integumentary system Flashcards
what is the integumentary system, generally
organ system composed of the skin and accessory organs
weight and thickness of skin
skin makes up about 15% of body weight and is 1.5-4.0 mm in thickness
heaviest and largest organ
what two layers make up the integument, what layer is not included
epidermis and dermis make up the integument
the hypodermis (subcutaneous layer) is not included
what tissue type makes up the epidermis, dermis, and hypodermis?
epidermis: stratified squamous epithelium
dermis: dense irregular connective tissue
hypodermis: adipose tissue
thick skin
located on palms, soles, fingers, and toes
due to a thick stratum corneum
sweat glands are present
no hairs or sebaceous glands present
thin skin
located on all parts of the body except for where thick skin is
due to a thin stratum corneum
sweat glands are present
hair follicles and sebaceous oil glands are present
what are three general functions of skin
- resistance to trauma and infection (epidermis)
-keratinized, acid mantle, and defensins - other barrier functions
-water barrier and UV radiation protection - vitamin D synthesis
-bone development and maintenance
explain the vitain D synthesis pathway
- through a normal cholesterol synthesis pathway, there is 7-dehydrocholesterol in the skin
- with the use of UV light (a light dependent reaction), the 7-dehydrocholesterol is converted into cholecalciferol (which is an inactive form of vitamin D)
^^ this all happens in the epidermis
- the cholecalciferol travels to the liver where it is hydroxylated by and enzyme called 25-hydroxylase. the molecule is now called calcidiol.
- calcidiol then travels to the kidneys where it is hydroxylated by enzyme 1-hydroxylase. the molecule is now called calcitriol which is active vitamin D
what three structures are responsible for the function of sensation in the skin
- tactile corpuscle - feeling light touch (on basal edge of epidermis)
- tactile disk - feeling heat/cold (on basal edge of epidermis)
- lamellar corpuscle - feeling pressure/vibration (deeper in dermis)
explain how skin functions with thermoregulation
vasodilation and vasoconstriction of blood vessels
vasodilation increases blood flow (widens blood vessels) near the epidermis. this allows the blood vessels to release more heat across the epidermis
ex. face turns red while exercising.
vasoconstriction - blood vessels near the epidermis constrict, retaining more heat by reducing blood flow
ex. you get rlly pale when you are very cold
how do sweat glands help with thermoregulation
eccrine (sweat) glands release sweat onto the skin, which through evaporative cooling, cools the surface of the skin
list the layers (strata) of the skin from top to bottom
top
stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale
dermis
bottom
what are the five cell types of the epidermis & explain
- keratinocytes
-specific name for epithelial cells of the epidermis
- most abundant
- derived from stem cells
- keratin, acidity, defensins, 7-dehydrocholesterol
- responsible for water boundary (waterproofing - not losing water through skin other than sweat) - stem cells
- undifferentiated cells
-give rise to keratinocytes - melanocytes
-produce the pigment, melanin
- continually shed melanosomes
- protection from UV light - tactile cells
-touch receptors in epidermis and dermis
-tactile disc –> a tactile cell(epidermis) connected by a neuron (dermis) - dendritic cells (langerhans cells)
-macrophages
-toxins, microbes, other pathogens
- alerts immune system to pathogens or removes pathogens
- about 800 cells per mm2
- have arm like projections (dendrites)
explain the process that melanin goes through
a cell called a melanocyte possesses appendages called psuedopodium (ia)
they produce melanosomes which are organelles with melanin in them (in the psuedopodia)
the melanocyte exocytoses the melanosome which gets endocytosed by a keratinocyte.
the melanin from the melanosome covers the superficial portion of the nucleus to protect it from UV radiation
responsible for darker pigmented skin
eventually the keratinocytes die and the color fades
explain how melanin amount controls skin color
everyone has a similar number of melanocytes but darker skin possesses more melanin and lighter skin possesses less melanin.
under a slide, you can see more melanin being accumulated at the basal membrane in darker skin but in lighter skin there is not much accumulation of melanin
why is there variation in skin color
due to variation in ancestral exposure to UV light
there is more UV radiation in tropical regions while the poles of the world have a lot less
explain the relationship between folate and vitamin D
UV light breaks down folate
UV light stimulates vitamin D synthesis in keratinocytes
folate=folic acid, vitalin B9
^ needed for cell division, fertility, and fetal development
vitamin D is needed for absorption of Ca2+ and therefore bone development
balancing how much UV light is required to not break down folate and to stimulate vit D synthesis
in tropics, ppl have melanized skin to block out excess UV light
in poles, ppl have less melanized skin to take in more UV light
globally, women have 4% lighter skin than men do so that they can get more vit D to support preganancy and lactation
characteristics of keratinocyte development
journey takes 30-40 days
slower as you age – less skin regeneration leads to wrinkles, coarse skin, etc.
quicker in injured tissue
quicker and thicker stratum corneum in stressed tissues – calluses due to injuries, repeated using of hands/feet (ex. weight lifting, running)
sstratum basale
single layer of cells on basement membrane
stem cells (becoming keratinocytes), melanocytes, tactile cells
^^need a major blood supply (closest to CT)
stratum spinosum
thick layer of cells becoming developmentally mature
producing keratin inside of the cell
cells are connected by desmosomes - you can see spines coming out of dehydrated, shriveled up cells on a slide but not when they are alive and hydrated
stratum granulosum
keratinocytes are developmentally mature
cells develop conspicuous granules
what are the functions of the granules in the stratum granulosum cells
epidermal water barrier
protective keratin layer
what are the two types of granules in the stratum granulosum, what do they each release
keratohyalin - release a protein called filaggin
lamellar - release lipids
explain the purpose of granules in the stratum granulosum
keratohylain granules produce the protein filaggrin which binds keratin fibers from the stratum spinosum together into bundles
this strengthens the keratinocyte
lamellar granules exocytose lipids and forms the epidermal water boundary just above the stratum granulosum
explain the lipid water boundary
without the lipid water boundary, we would lose so much water and maybe live for a day
this is why burn victims need hydration because their lipid layer is damaged and they cannot retain water
water gets stopped at the lipid boundary right above the stratum granulosum
the stratum corneum swells with water bc it cant pass through the boundary (this is why fingertips prune in water)
why can some drugs be creams
because they can go through the lipid water boundary (they are lipid soluble not water soluble)
ex. nicotene patches, estrogen patches/creams, lidocaine patches (steroids)
stratum lucidium
cells begin to lose organelles and die
densely packed with keratin
stratum corneum
cells are dead, filled with keratin
provides physical protection
what is the final process in keratinocyte development
desquamation
desquamation
separation of the cell from the surface of the stratum corneum
what is dandruff
accelerated desquamation
caused by yeast in genus Malassezia
a buildup of sebum can sometimes lead to a buildup of fungus which is the dandruff
when the superficial layer of the epidermis gets damaged, the rate of keratinocyte production increases and therefore the rate of desquamation increases
Zinc in dandruff shampoos kills the yeast
what do lotions and creams do for dry skin
traps in moisture which moisturizes dead skin cells
contains two things:
1. humectants
2. emollients
what do humectants and emollients do
humectants attract water from the air
they are negatively charged particles that attract ions to skin and therefore water
can be urea, glycerine, or any type of acid
emollients fill spaces in the stratum corneum between cells
hydrates skin and looks more full
typically are fats, petroleum, or mineral oil
purpose of dermis and what kind of tissues are found
provides blood and nutrients to the epidermis
composed of
dense irregular connective tissue
loose areolar connective tissue
adipose tissue
stratified cuboidal epithelium (sweat glands)
what makes the waves in the epidermis-dermis boundary
dermal papillae and epidermal ridges
dermal papillae
extensions of the dermis into the epidermis
epidermal ridges
extensions of the epidermis into the dermis
what is the function of dermal papillae and epidermal ridges?
- joining of the epidermis and dermis
- thermoregulation - blood vessels from dermis are closer to the surface (vasoconstriction and dilation)
- sensation - things like tactile corpuscles and such closer to the surface for pressure receptions
- provide surface for friction (grasping objects)
what are fingerprints
friction ridges
used for better gripping and increased sensation (sensors in the epidermal ridges)
what are the two major layers of the dermis
papillary layer (dermal papillae)
reticular layer (everything deep to papillary)
papillary layer of dermis
mostly areolar connective tissue
loosely organized
leukocyte mobility – they leave the circulatory system and move through the dermis to catch pathogens
rich in blood vessels
reticular layer of the dermis
mostly dense irregular connective tissue
lots of thick collagen bundles
resists stretching and provides support
space for glands/hairs/blood vessels
there are NO reticular fibers here
the word reticular = net/fiber - like structure
what makes up the hypodermis
HD = layer below the skin
the most vascularized layer
largely adipose tissue
energy reserve, thermal insulation, protection
why is it called a hypodermic needle and why is it used for vaccines, etc
bc it reaches the hypodermis layer
so that the vaccines/whatever they are injecting can reach the highly vascularized tissue of the hypodermis (it can enter the blood stream easily)
explain the extent of each type of burn
burns are damage due to heat, sunlight, acids/bases, or electrical shock
classified according to the depth of tissue damage
1st degree burns only breach the epidermis
- sunburns, etc
2nd degree burns get through the epidermis and dermis
- leakage of blood plasma (blister bubbles)
3rd degree burns get through the epidermis, dermis, and hypodermis
- destroying integument into the HD
why does dehydration occur in burn victims/what is impact
loss of liters of water
loss of 75% of blood plasma in a few hours
death due to cardiac arrest
bc of damage done to the lipid water boundary
bc they are losing a lot of their blood volume in plasma, they are not moving nutrients or oxygen through the body
why does infection occur in severe burn victims
patients are kept in an aseptic environment and are given antibiotics in high doses
they lose macrophages (dendritic cell) (or leukocytes potentially) that get rid of pathogens and the physical barrier of the integument is damaged
why do severe burn patients require extra calories
require thousands of extra calories per day
to heal the damaged skin
the integumentary system is very metabolically active
what are the three types of skin cancer caused by UV radiation
- basal cell carcinoma
happens in stratum basale
most common
curable by removal - squamous cell carcinoma
mostly impacts the squamous spinosum
second most common
curable by removal
often metastasizes to adjacent lymph nodes - melanoma
affects melanocytes in the stratum basale
least common
most deadly
metastasizes very quickly
what is SPF
sun protective factor
calculating SPF:
time to burn with sunscreen divided by time to burn without sunscreen
a higher SPF is not always better
SPF 30,50, and 100 are basically the same
you need a copious amount of sunscreen for it to be effective
vitaligo
disease that causes the loss of skin color
often in patches that tend to grow over time
symptoms:
hypopigmentation (often first on hands and feet)
premature hair whitening
cause:
destruction of melanocytes
autoimmune disorder, typically genetic
prognosis:
not life threatening or contagious but it does spread
no known cure
how does hemoglobin influence skin color
hemoglobin is a blood protein that transports oxygen
it has the red pigment that makes all blood red
oxygenated blood is bright red while deoxygenated blood is a little less red
veins are green/purple bc you are looking at hemoglobin through layers of dense irregular connective tissue with lots of collagen
lips are pink bc they are highly vascularized in dermis
how does carotene influence skin color
carotene is a yellow pigment from egg yolks and yellow/orange vegetables
accumulates in thick skin of stratum corneum or in subcutaneous fat
ex. calluses in foot turn an orange/yellow color
erythema
abnormal redness of the skin
short term: caused by exercise, hot weather, sun burns, rosacia
rosacia is the dilation of blood vessels
we dont know what causes it (most likely autoimmune, hereditary)
pallor
abnormal paleness
could be caused by:
indication of low blood pressure
cold weather which causes vasoconstriction
extreme anemia - not enough RBCs - not enough hemoglobin
cyanosis
abnormal blueness of skin
blue tips of fingers
linked to oxygen deficiency/obstruction
blocked airway, lung disease, etc.
cardiac arrest
jaundice
abnormal yellowness of skin and whites of eyes
caused by buildup of the pigment bilirubin
-bilirubin forms when hemoglobin gets broken down
- normally, it doesnt stay in the body bc the liver collects it and puts in bile in the gallbladder –> small intestine –> poop (why poop is brown (bilirubin is broken down by bacteria which turns it brown))
jaundice is indicative of liver or gallbladder problems bc it accumulates in the body
newborns are often born with jaundice bc their livers are underdeveloped
- they use UV lights in baby rooms to break down the bilirubin (it usually is not a health issue)
hematoma
bruise
skin changing colors –> red/purple bleeding bc of a broken blood vessel
eventually it turns a green ish color – bilirubin is accumulated in the skin
when bilirubin sits for a while, it gets broken down into biliverdin (green color)
what are hair and nails made of (generally)
keratin bundled by filaggrin
what are hairs
pilus (pili)
slender filament of keratinized cells
-there are about 5 mil hairs on body
- there are 100,000 hairs on scalp
- you lose about 50-100 scalp hairs daily
- hair grows abot 1 mm per 3 days
- hair color is due to the pigment melanin
hair is metabolically active
layers of dead keratinocytes
what is determinant/indeterminant hair
determinant - hair that grows to a certain length and then stop
indeterminant - hair that grows infinitely
what kind of melanin causes hair color
pheomelanin causes red hair color
varying amounts of eumelanin causes all the rest of the hair colors
what causes different hair textures
the shape of a cross section of hair
straight hair is circular
wavy hair is slightly oblong (oval)
curly hair is super oblong
what are hair follicles
epidermal invagination deep into the dermis
explain the hair growth cycle
- mature anogen
-growing phase - 6-8 years
stem cells multiply and follicle grows deeper into the dermis
hair matrix cells multiply and keratinize, causing hair to grow upward
epidermis envaginates into dermis (follicle development) - catagen
-degenerative phase - 2-3 weeks
hair growth ceases
hair bulb keratinizes and forms club hair (detaches from papilla and dies) - telogen
-resting phase - 1-3 months
dermal papilla has ascended to level or bulge
club hair falls out, usually in telogen or next anagen
deep follicle ascends falling out hairs (club hairs)
are usually in telogen
it doesnt have to fall out it can stay in there - early anogen
old club hair may persist temporarily alongside newly growing hair
and it will be pushed out by new hair
active throughout life
describe the area where a hair follicle forms
the epidermis invaginates and becomes only one cell layer thick (stratum basale) on the basement membrane with stem cells (which produce the hair) and melanocytes (which give the pigment)
the hair matrix begins at a dermal papilla which has lots of blood vessels to support it
there is massive differentiation of stem cells into keratinocytes and massive mitosis
what is alopecia
the general term for hair loss from all or some of the body
4 different types:
1. autoimmune - alopecia areata
dont know what causes it
2. mechanical damage - traction alopecia
long term damage, ex. pulling on long hair into buns for extended periods, burns, etc.
3. stress or childbirth - telogen alopecia
4. hormone imbalance - androgenic alopecia
caused by imbalance in androgens (testosterone)
common in males (male pattern baldness)
can be treated
what is used to treat male pattern baldness
rogaine – minoxidil
opens up potassium channels which strengthens hair follicles that are already there
can be applied to the scalp bc it can pass through the lipid water boundary
when men have low testosterone levels, that leads to vasoconstriction, ceasing growth of hair bc it is not supported by blood vessels
–> male pattern baldness
process:
smooth muscle cells around blood vessels contract to restrict blood flow
to do this, they need to let calcium channels open so calcium can get in
to do that, they need to open Na and K channels to allow Na in and K out (this is the trigger for letting Ca in)
Minoxidil opens K channels and prevents blood vessels from contracting
what is an ingrown hair
when a hair shaft that should normally exit the skin does something like:
grow back on itself and back into the skin surface (mostly this)
has been blocked from growing out and started to grow to the side before breaching the skin
get trapped on its way out of the skin
causes inflammation and infection
what is keratosis pilaris (follicular keratosis)
lots of ingrown hairs on the skin
chicken skin
normal skin growth and typically goes away at around year 30
can use abrasives to break hair up
what are nails
clear and hard stratum corneum
they grow about 3.5 mm per month
found on fingers and toes
lunule is due to rapid growth
what are the white spots on the proximal portion of nails and what is it caused by
lunule
massive quick growth
multiplying and pushing away keratinocytes creates pressure near blood vessels
^so much pressure that it pushes on the epithelium and pushes away blood permanently
what are the white spots on nails
leukonychia
not from a Ca deficiency, they are just abrasions
what are ingrown nails
nails that grow back into the epidermis
can lead to infection, inflammation
caused by damage, weird cutting of toenails, etc.
what is a gland
an organ that releases substance(s) for:
1. use somewhere else in the body
2. elimination from the body
what are the two major types of glands
- endocrine
NO contact with free surface (facing outside of the body or inside a cavity)
no ducts
highly vascularized (secrete hormones directly into the blood stream - exocrine
have contact with free surfaces
duct present - contact with outside world or cavity of an organ
what are the four types of cutaneous glands
- sudoriferous glands
- eccrine glands
- apocrine glands - sebaceous glands
- ceruminous glands
- mammary glands
sudoriferous glands
commonly called sweat glands
1. eccrine glands
evaporative cooling
waste excretion of urea, Na, waste nitrogenous products
widely distributed (3-4 mil)
duct to the skin surface
all of them basically make up one kidneys worth
- apocrine glands
scent glands
pubic, anal, axillary, areola, beard areas
release sex pheromones
duct to a hair follicle
sebaceous glands
oil glands, associated with hair follicles
secrete sebum - oily secretion with cell particles
^ prevents dry, brittle, and cracked hair and skin
duct opens into hair follicle which goes to skin
shampoos have synthetic sebum to keep hair moist
what is acne
when sebum gets stuck under pores
sebum is good food for bacteria
^pus, inflammation, etc.
due to hormone production
androgens
^ dehydroepiandrosterone (testosterone)
causes the overproduction of sebum = clogged follicles
bacne = due to steroids (injecting testosterone)
typically in males
lots of sebum on back
ceruminous glands
glands of the ear canals
stratified squamous cells
cerumen = sebum and dead epidermal cells (earwax)
results in pliable eardrum (needs to vibrate to hear), waterproofs, kills, and traps stuff
what is earwax made up of
cerumen
sebum and dead epidermal cells
mammary glands
milk producing glands located in breasts
lactation during pregnancy
duct like structures (tubes)
in lactating mammary glands, the tubes are swollen and distended with milk product
