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Questions and Answers
What percentage of body weight is constituted by the skin?
Which layer of the skin contains melanocytes?
What is the primary blood supply to the skin derived from?
Where are pressure ulcers most likely to develop?
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Which statement characterizes keloids?
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What triggers irritant contact dermatitis?
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What characterizes stasis dermatitis?
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Which skin condition is associated with a family history of allergies?
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What cells are primarily responsible for transmitting itch sensations?
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What distinguishes hypertrophic scars from keloids?
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What is the primary characteristic of psoriasis?
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Which of the following diseases is characterized by target-like lesions?
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Which condition is associated with the overproduction of collagen leading to skin sclerosis?
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What typically causes acne rosacea?
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What characterizes a carbuncle?
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Which type of skin cancer is most commonly associated with ultraviolet radiation exposure?
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What is a major consequence of major burn injury?
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What causes the characteristic lesions of Pityriasis rosea?
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Which fungal infection is commonly known as ringworm?
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What are the clinical features of cutaneous melanoma?
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Study Notes
Overview of Integumentary System
- Skin comprises 20% of body weight and serves as a protective barrier while regulating body temperature.
Structure and Function of the Skin
- Skin consists of two primary layers: the epidermis (outer layer) and the dermis (inner layer).
- The hypodermis underneath contains connective tissue, fat, fibroblasts, and macrophages.
- Epidermis features basal and spinous layers containing melanocytes, Langerhans cells, and Merkel cells.
- Dermis contains connective tissue, hair follicles, sweat and sebaceous glands, blood vessels, nerves, and lymphatics.
- Dermal appendages include nails, hair, sebaceous glands, and sweat glands (eccrine and apocrine).
- Papillary capillaries from deeper arterial plexuses provide the main blood supply.
- Heat regulation is managed by arteriovenous anastomoses involved in blood flow to the papillary capillaries.
- Pressure ulcers arise from prolonged pressure that occludes blood flow, especially at bony prominences.
- Keloids are raised scars extending beyond the original injury site, unlike hypertrophic scars which remain within the borders.
- Pruritus (itching) results from unmyelinated C nerve fibers activated by skin disorders.
Disorders of the Skin
- Allergic contact dermatitis results from sensitization to allergens, such as metals or poison ivy.
- Irritant contact dermatitis stems from chemical exposure leading to skin barrier disruption.
- Atopic dermatitis is linked to family history of allergies and leads to pruritus and skin infections.
- Stasis dermatitis occurs in the lower legs due to chronic venous stasis.
- Seborrheic dermatitis presents with scaly, yellowish inflammatory lesions, often linked to Malassezia yeasts.
- Papulosquamous disorders manifest as papules, scales, and erythema, with psoriasis being a significant example.
- Psoriasis involves inflammatory cascades leading to thick, scaly, and itchy plaques.
- Pityriasis rosea is a self-limiting condition with oval lesions aligning with skin lines.
- Lichen planus is characterized by violet papular lesions and severe pruritus.
- Acne vulgaris originates from inflammation of pilosebaceous follicles.
- Acne rosacea causes redness and inflammation, typically on the central face.
- Discoid lupus erythematosus presents with inflammatory lesions on sun-exposed skin and has a "butterfly" distribution.
- Pemphigus is a severe autoimmune condition leading to blister formation beginning in the mouth.
- Erythema multiforme produces target-like lesions and may react to medications.
- Folliculitis involves infection of hair follicles, commonly by Staphylococcus aureus.
- A furuncle is a deeper infection of a hair follicle, while a carbuncle is a cluster of infected follicles.
- Cellulitis is a widespread infection of dermis and subcutaneous tissue; erysipelas is a specific type caused by beta-hemolytic strep.
- Impetigo is characterized by bullous or ulcerative lesions originating from Staphylococcus or streptococci.
- Lyme disease is transmitted by ticks as an immune response to Borrelia burgdorferi.
- Herpes simplex virus type 1 (HSV-1) causes cold sores and can infect the cornea and genital areas.
- Varicella-zoster virus causes both herpes zoster (shingles) and varicella (chickenpox).
- Warts, caused by human papillomavirus, can be benign or venereal (condylomata acuminata).
- Tinea infections (ringworm) can occur in various forms depending on the body area affected.
- Candidiasis results from Candida albicans infections on skin and mucous membranes.
- Cutaneous vasculitis is an immune-related inflammation causing purpura and ischemia.
- Urticaria (hives) often relates to type I hypersensitivity reactions and presents as wheals.
- Scleroderma involves autoimmune skin thickening and may impact systemic organs.
- Seborrheic keratosis leads to elevated, warty lesions, commonly in older adults.
- Keratoacanthoma appears as dome-shaped lesions filled with keratin that resolve spontaneously.
- Actinic keratosis, a result of sun exposure, can progress to squamous cell carcinoma (SCC).
- Nevi are melanocyte-derived moles that can be pigmented or pink and may become malignant.
- Basal cell carcinoma is the most common skin cancer, primarily due to UV exposure.
- Squamous cell carcinoma (SCC) originates from the epidermis and can be in situ or invasive.
- Cutaneous melanoma originates from melanocytes and has high metastasis risk if untreated.
- Kaposi sarcoma is a cancer related to human herpesvirus 8 and often observed in immunocompromised individuals.
- Burns are categorized by degree: first, second, third, or fourth, based on depth and severity.
- Major burn injuries lead to profound cardiovascular changes and require fluid resuscitation.
- A hypermetabolic response occurs after major burns, increasing metabolic hormones and gluconeogenesis.
- Immune suppression post-burn increases infection risk and slows healing.
- Cold injuries, affecting primarily the face and digits, result from direct cellular damage.
Disorders of the Hair
- Alopecia refers to hair loss on the scalp or body, with different patterns recognized.
- Male pattern alopecia is an inherited condition leading to central scalp hair loss.
- Female pattern alopecia presents as thinning of hair in women, typically starting from the age of 20-30.
- Alopecia areata is an autoimmune condition that often reverses, sometimes linked to stress.
- Hirsutism in women presents as excessive hair growth in a male pattern, possibly due to androgen excess.
Disorders of the Nail
- Paronychia is inflammation of the cuticle, often caused by bacterial or fungal infections.
- Onychomycosis is a fungal infection affecting the nail, leading to changes in its appearance.
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Description
Explore the fascinating structure and function of the integumentary system. This quiz covers key concepts like the layers of skin, their components, and the system's role in body regulation and protection. Test your knowledge on skin anatomy and physiology.
