Language of Medicine - Chapter 16 Flashcards
skin
what makes up the integumentary system?
skin + accessory organs (hair, nails, glands)
true or false
the skin is the largest organ in the body
explain your answer
true
skin weighs 8-10lbs + extends over 22sq ft in average person
what are functions of the skin
- protective membrane - skin guards deeper tissues of the body against excessive loss of water, salts, and heat against invasion of pathogens + toxins
- produce secretions - 2 glands (sebaceous + sweat glands), sebaceous glands produce sebum (oily secretion) + sweat glands produce sweat which passes through outer skin through ducts and leaves through pores = sebum lubricates skin + sweats cools the skin
- receptors for sensations = like pain, temperature, pressure + touch, bodies adjustment depends on sensory messages relayed to brain + spinal cord by nerve endings
- maintain body temperature - nerve fibres coordinate thermoregulation by carrying messages to skin from heat centers in brain that are sensitive to increases + decreases in body temp
what are the 3 layers of the skin
- epidermis
- dermis
- subcutaneous layer
define epidermis
cutaneous layer - thin, cellular membrane layer; contains keratin
- composed of squamous epithelium (flat + scale like cells), cells are arranged in several layers (strata) to form stratified squamous epithelium
- lacks blood vessels, lymphatic vessels + CT (elastic fibres, cartilage + fat)
- dependent on dermal layer
- basal layer (bottom layer) cells constantly grow + multiply
- stratum corneum (top layer) cells are flat, shrink, lose their nuclei + die - become filled with protein called keratin
define melanocytes
specialized cells, located in the basal layer of the epidermis
- same number of melanocytes in all humans no matter the race
- people with darker skin possess more melanin within melanocytes
describe melanin
- melanin production increases with exposure to UV light (creates a suntan)
- when melanocytes cannot absorb all the UV rays sunburns occur
people who cannot form melanin have what condition?
albinism
what is albinism?
people who cannot form melanin have this condition and it is when the skin + hair are white
define dermis
cutaneous layer - located directly below epidermis + composed of blood vessels + lymph + nerve fibres + accessory organs of skin (hair follicles, sweat glands + sebaceous glands)
- composed of elastin (elastic + helps skin recoil when pinched) + collagen fibres (fibrous protein found in bone, cartilage, tendons, ligaments + skin)
- tough + flexible
- overstretching of the skin (by gaining weight (pregnancy) may break elastic fibres resulting in striae)
describe scleroderma
immune system attacks + damages healthy tissue, leading to abnormal buildup of collagen + tight, thick skin
define the subcutaneous layer
specializes in formation of fat
- adipose (fat cells) are predominant in this layer + manufacture + store large quantities of fat
- protects deeper tissues of the body
- acts as a heat insulator
functions in energy storage
describe hair
composed of tightly fused meshwork of cells filled with keratin
- hair growth is similar to growth of epidermis, deep lying cells in hair root produce keratin cells that move upward through hair follicles
- melanocytes donate melanin pigment to give hair color
- hair grows 1/2 in per month
describe nails
hard keratin plates covering dorsal surface of the last bone
- composed of keratinocytes cemented tightly together
- fingernails can grow 1mm per week (replaced in 3-5 months if taken off) toenails grow slower + can take a year to grow back fully
- lunula is a semilunar (half moon shape) whitish region at base of nail (white color comes from air mixed with keratin)
- cuticle narrow band of epidermis at base/sides of nail plate
- paronychium soft tissue surrounding the nail boarder
describe onycholysis
loosening of the nail plate with separation from the nail bed
- may occur with an infection of the nail
describe sebaceous glands
located in dermal layer of skin of entire body except the palm of hands + soles of feet + lips
- secrete oily substance called sebum
- sebum contains lipids, lubricates the skin + minimizes water loss
- closely associated with hair follicles
- influenced by sex hormones - causes hypertrophy in puberty + atrophy in old age
- increased sebum during puberty results in blackheads
describe sweat glands
- most common = eccrine sweat glands - tiny, coiled glands found on almost all body surfaces (~2 million in body)
- most numerous in palm of hand + sole of foot
- originates deep in dermis + straightens out to extend through the epidermis
- tiny opening on surface is a pore
- sweat / perspiration is almost pure water with dissolved minerals like salt
- sweat cools body as it evaporates the air
- perspiration is controlled by the SNS
adip/o
fat
albin/o
white
caus/o
burn, burning
cauter/o
heat, burn
cutane/o
skin
derm/o
dermat/o
skin
diaphor/o
profuse sweating
erythem/o
erythemat/o
redness
hidr/o
sweat
ichthy/o
dry, scaly (fish like)
kerat/o
hard
leuk/o
white
lip/o
fat
melan/o
black
myc/o
fungus (includes fungi, yeast, molds + mushrooms)
onych/o
nail
phyt/o
plant
pil/o
hair, hair follicle
py/o
pus
rhytid/o
wrinkle
seb/o
sebum
squam/o
scale like
trich/o
hair
ungu/o
nail
xanth/o
yellow
xer/o
dry
