Highison: Integument Flashcards
The skin makes up (blank)% of total body weight
16%
The skin is a window to disease states. List three.
Jaundice
Cyanosis
Measles and chicken pox
Functions of the skin: protection, (blank) receptor, role in (blank), metabolism of (blank), and regulation of (blank x2)
sensory; excretion; VitD; blood pressure and body temperature
General organization of the skin: two parts. What lies beneath these two parts?
epidermis and dermis; hypodermis
What is the epithelium of the epidermis?
keratinized stratified squamous epithelium
What is the epidermis derived from? How often is it regenerated?
derived from surface ectoderm; regenerates every 30 days
When do keratinocytes divide?
at night - get your beauty sleep ;)
The epidermis overlies projections of the (blank) forming a series of epidermal ridges, or (blank)
dermis; fingerprints
How many layers in the epidermis? List them from deep to superficial
5 layers
basement membrane 1. stratum basale 2. statum spinosum 3. stratum granulosum 4. stratum lucidum 5. stratum corneum layers of thick skin
These cells make up most of epidermis and display continuous turnover
keratinocytes
Describe the process of cell turnover
cell renewal (mitosis)
differentiation (keratinization)
cell death
exfoliation
The stratum basale is a layer of the epidermis. It rests on a (blank). It has these cells which divide continuously. It also contains these two cell types
basal lamina; keratinocytes; melanocytes; Merkel’s cells
What do keratinocytes possess? What increases as these cells approach the surface?
desmosomes, hemidesmosomes, cytokeratin; cytokeratin increases as these cells approach the surface
This layer of the epidermis is several layers thick.
It has tonofibrils and desmosomes which create spiny processes.
Characteristic cell of this layer = prickle cells with intercellular bridges.
Keratinocytes in deepest layers are mitotically active.
Also contains melanocytes and Langerhans cells.
Stratum spinosum
Spiny processes of the stratum spinosum are made up of these two things
tonofibrils (bundles of cytokeratin) and desmosomes
These cells are characteristic of the stratum spinosum
prickle cells with intercellular bridges
These cells in the deeper layers of the stratum spinosum are mitotically active
keratinocytes
Stratum spinosum also contains these cell types
melanocytes
Langerhans cells
These two layers together are known as the Malpighian layer, they are the mitotically active layers of the epidermis
stratum basale
stratum spinosum
This layer of the epidermis contains lamellar bodies, membrane-less keratohyalin granules, and bundles of tonofilaments (cytokeratin).
Contains membrane coated lamellar bodies that fuse with the plasma membrane and release GAGs and phospholipids into the intercellular spaces. This is important in sealing the deeper layers and water proofing.
stratum granulosum
3 components of stratum granulosum
- lamellar bodies
- membrane-less keratohyalin granules
- bundles of tonofilaments
The stratum granulosum contains membrane coated lamellar bodies that fuse with the plasma membrane. What two things do they release into the intercellular spaces? Why is this important?
GAGs and phospholipids
This is important in sealing the deepest layers and water proofing the skin
What do the keratohyaline granules of the stratum granulosum contain to bind the tonofilaments together to form keratin? This marks the first step in what process?
keratohyalin granules contain HISTADINE and CYSTINE rich proteins which bind to tonofilaments together to form keratin; this is the first step in keratinization
What is keratinization?
the conversion of granular cells to cornified cells
3 features of keratinized cells
- loss of organelles
- thickened plasma membrane
- bundles of tonofilaments
This layer of the epidermis is seen only in thick skin. It is acidophilic, and contains immature keratin which is called eleidin.
stratum lucidum
What does the stratum lucidum contain?
immature keratin, called eleidin
Where is stratum lucidum found?
thick skin –> palmar and plantar skin
This is the most superficial layer of the epidermis. It contains dead, plate-like enucleated keratinocytes containing mature keratin. The keratin birefringement scleroprotein has at least 6 polypeptides + tonofilaments.
stratum corneum
Disease state: accelerated keratinocyte mitosis in stratum basale and spinosum. Turnover (1 week instead of 4 weeks) leads to thickening of epidermis.
psoriasis
Psoriasis is a chronic epidermal-dermal disease. What are two characteristics of this disease?
- persistent hyperplasia of the epidermis by abnormal cell proliferation
- abnormal microcirculation in the dermis capillary plexus
2 nonkeratinocytes in the epidermis
- Langerhan’s Cells
2. Merkel’s cells
Where do Langerhans’ cells originate? What system are they a part of? What do they contain? What’s on their surface?
originate in bone marrow, part of MNP system, contain Birbeck’s Granules (rod like or racket shaped), have cell surface antibody and compliment receptors
Langerhans’ cells are capable of (blank). In which layer are they primarily located? Other places they might be found? What’s their function?
phagocytosis; primarily located in the stratum spinosum; also found in oral, esophageal, rectal, vaginal epithelium and thymus; antigen presenting cells though to initiate allergic contact dermatitis reaction
Where are Merkel’s cells found? What are they derived from? What two things do they possess? Where are they most numerous and when do they appear there? What are they considered?
stratum basale; derived from neural crest; possess desmosomes and tonofilaments; most numerous in thick skin (plantar and palmar epidermis) and appear there at about 8-12 weeks gestation; they are sensory/tactile mechanoreceptors
Merkel cells are associated with the (blank). The cytoplasm contains (blank). A small nerve plate is connected to a (blank)
basal lamina; granules; myelinated axon
Melanins contribute to pigmentation of these three things
skin
eyes
hair
patches of epidermal melanin
freckles
What are melanins synthesized by?
melanocytes
What are melanocytes derived from? When are they visible? Where are their cell bodies found? Do they have desmosomes? Melanocytes have cytoplasmic extensions that make contact with about 36 keratinocytes and form this.
derived from neural crest; 8th embryonic week; in stratum basale; NO desmosomes; epidermal-melanin unit
Where is the site of melanin granule synthesis?
melanosomes
Melanosomes contain this UV-sensitive enzyme involved in melanin synthesis
tyrosinase
What accounts for the differences in color in different races?
NOT a difference in number of melanocytes per unit area. Rather, differences in the rates of melanin synthesis, accumulation, and degradation.
Where do mature melanin granules from the Golgi move to? Where are they injected into?
tips of melanocytes; injected into keratinocytes of basale and spinosum via cytocrine secretion
Most melanin is found in (blank) rather than melanocytes
keratinocytes
Melanin granules accumulate over the nuclei of diving keratinocytes. What does this do?
protects the DNA from damaging effects of the sun’s rays
Eventually the melanin pigment is attacked and degraded by (blank) of the keratinocyte over a period of several days
lysosomes
The sun causes formation of highly reactive free radicals, which are bad for diving cells. What does melanin do to help?
Melanin helps absorb some of the rays, but most importantly it absorbs the free radicals!!
What is the dermis made up of?
vascular CT (collagen and elastic fibers)
What is the dermis derived from? What does it possess for temperature regulation?
derived from mesoderm; arteriovenous shunts
2 layers of the dermis
papillary layer (superficial) reticular layer (deep)
Within the papillary layer, dermal papillae interdigitate with the epidermal ridges. What does this layer contain for fine touch reception? What types of fibers are found in this layer? What type of fibers bind the epidermis to the dermis?
Meissner’s corpuscles; type III collagen and elastic fibers; type VII anchoring fibers bind epidermis to dermis
What is the reticular layer of the dermis made up of?
dense irregular CT
Things found in reticular layer of dermis? (list
follicles
sweat and sebaceous glands
elastic fibers
bundles of collagen fibers (mostly Type I)
pacinian corpuscles (pressure receptors) and Ruffini corpuscles (temp/pressure receptors)
These are pressure receptors in the reticular layer of the dermis
Pacinian corpuscles
These are temperature and pressure receptors in the reticular layer of the dermis
Ruffini corpuscles
Is the hypodermis part of the skin? What can cause the thickness of the hypodermis to vary?
NO! Thickness varies with nutrition, level of activity, body region and gender
What is the hypodermis made up of?
loose CT and adipose tissue
Hypodermis is also called…
subcutaneous fascia
When it’s really thick, what is the hypodermis referred to as?
panniculus adiposus
Where is thick skin found?
palms and soles of the feet
How does the stratum corneum differ in thick vs thin skin? Stratum lucidum? Granulosum? Basale? Dermatoglyphics present? (fingerprints)
In thick skin, stratum corneum is thicker. In thick skin, stratum lucidum is present, but usually absent in thin skin. In thick skin, stratum granulosum is a few layers thick, but often a single discont. layer in thin skin. In the stratum basale, there are more Merkel’s cells. Dermatoglyphics present in thick skin.
Are there hair follicles in thick skin and thin skin?
Hair follicles are absent in thick skin and present in thin skin (except for private parts and lips)
Are there more sebaceous glands in thick or thin skin?
More sebaceous glands in thin skin
Are there more eccrine sweat glands in thick or thin skin?
More in thick skin
Are there more Meissner’s corpuscles in thick or thin skin?
More in thick skin (dermal papillae)
Are there more elastic fibers in thick or thin skin?
More in thin skin!!!
What two portions of the skin form hair follicles?
dermis
epidermis
What two things comprise a hair follicle?
hair shaft
hair bulb
Are hair follicles formed after birth? Is hair growth cyclic?
NO; yep
What type of muscles are arrector pili muscles? What do they do?
smooth muscles; elevate the hair and cause goose bump depressions of skin where the muscle attaches to the dermis
Eccrine sweat glands are (blank) and possess a long excretory duct. What are three cell types of eccrine sweat glands?
coiled; clear cell; dark cell; myoepithelial cell
Where do sebaceous glands empty their contents? In which parts of the body are they embedded in the dermis? Where are they most abundant?
into the neck of a hair follicle; embedded in dermis over entire body, except palms and soles; most abundant on face, forehead, scalp
What is the oily secretion of sebaceous glands? What type of secretion is this considered? What does it do?
sebum; holocrine secretion; makes hair shine, skin supple, and ACNE
By what month are mature sebaceous glands present on the face in utero? At birth what happens to sebaceous glands? When do they become active again?
6 months; become inactive at birth until puberty
What causes acne during puberty?
increase in androgens in both males and females leads to abundant quantities of sebum
Sebaceous glands are appendages of the (blank). Their short ducts - lined by stratified squamous epithelium continuous with the external root sheath of the hair - open into the hair canal. Where are hair independent sebaceous glands found?
hair follicle; lips, areolae of the nip, labia minora, inner surface of the prepuce
During holocrine secretion, these cells regenerate sebum-producing cells lost during the secretory process. They divide by mitosis and accumulate lipids as they move into the central part of the acinus.
basal cells
These cells, on top of the basal cells, begin to store the oily secretion within cytoplasmic droplets
sebum-secreting cells
In proximity to the acinar duct, the nuclei of sebum-secreting cells shrink and degenerate, and coalescing droplets of (blank) are released into the short duct. The acini lack a proper lumen.
sebum
What is sebum? How is it released?
oily secretion of sebaceous cells; secreted by a holocrine mechanism (rupturing of the cell, which causes destruction of entire cells which become part of the secretion)
Eccrine sweat glands are simple (blank) tubular glands. List the three cells of eccrine sweat glands.
coiled; dark, clear, myoepithelial cells
Eccrine sweat glands have ducts lined with what type of epithelium? What do these ducts do to sweat?
stratified cuboidal epithelium; these ducts modify sweat by absorbing electrolytes, excreting ions, urea, and lactic acid
Eccrine sweat glands have an unlimited distribution. What type of secretion do eccrine sweat glands exhibit?
merocrine
What do eccrine sweat glands respond to? What is their purpose?
respond to heat and nervous stress
play a role in cooling/thermoregulation and excretion of urea and ammonia
What’s this?
excessive sweating
primary - essential - idiopathic
sweating of hands most distressing
hyperhidrosis
What's this: antiperspirant lontophoresis drugs surgery for axillary glands
Treatments for hyperhidrosis
Dark vs clear cells of eccrine sweat gland. What do dark cells secrete via exocytosis? What do clear cells secrete into the intercellular canaliculi which reach the lumen of the acinus thru intercellular spaces b/w apical dark cells?
glycoproteins
water and electrolytes
Where are apocrine sweat glands found?
axilla areola of the nip perianal region mons pubis glands of Moll in eyelids ceruminous glands of ear
These are vestigal scent glands
aprocrine glands
When do apocrine glands begin to function? What are they a response to? What do they respond to? What don’t they respond to?
at puberty; response to hormonal influences; respond to emotional and sensory stimuli but NOT heat
Aprocrine glands have a (blank) coiled region than eccrine sweat glands. In what region of the skin are they located? Where does the excretory duct opens into? What cells lie on their basal surface? Why do they give off a conspicious odor?
larger; dermis; canal of hair follicle; myoepithelial cells; bacteria
Through what mechanism do these apocrine sweat glands release their secretions?
merocrine process
The effects of photoaging accumulate over years of chronic sun exposure. At first, the effects may be invisible to the casual glance, even while they are on the increase. At 18 months, is sun damage apparent? At 4 years?
Not at 18 months, but yes at 4 years
What is sunlight needed for?
Vit D homeostatis and… that’s it.
Sun exposure is cumulative. Between age 1-18, how much sun exposure? 19-40? 41-59? 60-78?
22%
46%
74%
100%
What is tanning?
pathological damage to the skin
What happens to keratinocytes during a sun burn/tan?
they lose alignment, flatten, obtain nuclear inclusion
What attempts to protect DNA from UV radiation?
melanosomal nuclear capping
With a sun burn/tan, what do melanocytes do?
enlarge, increase in number, and migrate to higher levels of epidermis
Does tanning affect immune properties of skin? How does it affect Langerhans cells?
yes; affects Langerhans cells by reducing antigen-presenting capabilitie and activates T suppressor networks
T/F: With sun burn, skin will undergo dermal changes in elastic tissue and collagen fibers, leaky vasculature, and increase in mast cells.
True
Premalignant condition of thick, scaly, or crusty patches of skin. More common in fair-skinned people and it is associated with frequent exposed to the sun. Some progress to squamous cell carcinoma. Range in size from as small as a pinhead to over an inch across. They may be flat or raised on appearance. Light or dark, tan, pink, red, a combination of these, or the same color as ones skin.
actinic keratosis
Dry, rough crust on skin is often recognized by touch, rather than sight. May disappear and appear later. Half of it will go away if avoid sun for a few years. Most likely to appear on sun-exposed areas.
actinic keratosis
Most common form of cancer in the US
skin cancer
T/F: each year there are more cases of skin cancer than combined incidence of breast, prostate, lung, and colon cancer.
True
T/F: Between 40 and 50 percent of Americans who live to age 65 will have either basal cell carcinoma or squamous cell carcinoma at least once
True
Which is the most common skin cancer? In what layer does it arise? Does it grow slow or fast? High cure rate?
basal cell carcinoma (75%); arises from stratum basale; slow growing; high cure rate w early diagnosis
Which type of skin cancer has a significant risk of metastatic spread, esp with lesions larger than 1-2cm in diameter? What portion of skin cancers fall in this category? What layer do they arise in? What population? Do they grow slow or fast? High cure rate?
squamous cell carcinoma; 20% of all skin cancers; stratum spinosum; elderly; grow fast and ulcerate; high cure rate w early diagnosis
- 5% of all skin cancers
- most dangerous of three
- usually appears as dark brown or black mole like lesions
- any changes in mole appearance should be checked out
- most common sites: upper back in men and legs in women
- grows rapidly, metastasizes quickly
melanoma
most common form of cancer for young adults 25-29 years old and the second most for young people 15-29 years old
melanoma
T/F: Melanoma accounts for less than five percent of skin cancer cases, but it causes more than 75 percent of skin cancer deaths
True
T/F: One or more blistering sunburns in childhood or adolescence more than double a person’s chances of developing melanoma later in life. A person’s risk for melanoma doubles if he or she has had more than five sunburns at any age.
True
What are the ABCD’s in diagnosis of melanoma?
A: asymmetry
B: irregular border
C: color - black, darker, red, blue, white
D: diamter > 6mm
What is the vernix caseosa?
Vernix caseosa protects the skin from the amniotic fluid during the third trimester, because it’s full of urine
