wound care intro

Question 1

Skin functions

Answer 1

Protection
Water balance
Produces sebum
Acid mantle (pH 4-5.5  slightly acidic)
Metabolism
Synthesis of vitamin D in sunlight
Important bone mineralization
Melanin

Thermoregulation
-Blood vessels dilate to dissipate heat (flush) or constrict to shunt heat (blue lips)
Sweating
Cooling when fluid is evaporated from surface
Sensation
Pain, touch, temperature, pressure
Communication
Facial expressions

Question 2

Epidermis

Answer 2

1st line of defense against microorganisms, mechanical trauma, chemicals, and sun exposure
Rapidly regenerates
Retains moisture
Pigmentation
Synthesis of vitamin D (sun)

Question 3

Specialized Cells of the Epidermis

Answer 3

-Keratinocytes
90% of cells in epidermis
-Melanocytes
Pigment producing cells
-Merkel cells
Touch receptors
-Langerhans cells
Recognize antigens and present them to leukocytes
Macrophages used in the defense against microorganisms
May be involved in skin graft rejection

Question 4

Keratins

Answer 4

Tough, flexible, fibrous proteins
Resistant to changes in pH, temperature, and enzymatic digestion
Repel pathogens and prevent excess fluid loss
Types
Hard (hair, nails)
Soft (found in cells of the stratum corneum)

Question 5

Epidermal Make-up

Answer 5

Cellular, avascular
Relies on capillary support from the dermis
Composed of several layers of skin

Question 6

Five Layers of the Epidermis

Answer 6

Stratum corneum
Stratum lucidum (palm/feet)
Stratum granulosum
Stratum spinosum
Stratum basale (germinativum)

Question 7

Stratum Corneum

Answer 7

Outermost layer is dead skin cells which are filled with keratin
Organized as a “brick and mortar” complex
Corneocytes (flattened, dead cell bodies of keratinocytes) = “bricks”
Desmosomes = “mortar”
Provides a moisture barrier
Effectiveness varies depending on body location
Constantly shed as a result of mechanical and chemical treatment
Constantly replaced from the layer below

Stratum Corneum Damage
Mechanical – tape stripping
Chemical – fecal/urinary incontinence
Excessive of insufficient hydration

Question 8

Stratum Lucidum

Answer 8

Cells appear clear
Replaces shed stratum corneum
Found only in palms of the hands, soles of feet and fingertips

Question 9

Stratum Granulosum and Spinosum

Answer 9

Stratum Granulosum
Also known as granular layer
Cells contain granules of the precursor of keratin
1-5 cells thick
Stratum Spinosum (prickle cell layer)
Histological preparations shrink these cells and make them look prickly hence the name: spinosum = “little spine”
Langerhans cells (bone marrow derived

Question 10

Stratum Basale

Answer 10

Also called stratum germinativum
Mitotically active (a lot of proliferation)
Cell division takes place here
Keratinocytes divide and begin differentiation
Contains stem cells, melanocytes and merkel cells
Contains Rete Ridges

Question 11

Rete Ridges

Answer 11

Aka Rete Pegs, Epidermal ridges
Epidermal protrusions that point downward into the dermis
Partly responsible for skin integrity
Resistant to shear and friction
Minimal regeneration
Facilitates fluid and cell exchange between layers
Height of protrusions declines with age

Question 12

Basement Membrane Zone (BMZ)

Answer 12

Dermal-epidermal junction
Separates epidermis from dermis
Functions as a semi-permeable membrane regulating transfer of materials between the dermis and epidermis
Blister forms with loss of anchor

Question 13

Dermis

Answer 13

Second layer of skin
Thick (~2 mm or thickness of a credit card)
Up to or >3 mm on soles and palms
Largest of the skin layers
Provides strength and structure to the skin
Contains nerve fibers, sensory receptors, blood and lymphatic vessels, hair follicles, and sebaceous (oil) and sweat (moisture) glands
Extracellular matrix (ECM)
Made up of sugars and proteins

Question 14

2 layers of the Dermis

Answer 14

-Papillary layer
Below BMZ (directly under epidermis)
Forms structures with rete ridges
Contains fibroblasts that produce collagen
Contains macrophages, lymphocytes, and mast cells
-Reticular layer
Found beneath the papillary layer
Collagen fibers more dense; increase tensile strength

Question 15

Specialized Cells of the Dermis

Answer 15

-Mast cells
Primary effector cells in allergic reaction
Contain histamine and heparin
Responsible for cellular defense mechanisms (ex. blood clotting)
-Macrophages
Scavenger cells that ingest dead tissue
Repair injured tissues
-Lymphocytes
Help mediate the immune response in the skin
-Fibroblasts
Active during inflammation
Secrete collagen and elastin
-Langerhans cells (both epidermis AND dermis)
First line of defense, epidermal immunity
Transports antigens to lymph nodes