Dermis and Skin Structure Quiz
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Questions and Answers

What is the function of the cuticle in hair structure?

  • It contains sebaceous glands.
  • It serves as the outer protective layer. (correct)
  • It provides strength and stiffness.
  • It acts as the central core of the hair.
  • Which layer of the hair follicle surrounds the hair root?

  • Cortex
  • External root sheath (correct)
  • Connective tissue sheath
  • Glassy membrane
  • What is the role of the arrector pili muscle?

  • It helps in the growth of hair follicles.
  • It induces hair stiffness.
  • It stores keratin resources.
  • It contracts to raise hair follicles. (correct)
  • Which statement correctly describes the cortex of the hair?

    <p>It provides the hair with its color and strength.</p> Signup and view all the answers

    What characterizes the glassy membrane in the hair follicle?

    <p>It is a clear layer within the dense connective tissue sheath.</p> Signup and view all the answers

    What type of keratin is found in the medulla of hair?

    <p>Soft keratin</p> Signup and view all the answers

    Which structure wraps around the base of the hair follicle?

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

    What type of muscle makes up the arrector pili muscle?

    <p>Involuntary smooth muscle</p> Signup and view all the answers

    Which of the following statements about the external root sheath is correct?

    <p>It extends from the skin surface to the hair matrix.</p> Signup and view all the answers

    Where in the human body is hair NOT present?

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

    What is the role of sebaceous glands associated with hair?

    <p>To secrete oil and lubricate the hair</p> Signup and view all the answers

    What characterizes terminal hairs?

    <p>They are heavy and pigmented.</p> Signup and view all the answers

    What type of scar is characterized by being raised and occurs within the boundaries of the original injury?

    <p>Hypertrophic scar</p> Signup and view all the answers

    What structure is responsible for hair production?

    <p>Hair bulb</p> Signup and view all the answers

    In first degree burns, which layer of the skin is affected?

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

    What is a potential danger associated with burns that occur on the face?

    <p>Risk of infection</p> Signup and view all the answers

    Which of the following is NOT a characteristic effect of aging on the skin?

    <p>Increased vitamin D3 production</p> Signup and view all the answers

    What is the purpose of the Rule of Nines in relation to burns?

    <p>To estimate the surface area affected by burns</p> Signup and view all the answers

    What type of tissue primarily makes up the papillary layer of the dermis?

    <p>Areolar tissue</p> Signup and view all the answers

    Which factor is NOT associated with decreased skin turgor?

    <p>Increased hydration</p> Signup and view all the answers

    What characterizes dermatitis?

    <p>Inflammation of the papillary layer</p> Signup and view all the answers

    Which receptors in the dermis are responsible for light touch sensations?

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

    Which statement is true regarding the lines of cleavage in the dermis?

    <p>A cut across them can lead to increased scarring.</p> Signup and view all the answers

    What is the primary function of the hypodermis?

    <p>To stabilize the skin and allow independent movement</p> Signup and view all the answers

    Which layer of the dermis contains larger blood vessels and lymphatics?

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

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

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

    What primarily causes a bruise (contusion)?

    <p>Damage to blood vessels in the dermis</p> Signup and view all the answers

    Which of the following statements about the dermal blood supply is true?

    <p>The dermis has a highly vascular supply through the cutaneous and papillary plexuses.</p> Signup and view all the answers

    What is the primary role of melanocytes in hair color?

    <p>Producing melanin</p> Signup and view all the answers

    Which of the following correctly describes the properties of sebum?

    <p>It lubricates and protects the epidermis</p> Signup and view all the answers

    What distinguishes apocrine sweat glands from merocrine sweat glands?

    <p>Apocrine glands discharge into hair follicles</p> Signup and view all the answers

    Which of these options is NOT a function of hair?

    <p>Regulates body temperature</p> Signup and view all the answers

    What condition is characterized by inflammation around a hyperactive sebaceous gland?

    <p>Seborrheic dermatitis</p> Signup and view all the answers

    How do merocrine sweat glands primarily cool the body?

    <p>By discharging sweat directly onto the skin</p> Signup and view all the answers

    Which glands are correctly described as compound alveolar glands producing milk?

    <p>Mammary glands</p> Signup and view all the answers

    What role does the autonomic nervous system play in gland secretion?

    <p>It provides global control over all glands</p> Signup and view all the answers

    What is the primary function of sensible perspiration?

    <p>Regulating body temperature</p> Signup and view all the answers

    Which structure is produced in the nail root and is primarily dermal in origin?

    <p>Nail body</p> Signup and view all the answers

    Study Notes

    Dermis

    • Lies between the epidermis and hypodermis.
    • Anchors accessory structures, including hair follicles and sweat glands.
    • Consists of two layers: the papillary layer and the reticular layer.

    Papillary Layer

    • Superficial layer of the dermis.
    • Composed of areolar tissue.
    • Contains smaller capillaries, lymphatics, and nerve fibers.
    • Contains dermal papillae that project between epidermal ridges.

    Reticular Layer

    • Deep layer of the dermis.
    • Composed of dense irregular connective tissue.
    • Contains larger blood vessels, lymphatics, and nerve fibers.
    • Connected to the hypodermis.

    Characteristics of the Dermis

    • Strong due to collagen fibers.
    • Elastic due to elastic fibers, which contribute to skin turgor.

    Decreased Skin Turgor

    • Reduced skin elasticity that leads to sagging and wrinkles.
    • Caused by dehydration, hormonal changes, exposure to UV radiation, and aging.

    Dermatitis

    • Inflammation of the papillary layer.
    • Caused by infection, radiation, mechanical irritation, or chemicals.
    • Characterized by itching or other pain.

    Lines of Cleavage (Langer's Lines)

    • The collagen and elastic fibers in the dermis are arranged in parallel bundles.
    • Resist force in a specific direction.
    • Clinically important because parallel incisions remain shut and heal well while cuts made across the lines pull open and scar.

    Dermal Blood Supply

    • Arteries:
      • Cutaneous plexus: network of arteries along the reticular layer.
      • Papillary plexus: network of capillaries in the papillary layer.
    • Veins:
      • Venous plexus: receives blood from capillaries.

    Contusion (Bruise)

    • Blunt trauma to the skin that damages blood vessels.
    • Blood leaks into the dermis, resulting in a "black and blue" discoloration.

    Bed Sores (Decubitus Ulcers)

    • Result from disturbances of dermal circulation.
    • Affect the skin at pressure points.
    • Prevention includes changing position frequently and using air mattresses.

    Dermis & Nerve Supply

    • Nerve fibers in the skin control blood flow, gland secretions, and sensations.
    • Contains numerous receptors:
      • Pacinian (lamellar) corpuscles: sense pressure and vibration.
      • Meissner’s (tactile) corpuscles: sense light touch.
      • Merkel discs: sense pressure, position, and deep touch.
      • Ruffini (bulbous) corpuscles: sense skin stretch.
      • Free nerve endings: sense pain and temperature.

    Dermis at a Glance

    • Provides mechanical strength, flexibility, and protection.
    • Consists of two layers of connective tissue.
    • Highly vascular.
    • Contains a variety of sensory receptors.

    Hypodermis

    • Also known as subcutaneous tissue or superficial fascia.
    • Not part of the skin; lies underneath the integument.
    • Quite elastic and stabilizes the skin, allowing independent movement.

    Structure of the Hypodermis

    • Composed of areolar and adipose tissues.
    • Connected to the reticular layer of the dermis by connective tissue fibers.

    Clinical Importance of the Hypodermis

    • Has few capillaries and no vital organs.
    • Site of subcutaneous injections and liposuction.

    Accessory Structures of the Integumentary System

    • Hair.
    • Glands (sebaceous, sweat, mammary, and ceruminous).

    Hair

    • Structure:
      • Hair shaft: upper portion, sticks out of the integument.
      • Hair root: lower portion, attached to the integument.
      • Hair follicle: factory of hair, located in the dermis and wrapped with dense connective tissue.
      • Accessory structures: sebaceous glands, arrector pili muscle, and connective tissue sheath.

    Regions of the Hair

    • Hair root: lower part, attached to the integument.
    • Hair shaft: upper part, sticks out of the integument.

    Layers in a Hair

    • Medulla: central core, contains soft and flexible keratin.
    • Cortex: middle layer, contains thick layers of hard keratin, giving hair its stiffness.
    • Cuticle: outer layer, thin but tough, contains hard keratin.

    Keratin

    • Hair is keratinized during production:
      • Medulla contains flexible soft keratin.
      • Cortex and cuticle contain stiff hard keratin.

    Hair Follicle

    • Located deep in the dermis.
    • Factory of hair.
    • Wrapped in a dense connective tissue sheath.
    • Base is surrounded by sensory nerves (root hair plexus).

    Layers of the Hair Follicle

    • Internal root sheath: surrounds the hair root and deeper part of the shaft.
    • External root sheath: extends from the skin surface to the hair matrix.
    • Glassy membrane: thickened, clear layer wrapped in the dense connective tissue sheath.

    Hair Production by the Follicle

    • Hair papilla: contains capillaries and nerves.
    • Hair bulb: surrounds the papilla and produces:
      • Hair layers.
      • Hair matrix which produces hair cells.

    Accessory Structures of Hair

    • Arrector pili muscle: involuntary smooth muscle causing hair to stand up which produces "goose bumps."
    • Sebaceous glands: secrete sebum (oil) to lubricate the hair and inhibit bacteria.

    Location of Hair

    • The human body is covered with hair except on the palms, soles, lips, and portions of the external genitalia (labia minora and penis).

    Types of Hairs

    • Vellus hairs: soft, fine hairs covering the body surface.
    • Terminal hairs: heavy, pigmented hairs found on the head, eyebrows, and other areas after puberty (pubic, axillary).

    Hair Color

    • Melanin produced by melanocytes at the hair papilla determines hair color.
    • Determined by genes.

    Functions of Hair

    • Provides protection and insulation.
    • Guards openings against particles and insects.
    • Sensitive to very light touch.

    Integumentary Glands

    • Sebaceous (oil) glands.
    • Sweat glands.
    • Mammary glands.
    • Ceruminous glands.

    Sebaceous Glands

    • Simple branched alveolar glands.
    • Holocrine glands, meaning they secrete sebum through the breakdown of their cells.
    • Secrete sebum (oil).

    Sebum

    • Oily material containing lipids and other ingredients.
    • Lubricates and protects the epidermis.
    • Inhibits bacteria.
    • Seborrheic dermatitis is an inflammation around hyperactive sebaceous gland.

    Sweat Glands

    • Simple coiled tubular glands.
    • Produce sweat.
    • Two types: merocrine (eccrine) and apocrine.

    Merocrine Sweat Glands

    • Widely distributed on the body surface, especially on palms and soles.
    • Discharge directly onto the skin surface.
    • Function:
      • Excrete water, salts, and organic compounds.
      • Cool down the skin.
      • Flush microorganisms and harmful substances.

    Apocrine Sweat Glands

    • Found in the axilla, around the nipples, and the pubic region.
    • Discharge onto hair follicles.
    • Produce sticky and cloudy secretions, which are acted upon by bacteria to intensify their odor.

    Mammary & Ceruminous Glands

    • Mammary glands:
      • Compound alveolar glands.
      • Apocrine glands.
      • Produce milk.
    • Ceruminous glands:
      • Simple coiled tubular glands.
      • Modified apocrine sweat glands.
      • Produce cerumen (earwax) that protects the eardrum.

    Control of Glands

    • Autonomic nervous system controls gland secretion:
      • Global control: works simultaneously over the entire body.
      • Regional control: sweating occurs locally (e.g., palms).

    Skin & Thermoregulation

    • Main function of sensible perspiration:
      • Regulates body temperature.
      • Works with the cardiovascular system.
    • Skin plays a major role in controlling body temperature:
      • Acts as a radiator.
      • Removes heat from dermal circulation.
      • Works by evaporation of sensible perspiration.

    Nails

    • Produced in the nail root, a deep epidermal fold near the bone.

    Nails & Disease

    • Clubbing: abnormal rounded nails seen in various diseases.
    • Spoon nail (koilonychia): concave nails associated with iron deficiency.
    • Psoriasis: chronic skin disease.

    Skin Injuries & Repair

    • Inflammatory phase:
      • Bleeding occurs at the site of injury.
      • Mast cells trigger an inflammatory response.

    Abnormal Scars

    • Hypertrophic scar: raised scar.
    • Keloid: raised scar that extends beyond the original wound.
    • Atrophic scar: sunken scar (e.g., healed acne).
    • Stretch marks (striae gravidarum): thinned scar.

    Burns & Scalds

    • Result from denaturation of cell proteins.
    • Dehydration, protein loss, and infection are a concern.
    • Degrees:
      • First degree: epidermis only.
      • Second degree: epidermis and upper dermis, may include blisters.
      • Third degree: full thickness, ± underlying tissues (fourth degree), skin grafting is necessary.

    Rule of Nines

    • Used to estimate burn damage by dividing the surface area into multiples of nine.

    Effects of Aging

    • Epidermal thinning.
    • Decrease in:
      • Number of Langerhans cells.
      • Vitamin D3 production.
      • Glandular activity.
      • Blood supply.
      • Function of hair follicles.
      • Melanocyte activity.
      • Elastic fibers.
    • Slower repair rate.

    Integument & Other Systems

    • The integumentary system interacts with other systems in the body, including:
      • Endocrine system: hormones influence skin growth and development.
      • Nervous system: regulates temperature, controls blood flow, and transmits sensations.
      • Immune system: protects against pathogens.
      • Cardiovascular system: provides blood supply.
      • Skeletal system: supports and protects the skin.

    Summary

    • The integumentary system comprises the skin, hair, glands (sweat, sebaceous, mammary, ceruminous), and nails.
    • The skin consists of:
      • Epidermis: thin outer layer made of epithelial tissue.
      • Dermis: thicker inner layer composed of connective tissue.

    Differences Between Thick & Thin Skin

    • Thick skin: 5 epidermal layers, found on palms and soles, lacks hair follicles, and has more sweat glands.
    • Thin skin: 4 epidermal layers, covers most of the body, has hair follicles, and fewer sweat glands.

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    Description

    Test your knowledge about the dermis, including its layers, characteristics, and conditions that affect skin turgor. This quiz covers key concepts such as the papillary and reticular layers, as well as dermatitis and skin aging. Perfect for students of anatomy or dermatology.

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