Integumentary System Wk 1

functions of the skin

protection (barrier), immunity (langerhans), thermoregulation (sweat, evaporation, radiative heat loss)

sensation

(somatosensation)

metabolism

communication

excretion

functions of metabolism includes

excretion, absorption, UV degradation (vitamin d, bilirubin)

Protection: outtermost layer of epidermis

stratum corneum

protect against water loss

BLANK is an acidic coating that delays growth of micoorganisms on skin

Acid Mantle

Disruption or loss of acid mantle on skin surface increases risk of

skin damage and infection

the release of BLANK and trigger of inflammation and angiogenesis

cytokines

When body temperature rises, blood flow increases to the skin causing sweat glands to release heat which is controlled by

hypothalamus

the function of the skin in metabolism includes vitamin d, which is a

Long process that keeps calcium and phosphorous in the blood and bones at normal levels

epidermis is completely

avascular and aneural

what layer are blood vessels at?

dermis

basement membrane zone ?

a zone of complex protein bonds that seperates the epidermis from dermis

5 layers of epidermis

stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale

what makes up the stratum corneum

dead skin cells that shed daily, protects against water loss

where can the 2nd outtermost layer, the stratum lucidum, be found?

only found in thick skin (palms of hand and soles of feet)

'clear' cells

the stratum granulosum assists with

keratin formation

nucleus of cells begin to die here

stratum spinosum

THICKEST LAYER

MOSTLY LIVING CELLS

produce keratin

spikey cells under microscope

melanin is injected into keratinocytes, and protects nucleus.

Stratum germinativum/basale

melanocytes

outer layer that undergoes mitosis to produce new cells

fluid and cell exchange between layers of skin occurs here

living cells.

MAJORITY of cells in epidermis

keratinocytes (90% ish)

life span of keratinocytes

28 days

Desmosomes bind keratinocytes together to

improve strength

Langerhans cells (2%)

Capture, uptake and processing of antigens

immune response

Recruit T cells to attack pathogens

First line of defense against environment

where are merkel cells found

stratum germinativum

what do merkel cells do

detection of touch

what seperates epidermis from dermis

basement membrane zone

Responsible for communication between skin layers via rete ridges****

where do blisters form?

in basement membrane zone

rete ridges do what?

Rete ridges in epidermis extend downward and interlock with rete ridges from dermis

Helps protect against shear and friction

dermis function

provides nutrients and support to epidermis

what is dermis made of

thick, dense, fibroelastic connective tissue

highly vascularized

base of hair follicle found here***

appearance of dermis

pink/red and appears wet when exposed

more superifical layer of dermis that connects to epidermis

papillary layer

what is within the papillary layer of dermis

blood vessels, lympathics, epipthelial cells, small muscles, neurons

what is papillary layer made up of

connective tissue

extracellular matrix and fibroblasts

LARGEST component of dermis

extracellular matrix

(collagen and elastin)

structural integrity of skin

JOB of ECM

Cell adhesions, lubricates cells and transport system for nutrients and waste products

INNERMOST layer of dermis

reticular layer

Collagen layer arranged in basket-like weave attaching it to the subcutaneous tissue

tensile strength.

where are sweat glands, nerves and hair follicles and blood vessels found within the dermis

reticular layer

cells within the dermis include

macrophages, mast cells, fibroblasts, langerhans

macrophages

front line of defense, ingest dead tissue

mast cells

assist with blood clot in early stage of wound healing

fibroblasts

cells form which connective tissue is developed, improve tensile strength

langerhans (dermis)

first line of defense, assist with epidermal immunity

Structures underneath the dermis include

Subcutaneous tissue

Fascia

Muscle

Tendon

Ligament

Bone

Cartilage

subcutaneous tissue includes

Fat

Loose connective tissue beneath dermal layer of skin

Location of lymphatics and blood vessel supply

cells in the subcutaneous tissue are

adipocytes

layer of padding

appearance in wound in subcutaneous tissue

Pale yellow, waxy, globular, oily substance that glistens if healthy

Dries or turns tan or yellow-brown if more chronic

Fascia layering underneath subcutaneous tissue?

Sheath covering muscle, nerves and blood vessels keeping them in tight bundles as a single unit

appearance of fascia wound?

White and shiny

Grayish if non-viable

appearance of a muscle wound?

dark red, highly vascularized, striated

will contract if stimulated!

ischemic muscle appearance?

mushy, dull red, cyanotic or pale

necrotic muscle appearance?

will turn liquid causing a dark brown, odorous tissue

BLANK tissue must cover exposed muscle

granulation tissue

required to cover muscle in order to close up wound

why cant epithelial tissue grow over exposed muscle?

lack of basal lamina to allow for epithelial cell migration

appearance of tendon wound

Gleaming yellow or white, shiny

appearance of bone wound

Shiny, hard, milky white

Slick to touch

Flaky with a gray, brown or black color if necrosing

Mushy or rough, falling apart if osteomyelitis present

ligament appearance of wound

ribbon-like, striated, pearly white

difference in wound appearance between ligament and tendon

broader, flatter, more loosely woven compared to tendon

appearance of cartilage wound

very white and shiny, POOR VASCULAR SUPPLY

total time for a wound to repair is BLANK weeks

4-6 weeks

4 major steps of wound repair

hemostasis

inflammation

proliferation

remodeling

what two main things will limit wound repair?

anything that promotes necrosis or limited vascularization will extend this time