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List the major functions of the skin.
- 1. protection
- 2. synthesis of vitamin D
- 3. thermoregulation
- 4. somatosensory perception
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List of layers of epidermis from deepest to outermost layer.
- stratum basale or stratum germinativum
- (new keratinocytes are formed here)
- stratum spinosum
- stratum granulosum
- (synthesize and store keratohyalin)
- then in hands and feet go to stratum lucidum
- (here cells are filled with elaidin)
- other parts of body go to stratum corneum
- (dead keratinocytes filled with keratin)
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Three types of specialized epidermal structures.
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areolae
pigmented areas of the breasts
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arrector pili
a tiny bundle of smooth muscle that is attached to each hair follicle
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basal cell carcinoma
- arises from cells in the basal layer of the epidermis
- does not spread rapidly
- tends not to metastasize
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carcinoma
malignant tumor
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cerumen
a protective coating for the meatus (ear wax)
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ceruminous glands
located in the external auditory meatus (ear canal) and secrete cerumen
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conduction
as long as the temperature of the body surface exceeds that of the environment, heat can be lost through direct heat flow if the skin is in contact with a cooler object
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convection
as long as the temperature of the body surface exceeds that of the environment, heat can be lost to the environment through the air movement across the skin surface if the skin is in contact with a cooler object
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core body temperature
temperature of the central thorax, abdomen, and brain
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cornified layer
outermost layer of the skin, the stratum corneum
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deep-coiled portion
part of the eccrine sweat glands, the coiled portion generates a primary secretion of fluid by secreting NaCl into the gland lumen
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dermal glands
- include the sebaceous glands, sudoriferous glands, mammary glands, and ceruminous glands
- arise from the epidermis in the process of embryonic development
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dermis
- Made up of connective tissue with abundant extracellular fibers of collagen and elastin. Within this layer of skin are:
- hair follicles, sebaceous glands, the ducts of sweat glands, capillaries, and the sensory receptors responsible for sensitivity to pressure and vibration.
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duct portion
part of the eccrine sweat glands, the primary secretion of fluid from the deep-coiled portion passes through this
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eccrine sweat glands
- type of sudoriferous gland
- most dense in the palms of hands and soles of feet
- produce a dilute solution containing many of the constituents of blood plasma
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elaidin
translucent substance formed from keratohyalin
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epidermis
- stratified squamous epithelium that contains
- keratinocytes, melanocytes, and immunocytes
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evaporative cooling
promotes heat loss from the body surface in which some heat is absorbed by the water in the process of it transformation from a liquid to a gas
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first-degree burns
- burns that involve mainly damage to the epidermis
- require no special treatment
- typically heal rapidly without scarring
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full-thickness burns
third-degree burn affecting the dermis and subcutaneous tissue
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hair follicle
encloses the root of a hair in the skin
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holocrine glands
sebaceous glands in which the secretions are formed as a product of the breakdown of dead gland cells
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hypodermis
- underneath the dermis and is not technically part of the skin
- subcutaneous layer containing loose connective tissue, arterioles, venules, and adipose tissue
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immunocytes
provide a first line of defense against invasion by microbes, fungi, and parasites
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keratin
protein produced by keratinocytes
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keratinocytes
cells responsible for the wear resistance and waterproof qualities of skin
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keratohyalin
precursor of keratin
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lactation
production of milk by the mammary glands during a period of infant nutrition after birth
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lunula
the crescent shaped region at the base of the nail
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malignant melanoma
- arises from melanocytes in the skin or in pigmented moles
- some forms spread very rapidly and also metastasize freely to other body tissues
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mammary glands
- located within the breasts of females
- modified sweat glands that have evolved to produce milk during a period of infant nutrition after birth
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matrix
located at the base of each hair follicle where the hair grows
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melanin
pigment in the skin
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melanocytes
- produce melanin
- partly responsible for skin color
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merocrine glands
sudoriferous glands in which part of the secretory cells themselves appears in the secretion
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metastasize
carcinoma spreads to other areas of the body
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nail groove
nails arise from the matrix of stem cells located here at the base of each nail
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nail matrix
where the growth of the nail occurs
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papillary layer
- layer of the dermis, consisting of fingerlike projections that project into the overlying epidermis
- contain an extensive capillary network that supplies the needs of the basal layers of the epidermis
- plays an important role in heat loss from the body core
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partial thickness burns
second degree burns
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radiation
as long as the temperature of the body surface exceeds that of the environment, heat can be lost to the environment through the transfer by electromagnetic radiation if the skin is in contact with a cooler object
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reticular layer
layer in the dermis, largely composed of a network of crisscrossing collagen and elastin fibers that give the skin its elasticity and resilience
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sebaceous glands
holocrine glands that are associated with hair follicles and secrete an oily sebum onto the skin surface
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sebum
an oily substance secreted by the sebaceous glands onto the skin that reduces the loss of moisture and contains antimicrobial chemicals
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second degree burns
these burns involve at least some damage to the dermis
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skin grafts
- islands of transplanted skin are created within the burned region, using small flakes of skin removed from unburned body surfaces
- increase the rate of recolonization of new skin cells to the burned area
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squamous cell
- arises from cells in the stratum spinosum
- has a higher probability of metastasis
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stratum basale
- deepest layer of the skin
- also called the stratum germinativum
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stratum corneum
outermost layer of skin, twenty to thirty cells deep, consisting entirely of dead keratinocytes filled with keratin
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stratum germinativum
deepest layer of skin where new keratinocytes are continuously produced from stem cells
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stratum granulosum
- cells begin to synthesize and store keratohyalin here
- layer after stratum spinosum
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stratum lucidum
consists of cells filled with droplets of elaidin
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stratum spinosum
new keratinocytes push upward into this layer above the stratum germinativum
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subcutaneous fat
- adipose tissue that protects underlying organs from mechanical shock
- serves a thermal insulation
- contributes to the sex specific body contours of men and women
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sudoriferous glands
sweat glands
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thermoregulation
process that maintains the core body temperature constant within a few tenths of a degree celsius
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third degree burns
- also called full thickness burns
- both the dermis and subcutaneous tissue are affected
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tonic
a steady rate of nerve impulses along sympathetic nerves to superficial blood vessels that maintains some degree of vascular tone in those vessels
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the skin plays a role in several important bodily functions, including synthesis of _______.
vitamin D
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______ are the most abundant cells in the epidermis, and they give skin its waterproof qualities.
keratinocytes
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All keratinocytes originate in the epidermal layer known as the ______.
stratum basale
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Goosebumps occur because of the action of tiny muscles called ______, which are attached to each of a person's hair follicles.
arrector pili
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Epidermal derivatives called ______ glands are responsible for the skin's production of sweat.
sudoriferous
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The cell type in the skin that is responsible for the skin color is _____.
melanocytes
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The most abundant type of cell in the epidermis is called ______.
keratinocytes
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The two most common protein molecules in the dermis are _______ and _______.
collagen and elastin
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Hair and nails are dead epithelial derivatives that are durable because the possess an abundance of what protein?
keratin
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