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Flashcards in Intro to General Dermatology Deck (51)
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What are the three layers of the skin?

1. Epidermis
2. Dermis
3. Hypodermis (subcutaneous tissue)


Describe the epidermis of the skin

• Keratinised squamous cell epithelium
• 3 cell types: keratinocytes, melanocytes and langerhans cells
• Avascular and so receives O2 from diffusion from atmosphere


What are melanocytes?

Cells in the epidermis which make melanosomes (collections of melanin) excreted and phagocytose into keratinocytes where they sit above the nucleus


What are langerhans cells?

Cells in the epidermis which processes antigens and migrates to lymph nodes to induce an immune response


Describe the dermis of the skin

Collagen and elastin matriculates with mucopolysaccharide gel also fibroblasts, dermal dendritic cells and macrophages

• Contains hair follicles and the follicular bulge contains stem cells
• Muscle - thermoprotective mechanisms


Describe the hypodermic of the skin

Fat energy store, insulation, fibrous bands anchour skin to fascia


Name the five layers of the epidermis

5. Stratum corneum
4. Stratum lucidum
3. Stratum ganulosum
2. Stratum spinous
1. Stratum basale


What is found in the 5. stratum corneum of the epidermis?

Dead cells with a hard protein envelop: cells contain keratin and surrounded by lipids


What is found in the 4. stratum lucidum of the epidermis?

Dead cells lies within dispensed keratohyalin


What is found in the 3. stratum granulosum of the epidermis?

Keratohyalin and a hard protein envelop: lamellar bodies release lipids -> cells die


What is found in the 2. stratum spinosum of the epidermis?

Keratin fibres and lamellar bodies accumulate


What is found in the 1. stratum basale of the epidermis?

Cells divide by mitosis and some of the newly formed cells become the cells of the superficial strata


What are the different parts to the nail anatomy?

• Hyponychium (epithelium underlying free edge of the nail plate)
• Nail plate
• Lateral nail fold
• Nail bed
• Lanula (visible part of nail matrix)
• Cuticle
• Proximal nailfold
• Nail matrix


What are the three stages of the hair cycle?

1. Anagen
2. Catagen
3. Telogen


What is the anagen stage of the hair cycle?

Active growing phase


What is the catagen stage of the hair cycle?

2-3 week phase growth stops/follicle shrinks


What is the telogen stage of the hair cycle?

Resting phase for 1-4 months


What are the functions of the skin?

• Thermoregulation - insulation
• Skin immune system - innate and adaptive functions
• Barrier
- Protection against mechanical, chemical, UV light
- Keeps in water and electrolytes
• Sensation
• Vitamin D synthesis
• Interpersonal communication (self-identity)


Describe the innate and adaptive immune functions of the skin

• Innate is non-specific with leukocytes i.e. natural killer cells, mast cells
• Adaptive is specific and T cell regulates; antigen presenting cells which present to T cells to produce specific antibodies


Describe the vitamin D synthesis that occurs in the skin

UV light converts 7-dehydrocholesterol to cholecalciferol (which is then processed through the liver and kidney into the active form)


What are the 5 Ds as to why skin disease is important?

• Disfigurement
• Discomfort
• Disability
• Depression
• Death


What are the two categories of causes of skin disease?

External and internal


What are external causes of skin disease?

• Temp
• UV
• Chemical (allergen to irritant)
• Infection
• Trauma


What are the internal causes of skin disease?

• Systemic disease
• Genetics
• Drugs
• Infection


Describe the external cause of photosensitivity

• Commonly caused by medications
• Exposed sites affected (t-shirt lines)
• Can be sensitive to UVA, UVB, visible light or a combination
• Test patients against different light of electrochemical spectrum


Describe the external cause of cold injury

• Vasoconstriction and skin necrosis
• Chillblains - small, itchy swellings on the skin
• Frostbite is a cause, but also other diseases i.e. cryoglobulinaemia (more circulated protein) which causes similar response at normal temps


What is cold urticaria?

Skin disease with external cause (cold water/weather etc)


What is dermatitis artefacts?

Condition in which skin lesions are solely produced or inflicted by the patient's own actions; manifestion of psychological problem


Name a condition cause by trauma

Dermatitis artefacts
• Unusual distribution
• Most caused by scratches


Name conditions cause by genetics (internal cause)

• Neurofibromas
• Ichthyosis vulgaris