The Integument System Flashcards
what does the term integument mean?
outer covering of the body (skin)
what are skin appendages?
- nails
- glands
- hair
what are the 3 layers of the skin?
epidermis
dermis
hypodermis
what cells are present in the epidermis?
keratinocytes
corneocytes
true or false
the epidermis is lipid rich
true
true or false
the dermis is lipid poor
true
what is the dermis comprised of?
collagen and fibroblasts
what type of tissue is the hypodermis considered?
connective
what is the function of each layer of the skin?
Epidermis: protects from external harm
Dermis: thermoregulation/sensation
Hypodermis: attach skin to structures beneath it
what roles does the skin have?
- water proofing
- vitamin D synthesis
- thermoregulation
- sensation
- immune surveillance
- excretion
what are the layers of thin skin and thick skin?
thin skin
- stratum basale
- stratum spinosum
- stratum granulosum
- stratum corneum
in thick skin, there’s an extra layer (stratum lucidum) between 3 and 4
what are keratinocytes?
cells in all layers of the skin except stratum basale, that produce and store keratin
what is keratin?
Fibrous protein that gives rigidity to skin,nails, and hair
what gives skin water resistant properties?
keratin
interwining collagen fibers that bind stratum basale to dermis are known as …..
basement memebrane
what is the function of the dermal papilla?
increases the strength of the connection between epidermis and dermis
which cells are precursors for keratinocytes?
basal cells
what cells are present in the stratum basale?
keratinocytes: keratin → skin rigidity
merkel cells: receptors for sensory functions
melanocytes: melanin & protection from uv light
protruding cell processes that join cells via desmosomes are know as …..
stratum spinosum
true or false
stratum spinosum is comprised of 8-10 layers of keratinocytes
True, it also has langerhans
what is the function of langerhans in stratum spinosum?
acts as a macrophage, engulfing bacteria, foreign particles and damaged cells that occur in that layer
how is the skin water proof?
keratinocytes in the stratum spinosum produce keratin and a water replling glycolipid which helps retain water inside the body
what happens to keratinocytes when there are new ones?
they are pushed towards stratum granulosum
what is the bulk of keratinocytes made up of?
keratohyalin (lamellar granules), and keratin
what happens to skin cells when they disintegrate and die?
they leave behind keratin, keratohyalin, and cell membrane which make the next layers (lucidum and corneum), hair and nails.
where is stratum lucidum present?
palms of the hands
soles of the feet
fingers
keratinocytes in the stratum lucidum are dead and flat
read it again
what is eleiden?
clear protein, rich in lipids derived from keratohyalin.
it acts as a barrier to water
what is the superficial layer called? the one exposed to the environment
stratum corneum
what is the function of stratum corneum?
prevents microbial penetration
mechanical protection against abrasion to deeper cells
an entire layer is replaced every ……… weeks
4
what does the hypodermis connect skin to?
bone and muscles
what is responsible for pigmentation?
melanin
hemaglobin
carotene
define a melanosome
vesicle that transfers melanin into keratinocytes
list the forms of melanin
eumelanin:
- associated with dark skin
- protects DNA from UV ray damage & folic acid breakdown
pheomelanin
associated with red pigment
list skin glands
sudoriferous glands:
sweat/merocrine glands
eccrine glands
deep in dermis/pores/water/salt/antibodies/metabolic waste/antimicrobial peptide
apocrine glands
duct empties in hair follice/associated with hair/thicker swear
sebaceous glands
oil gland/skin lubrication/generate sebum
what are the benefits of sebum produced by sebaceous glands?
antibacterial properties
prevent water loss
however it is inactive at childhood
what is hair?
a keratinous filament growing out of the epidermis
function of the nail body
protect extremities from mechanical stress
back support for picking up objects
what is hyponchium?
beneath the edge of the nail, consisting of thick stratum corneum
what are the 3 layers of hair?
internal root sheath (surround root of growing haair to hair shaft)
glassy membrane (thick clear connective tissue sheath covering hair root)
external root sheath (extension of epidermis encloses hair root)
what functions does the hair perform?
protection from the (head)
traps particles (eyebrows/nose)
prevent sweat from getting in the eyes (brows)
detection of insect presence
what is responsible for goose bumps?
arrector pili, smooth muscle that contracts in response to nerve signals from sympathetic nervous system
what do merocrine glands do?
they are involved in thermoregulation, cooling the body via secretions excreted by exocytosis through a duct not affecting the cells of the gland
what do eccrine glands do?
produce hypotonic sweat for thermoregulation
what are the phases of hair growth?
anagen: cell divide rapidly at root pushing hair out (2-7years)
catagen: transition from active growth to telogen phase (2-3weeks)
telogen: hair at rest, no new growth (2-4months)
meissner corpuscle and pacinian corpuscle are associated with sensory function? allocated a sensation for each them
meissner corpuscle: light touch
pacinian corpuscle: vibration
how does skin offer protection to the body?
- keratin layers and glycolipids in the stratum corneum make skin water resistant
- it is the first line of defense against direct contant with microbes and harmful chemicals
- produces sweat, which prevents microbes from colonizing the skin by generating dermacin which has antibacterial properties
what is the sensory function of the skin?
- hair roots comprise plexuses that are able to sense changes in the external environment
- it has sensory nerves able to sense touch, heat, and pain
- meissner and pacinian corpuscles can sense vibration and light touch
what makes skin a component of the immune system?
langerhans cells + dendritic cells + microbiome
how does the body regulate its temperature in hot weather?
when in hot weather, glands produce excessive sweat which evaporates from the surface of the skin and dissipates heat. arterioles in the dermis vasodilate for heat to travel to the surface of the skin leaving skin red and dissipating heat
how does the body regulate its temperature when its cold?
arterioles in the dermis constrict to prevent heat from leaving especially on the nose and extremities (passive heat loss)
how is vitamin D synthesized in the skin?
after exposure to uv light, cholecalciferol is synthesized from cholesterol in the skin
the liver then converts cholecalciferol to calcidiol
which is then converted by the kidneys to calcitriol
what is the role of vitamin D?
- absorption of calcium and phosphorus
- immunity against infection
what is eczema?
allergic reaction that manifests as dry, itchy, patches of skin as rashes
what is psoriasis?
decrease in oxidized lipids, perturbed barrier & hyperproliferation of keratinocytes
what is ichthyosis?
mutation in lipid processing enzymes and hyperproliferation of keratinocytes
