Chapter 4: Skin and Body Membranes
ulcers
a sore caused by any severe or prolonged restriction of the normal blood supply to the skin-- results in cell death
cutaneous glands
all exocrine glands that release their secretions to the skin surface via ducts; 2 types: sebaceous & sweat; formed by cells of the stratum basale
squamous cell carcinoma
arises from cells of the stratum spinosum; lesion appears as a scaly, reddened circle, that eventually turns into an ulcer
4th degree burns
beyond the skin into connective tissue, muscle, and bone
ceruminous glands
in the ear canal (produce ear wax); keeps things from growing in your ear
sebum
product of the sebaceous glands that is a mixture of oily substances and fragmented cells
integument
skin
desiccation
stops organs from drying out
Why are the more superficial epidermal cells unable to get adequate nutrients and oxygen?
the combination of accumulating keratin inside them, secretion of a water-repellent glycolipid into the extracellular space, and their increasing distance from the blood supply in the dermis
dermis
the deep layer of the skin; composed of dense irregular connective tissue; phagocytes found here (to prevent bacteria that managed to get through the epidermis from going deeper in the body)
stratum basale
the deepest cell layer of the epidermis; these cells are constantly dividing;
reticular layer
the deepest skin layer; contains irregularly arranged connective tissue fibers, blood vessels, sweat/oil glands, & deep pressure receptors (lamellar corpuscles)
herpes simplex
virus causing cold sores
vitiligo
-autoimmune disease that attacks your own body's melanocytes -non-segmental = symmetrical (90% people have this) -segmental = spreads the most, asymmetrical
Why do we need vitamin D?
-ensures the growth of healthy bones in children/maintain healthy bones in adults -ensures that blood has sufficient levels of calcium and phosphorus
necrotizing faciitis
-flesh-eating disease -bacteria gets under skin & releases toxins which infects the connective tissue that surrounds muscles, nerves, and blood vessels -contagious
epidermolysis bullosa
-group of rare diseases that causes the skin to blister -3 types: epidermolysis bullosa simplex, dystrophic epidermolysis bullosa, junctional epidermolysis bullosa -people with EB lack collagen fibers so epidermis/dermis layers rub against each other = blisters
Why do we need folic acid?
-helps the body replicate DNA during mitosis -helps produce red blood cells
When are burns considered critical?
-if over 25% of the body has 2nd degree burns -if over 10% of the body has 3rd degree burns -if there are 3rd degree burns of the face, hands, or feet
porphyria
-problem in the production of heme -cutaneous (outside) and acute (affects nervous system) -erythropoietic = low red blood cells, enlargement of spleen -hepatic = liver -can treat with repeated phlebotomies
What are the functions of the integumentary system?
-protects deeper tissues from mechanical damage (bumps), chemical damage (acids and bases), bacterial damage, UV radiation, thermal damage (heat or cold), desiccation (drying out) -aids in body heat loss/retention (controlled by nervous system) -aids in excretion of urea and uric acid -synthesizes vitamin D
Why do we need cholesterol?
-required to make & maintain cell membranes -helps the brain send messages to protect against diseases -building block for estrogen/testosterone -essential for processing vitamin D
decubitus ulcers (bed sores)
-tissue damage that causes open sores -affects elderly, disabled, and coma patients
hair follicles
2 compound structures: inner root sheath (composed of epithelial tissue, forms the hair) & outer fibrous sheath (dermal connective tissue, supplies blood vessels to the epidermal portion)
connection between tanning beds & birth defects
UV rays destroy folic acid in the body, so if a pregnant woman goes to a tanning bed, she will lower her folic acid, making the child more prone to birth defects
melanin
a pigment that ranges in color from yellow to brown to black
keratin
a tough, insoluble protein found in tissues such as hair, nails, and epidermis of the skin
hypodermis (superficial facia)
adipose tissue deep to the dermis; not considered part of the skin but anchors skin to underlying organs; provides a site for nutrient storage; serves as a shock absorber & insulates the deeper tissues from extreme temperature changes outside the body
disadvantages of ApoE4
all the extra cholesterol puts people at higher risk for heart disease & stroke, sometimes Alzheimer's
3 pigments contributed to skin color
amount & type of melanin in the epidermis (yellow, reddish brown, black)
Why do nails look pink?
blood supply in the dermis
2 life-threatening results from burns
body loses supply of fluids & infection
How are burns classified?
by their severity (depth)
malignant melanoma
cancer of melanocytes, uses ABCD rule to recognize
epidermal dendritic cells
cells scattered in the epidermis which are important in alerting & activating immune system cells to a threat
Merkel cells
cells sometimes seen at the epidermal-dermal junction which are associated with sensory never endings and serve as touch receptors called Merkel discs
stratum lucidum
clear layer of the epidermis superficial to the stratum granulosum; this layer is not present in all skin regions (only where skin is hairless & extra thick)
cortex
composed of layers of flattened cells; surrounds the medulla
How does the integumentary system aid in excretion of urea and uric acid?
contained in perspiration produced sweat glands
How does the integumentary system protect deeper tissues from desiccation?
contains a water-resisting glycolipid and keratin
How does the integumentary system protect deeper tissues from thermal damage?
contains heat/cold/pain receptors
skin appendages
cutaneous glands, hair, hair follicles, & nails
skin
cutaneous membrane
hair bulb
deepest part of the follicle, base of root
Where are glands found?
dermis
3rd degree burns
destroy the entire thickness of the skin
What 2 types of tissues is the skin composed of?
epidermis & dermis
whiteheads
formed when a sebaceous gland's duct is blocked by sebum
blackheads
formed when the accumulated material oxidizes & dries
sebaceous (oil) glands
found all over the skin except of palms of hands and soles of feet
3 parts of nails
free edge, body (visible attached muscle), root (embedded in the skin)
elastic fibers
gives the skin elasticity when we are young
matrix
growth zone of the hair bulb
How does the integumentary system protect deeper tissues from chemical damage?
has relatively impermeable keratinized cells; contains pain receptors, which alert the nervous system to possible damage
How does the integumentary system aid in body heat loss or heat retention?
heat loss: by activating sweat glands and by allowing blood to flush into skin capillary beds so that heat can radiate from the skin surface heat retention: by not allowing blood to flush into skin capillary beds
How does the integumentary system synthesize vitamin D?
modified cholesterol molecules in skin converted to vitamin D by sunlight
sweat (sudoriferous) glands
more than 2.5 million per person; 2 types: eccrine & apocrine
How does geography impact skin color?
near the equator = higher sunlight intensity = darker skin; away from the equator = lighter skin
1st degree burns
only the epidermis is damaged
carotene
orange-yellow pigment coming from mainly carrots; rests in stratum corneum & subcutaneous tissue
cuticle
outermost layer formed by a single layer of squamous cells that overlap like a roof (most heavily keratinized)
What 2 major regions make up the dermis?
papillary & reticular
hair root
part of the hair enclosed in the follicle (alive)
How does the integumentary system protect deeper tissues from mechanical damage?
physical barrier contains keratin, which toughens cells; fat cells to cushion blows; and pressure receptors, which alert the nervous system to possible damage
eccrine glands
produce sweat; import part of heat regulation (supplied w nerve endings that sense when external temp is high)
hair
produced by a hair follicle, a flexible epithelial structure (long chain of dead cells); forms by division of stratum basale cells; everywhere except palms, soles, nipples, & lips
hair papilla
provides the blood supply to the matrix (melanocytes here produce pigment)
hemoglobin
red coloring from blood cells in dermis capillaries; oxygen content determines the extent of redness
functions of hair
reduces heat loss, guarding the head against bumps, shielding the eyes (eyelashes), and helping keep foreign particles out of the respiratory tract (nose hairs)
lunula
region over the nail matrix that appears as a white crescent
excretion
removal of salts, water & wastes
collagen fibers
responsible for the toughness of the dermis; they attract/bind water which helps keep the skin hydrated
nail
scalelike modification of the epidermis that corresponds to the hoof or claw of the other animals; protects distal phalanges & makes it easier to grab things; forms epithelial cells
cutaneous sensory receptors
sensors apart of the nervous system but located in the skin that provide info about our external environment (i.e. touch, pressure, temperature, and pain receptors)
synthesis
skin is able to create vitamin D with sunlight
arrector pili
small bands of smooth muscle cells, connect each side of the follicle to the dermal tissue (muscle only contracts when you're cold/scared aka cause of goosebumps) (smallest muscle in the body)
melanocytes
special spider-shaped cells found in the stratum basale that produce melanin
nail bed
stratum basale beneath the nail
What 5 layers is the epidermis composed of?
stratum basale, spinosum, granulosum, lucidum, and corneum
epidermis
the outer layers of the skin made up of stratified squamous epithelium; capable of keratinizing (becoming hard/tough); avascular (no blood supply of its own)
stratum corneum
the outermost layer of the epidermis; rubs & flakes off slowly & replaced by the division of cells in the basale
hair shaft
the part projecting from the surface of the skin
connection between sunglasses & sunburns
the pituitary gland produces hormones that act as boosters for melanocytes; the pituitary gland gets its info from the optic nerve so when you wear sunglasses much less sunlight gets to your optic nerve, which gives much less warning to the pituitary gland, much less melanocyte-stimulation, and therefore less melanin produced & less UV ray protection
regulation
the skin allows our temperature to remain at a steady state using blood flow and sweat
integumentary system
the skin and its derivatives (sweat/oil glands, hair, nails)
What would eventually happen to your skin if it had constant pressure applies & why?
the skin would die because it would not be able to get the nutrients through the compressed capillaries
dermal papillae
the superior surface of the papillary layer
papillary layer
the upper dermal region; uneven & has peg-like projections
nail matrix
thickened proximal area of nail bed responsible for nail growth
evolution of skin color
thought to have been driven by a balance between protection against UV decomposition & use of UV to synthesize vitamin D
burns
tissue damage and cell death caused by intense heat, electricity, UV radiation, or certain chemicals
How is a blister formed?
when the epidermis and dermis are separated, allowing interstitial fluid to accumulate in the cavity between the layers
medulla
central core of hair
acne
infection of the sebaceous gland that causes pimples
2nd degree burns
injury to the epidermis and upper region of the dermis
What is the significance of keratin in the stratum corneum?
it allows that layer to provide a durable "coat" for the body which protects deeper cells from the external environment
How is melanin protective?
it forms a pigment umbrella over the superficial side of their nuclei and shields their DNA from the damaging effects of UV radiation
Why is the integument absolutely essential?
it keeps water and other precious molecules in the body while keeping more water and other bad things out
benefits of ApoE4
keeps cholesterol levels cranked up to maximize what can be converted to vitamin D
apocrine glands
largely confined to the armpit and genitals; usually larger than eccrine; activated during puberty
stratum spinosum
layer of the epidermis superficial to the stratum basale
stratum granulosum
layer of the epidermis superficial to the stratum spinosum; when epidermal cells leave this layer they die & form the lucidum
basal cell carcinoma
least malignant and most common skin cancer; cells of stratum basale alter so they cannot form keratin; the cells no longer define the boundary between epidermis/dermis
3 parts of hair
medulla, cortex, cuticle
How does the integumentary system protect deeper tissues from ultraviolet radiation?
melanin produced by melanocytes offers protection from UV damage
rule of nines
method to determine extent of burns
