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B4 > Wound Healing & Skin > Flashcards

Wound Healing & Skin Flashcards

1
Q

Define parenchyma and stroma

A 
Parenchyma = organ specific cells related to function
Stroma = background tissue providing structure, mechanical and nutritional support
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2
Q

What are the 4 stages of wound healing?

A

Haemostasis (<24 hrs)
Inflammation (0-4d)
Proliferation (1-14d)
Remodelling (day 21+)

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3
Q

Outline tissue regeneration

A

Complete restoration of damaged tissue, driven by growth factors (PDGF, VEGF, TGF-B)

Only occurs in labile/stable tissues

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4
Q

Broadly, what do growth factors do?

A

Stimulate entry of cells into cell cycles
Bind to cellular receptors
Produced mainly by macrophages/lymphocytes at site of injury
Proteins that stimulate cell survival and proliferation

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5
Q

What’s granulation tissue?

A

New connective tissue + new blood vessels = pink granular tissue

Laying down of new connective tissue: migration and proliferation of fibroblasts (FGF) and deposition of ECM proteins

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6
Q

What are labile and stable tissues? What’s the 3rd type of tissue? Give organ examples

A

Labile = cells continuously proliferating in order to replace dead/sloughed off cells (skin, GI, salivary gland)

Stable = cells normally exist in a non-dividing state but enter cell cycle in response to stimuli (growth factors) (liver, kidney, pancreas)

Permanent tissue = non-dividing cells that lead to scar tissue when damaged (bone, cardiac, skeletal)

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7
Q

Outline the process of remodelling

A

Collagen is remodelled to 80% of its normal tensile strength
Matrix metalloproteases degrade collagen/ECM components (balance between ECM protein synthesis and degradation)
If weak, opportunity of wound reopening is likely

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8
Q

What local and systemic factors affect tissue repair?

A

Local: infection, mechanical factors, foreign bodies, size of wound, location, type of wound

Systemic: nutritional status, metabolic status, circulatory status, hormones, age, collagen disorders

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9
Q

What causes fibrosis?

A

Excessive deposition of collagen and other ECM components

= sign of organ failure

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10
Q

What are some key factors delaying healing?

A

Infection is main factor - prolongs inflammation and potential tissue injury
Nutrition - collagen synthesis inhibited by vitamin C deficiency
Poor perfusion - diabetes/arteriosclerosis
Foreign bodies - fragments of steel, glass, bone
Mechanical variables - increased local pressure cause dehiscence (wound pulls apart)

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11
Q

What are 3 complications of tissue repair?

A

Inadequate formation (dehiscence, evisceration, ulceration)

Excessive formation (keloid scar formation/excessive granulation tissue which hinders re-epithelialisation)

Contracture formation (myofibroblasts)

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12
Q

What’s the difference between first and second intention healing?

A

First intention: clean cut to skin, epithelial regeneration is main focus of repair (only focal disruption to epithelial membrane)

Second intention: more chronic wounds, requires lots of granulation tissue, ECM tissue and scar formation (complex repair)

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13
Q

Outline the stages of fracture healing

A

Haematoma
Granualtion tissue formation (replaces haematoma)
Callus (bridges between bone ends)
Woven bone (OPGs strengthen callus)
Lamellar bone (replaces woven bone)
Remodelling (osteoblasts and osteoclasts)

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14
Q

Which growth factor converts fibroblasts -> myofibroblasts?

A

TGF-B

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15
Q

Outline healing by first intention

A 
Fibrin clotted scab
Neutrophils migrate towards fibrin clot
Acute inflammation at site of injury
Epithelial cells from both edges migrate towards each other and proliferate along dermis
Neutrophils replaced by macrophages
Angiogenesis
Pink granular tissue
Continued collagen accumulation and fibroblast proliferation
= scar maturation
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16
Q

Outline haemostats -> inflammation -> proliferation -> remodelling

A

Haemostasis: wound closed by coagulation, platelets and fibrin adhere to site, thrombus formation

Inflammation: platelets control bleeding, macrophages prevent infection, neutrophils control inflammation

Proliferation: angiogenesis, epithelialisation, contraction and fibrous tissue formation to close wound

Remodelling: restored to normal function, collagen remodelled to normal tensile strength

17
Q

What are the 5 functions of skin?

A 
Sensation
Thermoregulation
Metabolic function (vitamin D)
Protection (abrasion and impermeable, prevents dehydration and microorganism entry)
Psychosocial
18
Q

What’s the macroscopic structure of skin?

A

Epidermis
Basement membrane
Dermis: papillary then reticular layers
Subcutis

19
Q

What’s the microscopic structure (layers) of the epidermis?

A

Stratum basale
Stratum spinosum
Stratum granulosum
Stratum corneum

20
Q

What’s the extra epidermal layer in thick skin?

A

Stratum lucidum (between corneum and granulosum)

21
Q

What are lamellar bodies and keratinohyaline granules?

A

Involved in formation of keratin

Contain water repellent glycophospholipid to bind keratin flakes (in stratum corneum)

22
Q

What are some different skin appendages?

A 
Sebaceous glands
Eccrine sweat glands
Apocrine hormonal glands in axilla/groin
Nails (dense keratin on nail bed)
Hair follicles (made of keratin and associated with sebaceous glands)
23
Q

What’s the circulation of the skin?

A

Subpapillary superficial plexus in dermis
Cutaenous deep plexus in subcutis
Form anastomoses to regulate heat loss/preservation and supply epidermis/appendages with nutrition

24
Q

In which layer are melanocytes founds?

A

Stratum basale

25
Q

What are terms for flat skin lesions?

A

Maccule <5mm
Patch
Can be seen but not palpable

26
Q

What are terms for raised skin lesions?

A

Papule <5mm
Nodule >5mm
Raised solid

27
Q

What’s a plaque skin lesion?

A

Raised solid lesion where the area is much greater than the height
Seen in psoriasis, silvery scales

28
Q

What are terms for skin lesions filled with fluid?

A

Vesicles (clear serous fluid)
Bullae >5mm
Pustules filled with pus -> abscess

29
Q

What’s a skin neoplasm?

A

A lesion resulting from the autonomous abnormal growth of cells that persists in the absence of an initiating stimulus

30
Q

What are 3 different types of malignant neoplasm?

Define malignant neoplasm

A

Basal cell carcinoma
Squamous cell carcinoma
Melanoma

Malignant neoplasm = lesion resulting from autonomous abnormal growth in absence of a stimulus, with characteristics enabling them to invade into surrounding tissues and metastasise to distant sites

31
Q

What’s the key diagnostic factor for malignant neoplasms?

A

Depth of invasion

Clark levels I-V

32
Q

What’s the most common form of skin cancer in the UK, what are its risk factors?

A

Basal cell carcinoma
UV radiation exposure
Immunosuppression
Inherited conditions

Can be locally destructive - rodent ulcer

33
Q

What’s the 2nd most common type of skin cancer, what are risk factors?

A 
Squamous cell carcinoma
UV radiation
Male
Fair skin
Occupational exposure
Immunosuppression
34
Q

What are some cellular/nuclear examples that may indicate malignant change in skin histology?

A

Hyperchromatism
Pleomorphism
High nuclear:cytoplasm ratio
Loss of normal tissue architecture

35
Q

What does ABCD stand for?

A

Macroscopic assessment of melanoma

```
Assymetry
Border
Colour
Diameter
Evolving
~~~

36
Q

What are risk factors for melanoma?

A

UV radiation exposure
Personal/family history
Presence of dysplastic or abundant naevi

37
Q

How are skin cancers graded and staged?

A 
Stage = size of tumour and how far its spread from origin (0-4)
Grade = appearance of cancerous cells
38
Q

What’s the relevance of using an elliptical incision for skin cancers?

A

Allows edges to easily come together

Incision parallel to resting skin tension lines

B4 (13 decks)

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