ch. 6 the integumentary system Flashcards
skin and subcutaneou tissue
integumentary system
consists of the skin and accessory organs
* hair
* nails
* cutaneous glands
skin and subcutaneou tissue
skin is the body’s
largest and heaviest organ
* covers 1.5 to; composes 15% of body weight
skin and subcutaneou tissue
layers
- epidermis stratified squamous epithelium
- dermis deeper connective tissue
- hypodermis connective tissue layer below dermis (not part of skin, associated with it)
functions of skin
resistance to
trauma and infection
* keratin
* dermacidin and defensins
* acid mantle
functions of skin
other barrier functions
- water
- UV radiation
- harmful chemicals
functions of skin
vitamin D synthesis
- skin carries out first step
- liver and kidneys complete process
functions of skin
sensation
- skin is an extensive sense organ
- receptors for temp, touch, pain, more
functions of skin
thermoregualtion
- thermoreceptors
- vasoconstriction/vasodilation
- perspiration
the epidermis
epidermis
keratinized stratified squamous epithelium
the epidermis
includes
- dead cells at skin surface packed with tough keratin protein
- lacks blood vessels–depends on the diffuiosn of nutrients from underlying connective tissue
- contains sparse nerve endings for touch and pain
cells of epidermis
5 cell types
- stem cells
- keratinocytes
- melanocytes
- tactile cells
- dendritic cells
cells of the epidermis
stem cells
- undifferntiated cells that give rise to kertainocytes
- in deepest layer of epidermis (stratum basale)
*
cells of the epidermis
keratinocytes
- greates majority of epidermal cells
- synthesize keratin
cells of the epidermis
melanocytes
- synthesize pigment melanin that shields DNA from ultraviolet radiation
- occurs only in stratum basale but have branches processes that spread among keratinocytes and distribute melanin
cells of the epidermis
tactile cells
- touch receptor cells associated with dermal nerve fibers
- in basal layer of epidermis
cells of the epidermis
dendtritic cells
- macrophages originating in bone marrow that guard against pathogens
- found in stratum spinosum and granulosm
the dermis
dermis
connective tissue layer beneath epidermis
dermis
composed mainly with
collagen
dermis
well supplied with
- blood vessels
- sweat glands
- sebaceous glands
- nerve endings
dermis
has a wavy conspicuous boundary with the
superficial epidermis
dermis
dermal papillae are
upward
finger-like extensions of dermis
dermis
epidermal ridges are
downward waves of epidermis
dermis
prominent waves on
fingers produce friction ridges of fingerprints
hypodermis
hypodermis
- subcutaneous tissue
- has more areolar and adipose than dermis has
- pads body and binds skin to underlying tissues
- common site of drug injection since it has many blood vessels
hypodermis
subcutaneous fat
- energy reservoir
- thermal insulation
- thicken in women
- thinner in infants, elderly
skin color
melanin
most significant factor in skin color
skin color
melanin is produced by
melanocytes
accumulates in keratinocytes
skin color: melanin
two forms of pigment
- eumelanin–brownish black
- pheomelanin–reddish yellow (sulfur containing)
skin color
people of different skin colors have the same
number of melanocytes
skin color
darker skinned people
- produce greater quantities of melanin
- melanin breaks down more slowly
- melanin granules more spread out in keratinocytes
- melanized cells seen throughout the epidermis
skin color
lighter skinned people
- melanin clumped near keratinocyte nucleus
- little melanin seen beyown stratum basale
skin color
exposure to UV light stimulates
melanin secretion and darkens skin
* this color fades as melanin is degraded and old cells exfoliated
skin color
other pigments can influence skin color
- hemoglobin–pigment in RBCs-adds reddish to pinkish hue to skin
- carotene–yellow pigment acquired from egg yolks and yellow/orange vegetables–concentrates in stratum corneum and subcutanous fat
skin color
colors of diagnostic value
- cyanosis
- erythema
- pallor
- albinism
- jaundice
- hematoma
skin color: colors of diagnostic value
cyanosis
blueness due to oxygen deficiency
skin color: colors of diagnostic value
erythema
redness due to increased blood flow to skin
skin color: colors of diagnostic value
pallor
palness due to decreased blood flow to skin
skin color: colors of diagnostic value
albinism
milky white skin and blue-gray eyes due to genetic lack of melanin-synthesizing enzyme
skin color: colors of diagnostic value
jaundice
yellowing due to bilirubin in blood (can be caused by compromised liver function)
skin color: colors of diagnostic value
hematoma
bruising
(clotted blood under skin)
skin cancer
skin cancer
most cases causes by UV rays of the sun damaging skin cell DNA
skin cancer
most often on the
- head
- neck
- hands
most common in fair-skinned people and the elderly
one of the most common easily treated cancers
has one of the highest survival rates if detected and treated early
skin cancer
3 types of skin caner names for the epidermial cells in which they orginate
- basal cell carcinoma
- squamous cell carcinoma
- malignant melanoma
skin cancer: basal cell carcinoma
basal cell carcinoma
- most common type
- least dangerous b/c it seldom metastasizes
- forms from cells in stratum basale
- lesion is small shiny bump with central depression and beaded edges
skin cancer: squamous cell carcinoma
squamous cell carcinoma
- arises from keratinocytes of stratum spinosum
- lesions usually on scalp, ears, lower lip, or back of hand
- have raised, reddened scaly appearance later forming a concave ulcer
- chance of recovery good with early detection and surgical removal
- tends to metastasize to lymph nodes and may become lethal
skin cancer: malignant melanoma
malignant melonoma
- skin cancer that arises from melanocytes
- less than 5% of skin cancers but MOST DEALDY form
- can be successfully removed if caught early but if it metasizes it is usually fatal
- greated risk factor: famillial histoey of malignant melanoma
- highest incidence in men, redheads, and people who has severe sunburn as a child
burns
burns
leading cause of accidental death
* fires
* kitchen spills
* sunlight
* ionizing raditation
* strong acids/bases
* electrical shock
burns
deaths result primarily from
- fluid loss
- infection
- toxic effects of eschar (burned, dead tissue)
debridement: removal of eschar
burns
classified according to depth of
tissue involvement
burns
first-degree burns
- involves only epidermis
- redness
- slight edema
- pain
- heals in days
burns
second degree burns
- partial-thickness burn
- involves part of dermis
- may appear red, tan, white
- blistered and painful
- 2 weeks–several months to heal and may leave scars
burns
third degree burns
- full-thickness burn
- involves epidermis, all of dermis, and often some deeper tissues
- often requires skin grafts
- needs fluid replacement, infection control, supplemental nutrition
UV rays and sunscreen
UVA and UVB are improperly called
tanning rays and burning rays
* both thought to initiate skin cancer
* no such thing as a healthy tan
UV rays and sunscreen
sunscreens protect you from
sunburn but unsure if they provide protection against cancer
* high SPF numbers can give false sense of security
* chemical in sunscreen damage DNA and generate harmful free radicals
