Chapter 6 Flashcards
What are the layers of skin?
Epidermis
-Stratum corneum
-Stratum granulosm
-Stratum lucidum (palms & soles)
-Stratum spinosum
-Stratum basale/germinativum
Dermis
-Papillary layer
-Reticular layer
Describe stratum basale?
Deepenst layer of skin that is composed of a single row of stem cells that are attached to the dermis.
They are mitotic active and produce two daughter cells
Melanocytes compose 10-25% of this layer
Describe stratum spinosum?
Called the prickly layer. Several layers thick of cells containing intermediate prekeratin filaments attached to desmosomes.
Scattered amoung keratinocytes are dendritic cells which are APC that aid in immune function (carry invaders on head)
Describe stratum lucidum?
Only present in thick skin (palms and soles)
Describe stratum granulosum?
4-6 cell layers. Cells change by flattening, nuclei and organelles disintegrating, and keratinization beginimng. Cells above this layer die due to being too far from dermal capillaries
Describe stratum corneum?
20-30 rows of dead, flat, anucleate keratinized membranous sacs which comprise 3/4 of epidermal thickness that acts as protection
Describe melanocytes?
Located in stratum basale and produce the pigment melanin to absorb UV light from the sun and provide skin color
Describe tactile corpuscles?
Sensory receptors close to the surface of the skin that is sensitive to light touch as called Meissner’s corpuscles
Describe dendritic cells?
Part of the family of immune cells that capture (phagocyte), process, and present antigens to adaptive immune cells
Describe keratinocytes?
The major type of cell in the epidermis that receives and uses melanin
Describe pacinian corpuscles?
Detect pressuere also called lamellated corpuscles
Describe meissner’s corpuscles?
Detect light touch also called tactile corpuscles
What are the 3 pigments that influence skin color?
Melanin, carotene, and hemoglobin
Desciribe melanin?
Two two types. The common brownish-black is eumelanin and reddish-yellow pheomelanin. Skin color is determined by the amount produced. All people have the same number of melanocytes.
Describe carotene?
A yellow-orange pigment that accumulates in the stratum corneum and the hypodermis
Describe hemoglobin?
A protein that carries oxygen and when amount are rich provides a pinkish hue while if not enough present will result in a pale blueish-gray
Describe jaundice?
Skin becoming yellow because a liver dysfunction causes the build-up of bilirubin
Describe cyanosis?
Low hemoglobin causing the skin to appear blueish
Describe albinism?
A mutation in the melanin gene causes someone to have non-pigmented skin
What are the 5 parts of a nail?
Cuticle
Lunula
Nail bed
Nail plate
Free edge
What are the 6 main features of hair and their functions?
Dermal/hair papillae-nourishment
Hair bulb-cell division and growth (mitotically active)
Hair follicle-cells that surround the hair
Hair bulge-Site of stem cells located between arrector pili muscle and sebaceous gland
Hair root-shaft below the skin
Hair shaft-emerges from the surface of the skin
What determines hair coloration?
The type and amount of melanin produced
What are the 5 types of skin glands
Sebaceous glands
Merocrine/eccrine glands
Apocrine glands
Ceruminous glands
Mammary glands
Describe the sebaceous gland?
A type of holocrine gland associated with hair follicles that produces sebum to keep the hair soft and waterproof
Describe eccrine/merocrine glands?
The most numerous type of sweat gland that responds to elevated body temperature
Describe apocrine glands?
A type of sweat gland located in the axillary and groin area activated during puberty that respond to emotion and pain
What type of glands secrete ear wax?
Ceruminous glands
What type of glands secrete milk?
Mammary glands
What are the six functions of the skin?
Protective covering/barrier against harmful substances and microorganisms
Prevents water loss
Contains sensory receptors
Excretes waste
Helps regulate body temperature
Helps produce vitamin D
The four methods of heat loss?
Radiation-primary method, heat escapes via infrared heat rays
Conduction-Heat moves from the skin to cooler objects
Convection-Heat loss into circulation air currents
Evaporation-Sweat changing into a gas carrying heat away
What are the 4 steps of thermoregulation?
Thermoreceptors signal hypothalamus
Vasoconstriction/dilation of dermal blood vessels
Sweat glands inactivated/activated
Muscles contract (shivering)
Describe hyperthermia?
Abnormally high body temperature. Most likely to occur on hot, humid days when radiation is less effective and sweat cannot evaporate. Symptoms include dry skin, weakness, dizziness, nausea, headache, and rapid pulse
Describe hypothermia?
Abnormally low body temperature that results from prolonged exposure to cold or illness. Symptoms include shivering that progresses to confusion, lethargy, loss of reflexes, and loss of consciousness
Describe inflammation?
A normal response to injury and stress that is the body’s attempt to reduce the spread of infection. Blood vessels dilate and become more permeable to allow fluids to leak to damaged tissues causing reddened, swollen, warm, painful skin
What are the two types of cuts?
Shallow and deep
Describe a shallow cut?
A cut that only effects the epidermis that is healed by epidermal cells along the margin dividing more rapidly to fill the gap
What layer does a deep cut penetrate to?
The dermis or subcutaneous layer resulting in blood vessels breaking and releasing blood
What are the 7 steps for a deep cut to heal?
A clot consisting of fibrin, blood cells, and platelets form
Clot and dried tissue fluid form a scap
Epithelial cells reproduce and fill the wound
Fibroblasts secrete collagen fibers to bind the wound together
Growth factors stimulate new tissue formation
Phagocytic cells remove dead cells and debris and the scab sloughs off
Excess collagenous fibers form an elevated mass called a scar
Describe a first-degree burn?
A superficial, partial-thickness burn that only affects the epidermis such as a sunburn. Symptoms include redness, heat, and inflammation. Healing takes days-weeks with no scarring
Describe a second-degree burn?
A deep, partial-thickness burn that destroys the epidermis and some of the dermis such as a burn from a hot liquid. Symptoms include blistering. If stem cells in accessory structures survive then no scarring results. However, scarring is possible if the burn is deep enough
Describe a third-degree burn?
A full-thickness burn that destroys the epidermis, dermis, and accessory structures that results from prolonged exposure to heat, flames, or hot liquids. Some healing can come from the margins but often requires a skin graft of skin substitute
What is the role of skin for vitamin D?
7-dehydrocholesterol/provitamin D3 is changed in the presence of UV light and then is changed in the liver and the kidneys to form Dihydroxycholecalciferal/Vitamin D3
What is the role of melanin in skin color and pigmentation?
Melanin is distributed into keratinocytes to protect cells from the damaging effects of UV light (DNA damage, fibroblast damage, skin cancer). The transfer of melanin granules into keratinocytes darkens the cells.
What are the two layers of the dermis?
Papillary layer and Reticular layer
Describe the papillary layer of the dermis?
This layer comprised of aerolar tissue makes up 20% of the dermis. It contains dermal papillae that increase surface area so nutrients are more easily transferred. This layer contains Meissner’s/pacinian corpuscles.
Describe the Reticular layer of the dermis?
The deeper layer of the dermis that is composed of dense irregular connective tissue and makes up 80% of the layer. The fibers in this layer provide stretch-recoil properties along with strength and resiliency
How does tanning and UV cause skin cancer and melanoma?
Excessive tanning or tanning beds can overwhelm the body’s natural protective responses against cancer. A protein called p53 stimulates responses, such as redness, swelling, and inflammation, to protect. When this mechanism is overwhelmed, cancer ensues.
What are two main types of skin cancer?
Cutaneous carcinomas are when epithelial cells are affected (basal cell carcinoma and squamous cell carcinoma)
Melanoma is when melanocytes are affected. This type of cancer is the most deadly
