painful stimuli
most tumors on the skin are benign but some are malignant (cancerous) and metastasize
skin cancer
protein that causes genetically damaged skin cells to commit suicide
Fas
accelerate its production of Fas
Sunburned skin
Least malignant and most common skin cancer.
Cancer lesions occur most often on sun-exposed areas of the face.
Appear as shiny, dome-shaped nodules that later develop a central ulcer with a pearly, beaded edge.
Relatively slow growing cancer and metastasis rarely occurs before it’s noticed.
Full cure by surgical excision in about 99% of cases
Basal Cell Carcinoma
Lesion appears as a scaly reddened papule (small, rounded elevation).
Found mostly on the head (scalp, ears, and lower lip) and hands.
Grows rapidly and metastasizes if not removed.
If caught early and removed chance of complete cure is good.
Squamous Cell Carcinoma
Most dangerous skin cancer.
Highly metastatic and resistant to chemotherapy.
Accounts for only about 5% of skin cancers, but it is on the rise.
Begins wherever there is pigment on the skin and most cancers appear spontaneously; about one-third develop from pre-existing moles.
Usually appears as a spreading brown to black patch which metastasizes rapidly to surrounding lymph and blood vessels
Melanoma
The ABCDE rule is great for recognizing melanoma. What is the ABCDE rule?
Asymmetry – two sides of the pigmented spot or mole don’t match
Border irregularity – borders of the lesion exhibit indentations
Color – pigmented spot contains several colors (blacks, browns, tans, and sometimes blues and reds)
Diameter – spot is larger than 6mm in diameter (the size of a pencil eraser)
Elevation – elevation above the skin surface
tissue damage inflicted by intense heat, electricity, radiation, or certain chemicals, all of which denature cell proteins and cause cell death in affected areas.
burns
Burns are classified according to their
severity (depth) as first, second, or third degree burns
Burns-only the epidermis is damaged, Symptoms include localized redness, swelling, and pain.
Tend to heal in two to three days without special attention
Ex. Sunburn
First-degree burns
Burns-injures the epidermis and the upper region of the dermis.
Symptoms mimic those of first-degree burns, but blisters also appear.
Skin regeneration occurs with little or no scarring within three to four weeks provided no infection sets in
Second-degree burns
Burns-Involves the entire thickness of the skin.
The burned area appears gray-white, cherry red, or blackened and at first there’s no edema.
The nerve endings have been destroyed, the burn isn’t painful.
Skin will regenerate.
Skin grafting is usually done to cover the area(s).
Third-degree burns
