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Integumentary System - Anatomy & Physiology

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  • What are the two main regions of the skin?

    The skin has two main regions: the epidermis (keratinized stratified squamous epithelium) and the dermis (connective tissue, vascularized).
  • What are the four major cell types in the epidermis?

    Keratinocytes, melanocytes, dendritic (Langerhans') cells, and tactile (Merkel) cells.
  • What is the main function of keratinocytes?

    Keratinocytes produce keratin, a fibrous protein that provides protection and waterproofing to the skin.
  • What is the role of melanocytes?

    Melanocytes produce melanin, a pigment that protects against UV radiation by absorbing harmful rays.
  • What is the function of dendritic (Langerhans') cells?

    They are macrophages that activate the immune system by detecting pathogens in the epidermis.
  • What are tactile (Merkel) cells responsible for?

    They function as touch receptors located at the epidermis-dermis boundary.
  • Name the five layers of the epidermis from superficial to deep.

    Stratum corneum, lucidum (only in thick skin), granulosum, spinosum, and basale.
  • What is the stratum lucidum and where is it found?

    A clear, thin layer of dead keratinocytes found only in thick skin such as palms and soles.
  • What protein makes the stratum lucidum clear and waterproof?

    Eleidin, a transparent, lipid-rich intermediate protein between keratohyalin and keratin.
  • What are the two layers of the dermis?

    The papillary layer (areolar connective tissue with capillaries and nerve endings) and the reticular layer (dense irregular connective tissue).
  • What are dermal papillae and their function?

    Projections of the papillary dermis that indent the epidermis, containing capillaries and nerve endings for touch and pain.
  • What are friction ridges and where do they form?

    Raised epidermal ridges over dermal papillae on thick skin (palms, soles) that enhance grip and form fingerprints.
  • What are cleavage (tension) lines in the skin?

    Lines in the reticular dermis formed by collagen fiber orientation; important for surgical incisions to minimize scarring.
  • What is the subcutaneous tissue (hypodermis)?

    A layer of areolar connective tissue and adipose below the dermis that anchors skin, stores fat, and provides insulation.
  • What are the three pigments contributing to skin color?

    Melanin (made in skin), carotene (from diet), and hemoglobin (from blood circulation).
  • What are the main functions of hair?

    Sensing insects, protecting the head from trauma and heat loss, shielding eyes, and filtering inhaled particles.
  • What determines hair texture and thickness?

    Hair texture is determined by follicle shape; thickness is determined by follicle size.
  • What is the structure of a hair follicle?

    Includes the hair shaft, root, bulb (with papilla and root hair plexus), follicle sheaths, arrector pili muscle, and sebaceous gland.
  • What causes male pattern baldness?

    A genetically influenced altered response to androgens that shortens hair growth cycles, leading to hair thinning.
  • What are nails and their main parts?

    Nails are scale-like modifications of the epidermis consisting of the nail plate, nail bed, proximal nail fold, nail matrix, and lunula.
  • What are the two main types of sweat glands?

    Eccrine glands (thermoregulation, watery sweat) and apocrine glands (axillary, secrete fatty sweat, activated by stress).
  • What are the three types of barriers provided by the skin?

    Chemical (acid mantle, antimicrobial secretions), physical (waterproofing, keratin), and biological (immune cells).
  • What are the six major functions of the skin?

    Protection, body temperature regulation, cutaneous sensation, metabolic functions, blood reservoir, and excretion.
  • What are the degrees of burns and their characteristics?

    First degree: epidermis only; second degree: epidermis and superficial dermis; third degree: full thickness of skin.
  • What is the Rule of Nines?

    A method to estimate the percentage of body surface area affected by burns for treatment planning.