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Anatomy & Physiology: Skin Structure and Burn Classification

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  • What are the three main layers of the skin?

    The epidermis, dermis, and hypodermis (subcutaneous layer).

  • Name the sublayers of the epidermis from outermost to innermost.

    Stratum corneum, stratum lucidum (only in thick skin), stratum granulosum, stratum spinosum, and stratum germinativum (stratum basale).

  • What is the function of the stratum corneum?

    Consists of heavily keratinized, squamous-shaped cells that are resistant to abrasion.

  • Which epidermal sublayer appears translucent under a microscope?

    The stratum lucidum, found only in thick skin like the palms and soles.

  • What occurs in the stratum germinativum (stratum basale)?

    Contains cells undergoing mitosis, producing new epidermal cells.

  • How do epidermal cells receive oxygen and nutrients despite the epidermis being avascular?

    They receive oxygen and nutrients by diffusion from blood vessels in the underlying dermis.

  • Why do epidermal cells die as they move from the stratum germinativum to the stratum corneum?

    Because they move further from the blood supply and become keratinized, losing nutrients and organelles.

  • What are the two sublayers of the dermis and their main differences?

    The papillary layer is superficial and contains loose connective tissue; the reticular layer is deeper and denser, providing strength and elasticity.

  • Describe the structure and function of the hypodermis.

    The hypodermis is made of loose connective tissue and fat; it cushions, insulates, and anchors the skin to underlying tissues. It is not technically part of the skin.

  • What defines a first-degree burn?

    Damage to only the epidermis, causing redness and pain without blisters.

  • What characterizes a second-degree burn?

    Damage to the epidermis and part of the dermis, causing blisters, swelling, and pain.

  • What is a third-degree burn (full-thickness burn)?

    Damage through the epidermis and dermis, possibly affecting deeper tissues; the area may be painless due to nerve damage.

  • Why do blisters form only in second-degree burns?

    Blisters form due to fluid accumulation between the epidermis and dermis where partial dermal damage occurs.

  • Why can't full-thickness burns heal on their own?

    Because the stem cells in hair follicles and basal layers are destroyed, preventing regeneration.

  • What is the 'rule of nines' in burn treatment?

    A method to estimate the total body surface area affected by burns by dividing the body into sections of 9% or multiples thereof.

  • Why is it important to elevate a burned limb above heart level?

    To reduce swelling and fluid accumulation by promoting venous return.

  • What is an escharotomy?

    A surgical procedure to cut through burned skin (eschar) to relieve pressure and restore circulation.

  • What is the difference between an autograft and an allograft in skin grafting?

    An autograft uses the patient's own skin, reducing rejection risk; an allograft uses donor skin, which may be temporary and risk rejection.

  • Why are broad-spectrum antibiotics used in severe burn treatment?

    To prevent or treat infections due to the loss of the skin's protective barrier.

  • Estimate the percentage of body surface burned if only the dorsum of one hand is affected.

    Approximately 1% of total body surface area.