Chapter 6 Flashcards
What is the most vulnerable organ?
Skin
What harmful things can skin be exposed to?
Radiation, trauma, infection, and injurious chemicals
What system receives the most medical treatment?
Integumentary
What is dermatology?
The scientific study and medical treatment of the integumentary system
What composes the integumentary system?
Skin, accessory organs, hair, nails, and cutaneous glands
What is the largest and heaviest organ?
Skin, which composes 15% of body weight
What are the 2 cutaneous layers of skin?
Epidermis and dermis
What is the subcutaneous layer of skin?
Hypodermis
What cells are the epidermis made of?
Stratified squamous epithelium
What cells are the dermis made of?
Connective tissue
What cells are the hypodermis made of?
Connective adipose tissue. Not part of skin
Where is thick skin found and how thick is it?
Front of hands, bottoms of feet. 0.5 mm thick epidermis
Where is thin skin found and how thin is it?
The body except front of hands and bottoms of feet, 0.1 mm thick epidermis
What are the functions of skin?
Resistance to trauma and infection, barrier functions, vitamin D synthesis, sensation, thermoregulation, nonverbal communication, and transdermal absorption
Resistance to trauma and infection
Keratin, acid mantle
Other barrier functions
Water, UV radiation, harmful chemicals
Vitamin D synthesis
Skin starts process, liver and kidneys complete process
Sensation
Receptors for temperature, touch, pain, and more
Thermoregulation
Thermoreceptors, vasoconstriction and vasodilation, perspiration
Nonverbal communication
Facial expression
Transdermal absorption
Administration of certain drugs through the skin via patches
What is the epidermis cell type?
Keratinized stratified squamous epithelium
Most superficial layer of skin?
Epidermis
Is the epidermis vascular or avascular?
Avascular
First line of defense of the immune system?
Epidermis
What are the cells of the epidermis?
Stem cells, keratinocytes, melanocytes, tactile cells, and dendritic cells
What are stem cells?
Undifferentiated cells that give rise to keratinocytes
What are keratinocytes?
The great majority of epidermal cells, they synthesize keratin
What are melanocytes?
Synthesize pigment melanin that shields DNA from UV radiation. Have branched processes that spread among keratinocytes to distribute melanin
What are tactile cells?
Touch receptor cells associated with dermal nerve fibers
Where are stem cells found?
In deepest layer of epidermis (stratum basale)
Where are melanocytes found?
Stratum basale (deepest epidermus layer)
Where are melanocytes found?
Stratum basale (deepest epidermis layer)
Where are tactile cells found?
Basal layer of epidermis
What are dendritic cells?
Macrophages originating in bone marrow that guard against pathogens
What do dendritic cells guard against?
Toxins, microbes, and other pathogens that penetrate skin
Where are dendritic cells found?
Stratum spinosum and granulosum
How many layers are in the epidermis?
4 for thin skin, 5 for thick skin
What is stratum basale?
The deepest epidermal layer. A single layer of stem cells and keratinocytes resting on basement membrane.
What do stem cells in the stratum basale do?
Divide and give rise to keratinocytes, which migrate toward skin surface to replace lost cells
What is the stratum spinosum?
Epidermal layer. Several layers of keratinocytes joined together by desmosomes and tight junctions. Also has some dendritic cells
What is stratum granulosum?
Epidermal layer. 3-5 layers of flat keratinocytes.Contains keratohyalin granules
What is stratum lucidum?
Epidermal layer. Only in thick skin. Keratinocytes packed w/ eleidin
What is stratum corneum?
Epithelial layer. The surface layer. Up to 30 layers of dead, keratinized cells w/ tight junctions. Called epidermal water barrier
What does the stratum corneum do?
Resist abrasion, penetration, and dehydration
What are the layers of the epidermis?
Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
What is in the dermis?
Blood vessels, sweat glands, sebaceous glands, and nerve endings
What are the zones of the dermis?
Papillary layer, reticular layer
What are stretch marks?
AKA striae, tears in the collagen fibers. In reticular layer
What is the hypodermis also called?
Subcutaneous tissue
What is the hypodermis?
Not really a layer of skin. Has an abundance of apidose tissue. Common site of drug injection because of many blood vessels
What is melanin?
Significant factor in skin color. Produced by melanocytes. Accumulates in keratinocytes
How does melanin work?
Everyone has the same number of melanocytes, but darker skinned people have greater quantities of melanin and their melanin breaks down slower and are more spread out
What other 2 pigments influence skin color? Other than melanin/melanocytes
Hemoglobin and carotene
What is cyanosis?
Blueness of skin bc of oxygen deficiency
What is erythema?
Redness of skin bc of increased blood flow to skin
What is pallor?
Paleness of skin bc of decreased blood flow to skin
What is albinism?
Milky white skin and blue-gray eyes due to genetic lack of melanin-synthesizing enzyme
What is jaundice?
Yellowness of skin due to bilirubin in blood (can be bc of compromised liver function)
What is hematoma?
Bruising of skin, bc of clotted blood under the skin
What outside force can impact skin color, and to what degree?
UV light. Accounts for up to 77% of skin tone variation
Adverse effects of UV light?
Skin cancer, breaks down folic acid
Beneficial effects of UV light?
Stimulates vitamin D synthesis
What are friction ridges?
Markings on fingertips that leave oily fingerprints on thinga we touch. Qnique in everyone
What are flexion lines?
Lines on digits, palms, wrists, elbows. Mark sites where skin folds
What are birthmarks?
Patches of discolored skin caused by benign tumors of dermal capillaries. Different from freckles and moles!!!
What are hair and nails composed of?
Mostly dead keratinized cells
What is a pilus?
A hair. Plural form: pili
What are the 3 types of hair?
Lanugo, vellus, and terminal
What is lanugo?
Fine, unpigmented hair that appears on fetus during last 3 months of development
What is vellus?
Fine, pale hair that replaces lanugo by time of birth. 2/3 hair of women, 1/10 hair of men. All hair on children except eyebrows, eyelashes, and scalp
What is terminal hair?
Longer, coarser, pigmented hair. Forms eyebrows, eyelashes, and scalp hair. After puberty, forms axillary and pubic hair. Male facial hair and some trunk and limb hair
What is the bulb of hair?
A swelling at the base where hair originates in dermis or hypodermis. Only living hair cells are here
What is the root of hair?
The remainder of hair in the follicle (besides bulb)
What is the shaft of hair?
The portion above the skin surface
What is the hair matrix?
Region of mitotically active cells above papilla. Hair’s growth center
What is the medulla layer of hair?
A core of loosely arranged cells and air spaces
What is the cortex layer of hair?
Bulk of the hair, several layers of elongated keratinized cells
Where are sebaceous glands abundant?
The scalp
Where do merocrine sweat glands open to?
The surface of the skin
Where are apocrine sweat glands located?
Next to hair follicles
What do ceruminous glands do?
Produce ear wax
What is the epidermal layer only in thick skin?
Stratum lucidum
What layer do most sensations of the skin come from?
The dermis, but there are fine touch receptors in the epidermis
Layers of the epidermis in order from superficial to deep?
Corneum, lucidum(optional), granulosum, spinosum, basale
What cells make up the papillary layer?
Areolar connective tissue
What is the cuticle layer of hair?
Multiple layers of very thin, scaly cells that overlap each other
What is a hair follicle?
A diagonal tube that extends into the dermis and possibly hypodermis. Oblique epithelial tube
What is a piloerector muscle?
AKA arrector pili. Smooth muscle attaching follicle to dermis. Makes hair stand up
What hair colors is eumelanin in?
Brown and black, and some in blonde
What hair colors is pheomelanin in?
Red and blonde
What pigment granules are in gray and white hair?
There’s almost no melanin, but instead air in the medulla
What are the stages of the hair cycle?
Amagen, catagen, and telogen
What are nails made of?
Thin dead cells packed w/ hard keratin. Derivative of stratum corneum
What is the nail fold?
Surrounding skin rising above nail
What is the nail bed?
Skin underlying nail plate
What is the nail matrix?
Growth zone of thickened stratum basale at proximal end of nail
What is the lunule?
Opaque white crescent at proximal end of nail due to thickness of matrix
What is the eponychium?
AKA cuticle, narrow zone of dead skin overhanging proximal end of nail
What are the 4 types of glands?
Sweat, sebaceous, ceruminous, and mammary
What are the 2 types of sweat (sudoriferous) glands?
Apocrine and merocrine
What are apocrine glands?
Located in sensitive areas. Inactive until puberty. Produce milky sweat and secretes pheromones. Body odor comes from these glands
What are merocrine/eccrine glands?
Most numerous sweat glands; they make watery perspiration to cool the body. Sweat exits through a pore on the skin’s surface
What is sweat made up of?
99% water with a pH of 4-6. Some sodium chloride and small solutes can be present
What does the acid mantle do?
Inhibit bacterial growth
What is insensible perspiration?
The sweat we produce everyday through resting, up to 500mL/day
What is diaphoresis or sensible perspiration?
Sweat produced by exercise or hot temperatures, makes skin visibly wet. Up to 1L/hr
What do sebaceous glands open up into?
Hair follicles
What is sebum and what does it do?
Oily secretion of sebaceous glands. Keeps skin and hair from drying out
What are ceruminous glands and what do they do?
Tubular glands in external ear canal that produce earwax
What are mammary glands?
Milk-producing glands in females
What is skin cancer usually caused by?
UV rays damaging skin cell DNA
Where and in whom is skin cancer most common?
Head, neck, and hands. In fair-skinned people and the elderly. One of the most common and treatable cancers in general
What are the 3 types of skin cancer?
Basal cell carcinoma, squamous cell carcinoma, and malignant melanoma
Most common type of skin cancer?
Basal cell carcinoma
Least dangerous type of skin cancer and why?
Basal cell carcinoma, because it seldom metastasizes
What cell type does basal cell carcinoma come from?
Cells in stratum basale
What do basal cell carcinoma lesions look like?
A small shiny bump with a central hole and beaded edges
What type of cell does squamous cell carcinoma come from?
Ketatinocytes in the stratum spinosum
Where is squamous cell carcinoma usually located?
Scalp, ears, lower lip, back of hand
What do squamous cell carcinoma lesions look like?
Raised, reddened, scaly. Later form a concave ulcer
What are the chances of surviving squamous cell carcinoma?
Good with early detection and surgical removal. Though it tends to metastasize to lymph nodes and can become lethal
What type of cell does malignant melanoma come from?
Melanocytes
Most rare type of skin cancer?
Melanoma
Deadliest type of skin cancer?
Melanoma
Survivability of melanoma?
Good if caught early, but fatal if it metastasizes
Risk factor for melanoma?
Family history of melanoma, men, redheads, and having had sunburns as a child
ABCD rule for identifying melanoma?
A- asymmetry. 2 sides of mole don’t match
B- border irregularity. borders of mole arent smooth
C- color. different colors in pigmented area
D- diameter. larger than 6mm
What is the leading cause of accidental death?
Burns
How do deaths from burns occur?
Fluid loss, infection, and toxic effects of eschar (burned, dead tissue)
What is a first-degree burn?
Only the epidermis. Redness, slight edema (swelling), pain
What is a second-degree burn?
Partial-thickness, involves some part of dermis. Can look red, tan, or white. Blistered and painful. 2 weeks to several months to heal and can leave scars
What is a third-degree burn?
Full-thickness burn, involves all of epidermis and dermis and sometimes deeper tissues. Often requires skin grafts. Needs fluid replacement, infection control, supplemental nutrition
What are UVA and UVB rays sometimes called?
Tanning and burning rays
What type of rays can initiate skin cancer?
UVA and UVB rays. There is no “healthy tan”
What can sunscreens do?
Protect you from sunburn. Unknown if they protect from cancer. Some chemicals can damage DNA and generate free radicals
