Week 1: Skin, Wound healing

What are the three layers of skin and which wound types describe each?

Epidermis: superficial wound

Dermis: partial thickness wound

Subcutaneous Tissue: full thickness wound

What are the four dermal appendages?

Capillary networks, hair shafts, sweat glands, sebaceous glands

Epidermis replaces each _-_ hrs, and has what functions?

4-6 hrs

• Barrier, excretion, pigmentation, fluid/thermo regulation, sensation, etc

Dermis primarily functions to - the -. It also contributes to - and is known for its -/-.

Nourish the epidermis, sensation, strength/structure

The dermal appendages contribute - - to what process?

Epithelial cells to re-epitheliazation

Subcutaneous tissue functions?

Underlying attachment, mechanical shock absorption, thermal insulation, energy storage

Vascular review:

• Inflow is -, outflow is - and -

• Superficial veins found in -, deep in -, - feeds into -

• Perforating/Communicating veins most common in - -

• The legs have -, list the three most important!

• Veins are - - -, congestion can occur. Use - - to your advantage

• Arteries, veins and lymphatics

• SC tissue, fascia, superficial → deep

• Medial leg

• Angiosomes, PTA (medial heel) + ATA + dorsal pedis artery

• One way valves, calf pump

List out the main four wound healing steps and when each occurs!

1. Hemostasis (few hours): stops blood flow

2. Inflammation (1-6 days): cleans the wound

3. Proliferation (4-21 days): builds new tissue

4. Remodeling (3 weeks - 2 years): strengthens the healed area

Break down proliferation further (steps, what they each mean)!

1. Granulation- Fibroblasts lay down new ECM

2. Contraction- Myofibroblasts pull edges of wound together

3. Angiogenesis- endothelial cells create new blood vessels

4. Epitheliazation- keratinocytes resurface the epidermis, melanocytes come back later

The inflammatory phase involves multiple immune cells, but the - peak at 24 hrs and the - peak at 72 hrs

Neutrophils, macrophages

What are the inflammatory phase cells and their functions (6)

Neutrophils: reach out + kill

Lymphocytes: release antibodies

Macrophages: engulf + digest

Plasma proteins: communicators

Mast cells: histamine response

Langerhans cells: immune response

What is the most abundant component of the ECM?

Collagen

In order for remodeling to occur, collagen converts from type _ to type _. It is considered “mature” with what ratio?

III → I. Mature when 90% type I and 10% type III

Scar strength over time:

• week 1

• week 3

• month 3+

• 3%

• 30%

• 80%

What are the three main wound healing models?

1. Primary intention healing: when not overly complex, think stitches/glue/staples

2. Delayed primary intention healing: surgical wound left open due to infection, dressing + surg.

3. Secondary intention healing: wound deep + left open and needs skilled wound care

What are some examples of abnormal healing?

No/chronic inflammation, hypo/hypergranulation, hypertrophic scarring, keloids, contracture/dehiscence

Chronic wounds contain -, which inhibit - -. - is necessary in this scenario.

Proteases, growth factors. Debridement

Pulses:

• Where can you take them

• New force scale

• Femoral, popliteal, ant. tib, post. tib, dorsal pedis

• 0 (absent), 1+ (diminished), 2+ (normal)

How do you measure an ABI?

SBP ankle/higher SBP arm

ABI scale!

1= normal

>1= vessel calcification

<1= PAD, lower means less compression and more surgical management

What is venous filling time, how is it measured, give me the scale!

Venous filling time is the time it takes for your veins to rebound/fill after elevation (1-2 min)

• 20 seconds is normal, >30 is arterial compromise, <15 is venous reflux/incompetent valves