produce fibrous proteins, 90% of cells, connected by desmosomes, produced in stratum basale and pushed to surface, dead when they reach the surface 25-45 days from production to sloughing off FUNCTION: protective barrier
10-25% of cells in lower epidermis,produce brown-black pigment called melanin, melanin is accumlated in membrane bound granules called melanosomes and transferred to nearby keratinocytes
touch receptors, only present in stratum basale, form a merkel disc for sensation of light touch
everyone has the same number of melanocytes
immune system cells which detect and present antigens to other immune system cells, macrophages that ingestantigens and activate immune system
most superficial layer, 20-30 layers of dead cells represented only by flat membrane sacs filled with keratin. Glycolipids in extracellular space
three to five layers of flattened cells, organelles deteriorating, cytoplasm full of lamellated granules that release lipids and keratohyline granules
several layers of keratinocytes unified by desomoes, cells contain thick bundles of intermediate filaments made of pre-keratin
deepest epidermal layer, one row of actively mitotic stem cells, some newly formed cells become part of the more superficial layers
thick skin- bottoms of toes, soles, palms fingertips
5 layers of skin
anchored to basement membrane, consists of single layer of mostly stem cells undergoing mitosis to become keratinocytes, a few melanocytes that create skin pigment and occasionally merkel cells
Stratum Spinosum (prickly layer)
7-10 layers of cells, mostly keratinocytes with a few langerhans cells and some melanin granules
thin consists of 3-5 cell layers in which drastic changes in keratinocyte appearance occurs (cells flatten) keratohyaline -granules- precursors to keratin, lamellated granules- waterproofing glycolipids
cells in stratum granulsum die because
they are getting too far away from blood vessels in dermis,, they are programmed to die
only found in thick skin of palms, soles, fingerips, and bottoms of toes- 3-5 layers of flat clear dead keratinocytes
horny layer, 20-30 layers of dead keratinocytes, FUNCTIONS protects from abrasion, penetration, waterproofs,
contains flycolipid between cells to waterproof skin
serves as a physical barrier again light, heat, microorganisms, water and chemicals
thickening of epidermis due to frequent friction or abrasion
epidermal growth factor
protein hormone which stimulates stratum basale cells to undergo mitosis
found in saliva of many mammals and produced by other cells
epidermal growth factor
second major skin region containing strong flexible connective tissue
cell types include fibroblasts, macrophages and occasionally mast cells
rich supply of blood vessels and nerves, contains glands and hair follicles
Papillary layer (dermis)
superfical layer that makes up 20% of dermis, areolar connective tissue with collagen and elastic fibers and blood vessels
composed of small fingerlike projections called dermal papillae which push up into epidermis
dermal papillae (papillary layer of dermis)
contains capillary loops, meissnesr's corpuscles(touch receptors) and free nerve endings for pain. FUNCTION: to increase surface area of contract between epidermis and dermis, to increase diffusion and bettwe resistance to abrasion
caused by dermal ridges and dermal papillae resulting in erpidermal ridges FUNCTION to increase friction for gripping
reticular layer (deep layer of dermis)
80 % of dermis, dense irregular connection tissue with thich collagen and coarse elastic fibers
collagen fibers in the layer add strendth and resiliency to the skin, elastic fibers provide stretch-recoil properties
single outer layer of keratinized cells that overlap each other- surrounds cortex
extends from epidermal surface into dermis- lining of hair shaft
connective tissue root sheath
dermis-blue exterior area on outer follicle wall
thickened basement membrane- dark blue membrane between CT root sneath and external epithelial root sheath
external epithelial root sheath
tissue after the glassy membrane
internal root sheath
tissue after external epithelial root sheath before cuticle
expanded deep end, enlarged base of follicle-bottom of follicle directly under root
hair papilla of hair bulb
connective tissue with many blood vessels
hair matrix of hair bulb
ring of actively didving cells
sebaceous glands are with each hair
hair follicle receptor
sensory nerve endings around each hair bulb, stimulated by bending a hair
arrector pili muscle
smooth muscle that runs from connective tissue root sheath to suferficial dermis- contracts hair vertically
cause goose bumps, decreases heat loss by increasing the dead air space above skin, induced by stimuli
arrector pili muscle
2 cycles growth phase and resting phase
lasts 6-10 years in scalp, 3-4 months in eyebrows
last 1-3 months
pale, fine body hair of children and adult femals
coarse, long hair of eyebrows, scalp, axillary and pubic regions
excessive hairiness in women due to abnormal secretion of androgens
melanins in medulla and cortex
blonde and red hair
melanin variants with iron and sulfur
decreased melanain production, increased air bubble in shaft
hair thining in both sexes after age of 40
genetically determind and sex-influenced condition
scalelike modification of epidermis on distal dorsal surface of fingers and toes
pink due to blood underlying capillaries
white cresent shape at bottom of nail
white edge of nail
anchored in skin
thick stratum corneum
low pH secretions(acid mantle) and defensisn retard bacterial activity
melanin provides a chemical pigment to prevent UV damage to the viable skin cells
keratin and glycolipids block most water and water-soluble substances
The most abundant cells of the epidermis.
The protein found in the epidermis that is responsible for toughening the skin
Cells plus a disc-like sensory nerve ending that functions as a sensory receptor for touch
Skin macrophages that help activate the immune system
Epidermal dendritic cells
Cell remnants of the stratum corneum
The layer of the epidermis where the cells are considered protective but nonviable
The glands that serve an important function in thermoregulation
The layer that contains the mitotic viable cells of the epidermis
Hair that lacks pigment and is often called "immature hair."
May indicate embarrassment, fever, hypertension, inflammation, or allergy.
May indicate fear, anger, anemia, or low blood pressure
Usually indicates a liver disorder
Appearance of a permanent tan; bronzing.
A bluish color in light-skinned individuals
The apocrine sweat glands are fairly unimportant in thermoregulation
Skin surface markings that reflect points of tight dermal attachment to underlying tissues are called epidermal ridges
The dense fibrous connective tissue portion of the skin is located in the reticular region of the dermis
The outermost sheath of a hair follicle is the connective tissue root sheath
The protein found in large amounts in the outermost layer of epidermal cells is collagen.
Joe just burned himself on a hot pot. A blister forms and the burn is painful. Joe's burn would best be described as a third-degree burn
Destruction of the matrix of the hair bulb would result in its inability to produce oil
The hyponychium is commonly called the cuticle
The reason that the nail bed appears pink is the presence of a large number of melanocytes in the underlying dermis
During the resting phase of hair growth, the matrix is inactive and the follicle atrophies.
The most dangerous skin cancer is cancer of the melanocytes.
The skin is not able to receive stimuli because the cells of the epidermis are not living and therefore there are no sensory receptors in the skin
The dermis is rich in blood vessels and nerve fibers.
The hypodermis is composed of adipose and dense connective tissue
A physician is often able to detect homeostatic imbalances in the body by observing changes in the skin color
When an individual is exposed to extremely low air temperatures, the dermal blood vessels will dilate so that blood and heat will be dissipated.
Regardless of race, all human beings have about the same number of melanocytes
Ceruminous glands are modified merocrine glands
The stratum corneum (outermost layer of skin) is a zone of approximately four layers of viable cells that are able to synthesize proteins that keep the outer layer of skin smooth and soft
The pinkish hue of individuals with fair skin is the result of the crimson color of oxygenated hemoglobin (contained in red blood cells) circulating in the dermal capillaries and reflecting through the epidermis.
Hair growth and density are influenced by hormones, nutrition, and, in some cases, lifestyle
When a patient is said to have "third-degree burns," this indicates that the patient has burns that cover approximately one-third of the body.
Sweat glands continuously produce small amounts of sweat, even in cooler temperatures
Melanomas are rare but must be removed quickly to prevent them from metastasizing
________ is an inherited condition that affects the heme pathway; it leaves the skin scarred and gums degenerated, and may have led to the folklore about vampires.
A needle would pierce the epidermal layers of the forearm in which order
corneum, granulosum, spinosum, basale
The major regions of a hair shaft include all of the following except ________.
external root sheath
Acne is a disorder associated with ________.
The dermis ________.
has 2 layers
Which muscles attached to the hair follicles cause goose bumps
If a splinter penetrated the skin into the second epidermal layer of the sole of the foot, which cells would be damaged?
Which of the following cutaneous receptors is specialized for the reception of touch or light pressure?
Which of the following is a skin sensory receptor for touch?
Which statement correctly explains why hair appears the way it does
Kinky hair has flat, ribbonlike hair shafts
Sudoriferous glands vary in distribution over the surface of the body. Which of the following is correct?
Ceruminous glands secrete cerumen, which is thought to deter insects
Although the integument is a covering, it is by no means simple, and some of its functions include ________.
resident macrophage-like cells whose function is to ingest antigenic invaders and present them to the immune system
The function of the root hair plexus is to ________.
allow the hair to assist in touch sensation
Vernix caseosa is a ________.
whitish material produced by fetal sebaceous glands
The ________ gland is a modified sudoriferous gland that secretes wax
Nutrients reach the surface of the skin (epidermis) through the process of ________.
diffusing through the tissue fluid from blood vessels in the dermis
The reason the hypodermis acts as a shock absorber is that ________.
the major part of its makeup is adipose, which serves as an effective shock absorber
Which type of skin cancer appears as a scaly reddened papule and tends to grow rapidly and metastasize
Squamous cell carcinoma
Keratinocytes are an important epidermal cell because they ________.
produce a fibrous protein that gives the skin much of its protective properties
Melanocytes and keratinocytes work together in protecting the skin from UV damage when keratinocytes ________
accumulate the melanin granules on their superficial portion, forming a UV-blocking pigment layer
The epidermis consists of five layers of cells, each layer with a distinct role to play in the health, well-being, and functioning of the skin. Which of the following layers is responsible for cell division and replacement?
The integumentary system is protected by the action of cells that arise from bone marrow and migrate to the epidermis. Which of the following cells serve this function?
macrophages called epidermal dendritic cells
Water loss through the epidermis could cause a serious threat to health and well-being. Which of the following protects us against excessive water loss through the skin?
Lamellated granules of the cells of the stratum granulosum, a glycolipid that is secreted into extracellular spaces
The dermis is a strong, flexible connective tissue layer. Which of the following cell types are likely to be found in the dermis?
fibroblasts, macrophages, and mast cells
The dermis has two major layers; which of the following constitutes 80% of the dermis and is responsible for the tension lines in the skin?
the reticular layer
Despite its apparent durability, the dermis is subject to tearing. How might a person know that the dermis has been stretched and/or torn?
The appearance of visible, silvery-white scars is an indication of stretching of the dermis
The papillary layer of the dermis is connective tissue heavily invested with blood vessels. The superficial surface has structures called:
The design of a person's epidermal ridges is determined by the manner in which the papillae rest upon the dermal ridges to produce the specific pattern known as handprints, footprints, and fingerprints. Which of the following statements is true regarding these prints or ridges?
They are genetically determined, therefore unique to each person
Which of the following statements indicates the way in which the body's natural defenses protect the skin from the effects of UV damage?
Prolonged exposure to the sun induces melanin dispersion, which in turn acts as a natural sunscreen.
Changes in the color of skin are often an indication of a homeostatic imbalance. Which of the following changes would suggest that a patient is suffering from Addison's disease?
The skin takes on a bronze or metallic appearance
An epidermal dendritic cell is a specialized ________.
What are the most important factors influencing hair growth?
nutrition and hormones
Which of the following statements best describes what fingernails actually are
Fingernails are a modification of the epidermis
Sudoriferous (sweat) glands are categorized as two distinct types. Which of the following are the two types of sweat glands?
eccrine and apocrine
The composition of the secretions of the eccrine glands is ________.
99% water, sodium chloride, trace amounts of wastes, and vitamin C
Apocrine glands, which begin to function at puberty under hormonal influence, seem to play little role in hermoregulation. Where would we find these glands in the human body?
in the palms of the hands and soles of the feet
The sebaceous glands are simple alveolar glands that secrete a substance known as sebum. The secretion of sebum is stimulated ________.
by hormones, especially androgens
In addition to protection (physical and chemical barrier), the skin serves other functions. Which of the following is another vital function of the skin?
It converts modified epidermal cholesterol to a vitamin D precursor important to calcium metabolism.
Burns are devastating and debilitating because of loss of fluids and electrolytes from the body. How do physicians estimate the extent of burn damage associated with such dangerous fluid loss
by using the "rule of nines"
What is the first threat to life from a massive third-degree burn
catastrophic fluid loss
Male pattern baldness has a genetic switch that turns on in response to ________.
Eyebrow hairs are always shorter than hairs on your head because ________.
eyebrow follicles are only active for a few months
Cradle cap in infants is called ________.
The white crescent portion of the nail is called the ________.
The layer of the epidermis immediately under the stratum lucidum in thick skin is the stratum
The ________ are the small muscles located in the dermis that cause goose bumps.
A summertime golden bronze tan may not be a tan at all; especially if the skin appears almost metallic bronze, it may be the result of ________ disease.
The coarse hair of the eyebrows and scalp is called ________ hair.
________ burns injure the epidermis and the upper regions of the dermis
________ are pigment-producing cells in the epidermis
The only place you will find stratum ________ is in the skin that covers the palms, fingertips, and soles of the feet.
The dermis is composed of the reticular and ________ layers