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Integumentary System - Anatomy & Physiology

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Terms in this set (26)

  • What are the two major parts of the integumentary system?
    The integumentary system consists of the cutaneous membrane (skin) and accessory structures such as hair, nails, and glands.
  • What are the main layers of the cutaneous membrane?
    The cutaneous membrane has two main layers: the epidermis (outer, superficial epithelium) and the dermis (inner connective tissue layer).
  • What is the subcutaneous layer and its function?
    The subcutaneous layer (hypodermis) lies below the dermis, consists mainly of loose connective tissue and adipose tissue, and stabilizes the skin's position.
  • Describe the epidermis and its characteristics.
    The epidermis is a stratified squamous epithelium, avascular, and nourished by diffusion from dermal capillaries.
  • What are keratinocytes and their role?
    Keratinocytes are the most abundant epidermal cells, producing keratin which provides protection and waterproofing.
  • Difference between thin and thick skin?
    Thin skin covers most of the body with four layers of keratinocytes; thick skin covers palms and soles with five layers including the stratum lucidum.
  • Name the five strata of the epidermis in thick skin from deepest to surface.
    Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.
  • What is the function of the stratum basale?
    The stratum basale contains stem cells that divide to replace superficial keratinocytes and contains melanocytes and tactile cells.
  • What cells are found in the stratum spinosum and their function?
    Stratum spinosum contains keratinocytes bound by desmosomes and dendritic (Langerhans) cells active in immune response.
  • What happens in the stratum granulosum?
    Keratinocytes stop dividing, produce keratin and keratohyalin granules, then die to form a tough, dehydrated layer.
  • What is unique about the stratum lucidum?
    The stratum lucidum is a clear layer found only in thick skin, covering the stratum granulosum.
  • Describe the stratum corneum.
    The stratum corneum is the outermost layer with 15-30 layers of dead, keratinized cells providing a water-resistant barrier.
  • How does the skin lose water?
    Water loss occurs via insensible perspiration (diffusion through stratum corneum) and sensible perspiration (sweat gland secretion).
  • What is the dermis and its two layers?
    The dermis is connective tissue beneath the epidermis, composed of the papillary layer (areolar tissue) and reticular layer (dense irregular connective tissue).
  • What are tension lines in the dermis?
    Tension lines are patterns of collagen and elastic fibers that resist forces; incisions parallel to these lines heal better.
  • What sensory receptors are found in the dermis?
    Light touch is detected by tactile (Meissner) corpuscles in the papillary layer; deep pressure and vibration by lamellar (Pacinian) corpuscles in the reticular layer.
  • What pigments influence skin color?
    Skin color is influenced mainly by melanin (brown-black pigment) and carotene (orange-yellow pigment).
  • How does melanin protect the skin?
    Melanin absorbs ultraviolet radiation, protecting DNA from damage and reducing skin cancer risk.
  • What is the role of vitamin D3 in the skin?
    Vitamin D3 is produced by epidermal cells exposed to UV radiation and is converted to calcitriol, essential for calcium and phosphate absorption.
  • Describe the structure and function of hair follicles.
    Hair follicles extend into the dermis, produce nonliving hairs, and are surrounded by sensory nerves and arrector pili muscles.
  • What are the types of hair and their characteristics?
    Vellus hairs are fine and soft covering most body; terminal hairs are thick, pigmented, found on scalp, eyebrows, and after puberty on other areas.
  • What are sebaceous glands and their secretion?
    Sebaceous glands are holocrine glands that secrete sebum, an oily substance that lubricates hair and inhibits bacterial growth.
  • Difference between apocrine and eccrine sweat glands?
    Apocrine glands secrete thick, odorous fluid into hair follicles in armpits and groin; eccrine glands secrete watery sweat directly onto skin for thermoregulation.
  • What structures form nails and their function?
    Nails are made of dead keratinized cells produced in the nail root; they protect fingertips and aid in grasping.
  • How does the skin repair itself after injury?
    Skin repair involves inflammation, scab formation, macrophage cleanup, fibroblast proliferation producing granulation tissue, and scar tissue formation.
  • What changes occur in the skin with aging?
    Aging causes epidermal thinning, reduced melanocytes and gland activity, decreased vitamin D3 production, dermal thinning, and slower repair.