Chapter 4: Skin and Body Membranes

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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


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