Chapter on Skin Anatomy and Function
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Questions and Answers

What percentage of body weight does the integument, or skin, represent?

  • 30-35%
  • 5-10%
  • 15-16% (correct)
  • 20-25%

    • The thinnest skin is found on the palms of the hands.

    False

    What are the three main layers of the skin?

    epidermis, dermis, hypodermis

    The skin contains sensory receptors for touch, pressure, pain, and __________ stimuli.

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

    Match the following skin structures to their functions:

    <p>Epidermis = Protects from impacts and infections Dermis = Contains nerves and blood vessels Hypodermis = Stores adipose tissue Accessory structures = Includes hair, nails, and glands</p> Signup and view all the answers

    Which cell type is predominant in the stratum corneum layer of the epidermis?

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

    Sodium hydroxide (NaOH) can burn the skin.

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

    The majority of the body's energy storage is in __________ tissue directly under the skin.

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

    What is the primary function of keratin in the skin?

    <p>Acts as a durable barrier</p> Signup and view all the answers

    The stratum corneum is comprised of living cells.

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

    What triggers the rapid growth of skin cells in psoriasis?

    <p>Cells in the immune system</p> Signup and view all the answers

    Melanocytes produce the pigment _____ that colors the epidermis.

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

    Match the skin condition or characteristic with its description:

    <p>Keratinization = Accumulation of keratohyaline and lamellar granules Stratum Lucidum = Layer of keratinized cells found only in thick skin Psoriasis = Skin cells grow at an abnormally fast rate Freckles = Concentrated spots of melanin in light-skinned individuals</p> Signup and view all the answers

    Which of the following layers contains blood vessels?

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

    Having a darker skin tone increases vitamin D production.

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

    How long does it typically take for skin cells to reach the stratum corneum?

    <p>7-10 days</p> Signup and view all the answers

    What is the primary function of hair?

    <p>To provide insulation and guard sensory openings</p> Signup and view all the answers

    Sebaceous glands produce sweat to prevent the skin from drying out.

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

    What is the genetic trait responsible for male pattern baldness?

    <p>Sensitivity to male sex hormone (DHT)</p> Signup and view all the answers

    Hair color results from different amounts and types of __________.

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

    What happens to hair pigment production as one ages?

    <p>It decreases, leading to grey or white hair</p> Signup and view all the answers

    Match the following types of hair with their descriptions:

    <p>Vellus hair = Fine, light hair on most of the body Terminal hair = Thicker, darker hair on the scalp and body Arrector pili = Muscle that causes hair to stand up Sebaceous gland = Gland that secretes oil</p> Signup and view all the answers

    What is the average number of scalp hairs lost per day?

    <p>Approximately 90</p> Signup and view all the answers

    Alopecia is only common in males.

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

    What is the main component of pus?

    <p>Dead white blood cells</p> Signup and view all the answers

    Blackheads contain infected material.

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

    What do apocrine sweat glands secrete?

    <p>an oily fluid that acts as a pheromone</p> Signup and view all the answers

    Cyanosis is a bluing of the skin caused by poor circulation or inadequate _____ in the blood.

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

    Match the following sweat gland types to their characteristics:

    <p>Apocrine glands = Secrete oily fluid, found in axillary and anogenital areas Eccrine glands = Most numerous, secrete mostly water and electrolytes Sebaceous glands = Produce sebum, which oils hair and skin Mammary glands = Specialized glands that produce milk</p> Signup and view all the answers

    What causes jaundice?

    <p>Buildup of bilirubin in the blood</p> Signup and view all the answers

    Nails are made of live epidermal cells.

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

    What is the main appearance indicator that the nail bed gives to nails?

    <p>pink appearance</p> Signup and view all the answers

    What is the most dangerous form of skin cancer?

    <p>Malignant melanoma</p> Signup and view all the answers

    Excessive UV exposure is the biggest risk factor for skin cancer.

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

    What rule is used to differentiate malignant melanomas from normal moles?

    <p>ABCD(E) rule</p> Signup and view all the answers

    Harlequin ichthyosis is caused by a mutation in a protein that transports ______ in the cells of the epidermis.

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

    Match the types of skin burns with their characteristics:

    <p>First-degree burns = Only epidermis is damaged Second-degree burns = Epidermis and upper dermis are damaged Third-degree burns = Destroys all layers, including nerves and blood vessels Rule of Nines = Used to assess total body surface area for burns</p> Signup and view all the answers

    Which of the following is true regarding scar tissue?

    <p>Scar tissue is stronger due to more collagen fibers</p> Signup and view all the answers

    Epidermolysis bullosa is caused by a genetic mutation that affects collagen binding between the epidermis and dermis.

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

    What happens during the inflammation stage of healing?

    <p>Blood vessels leak fluid, causing swelling and redness.</p> Signup and view all the answers

    What is the primary function of the hair papilla?

    <p>To contain hair's capillaries and nerves</p> Signup and view all the answers

    The epidermis contains fat cells that provide energy reserves.

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

    What causes a bruise?

    <p>Broken blood vessels leaking blood into surrounding tissue.</p> Signup and view all the answers

    The deepest layer of skin, containing areolar and adipose tissue, is called the ______.

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

    Which layer of the skin contains dense irregular connective tissue?

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

    Match the following skin structures with their primary functions:

    <p>Sebaceous gland = Produces oil to lubricate skin Merocrine sweat gland = Regulates body temperature Hair = Provides warning against insects Nerve = Senses touch and pain</p> Signup and view all the answers

    Which statement is true regarding tattoos?

    <p>The ink droplets are permanently trapped in the dermis.</p> Signup and view all the answers

    The ______ layer of skin contains capillaries and nerves that respond to touch.

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

    Study Notes

    Integumentary System Overview

    • The integument, or skin, is the largest organ in the body.
    • It makes up 15-16% of body weight.
    • The surface area is about 1.5-2 square meters (~21 square feet).
    • The skin contains approximately 11 miles of blood vessels.
    • The thinnest part of the skin is the eyelids (0.05mm).
    • The thickest part of the skin is the soles (1.5mm).

    Skin as a Membrane

    • The skin is a membrane composed of multiple tissues.
    • These tissues serve as a boundary.
    • The skin includes stratified squamous epithelium, areolar connective tissue, and dense irregular connective tissue.

    Accessory Structures

    • Skin includes accessory structures like hair, nails, and glands.

    Functions of Skin

    • The skin protects the body from impacts, chemicals, infection, and radiation.
    • It prevents the loss of body fluids.

    Homeostasis of Body Temperature

    • The skin regulates body temperature.
    • It insulates the body during cold weather and sweats when the body is hot.

    Energy Storage

    • Most of the body's energy storage is in adipose tissue directly beneath the skin.

    Sensory Receptors

    • The skin contains sensory receptors for touch, pressure, pain, and temperature stimuli.

    Secretions

    • Salts, water, organic wastes, and milk (in women) are secreted by the skin.

    Skin Layers

    • The skin includes three layers:
      • Epidermis (4-5 layers of keratinized squamous cells with 4 types of cells).
      • Dermis (2 layers of areolar and dense irregular connective tissues, nerves, blood, and lymph vessels).
      • Hypodermis (adipose tissue).

    Epidermis Variations

    • The number of cell layers in the epidermis varies depending on location.
    • Thick skin (palms and soles) has five layers.
    • Thin skin (all other locations) has four layers.

    Epidermis Life Cycle

    • Cells are produced near the dermis and gradually move outwards.
    • Each layer is called a stratum and represents a different stage in a skin cell's life.

    Epidermal Cells

    • Keratinocytes produce keratin (a fibrous protein found in skin, fingernails, and hair).
    • Melanocytes produce melanin, which is packaged into melanosomes and protects skin cells from UV damage.
    • Dendritic (Langerhans) cells are macrophages that activate the immune system.
    • Tactile (Merkel) cells are sensory receptors.

    Stratum Spinosum and Granulosum

    • The stratum spinosum contains daughter cells formed from the stratum basale mitosis..
    • The stratum granulosum is where cells die, flatten, and organelles disintegrate.
    • Keratinization occurs here, with accumulation of keratohyaline and lamellar granules.

    Keratin

    • Keratin is a durable, water-resistant protein found in skin, fingernails, and hair.

    Stratum Lucidum

    • This is a layer of keratinized cells only present in thick skin.

    Stratum Corneum

    • This is the outermost and exposed layer of skin
    • It consists of 15-30 layers of dead, flattened keratinized cells.
    • It makes up about 3/4 of the epidermis and is a barrier layer.

    Epidermal Friction Ridges

    • These raised areas of dermis increase the surface contact area with the dermis.
    • Epidermis has no blood vessels; nutrients and oxygen diffuse from the dermis.
    • Epidermal ridges create whorls and contours of fingerprints, increasing grip when wet.
    • Cells take about 7-10 days to reach the stratum corneum and about two weeks to shed.

    Psoriasis

    • Psoriasis is a skin disorder where skin cells in the epidermis grow at an abnormally fast rate.
    • Skin cells are replaced every 3–5 days rather than 28–30 days.

    Skin Color (and UV light)

    • Ultraviolet light exposure helps the body produce vitamin D, essential for absorbing calcium and phosphorus in the intestines.
    • Vitamin D deficiency leads to rickets, a bone softening disease.

    Stratum Basale

    • The stratum basale is the deepest layer of the epidermis and is also called the germinativum.
    • Contains stem cells that continuously divide, attached to each other through desmosomes.
    • Takes 25-45 days for cells to surface.
    • Contains melanocytes(10-25%).

    Skin Color Pigments

    • Melanocytes produce the pigment melanin, which gives skin its color.
    • Freckles are clustered spots of melanin in lighter-skinned individuals.
    • Darker skin tones provide more protection against UV damage but have less Vitamin D production.

    Skin Damage

    • A bruise is caused by broken blood vessels in the dermis that leak into surrounding tissues.
    • Tattoos involve forcing ink into the dermis, making them permanent.
    • Laser treatments can break up ink droplets to allow white blood cells to carry them away.

    Hypodermis

    • This layer contains areolar and adipose tissue with many fat cells.
    • It provides insulation, shock absorption, and an energy reserve.

    Hair

    • Hair is a nonliving structure produced in hair follicles.
    • Hair follicles project into the hypodermis.
    • Exceptions are palms, soles, lips, nipples, and external genitalia.
    • Hair functions including warmth, protection against physical trauma and sunlight, and reduction in heat loss.
    • Hair papilla contains the hair's capillaries and nerves.
    • Hair matrix contains epithelial stem cells that divide, pushing themselves towards the surface.
    • Hair cells die halfway between the papilla and surface
    • The hair root (matrix) is the portion below the surface under the split
    • Above the split is the hair shaft.

    Hair Color

    • Hair colour results from different amounts and types of melanin
    • Pigment production decreases with age resulting in grey or white hair (decreased melanin) or white (air bubbles).
    • Loss of ~90 scalp hair/day and about 2.25mm per week.

    Hair Disorders

    • Male pattern baldness is a genetic trait causing hair follicles to be overly sensitive to male sex hormones (DHT).
    • Alopecia is a broad term for hair loss.

    Sebaceous Glands

    • Sebaceous (holocrine) glands are exocrine glands that secrete sebum, an oil that prevents drying and is antibacterial and antibacterial oil.
    • Sebum production increases with hormone secretion during puberty.

    Acne

    • Acne is the formation of pimples due to blockage of sebaceous glands, usually due to infected sebum.
    • Whiteheads are infected.
    • Blackheads contain sebum and debris.
    • Pus is a mixture of dead white blood cells that is a sign inflammation.

    Sweat Glands

    • Apocrine sweat glands secrete an oily fluid acting as a pheromone.

    • They are only found in axillary and anogenital areas and begin functioning at puberty.

    • They are degraded by bacteria, causing body odor.

      • Ceruminous: modified apocrine glands producing earwax.
      • Mammary: modified apocrine glands producing milk.

    • Eccrine sweat glands produce sweat (mostly water with salts, antibodies, and metabolic wastes).

    • Most numerous, found on palms, soles, and forehead.

    • Sweat's evaporation helps lower body temperature.

    Nails

    • Nails are keratinized epidermal cells protecting fingertip and toe tips.
    • Production of nails originates in the nail root, where the cuticle overlaps part of the nail.
    • Pink appearance from blood in the underlying nail bed.

    Skin Color Disorders

    • Cyanosis is a bluish discoloration of the skin caused by poor circulation or lack of oxygen.
    • Jaundice is a yellowish discoloration due to a buildup of bilirubin.

    Skin Cancer

    • Skin cancers are due to uncontrolled cell division in the epidermis.
    • Basal cell carcinoma affects stratum basale cells.
    • Squamous cell carcinoma occurs in stratum spinosum cells.
    • Malignant melanoma is the most dangerous type, originating in melanocytes, and often metastasizes.
      • ABCD(E) rule for identifying: Asymmetry, Border irregularity, Color variegation, Diameter, Evolving

    Excessive UV Exposure

    • Excessive exposure to UV light (sun or tanning booths) is the greatest risk factor for skin cancer.

    Genetic Disorders of Epidermis

    • Harlequin ichthyosis is caused by a mutation in a protein that transports lipids in epidermal cells. Without this lipid, the skin dehydrates and cracks easily.
    • Epidermolysis bullosa is a genetic disorder that impairs collagen formation, causing painful, widespread blistering.

    Skin Repair

    • Skin repair goes through stages:
      • Bleeding: Blood escapes, forming a clot later becoming a scab.
      • Inflammation: Injured blood vessels leak fluid, causing swelling and redness.
      • Proliferation: New tissue formation due to cellular division and collagen/extracellular matrix laying down.
      • Remodeling: Tissue resembles the original form. Scar tissue may remain.

    Skin Burns

    • First-degree burns only damage the epidermis (e.g., sunburns).
    • Second-degree burns damage the epidermis and upper dermis, causing redness and blisters.
    • Third-degree burns destroy all layers of skin including nerves, causing gray or black appearance. Often causing no pain.

    Rule of Nines

    • Used to estimate the extent of burn injuries of the body.

    Burn Severity and Treatment

    • Critical burns are >25% second-degree burns, 10% third-degree burns, or face, hands, or feet with third-degree burns.
    • Treatment includes debridement (removing burnt skin) and antibiotics, temporary covering or skin grafts.

    Effects of Aging

    • Epidermis thins, stem cell activity declines, Vitamin D production declines, reduced bone strength, less melanin production causing wrinkling.
    • Gland activity declines leaving skin drier.

    Wrinkling

    • After 30 minutes in water the skin wrinkles, due to nerve cells causing blood vessels in the dermis to constrict.
    • Wrinkled fingers give better grip when wet.

    Botox

    • Botox is a toxin produced by bacteria that blocks neurotransmitters in muscles, reducing muscle contraction; diminishes wrinkles.

    Skin Infections

    • Most skin infections spread by contact.
    • Fungal infections include athletes foot, toenail fungus and ringworm.
    • Only antifungal medicines are effective in treating fungal infections.
    • Bacterial infections like impetigo, boils, and staph (common species is Staphylococcus aureus) treated by antibiotics.
    • MRSA is resistant to many antibiotics.
    • Viral infections include chickenpox, warts, and cold sores (treatment may be difficult, but vaccinations can be preventative).

    Skin Irritation and Eczema

    • Itching is a response triggered by nerves when an irritant lands on the skin surface and is rubbed into the dermis.
    • Scratching is to remove the irritant with the nails.
    • Eczema (dermatitis), a group of skin conditions characterized by itchiness, red skin, and rash, is caused by the immune system overreacting to normally harmless substances like dust mites.

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    Integumentary System PDF

    Description

    Test your knowledge on the integument system with this quiz covering the layers of skin, their functions, and related concepts. Explore key terms such as sensory receptors, keratin, and conditions affecting the skin. Perfect for students learning human anatomy and physiology.

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