Veterinary Anatomy Chapter 17: The Integumentary System
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Questions and Answers

What is the function of fibrous septa in the subcutis?

  • To connect dermal collagen bundles with the deep fascia (correct)
  • To attach the epidermis to the dermis
  • To separate the dermis from the epidermis
  • To form a thin, fibrous connective tissue layer in the head and legs

    • What is unique about the epidermis?

  • It is composed mostly of adipose tissue
  • It is devoid of blood and lymphatic vessels (correct)
  • It is the thickest layer of the skin
  • It is the outermost layer of the skin

    • What is the process by which keratinocytes are shed from the skin surface?

  • Migration
  • Desquamation (correct)
  • Differentiation
  • Proliferation

    • What is the approximate time it takes for a basal cell to complete the differentiation process?

    <p>1 month</p> Signup and view all the answers

    What type of epithelium is the epidermis composed of?

    <p>Stratified keratinizing epithelium</p> Signup and view all the answers

    What is the percentage of keratinocytes in the epidermis?

    <p>85%</p> Signup and view all the answers

    What is the outermost layer of the skin?

    <p>Epidermis</p> Signup and view all the answers

    What type of glands are present in the skin as specialized appendages?

    <p>All of the above</p> Signup and view all the answers

    In which region is the skin thickest?

    <p>Nasal planum and pawpads</p> Signup and view all the answers

    What is the main function of the dermis?

    <p>To provide structural support and resist tensile forces</p> Signup and view all the answers

    Which layer of the skin is composed of adipose tissue, skeletal muscle, and fibrous tissue?

    <p>Subcutis</p> Signup and view all the answers

    What is the purpose of the subcutis?

    <p>To provide structural support and maintain the shape of the skin</p> Signup and view all the answers

    What is the difference in skin thickness between larger and smaller animals?

    <p>Larger animals have thicker skin</p> Signup and view all the answers

    What are the distal extensions of the digits of the limbs formed from?

    <p>The skin layers</p> Signup and view all the answers

    What is the primary function of recognizing and interpreting clinical skin lesions?

    <p>To identify morphologic patterns</p> Signup and view all the answers

    What is the result of skin atrophy?

    <p>Thinning of the skin</p> Signup and view all the answers

    What can cause skin atrophy involving the epidermis, dermis, and hair follicles?

    <p>Excess steroids, chronic ischemia, and radiation injury</p> Signup and view all the answers

    What is the term for thinning of the follicular epithelium histologically?

    <p>Hair follicle atrophy</p> Signup and view all the answers

    What can cause atrophy of the epidermis alone?

    <p>Cytotoxic lymphocyte mediated killing</p> Signup and view all the answers

    What influences the gross and microscopic appearance of the skin?

    <p>A myriad of exogenous and endogenous factors</p> Signup and view all the answers

    What can result from actions of deleterious agents or processes that disrupt the structure and function of the skin?

    <p>Skin lesions</p> Signup and view all the answers

    What is essential for diagnosing skin disease?

    <p>Pattern recognition</p> Signup and view all the answers

    What is a common nonspecific component of scars?

    <p>Focal skin atrophy</p> Signup and view all the answers

    What is a raised soft mass that often occurs with calluses and/or ulcerated skin surfaces?

    <p>Hygroma</p> Signup and view all the answers

    What is the term for a focal superficial, solid, and raised area of thickened skin caused by chronic pressure and/or friction trauma?

    <p>Callus</p> Signup and view all the answers

    What is characterized by the loss of normal surface epidermal detail, such as the loss of the cobblestone appearance of the nasal planum in dogs?

    <p>Cutaneous lupus variants</p> Signup and view all the answers

    What can occur as a complication of excessive tissue loss in skin disorders?

    <p>Erosions and ulcers</p> Signup and view all the answers

    What is the term for a skin lesion characterized by comedones, scaling, and hyperpigmentation?

    <p>Callus pyoderma</p> Signup and view all the answers

    What is necessary to identify the cause of a skin disorder?

    <p>Both histopathologic evaluation and a history including clinical lesion distribution, appearance, duration, location, past medications, and other clinical data</p> Signup and view all the answers

    What can occur in conjunction with callus formation?

    <p>Scaling and hyperpigmentation</p> Signup and view all the answers

    What is a comedone?

    <p>An accumulated infundibular stratum corneum and sebum within the lumen of a hair follicle</p> Signup and view all the answers

    What is a callus?

    <p>A thick, firm, hyperkeratotic, and hairless plaque with increased skin folds, wrinkles, or fissures</p> Signup and view all the answers

    What is a crust?

    <p>A dried fluid or exudate on the skin surface mixed with various components</p> Signup and view all the answers

    What is an epidermal collarette?

    <p>A thin layer of scales that expands peripherally and forms a ring</p> Signup and view all the answers

    What is an erosion?

    <p>A partial-thickness loss of epidermis resulting in a shallow, moist, glistening depression</p> Signup and view all the answers

    What is a fissure?

    <p>A deep, vertically oriented linear cleft or break from the epidermis into the dermis</p> Signup and view all the answers

    What is lichenification?

    <p>Thickened skin with accentuation of skin surface lines and folds, often occurs with hyperpigmentation and alopecia</p> Signup and view all the answers

    What is a macule?

    <p>A flat, circumscribed, nonelevated area of color change of the skin</p> Signup and view all the answers

    What is a cyst?

    <p>A cavity lined by epithelium and filled with liquid or semisolid material</p> Signup and view all the answers

    What is an example of a skin lesion that may develop in haired skin?

    <p>Comedo</p> Signup and view all the answers

    What is the primary cause of Type I phototoxicity?

    <p>Ingestion of a preformed photodynamic substance</p> Signup and view all the answers

    Which type of pigments are found in plants such as Hypericum perforatum and Fagopyrum esculentum?

    <p>Helianthrone pigments</p> Signup and view all the answers

    What is the function of phytoalexins in plants?

    <p>To respond to fungal infection or other injury</p> Signup and view all the answers

    Which of the following drugs can cause primary phototoxicity in animals?

    <p>All of the above</p> Signup and view all the answers

    What is the result of the interaction between phytoalexins and UV light in the skin?

    <p>Phytophotodermatitis</p> Signup and view all the answers

    Where are photoreactive metabolites formed in the case of primary phototoxicity caused by drug administration?

    <p>Intestinal tract</p> Signup and view all the answers

    What is the term for the type of phototoxicity caused by the presence of psoralens in plants?

    <p>Furocoumarin phototoxicity</p> Signup and view all the answers

    Which of the following is an example of a plant that can cause primary phototoxicity?

    <p>All of the above</p> Signup and view all the answers

    What is the result of a pyrimidine dimer mutation in DNA?

    <p>Replacement of cytosine with thymine</p> Signup and view all the answers

    How often do photochemical reactions occur in a keratinocyte during exposure to sunlight?

    <p>Up to 100 per second</p> Signup and view all the answers

    What is the function of photolyase reactivation in DNA repair?

    <p>To correct damage within seconds</p> Signup and view all the answers

    What is the consequence of a cell undergoing mitosis before DNA damage is repaired?

    <p>A gap in the DNA strand remains</p> Signup and view all the answers

    What is the role of p53 in response to DNA damage?

    <p>To mediate cell cycle arrest and apoptosis</p> Signup and view all the answers

    What is the term for mutations caused by UV rays in skin tumors?

    <p>UV signature mutations</p> Signup and view all the answers

    What is the consequence of p53 gene mutations in keratinocytes?

    <p>Development of neoplasms</p> Signup and view all the answers

    What can increase the number of cells repaired by the postreplication repair method?

    <p>Factors that irritate the skin</p> Signup and view all the answers

    What is the result of the interaction between UV radiation and photodynamic molecules in the skin?

    <p>Phototoxicity</p> Signup and view all the answers

    What type of cells are stimulated by UV radiation, leading to immunosuppression?

    <p>T regulatory cells</p> Signup and view all the answers

    What is the consequence of the decreased production of IL-12 and IL-23 in lymph nodes?

    <p>Decreased T lymphocyte activation</p> Signup and view all the answers

    What is the result of the increased presence of mast cells and IL-10-producing monocytes in the dermis and lymph nodes?

    <p>Decreased antigen presentation</p> Signup and view all the answers

    What is the consequence of the activation of B regulatory cells?

    <p>Decreased antigen presentation</p> Signup and view all the answers

    What is the result of the inhibition of antigen-presenting dendritic cells?

    <p>Decreased T lymphocyte activation</p> Signup and view all the answers

    What is the outcome of the suppression of T lymphocyte activation?

    <p>Decreased immune response</p> Signup and view all the answers

    What is the long-term consequence of UV-induced immunosuppression?

    <p>Tolerance</p> Signup and view all the answers

    Study Notes

    Integumentary System

    • The skin is the largest organ of the body, composed of three layers: epidermis, dermis, and subcutis.
    • The epidermis is a stratified keratinizing epithelium, divided into four layers: stratum basale, stratum spinosum, stratum granulosum, and stratum corneum.
    • Keratinocytes continuously proliferate in the basal epidermal layer, migrate and differentiate to form the upper epidermal layers, and then shed from the skin surface.

    Skin Lesions

    • Clinical skin lesions can be categorized into primary and secondary lesions.
    • Primary lesions include:
      • Atrophy: thinning of the skin due to loss of epidermal and/or dermal thickness.
      • Callus: focal superficial, solid, and raised area of thickened skin caused by chronic pressure and/or friction trauma.
      • Comedo: small dilated follicular opening and infundibulum plugged by accumulated stratum corneum and sebum.
      • Crust: dried fluids or exudates on the skin surface mixed with various components.
      • Cyst: cavity lined by epithelium and filled with liquid or semisolid material.
      • Erosion: partial-thickness loss of epidermis resulting in shallow, moist, glistening depression.
      • Fissure: deep, vertically oriented linear cleft or break from the epidermis into the dermis.
      • Lichenification: thickened skin with accentuation of skin surface lines and folds, often occurs with hyperpigmentation and alopecia.
      • Macule: flat, circumscribed, non-elevated area of color change of the skin.

    Phototoxicity

    • Phototoxicity is caused by the interaction of UV rays with photodynamic molecules derived from plants, leading to skin lesions.
    • Types of phototoxicity:
      • Primary phototoxicity: caused by ingestion of preformed photodynamic substances, such as chemicals present in plants or some drugs.
      • Secondary phototoxicity: caused by percutaneous absorption of photodynamic molecules or complexes.
    • Factors that irritate the skin and increase the rate of cell division can enhance development of neoplasms.

    UV-Induced Damage and Immunity

    • UV rays can cause mutations in keratinocytes, leading to neoplasms.
    • p53 gene mutations can occur in keratinocytes when UV ray-induced dimers and photoproducts are not properly repaired.
    • UV signature mutations are unique to skin tumors and do not occur with other types of DNA damage or in tumors unassociated with UV rays.
    • UV exposure can also lead to immunosuppression, inhibiting the expansion of effector CD4+ and CD8+ T lymphocytes in lymph nodes draining the skin.

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    Description

    This quiz covers the structure, function, and dysfunction of the integumentary system in domestic animals, including horses. Topics include skin lesions, regeneration, and defense mechanisms.

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