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Indietro

Chapter 5

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Termini in questo insieme (27)

  • What are the main functions of the integumentary system?
    Protection, thermoregulation, sensory perception, blood reservoir, metabolic synthesis of vitamin D, and emotional expression.
  • What chemical barriers protect the skin?
    Skin secretions like sebum and sweat, and melanin which prevents bacterial colonization, drying, kills microbes, and shields from UV damage.
  • How does the skin act as a physical barrier?
    Through keratin protecting against microbes, abrasion, heat, and chemicals, and lipids preventing water evaporation and entry.
  • What biological barriers are present in the skin?
    Dendritic cells in the epidermis signal immune response; macrophages in the dermis degrade bacteria and viruses.
  • What substances can pass through the skin's protective barriers?
    Lipid-soluble substances like gases and steroids, plant resins (poison ivy), organic solvents (acetone), heavy metals (lead, mercury), and some drugs (nicotine).
  • How does the skin regulate body temperature during heat stress?
    By increasing sweat rate and dilating blood vessels in the skin to increase heat loss.
  • How does the skin respond to cold stress?
    By decreasing sweat rate and constricting blood vessels in the dermis to reduce heat loss.
  • What sensory perceptions does the skin provide?
    Touch, pressure, vibration, tickling, thermal sensations, and pain via sensory receptors like free nerve endings and tactile corpuscles.
  • What is the role of vitamin D synthesis in the skin?
    UV rays stimulate vitamin D production, which is converted in liver and kidney to calcitriol aiding calcium absorption.
  • What are the three major layers of the skin?
    Epidermis (outer, epithelial, avascular), dermis (inner, connective tissue, vascular), and subcutaneous layer (hypodermis, fat storage, not part of skin).
  • What type of epithelium makes up the epidermis?
    Keratinized stratified squamous epithelium.
  • Name the five layers (strata) of the epidermis.
    Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (only in thick skin), and stratum corneum.
  • What is the function of the stratum basale?
    Deepest layer with mitotic stem cells producing new keratinocytes; contains melanocytes (10-25%).
  • What happens in the stratum granulosum?
    Cells flatten, nuclei disintegrate, keratinization begins, and lamellar granules accumulate to slow water loss.
  • What is unique about the stratum lucidum?
    It is a thin, translucent layer of dead keratinocytes found only in thick skin like palms and soles.
  • What are keratinocytes and their role?
    Make up 85% of epidermal cells; produce keratin, a tough protein protecting skin from abrasion, heat, microbes, and chemicals.
  • What causes psoriasis?
    Rapid keratinocyte division and movement to the surface, leading to flaky, silvery scales due to abnormal keratinization.
  • What are melanocytes and their function?
    8% of epidermal cells; produce melanin pigment that absorbs UV light and protects keratinocyte nuclei.
  • What is albinism?
    A congenital disorder with partial or complete absence of pigment due to dysfunctional tyrosinase enzyme.
  • What causes vitiligo?
    Gradual loss of melanocytes in specific areas causing depigmentation, possibly autoimmune or genetic.
  • What pigments contribute to skin color?
    Melanin (yellow-red or black-brown), hemoglobin (red from blood), and carotene (yellow-orange from diet).
  • What are the characteristics of the dermis?
    Dense irregular connective tissue with collagen and elastin, thicker than epidermis, contains fibroblasts, macrophages, blood vessels, and glands.
  • What is the function of dermal papillae?
    Increase grip by raising epidermal ridges, forming fingerprints and footprints.
  • What are the two regions of the dermis?
    Papillary region (areolar CT with capillaries and sensory receptors) and reticular region (dense irregular CT with glands, hair follicles, and adipose).
  • What are the types of sweat glands and their functions?
    Eccrine glands secrete watery sweat for cooling; apocrine glands secrete viscous sweat in stress areas, active after puberty.
  • What is the role of sebaceous glands?
    Secrete sebum to prevent dehydration of hair and skin and inhibit bacterial growth; absent on palms and soles.
  • What is the subcutaneous layer composed of and its function?
    Areolar and adipose connective tissue; stores fat, insulates, anchors skin to underlying tissues.