A&P Integumentary System

percent of body weight

16%

3 components of the integument

cutaneous membrane, accessory structures, subcutaneous layer

2 components of the cutaneous membrane

epidermis and dermis

examples of accessory structures

hair, nails, hair follicles, sweat glands, sebaceous glands

where do accessory structures originate?

the dermis

where do accessory structures extend through?

epidermis to skin surface

dermis has an extensive network of what?

blood vessels

dermis has sensory receptors for...

touch, pressure, temperature, pain

what is the hypodermis also referred to as?

subcutaneous layer and superficial fascia

what is the hypodermis made of?

loose connective tissue (areolar and adipose)

what does the hypodermis separate?

the skin from the deep fascia and organs below

functions of integumentary system

protection (impact, abrasion, fluid loss, chemical attack), excretion (sweat), maintenance of body temperature (sweat, insulation), production of melanin, synthesis of Vitamin D3, storage of lipids, and detection (pressure, pain, touch, temp)

epidermis is made of...

avascular stratified squamous epithelium

how does the epidermis get nutrients?

O2 and nutrients diffuse from cells and fluid in the dermis (blood supply)

where are more active cells in the epidermis?

close to the dermis

what are the inactive or dead cells in the epidermis?

the superficial cells

keratinocytes

an epidermal cell that produces and contains keratin

keratinocytes gives strength to...

hair, skin, nails

why do keratinocytes give skin a water-resistant quality?

to slow down dehydration

thin skin

4 layers of keratinocytes, covers most of the body, thick as a plastic sandwich bag

thick skin

5 layers of keratinocytes, on palms of hands and soles of feet, thick as a paper towel

stratum basale

deepest layer of epidermis

what does the stratum basale form?

epidermal ridges (example: fingerprints)

what do the epidermal ridges in the stratum basale interlock with?

dermal papillae (creates a strong bond when interlocked)

cells in the straum basale

germinative cells and merkel cells

germinative cells

stem cells in the stratum basale that can divide to replace lost epidermal cells

merkel cells

sensory cells in the stratum basale that respond to touch

where are melanocytes located?

stratum basale

stratum spinosum

second deepest layer of epidermis

where do daughter cells from germinative cells get pushed to?

stratum spinosum

stratum spinosum cells...

are alive and continue dividing

Langerhans cells

a type of dendritic cell (white blood cell) found in the stratum spinosum that can activate on immune response if bacteria invade

stratum granulosum

middle layer of the epidermis

What occurs in the stratum granulosum?

keratinocytes stop dividing and start producing lots of keratin

stratum lucidum

fourth deepest layer in the epidermis, "missing layer" in thin skin

what are the cells like in the stratum lucidum?

flattened, densely packed and filled with keratin

stratum corneum

outermost layer of epidermis

what is the water-resistant layer of the epidermis?

stratum corneum

stratum corneum consists of...

15-30 layers of dead, keratinized cells, tightly interconnected by desmosomes

stratum corneum is described a the \______.

horn layer

what does the stratum corneum cover?

all exposed surfaces except eyeballs

keratinization

the formation of a layer of dead, protective cells filled with keratin

how many days for a cell to move from the stratum basale to the stratum corneum?

15-30 days

how long can cells stay in the stratum corneum before falling off and joining the dust?

up to 2 weeks

as the layers get closer and closer to the surface, what happens to the cells?

less active, flatter, more filled with keratin, dead

types of perspiration

insensible and sensible

insensible perspiration

interstitial fluid lost by evaporation through the stratum corneum, lose up to 500 mL of H2O per day by evaporation, includes water vapor you exhale

sensible perspiration

water excreted by sweat glands

wrinkly skin in water

occurs due to osmosis

what type of solution will cause wrinkly skin?

hypotonic solution (fresh water)

how does wrinkly skin in water occur?

water diffuses into the dead, flat, keratinocytes of the stratum corneum so they swell up to 4x the normal volume, noticeable in thick skin

basis of skin color

result of epidermal pigmentation and dermal circulation

epidermal pigments

carotene and melanin

carotene

yellow-orange pigment found in plants

where does carotene accumulate?

epidermal cells and fatty tissues

what can carotene be converted to?

Vitamin A

melanin

dark-brown or yellow-brown pigment produced by melanocytes in the stratum basale

number of melanocytes in darker vs light people

same number

how does melanin travel?

pigment molecules travel upwards from the stratum basale and enter into the keratinocytes

why do some people have darker skin?

melanin travels more toward the surface in darker skinned individuals

why do people have freckles?

overproduction of melanin

function of melanin

protects skin from sun damage by absorbing UV radiation

why do we need melanin to absorb UV radiation?

it causes DNA mutations and premature aging of skin

why does tanning occur?

increasing melanin protection for UV protection

what happens when melanin enters keratinocytes?

it specifically clusters around the cell nuclei

role of dermal circulation

redness

what happens if blood flow decreases to skin?

skin pales

why do old people look pale?

less melanin production, blood flow to the dermis decreases with age

cyanosis

a bluish skin tint caused by severe reduction in blood flow or lack of oxygen

jaundice

skin and whites of the eyes turn yellowish due to liver problems

why do people turn yellow due to liver problems?

if the liver cannot make bile, a yellowish pigment accumulates in body fluids

bile

a substance that helps break down fats in the digestive tract

why are babies sometimes born with jaundice? how long does it take to resolve itself?

their liver is not fully developed, resolves itself in 2-3 weeks

vitiligo

autoimmune disorder where there are patches of skin with no melanocytes

what percent of people have vitiligo?

1%, but is more noticeable in darker skin

is vitiligo dangerous?

no, it is mostly a cosmetic problem

how is vitamin D3 produced?

cells in the stratum spinosum and stratum basale produce vitamin D3 when exposed to UV rays

what does the "3" mean in vitamin D3?

3 is the form the body needs and makes

what vitamin comes from plants and in converted to D3 in the body?

vitamin D2

what do the kidneys convert vitamin D3 into?

calcitirol, a hormone essential for calcium absorption

vitamin D3 is needed to absorb calcium from \__________ into \__________.

the intestine, the blood

rickets

vitamin D3 deficiency

where is rickets most often seen?

in children living in extreme poverty

what does rickets result in?

weak, flexible bones with abnormal bone development

what anchors accessory structures?

the dermis

2 layers in the dermis

papillary layer and reticular layer

papillary layer

outer layer of the dermis, directly beneath the epidermis (adjacent to the stratum basale), name for the dermal papillae

what is the papillary layer made of?

areolar tissue

reticular layer

deeper layer of the dermis that supplies the skin with oxygen and nutrients

what is the reticular layer made of?

dense irregular connective tissue with collagen and elastin fibers and various cells found in the connective tissue proper

can the reticular layer stretch?

a bit, but the collagen protects it from stretching too much

papillary layer vs. reticular layer

capillaries, smaller lymphatics and nerve ending vs. longer blood vessels, lymphatics, and nerves

stretch marks

caused by tearing or rupturing collagen and elastic fiber bundles in the dermis

cleavage lines

bundles of collagen and elastic fibers in the dermis

why are cleavage lines useful for surgery?

A cut parallel to, or between the bundles heals well with minimal scarring, but a cut through a bundle leads to more difficult healing and greater scarring

contusion

(bruise) damaged blood vessels bleed blood into the dermis

what color appearance do contusions have?

black and blue

why do contusions turn yellowish-green?

as the hemoglobin in the trapped blood gets broken down, the bruise fades and a green pigment and yellow pigment get made (same yellow pigment that builds up in jaundice)

what are bedsores also referred to as?

pressure ulcers, decubitus ulcers

decubitus

lying down