L3 Skin I
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Questions and Answers

What is primarily responsible for the increase in maternal skin pigmentation during pregnancy?

  • Cortisol
  • Prolactin
  • Melanocyte-stimulating hormone (MSH) (correct)
  • Insulin

    • Which condition results from a mutation in the enzyme tyrosinase, affecting melanin production?

  • Vitiligo
  • Lentigo
  • Albinism (correct)
  • Melasma

    • What characterizes a Melanocytic Nevus?

  • Fibrous tissue overgrowth
  • Complete loss of pigment
  • Inflammatory response of the dermis
  • Hyperpigmentation due to melanocytic proliferation (correct)

    • What is the primary function of epidermal Langerhans cells?

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

    What type of connective tissue is primarily found in the dermis?

    <p>Reticular connective tissue</p> Signup and view all the answers

    Which layer of the skin is primarily responsible for thermoregulation?

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

    Which of the following correctly describes Merkel cells?

    <p>Specialized receptor neurons with no axon</p> Signup and view all the answers

    Pacinian corpuscles are best known for detecting which type of sensation?

    <p>Deep pressure and vibration</p> Signup and view all the answers

    Peripheral neuropathy can result in which of the following symptoms?

    <p>Numbness and pain</p> Signup and view all the answers

    Which structure is crucial for the skin’s ability to detect fine touch?

    <p>Meissner's corpuscle</p> Signup and view all the answers

    What impact does chronic sun exposure have on the skin?

    <p>Risk of skin cancers, including melanoma</p> Signup and view all the answers

    What is the primary role of hydroquinone creams concerning melanin production?

    <p>Decrease melanin production</p> Signup and view all the answers

    What structure acts as the primary blood supply to the capillaries in the dermal papillae?

    <p>Subpapillary plexus</p> Signup and view all the answers

    What are the main functions of the integument system?

    <p>Protects deeper tissues and plays a role in thermoregulation</p> Signup and view all the answers

    Which layer of the epidermis is responsible for the production of new keratinocytes?

    <p>Stratum basale</p> Signup and view all the answers

    What type of melanin is primarily found in the epidermis and contributes to brown or black coloration?

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

    Which cells are present in the epidermis and play a crucial role in detecting light touch?

    <p>Merkel cells</p> Signup and view all the answers

    In which layer of thick skin would you find the stratum lucidum?

    <p>Only in the epidermis of glabrous skin</p> Signup and view all the answers

    What is the role of keratinocytes in the epidermis?

    <p>To provide structural support and waterproofing</p> Signup and view all the answers

    What happens to the keratinization process during aging?

    <p>It slows down and causes skin thickness to increase</p> Signup and view all the answers

    What is the primary factor that influences the color of skin?

    <p>The amount of melanin present in keratinocytes</p> Signup and view all the answers

    Disruption of which structures can lead to vesicular dermatosis?

    <p>Desmosomes or hemidesmosomes</p> Signup and view all the answers

    What type of cells act as the first line of defense against ultraviolet irradiation in the skin?

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

    Which epidermal layer contains keratohyalin granules?

    <p>Stratum granulosum</p> Signup and view all the answers

    What is the correct sequence for melanosome maturation?

    <p>Stage I, Stage II, Stage III, Stage IV</p> Signup and view all the answers

    What is the primary location of melanocytes within the epidermis?

    <p>Stratum basale</p> Signup and view all the answers

    Which characteristic of the stratum corneum contributes to its barrier function?

    <p>Presence of multiple layers of flattened cells without nuclei</p> Signup and view all the answers

    What is the primary composition of the outer layer of skin?

    <p>Keratinized stratified squamous epithelium</p> Signup and view all the answers

    Which layer of the epidermis is characterized by its translucent appearance and is found only in thick skin?

    <p>Stratum lucidum</p> Signup and view all the answers

    Which type of melanin is responsible for the yellow to red pigmentation in skin and hair?

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

    What is the primary function of the stratum basale in the epidermis?

    <p>Production of new keratinocytes</p> Signup and view all the answers

    Which process describes the gradual change of keratinocytes as they move from the stratum basale to the stratum corneum?

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

    Which cells in the epidermis are responsible for producing melanin?

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

    Which layer is primarily responsible for the generation of keratin and keratohyalin granules within the cells?

    <p>Stratum granulosum</p> Signup and view all the answers

    The disruption of desmosomal connections between epidermal cells can lead to which condition?

    <p>Epidermolysis bullosa</p> Signup and view all the answers

    Which of the following factors predominantly increases melanin production in the skin?

    <p>Increased UV exposure</p> Signup and view all the answers

    What type of connections do hemidesmosomes form between keratinocytes and the basal membrane?

    <p>Strong adhesive connections</p> Signup and view all the answers

    Which feature characterizes the stratum corneum of the skin?

    <p>Layer of transparent cells without nuclei</p> Signup and view all the answers

    What effect does aging have on the epidermis, specifically at the dermoepidermal junction?

    <p>Flattening of the junction</p> Signup and view all the answers

    What distinguishes thick skin from thin skin?

    <p>Thick skin has a thick cornified layer and lacks hair follicles</p> Signup and view all the answers

    What is a potential effect of Addison’s disease related to skin pigmentation?

    <p>Hyperpigmentation due to excess ACTH production</p> Signup and view all the answers

    Which of the following factors is known to decrease melanin production?

    <p>Genetic defects like albinism</p> Signup and view all the answers

    What primarily characterizes the reticular dermis?

    <p>Contains sensory receptors and collagen fibers</p> Signup and view all the answers

    Which component is essential for the function of Meissner's corpuscles?

    <p>They detect fine touch and are shaped like coiled springs</p> Signup and view all the answers

    What condition is characterized by the destruction of melanocytes?

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

    What type of sensory stimulus do Pacinian corpuscles primarily respond to?

    <p>Deep pressure and vibration</p> Signup and view all the answers

    Which part of the skin is the subcutis also known as?

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

    What is the primary role of epidermal Langerhans cells?

    <p>Capture and present antigens to activate immune responses</p> Signup and view all the answers

    What is a characteristic of Birbeck granules found in Langerhans cells?

    <p>They are rod-shaped structures with zipper-like striations</p> Signup and view all the answers

    Which feature is essential for the blood supply in the dermis?

    <p>Subpapillary plexus</p> Signup and view all the answers

    Which skin function relates specifically to protection?

    <p>Prevention against dehydration and microbiological invasion</p> Signup and view all the answers

    What is a common result of peripheral neuropathy?

    <p>Numbness or abnormal sensation</p> Signup and view all the answers

    How does chronic sun exposure affect the skin?

    <p>Increases the risk of skin cancers, including melanoma</p> Signup and view all the answers

    Which layer of skin primarily contains collagen and elastic fibers?

    <p>Reticular dermis</p> Signup and view all the answers

    What is the primary consequence of genetic defects in melanin synthesis in individuals with albinism?

    <p>Increased sensitivity to UV light</p> Signup and view all the answers

    In which layer of the skin would you primarily find the sensory receptors for deep pressure?

    <p>Reticular dermis</p> Signup and view all the answers

    What role do Hydroquinone creams play in skin therapy?

    <p>Inhibit melanin production</p> Signup and view all the answers

    What type of structure is characterized by Birbeck granules?

    <p>Epidermal Langerhans cells</p> Signup and view all the answers

    Which part of the skin is primarily responsible for thermoregulation through blood supply?

    <p>Reticular dermis</p> Signup and view all the answers

    What sensory function is primarily associated with Meissner's corpuscle?

    <p>Fine touch sensation</p> Signup and view all the answers

    Which hormone is primarily linked to the increase in skin pigmentation in Addison's disease due to excess production?

    <p>Adrenocorticotropic hormone</p> Signup and view all the answers

    Pacinian corpuscles are specialized to detect which type of stimulus?

    <p>Deep pressure</p> Signup and view all the answers

    What is a primary factor contributing to the degeneration of the dermis as individuals age?

    <p>Loss of elastic fibers</p> Signup and view all the answers

    Which condition is characterized by the destruction of pigment-producing melanocytes?

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

    Which structure primarily contains adipose tissue and helps insulate the body?

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

    Which cells in the skin originate from bone marrow and play a crucial role in immune response?

    <p>Langerhans cells</p> Signup and view all the answers

    What is the primary purpose of the dermal papillae found in the papillary dermis?

    <p>Enhancement of sensory reception</p> Signup and view all the answers

    What characterizes the stratum spinosum layer of the epidermis?

    <p>It has spiny projections that aid in intercellular adhesion.</p> Signup and view all the answers

    Which type of melanin is specifically associated with the pigmentation of skin and hair in shades of yellow to red?

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

    How long does the keratinization process typically take?

    <p>30-45 days</p> Signup and view all the answers

    Which layer of the skin is exclusively found in areas like the palms and soles?

    <p>Stratum lucidum</p> Signup and view all the answers

    What important role do epidermal melanocytes play in the skin?

    <p>Producing melanin to protect against ultraviolet light.</p> Signup and view all the answers

    What is the primary function of the stratum granulosum?

    <p>Keratin and keratohyalin generation.</p> Signup and view all the answers

    What typically happens to the rete ridges and dermal papillae as a result of aging?

    <p>They flatten and reduce in visibility.</p> Signup and view all the answers

    Which of the following factors is known to increase melanin production in the skin?

    <p>Increased UV exposure</p> Signup and view all the answers

    What is unique about hemidesmosomes in the epidermis?

    <p>They anchor keratinocytes to the basement membrane.</p> Signup and view all the answers

    Which cell type is primarily responsible for forming a protective barrier and undergoes rapid turnover in the epidermis?

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

    What distinct structure characterizes the stratum corneum?

    <p>Absence of nuclei in the cells.</p> Signup and view all the answers

    Which epidermal layer contains the Langerhans’ cells, which contribute to immune responses?

    <p>Stratum spinosum</p> Signup and view all the answers

    Among the four cell types present in the epidermis, which cell type is primarily associated with mechanoreception?

    <p>Merkel cells</p> Signup and view all the answers

    What significant metabolic function does the integument system serve related to Vitamin D?

    <p>It converts cholesterol to Vitamin D via UV radiation.</p> Signup and view all the answers

    What results from the proliferation of melanocytes and can present as either flat or nodular?

    <p>Melanocytic Nevus</p> Signup and view all the answers

    Which condition occurs due to a significant loss of pigment-producing melanocytes?

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

    What skin structure contains both collagen and elastic fibers and serves as a support layer?

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

    What factors are known to contribute to a decrease in melanin production?

    <p>Genetic defects in melanin synthesis</p> Signup and view all the answers

    What is primarily responsible for the detection of deep pressure and vibration in the skin?

    <p>Pacinian corpuscle</p> Signup and view all the answers

    What is the role of E-cadherin in epidermal Langerhans cells?

    <p>Cell adhesion</p> Signup and view all the answers

    What is characterized by the presence of rod-shaped Birbeck granules in the cytoplasm?

    <p>Langerhans cells</p> Signup and view all the answers

    What constitutes a major consequence of chronic sun exposure on skin health?

    <p>Increased risk of skin cancers</p> Signup and view all the answers

    Which layer of skin is primarily responsible for storing fat and insulating the body?

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

    What is the primary function of Merkel cells in the skin?

    <p>Detecting fine touch</p> Signup and view all the answers

    What structure is primarily involved in thermoregulation by facilitating blood flow?

    <p>Cutaneous plexus</p> Signup and view all the answers

    Which type of nerve endings are involved in detecting fine touch and pressure?

    <p>Meissner's corpuscles</p> Signup and view all the answers

    Which layer of the dermis is specifically involved in supporting sensory receptors?

    <p>Reticular dermis</p> Signup and view all the answers

    What is the consequence of peripheral neuropathy on skin sensation?

    <p>Abnormal sensations like pain or numbness</p> Signup and view all the answers

    What is the main function of the stratum granulosum layer in the epidermis?

    <p>To generate large amounts of keratin and keratohyalin</p> Signup and view all the answers

    Which layer of skin would you primarily find melanin-producing melanocytes?

    <p>Stratum basale</p> Signup and view all the answers

    What type of cells are responsible for the initial defense against foreign organisms in the epidermis?

    <p>Langerhans’ cells</p> Signup and view all the answers

    Which epidermal structure is primarily involved in anchoring the epidermis to the dermis?

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

    What is the primary composition of the stratum corneum that contributes to its barrier function?

    <p>Dead keratinocytes and keratin filaments</p> Signup and view all the answers

    Which type of melanin is primarily associated with red and yellow pigmentation?

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

    What is the effect of increased UV exposure on melanin production?

    <p>Increases melanin production</p> Signup and view all the answers

    What forms the primary structure for intercellular adhesion between keratinocytes in the epidermis?

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

    Which layer of the epidermis is characterized by a significant increase in keratin as cells flatten?

    <p>Stratum spinosum</p> Signup and view all the answers

    What happens to the rete ridges with aging?

    <p>They flatten out.</p> Signup and view all the answers

    How does keratinization typically progress in the skin?

    <p>Gradual changes from basal to corneous cells</p> Signup and view all the answers

    Which type of cells help modulate the sensory response to light touch within the skin?

    <p>Merkel cells</p> Signup and view all the answers

    What occurs due to disruptions in hemidesmosomes or desmosomes within the epidermis?

    <p>Vesicular dermatosis</p> Signup and view all the answers

    What primarily influences the variation in skin color among individuals?

    <p>Amount of melanin in keratinocytes</p> Signup and view all the answers

    Study Notes

    Histology of Integument System I

    • Skin is composed of skin and appendages
    • Provides protection from injury, drying, and foreign organisms
    • Plays a role in thermoregulation, excretion, and absorption
    • Absorbs ultraviolet light
    • Metabolizes vitamin D
    • Contains peripheral endings of sensory nerves
    • Two types of skin exist:
      • Thick skin: Glabrous, found on palms, soles, and flexor surfaces of digits, with a thick cornified layer
      • Thin skin: Hirsute, majority of skin, with a thinner cornified layer (stratum corneum)
    • Skin structure includes the epidermis and dermis
      • Epidermis consists of layers:
        • Stratum corneum: Outermost layer, composed of dead, keratinized cells, forming a tough protective barrier, preventing water loss
        • Stratum lucidum: Found in thick skin; translucent layer between stratum granulosum and stratum corneum, composed of dead, flattened keratinocytes.
        • Stratum granulosum: Contains keratohyalin and lamellar granules, responsible for waterproofing and preventing dehydration. Lamellar granules release lipids to further waterproof the skin.
        • Stratum spinosum: AKA prickle layer; cells connected by desmosomes, contributing to skin strength and integrity. Desmosomes are intercellular junctions.
        • Stratum basale: Deepest layer, actively dividing cells and melanocytes, the source of new epidermal cells and responsible for pigment production. Hemidesmosomes attach the cells to the basement membrane, which is a specialized structure at the dermal-epidermal junction and consists of proteins, glycoproteins, and collagen that connects the epidermis to the dermis.

    Objectives

    • Describe the types of skin and their distribution
    • Compare and contrast the morphological features of the major layers of the skin
    • Compare and contrast the location, structure, and function of the four cell types of the epidermis
    • Describe melanin synthesis and distribution
    • Describe the skin's blood supply and sensory components in terms of structure, function, and location.

    Epidermal Melanocytes

    • Neural crest origin
    • Located in the basal keratinocytes
    • Produce melanin from tyrosine, involved in a complex enzymatic process. The main enzyme is tyrosinase.
    • Transfer melanin to adjacent epithelial cells
    • Protect against ultraviolet rays
    • Contains dendrites (processes), extending between keratinocytes.
    • Smaller nuclei, uniform chromatin, and indented nuclear contours.
    • Melanin production is regulated by various factors, including UV exposure and hormones like melanocyte-stimulating hormone (MSH).

    Epidermal Langerhans Cells

    • Bone marrow origin, monocyte-derived dendritic cells
    • Scattered in upper squamous layer and dermis
    • Express Langerin (CD207) and CD1a
    • Communicate with other cells through E-cadherin
    • Phagocytic and antigen presenting cells, crucial for the immune response.
    • Possesses unique Birbeck granules, rod-shaped structures with zipper-like striations often with bulbous ends.

    Merkel Cells

    • Specialized receptor neurons
    • No axon, relying on a secondary sensory neuron for signal transduction
    • Concentrated in skin of digits, finger pads, proximal nail folds
    • Common in outer root sheath of hair follicles and tactile hair discs, playing a role in touch sensation
    • Located in the epidermis

    Dermis

    • Contains collagen and elastic fibers, adnexa, nerves, and blood vessels
    • Degenerates with age and sunlight.
    • Usually thicker on the back
    • Two layers: papillary and reticular
    • Contains a blood supply network for thermoregulation. Arterial supply, including capillaries in the papillary dermis, cutaneous plexus at dermal-hypodermal junctions, and arteriovenous anastomoses, all contribute to regulating body temperature.

    Skin Pigmentation

    • Melanin is produced by melanocytes and transferred to keratinocytes
    • Skin color depends on the amount of melanin, not the number of melanocytes. The amount of melanin produced and transferred to keratinocytes determines skin color.

    Melanogenesis Regulation

    • Factors increasing melanin production include increased UV exposure (tanning), and melanocyte-stimulating hormone (MSH). Increased MSH can come from placental MSH sources.
    • Factors decreasing melanin production include genetic defects leading to conditions like albinism, and destruction of melanocytes, as in vitiligo. Also includes hydroquinone and other treatments.

    Skin Functions

    • Protection against harmful stresses
    • Sensation of touch, pressure, pain, and temperature
    • Thermoregulation via sweat glands, hair, and adipose tissue
    • Metabolic functions, including vitamin D production and triglyceride storage.

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    L3 Histology Skin I 2025 PDF

    Description

    This quiz focuses on the histological structure and functions of the integument system, specifically the skin. Topics include the composition, types of skin, and the epidermis layers. Test your knowledge on the protective, regulatory, and sensory roles of the skin.

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