Integumentary System Flashcards
what tissues make up the integument system?
epithelial and connective tissue
three major regions of integument
epidermis
dermis
hypodermis
epidermis
outermost region
epithelial cells
dermis
middle region
connective tissue
hypodermis
superficial fascia/subcutaneous fat
connective tissue
functions of integumentary system
protection
homeostasis
blood reservoir
sensation
metabolism
excretion
protection
chemical, physical, and biological barrier
cold and heat, mechanical impact, chemical and physical damage, microorganism penetration, pressure, vibration, excessive dehydration
homeostasis
control body temperature
dilation (cooling) and constriction (warming) of dermal vessels
sweat gland secretions to cool body
blood reservoir
skin blood vessels store up to 5% of blood volume
sensation
receptors for touch, pain, and temperature
metabolism
synthesis of vitamin D
detoxification
excretion
nitrogenous wastes, water and salt through sweat
cells of epidermis
keratinocytes
melanocytes
dendritic cells
Merkel cells
keratinocytes
produce fibrous protein keratin
main cell type
melanocytes
produce brown pigment melanin
dendritic cells
Langerhans cells
epidermal macrophages to help activate immune system
Merkel cells
touch receptors associated with sensory nerve endings
thick skin vs thin skin
thin is missing stratum lucidum layer
thinnest skin is eyelid
thickest skin is heel of foot
5 layers of epidermis
stratum basale
stratum spinosum
stratum granulosum
stratum lucidum
stratum corneum
stratum basale (basal)
deepest epidermal layer
rapid division
single cell layer at bottom of epidermis
give rise to keratinocytes and basale stem cells
stratum spinosum (prickly)
above basale
newly differentiated keratinocytes anchored by desmosomes
lots of melanin granules from melanocytes to protect keratinocyte from UV
dendritic cells
stratum granulosum (granular)
above spinosum
1-5 cell layers thick
waterproofing and toughness
keratinocytes start to accumulate much more keratin
release water resistant glycolipids
stratum lucidum (clear)
above granulosum
transparent band only few layers thick
made from flattened dead keratinocytes
only visible in thick skin
stratum corneum (horny)
outermost layer of keratinized cells, dead/dying cells undergoing apoptosis
makes up 75% of epidermis (20-30 cell layers thick)
function of stratum corneum
waterproofing
protection from abrasion and penetration
protection from biological, chemical, and physical assaults
contents of dermis
nerves
blood and lymph vessels
glands and follicles
cell types present in dermis
fibroblasts (connective tissue
macrophages
white blood cells
mast cells
two layers of dermis
papillary - loose areolar
reticular - dense irregular
papillary layer
areolar connective tissue with loose collagen and elastic fibers
dermal papillae- superior surface of finger like projections (make up fingerprints)
contents of dermal papillae
capillary loops for blood supple
Meissner’s corpuscles for touch receptors
free nerve endings for pain receptors
immune cells
reticular layer
dense irregular connective tissue
collagen fibers for strength and resiliency, elastic fibers for stretch-recoil
makes 80% of thickness of dermis
what makes the flexure lines on hands/fingers?
when reticular layer of dermis is deeply connected to fascia
occurs at joints
where is tattoo ink located?
in dermis
complications of tattoo
granuloma- local inflammation
allergic reaction to dyes
composition of hypodermis
subcutaneous layer
adipose tissue and areolar connective tissue
functions of hypodermis
insulation
shock absorption
anchors skin to muscles loosely
three pigments of skin color
melanin- yellow, red, brown, black
carotene- yellow orange
hemoglobin- reddish
melanin
made by melanocytes and transported to keratinocytes
more sunlight –> more melanin
how are freckles or moles formed?
local accumulations of melanin
how does melanin help with cancer?
more melanin in skin, lower incidence of skin cancer
more protection from UV rays
carotene
yellow/orange
found in palms and soles of feet
vitamin A
hemoglobin
reddish
responsible for pinkish hue of pale skin
blood in capillary beds close to skin
why did northwest europeans lose ability to tan?
produce a defective form of mc1r necessary for protection of melanin
skin burns and peels rather than tans
sun poisoning/sun burn
response to UV damaging DNA causes inflammation
stimulation of DNA repair and melanin production
damaged cells undergo apoptosis -shed skin
vitamin D
majority made by skin with UVB photons
increases intestinal absorption of calcium, iron, magnesium, phosphate, and zinc
sudoriferous sweat glands
sweat glands
four types of sudoriferous glands
eccrine
apocrine
ceruminous
mammillary
eccrine sweat glands
many, found in palms, soles of feet, and forehead
coiled gland with opening at surface
release dilute solution of salts, vit C, dermicidin, and wastes
part of autonomic nervous system
reactions lead to location of sweat
heat at forehead
fear at palms, armpits, and arms
apocrine sweat glands
found in axillary and anogenital areas
duct empties into follicles
function starts at puberty and influenced by hormones
releases sweat, lipids, and proteins by exocytosis
ceruminous glands
modified apocrine glands in external ear canal that secrete cerumen (earwax)
mammary glands
specialized sweat glands that secrete milk
sebaceous glands
oily secretion called sebum
most active after puberty due to hormones
all over body, out growth of hair follicle
cell rupture
what does sebum do?
softens skin and hair
slows water loss from skin
bactericidal
which gland is blocked in teenagers with acne?
sebacious
the most important role of the eccrine sweat gland?
body temperature regulation
(also stress inducing sweat)
why does skin wrinkle in water?
nervous system response- vasoconstriction
better at manipulating objects
types of sensory receptors
thermoreceptors
mechanoreceptors
Meissner’s corpuscles
Pacinian corpuscles
thermoreceptors
respond to temperature changes
non-encapsulated free nerve endings
mechanoreceptors
respond to mechanical forces like touch, pressure, and vibration
on hair follicles
Meissner’s corpuscles
found in dermal papillae in top of dermis
discriminates light touch
Pacinian corpuscles
deep in dermis/subcutaneous tissue
sense applied pressure
functions of hair
maintain warmth
alert system
guards scalp against physical trauma, heat loss, and sunlight
guards eyes and nose against foreign particles
distribution of hair
all over body except
palms, soles and lips, and nipples and portions of external genitalia
hair
strands of dead keratinized cells (like outer layer of epidermis)
produced by hair follicles
pigment from melanocytes
parts of hair follicle
shaft- projects from skin
root- embedded in dermis
arrector pili- smooth muscles that pull hair erect
three cell layers of hair shaft
medulla
cortex
cuticle
hair follicle
surrounds hair shaft
deep end expands to form bulb filled with stem cells
papilla provides nutrients and growth signals (made of connective tissue and capillaries)
hair color
blonde-brown-black- melanin pigments from melanocytes
red- iron containing pigment pheomelanin
gray-white- gene related reduction in melanin production or age related environmental stresses
hair cycles
amount of time spent cycling changes depending on type of hair
growth, regression, resting phases
hair thinning/baldness
hair growth rates slow in 40’s
alopecia- autoimmune attacks hair cells
male pattern baldness genetically determined
nails
scale like modification of epidermis (hard keratin)
provides protection and increased grasping ability
three skin injuries
blister
stretch marks
sun damage
blister
fluid filled pocket that forms between epidermis and dermis
stretch marks
striae
scars formed when dermis is torn by excessive stretching during pregnancy
sun damage
clumping of elastic fibers that leads to leathery skin
too much exposure to the sunlight
skin cancer
1 in 5 americans diagnosed
most are benign and do not metastasize
result from mutation of p53 gene
from UV exposure
three types of skin cancers
basal cell carcinoma
squamous cell carcinoma
melanoma
basal cell carcinoma
least malignant
stratum basale cells proliferate and invade the dermis and hypodermis
slow growing and rarely metastasize
cured by surgery
squamous cell carcinoma
arise from keratinocytes from stratum spinosum
found on scalp, ears, and lower lip
rapid growth and will metastasize if not removed
surgery or radiation therapy
melanoma
cancer of melanocytes
most dangerous- highly metastatic, resistant to chemotherapy
ABCD rule for melanoma
Asymmetry- two sides of pigmented area don’t match
Border- irregular and exhibits indentations
Color- pigmented area is black, brown, tan, sometimes red or blue
Diameter- larger than 6 mm
treatment for melanoma
wide surgical excision with immunotherapy
survival is poor if lesion is over 4 mm thick into skin
dermatofibroma
benign
epidermal layers normal
disordered collagen
age effects on skin
- thinner skin as replacement slows
- dry and itchy
- subcutaneous fat layer diminishes, intolerance to cold
- decreased elasticity- wrinkles
- skin cancer risk increases- fewer melanocytes and dendritic cells
urticaria
inflammatory disorder
hypersensitivity to environmental exposure
cells release inflammatory cytokines
capillaries leak into dermis leading to edema
eczema
inflammatory disorder
dry itchy red skin
autoimmune function - cells attack skin
intracellular edema
psoriasis
chronic inflammation
epidermal hyperplasia in spinosum layer
elongation of papillary projections
microbial disorders
impetigo- by staph or strep bacteria in children
ringworm- fungal infection, tinea, on groin, feet, scalp, nails
diabetic dermopathy
most common disorder in diabetes
found on lower legs
hypothesis- excess glucose leads to cross linking of collagen
dermis
acanthosis nigricans
rough dark patches on neck
linked to obesity and insulin resistance
epidermal keratinocyte and dermal fibroblast proliferate
burns
heat, electricity, radiation, chemicals
risk: dehydration, electrolyte imbalance, infection
first degree burn
only epidermis is damaged
localized redness, swelling and pain
second degree burn
epidermis and upper regions of dermis are damaged
blisters - fluid filled between dermis and epidermis
third degree burn
entire thickness of skin is damaged
burned area is gray-white, red, or black
no edema or pain bc nerve endings burnt off
treated with skin grafts to prevent fluid loss or infection
rule of nines
estimates severity of burns
divide body in 11 regions, each region accounts for 9% of body surface
critical burn criteria
- over 25% of body has second degree
- over 10% of body has third degree
- third degree burns on face, hands, or feet (respiratory passageways)
burn treatment
supplementary nutrients by IV to replace lost proteins and begin repair
sepsis
widespread bacterial infection
leading cause of death in burn victims
skin grafts
autografts from own skin to replace burnt skin
best method to prevent rejection
