Skin Basics and Conditions

What are the major derivatives of the ectoderm germ layer?

• Epidermis

• Hair

• Nails

• Glands on skin

• Brain

• SC

• Neural crest and derivatives (lots of nerves, pigment cells of skin)

What is the vernix caseosa?

Whitish paste that covers skin that is formed by secretions from sebaceous glands and degenerated epidermal cells and hairs

What is the purpose of the vernix caseosa?

Protect the skin against the macerating action of amniotic fluid

What are the layers of the epidermis? State from superficial to deep

Corneum → lucidum → granulosum → spinosum → basale

Describe the stratum corneum

Dead cells at the surface that are loose in appearance

Describe the stratum lucidum

Several layers of flattened dead cells that cannot commonly be identified in thin skin

What epidermal layer is only in thick skin?

Stratum lucidium

Describe the stratum granulosum

Few layers of flattened cells

Describe the stratum spinosum

Clefts that are spanned by spine-like cytoplasmic extensions of the cells which interconnect the cells in the layer

Describe the stratum basale

Deepest layer of the epidermis

How long does it take for our epidermis to renew?

3-4 wks

What layer of the skin has keratinocytes?

Epidermis

What layer of the skin has melanocytes?

Epidermis

What layer of the skin has langerhans cells?

Epidermis

What layer of the skin has Merkel cells?

Epidermis

What is the function of keratinocytes?

• Waterproof the skin

• Provide mechanical strength

• Stimulate melanocytes to release melanin

• Hold and transport water and urea

• Help with immunity via antimicrobial peptide secretion

What conditions can damaged keratinocytes lead to?

• Psoriasis

• Dermatitis

What is the function of melanocytes?

Produce melanin which gives the skin color and they give some UV protection

What can dysfunction of melanocytes lead to?

• Melanoma

• Vitiligo

What is the function of Langerhans cells?

Bind, process, and present antigens to T-lymphocytes

In what conditions would you see abnormal Langerhan cells/levels?

Dermatitis & cellulitis

What is the function of merkel cells?

They be mechanoreceptors for touch

The dermis is primarily composed of what?

Connective tissue

What are the layers of the dermis?

• Papillary dermis

• Reticular dermis

Describe the papillary dermis

• Loosely woven fibers that are embedded in a gelatinous matrix called ground substance

• Forms the minority of the dermis

Describe the reticular dermis

• Dense, irregularly arranged connective tissue

• Makes up most of the dermis

What layer of the skin are macrophages found?

Dermis

What layer of the skin are fibroblasts found?

Dermis

What layer of the skin is collagen found?

Dermis

What layer of the skin is elastin found?

Dermis

What layer of the skin are mast cells found?

Dermis

What layer of the skin are proteoglycans found?

Dermis

What layer of the skin are glands found?

Dermis

What layer of the skin are blood vessels found?

Dermis

What layer of the skin are nerve fibers found?

Dermis

What layer of the skin are hair follicles found?

Dermis

What layer of the skin are lymphatic vessels found?

Dermis

What is the function of macrophages?

• Involved in phagocytosis

• Produce enzymes and cytokines that facilitate wound healing

• Involved in immune processes

What cell is key in chronic inflammatory conditions and wound healing processes?

Macrophages

What is the function of fibroblasts?

• Make collagen, elastin, GAGs, proteoglycans, and glycoproteins

• Help form the skin’s structural integrity

What can dysfunction of fibroblasts lead to?

Fibrosis and abnormal scarring

What is the function of mast cells?

• Release histamine

• Help with inflammation and allergic responses

What cell is known to be crucial for conditions like eczema and anaphylaxis due to its ability to release histamine?

Mast cells

Where in the body is the epidermis thinnest? What is it’s thickness at that point?

Thinnest at eyelids at 0.05 mm

Where in the body is the epidermis thickest? What is the thickness at that location?

Palms/soles at 1.5 mm

Where in the body is the dermis thinnest? What is its thickness at that point?

Eyelids, 0.3 mm

Where in the body is the dermis thickest? What is its thickness at that point?

Back, 3.0 mm

What structures are in the subcutaneous tissue?

• Large nerves

• Blood vessels

• Fibroblasts

• Adipose tissue

• Fascia

What structures are in the papillary dermis layer?

• Mast cells

• Proteoglycans

• Glands

What structures are in the reticular dermal layer?

• Blood vessels

• Hair follicles

• Nerve fibers

What are the functions of adipose tissue?

• Energy storage

• Cushion and insulate the body

• Regulates skin and body temps

What is the function of fascia?

Connect the skin to underlying tissue

What are the functions of our skin?

• Protect against the environment, UV rays, and fluid loss

• Provide sensation

• Provide immunity

• Help with thermoregulation

• Make and store vitamin D

• Aesthetics and communication

What changes occur in the epidermis as we age?

• Flattening of dermal-epidermal junction

• Decrease in the quantity of Langerhan cells

• Decrease in the quantity of melanocytes

• Thins

What changes occur in the dermis with aging?

• Thinning

• Degeneration of elastin fibers

• Decrease in vascularization

Why does the likelihood of skin tearing increase with age?

Basement membrane gets increasingly more dysfunctional

What change occurs in the subcutaneous tissue as we age? What does this lead to?

It thins which decreases its ability to maintain body temp

What appendage changes will ya see in aging skin? What do these changes lead to?

• Distorted structure and decrease in the quantity of sweat glands

  • Makes it harder to keep cool and increases the risk of heat stroke

• Decreased quantity of…

  • Specialized nerve endings

  • Hair bulb melanocytes

  • Hair follicles

• Sebaceous glands produce less oil

Define erosion

The loss of superficial epidermis only with NO involvement of the dermis which means there’s NO bleeding

An abrasion or superficial burn would be considered what kind of skin loss?

Erosion

A stage II pressure injury, skin tear, or a deep partial thickness burn would be what kind of skin loss?

Partial thickness

What layers of skin are impacted by partial thickness skin loss?

• Epidermis

• Dermis

Define full thickness skin loss

Loss of the epidermis, dermis, and some amount of the subcutaneous tissue at MINIMUM. Could also include bone, tendon, and/or muscle

Surgical incisions, traumatic wounds, and stage III or IV pressure ulcers are examples of what kind of skin loss?

Full thickness

What layer of the skin does a stage III pressure ulcer get to?

The fascia, but doesn’t go past it

How deep can a stage IV pressure ulcer get?

It can a get to the bone

Describe primary intention

When the edges of a wound are approximated and secured with sutures, staples, or surgical glue

Describe secondary intention

When a wound that is deep and wide helps from the base of the wound upwards

What kind of wounds commonly heal via secondary intention?

• Pressure ulcers

• Traumatic wounds

• Arterial wounds

What kind of wounds commonly heal via tertiary (delayed primary) intention?

Infected wounds without a lot of destruction

What is tertiary (delayed primary) intention?

When a wounds edges are not approximated immediately due to the presence of pathogens, debris, and existing, abscess, or a loss of extensive tissue. The wound undergo primary intention once healed enough

How many days does a wound get irrigation and/or antibiotics and infected if trying to use primary intention?

7-14 days

Describe the partial thickness wounding healing response

Partial loss of the epidermis and/or superficial dermis where healing is accomplished via epithelial cell mitosis and migration

What are the acute wound healing phases in order?

1. Hemostasis

2. Inflammation

3. Proliferation

4. Remodeling

Describe the wound healing phase of hemostasis

• Blood vessels do be constricting

• Platelets be aggregating

• Clot be forming

Describe the wound healing phase of inflammation

• That immune response be kicking in

• Getting that debris crap out

• Cytokines are released

Describe the wound healing phase of proliferation

• New tissue is formed

• Angiogenesis occurs

• Granulation be happening

• Re-epithelialization be occurring

Describe the wound healing phase of remodeling

• Collagen is reorganized

• Wound be contracting

• Tissue is strengthening

Describe a macule

A circular and flat brown/blue/red or hypopigmented discoloration that is less than 10 mm in diameter and does NOT result in a change in skin texture or thickness

Describe a papule

A small, solid round bump that rises from the skin and is less than 1 cm in diameter

Describe a plaque

Superficial, elevated, solid red discoloration that is > 1 cm

Describe a nodule

A raised solid lesion that is more than 1 cm

Describe a vesicle

Small, fluid filled blister that is up to 1 cm and easily breaks

Describe a bulla

A clear, fluid elevated lesion that is greater than 1 cm

Describe a pustule

A small collection of pus in the epidermis or dermis that commonly forms in sweat glands or hair follicles. Pus is a mixture of inflammatory cells and liquid

Define dermatitis

Conditions that cause inflammation of the skin

What conditions are known to cause red rashes, dry skin, and itchiness?

Dermatitis

What are the S/S of eczema/atopic dermatitis?

• Itchy, inflamed skin

• Redness

• Dry patches

• Swelling

What are some potential causes of eczema/atopic dermatitis?

• Allergens

• Stress

• Irritants

• Temp changes

What are the potential treatments for eczema/atopic dermatitis?

• Moisturizers

• Topical corticosteroids

• Antihistamines

What can cause contact dermatitis?

• Chemical irritants (nickel, chromates, rubber agents, topical antibiotics, silicone)

• Mechanical irritants (wool, fats)

• Physical irritants

• Biological agents

What are the S/S of contact dermatitis?

• Intense pruritus

• Erythema

• Edema

• Oozing, crusting, and scaling

• Skin thickening (if persistent)

What are the S/S of stasis dermatitis?

• Itching

• Heaviness in legs

• Brown staining of skin

• Open shallow lesions

• Dry skin

• Thin skin

What is the primary cause of stasis dermatitis?

Venous insufficiency

What causes cellulitis? Where is it most commonly found?

• Caused by normal skin flora or bacteria where the skin has been broken

• Commonly happens on the face or lower legs

What are the S/S of cellulitis?

• Pain

• Erythematous

• Warmth

• Edema

• Advancing borders

• Fever

• Elevated WBC count

Necrotizing fasciitis infects what layer of the skin?

Subcutaneous tissue

What skin infection is known to result in necrosis of the skin?

Necrotizing fasciitis

What is osteomyelitis?

An infection of the bone

Acute osteomyelitis is diagnosed within ___ weeks of onset of S/S

2 wks