Integumentary System: Epidermis and Skin Color
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Questions and Answers

What happens to the cells as they move upward through the layers of the epidermis?

  • They turn into melanocytes.
  • They receive more nutrients.
  • They divide more rapidly.
  • They become keratinized and die. (correct)
  • What type of epithelium makes up the epidermis?

  • Stratified squamous epithelium (correct)
  • Simple columnar epithelium
  • Transitional epithelium
  • Cuboidal epithelium
  • What is the outermost layer of the skin called?

  • Epidermis (correct)
  • Dermis
  • Stratum corneum
  • Stratum basale
  • What is the primary purpose of melanocytes in the skin?

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

    What is keratinization?

    <p>The hardening of cells through the accumulation of keratin.</p> Signup and view all the answers

    Which layer of the epidermis is the deepest?

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

    What is the lifespan of skin cells in the epidermis before they are shed?

    <p>2-4 weeks</p> Signup and view all the answers

    How does skin color variation occur among individuals?

    <p>By the distribution and amount of melanin produced.</p> Signup and view all the answers

    What is the primary composition of adipose tissue?

    <p>Lipocytes, or fat cells</p> Signup and view all the answers

    What is one of the main functions of sweat glands?

    <p>To prevent overheating</p> Signup and view all the answers

    Where are most accessory structures of the integumentary system located?

    <p>In the dermis and protruding through the epidermis</p> Signup and view all the answers

    What percentage of sweat is composed of water?

    <p>99%</p> Signup and view all the answers

    What is the normal pH range of sweat?

    <p>4 to 6</p> Signup and view all the answers

    What is dermicidin?

    <p>A peptide that kills microbes in sweat</p> Signup and view all the answers

    How does sweating due to nervousness differ from regular sweating?

    <p>It starts on the palms, axillae, and soles</p> Signup and view all the answers

    What characterizes a first-degree burn?

    <p>Involves only the epidermis with redness and pain</p> Signup and view all the answers

    Which of the following is NOT an accessory structure of the integumentary system?

    <p>Muscle fibers</p> Signup and view all the answers

    What is a common symptom of a second-degree burn?

    <p>Redness, pain, and the presence of blisters</p> Signup and view all the answers

    How does a third-degree burn differ from a second-degree burn?

    <p>Presents with minimal pain due to nerve damage</p> Signup and view all the answers

    What determines the healing duration of a second-degree burn?

    <p>Depth and extent of the blistering</p> Signup and view all the answers

    Which features are typically found in first-degree burns?

    <p>Mild redness and swelling with no scars</p> Signup and view all the answers

    Which statement about second-degree burns is incorrect?

    <p>They only involve damage to the epidermis.</p> Signup and view all the answers

    What condition can significantly impact the assessment of burn damage?

    <p>Total surface of skin damaged</p> Signup and view all the answers

    What is a common cause for first-degree burns?

    <p>Sunburn from excessive sunlight</p> Signup and view all the answers

    What is the primary cause of dandruff?

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

    What is the primary function of merocrine (eccrine) sweat glands?

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

    Why do nails appear pink in color?

    <p>Due to underlying capillaries</p> Signup and view all the answers

    What is the nail matrix responsible for?

    <p>Producing new nail cells</p> Signup and view all the answers

    Where are apocrine sweat glands primarily located?

    <p>In the groin and armpits</p> Signup and view all the answers

    Which type of sweat gland is predominantly active in adults?

    <p>Merocrine (eccrine) glands</p> Signup and view all the answers

    What types of cells mainly compose hair?

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

    What happens when sebaceous glands become overactive?

    <p>Inflammation may develop around them</p> Signup and view all the answers

    How much of the human body hair is located on the body surface rather than the head?

    <p>75%</p> Signup and view all the answers

    Which of the following is NOT a type of hair follicle?

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

    Where does the most active growth of the nail occur?

    <p>In the nail matrix</p> Signup and view all the answers

    What is sebum primarily composed of?

    <p>Fatty material and cell debris</p> Signup and view all the answers

    Which body parts are typically hairless?

    <p>Fingers, toes, palms, and soles</p> Signup and view all the answers

    What is the role of apocrine sweat glands during puberty?

    <p>They become active and produce smell</p> Signup and view all the answers

    How do bacteria contribute to body odor?

    <p>They degrade sweat into chemicals that have strong smells</p> Signup and view all the answers

    Which glands are responsible for keeping hair and skin supple?

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

    Study Notes

    Epidermis

    • Outermost layer of skin, composed of 4-5 layers of squamous epithelial cells
    • Deepest layer is the stratum basale
    • Not vascularized, nutrients diffuse through dermal blood vessels and tissue fluid
    • Cells on the surface are constantly shedding and replaced by new cells from the stratum basale every 2-4 weeks
    • Cells in this layer divide and grow, moving towards the skin surface and away from the dermis
    • As they move upwards, they receive fewer nutrients and eventually die
    • Older cells are called keratinocytes, which harden with age through keratinization (keratin protein fills the cytoplasm of these cells forming stratum corneum layer)
    • Dead skin cells in this layer are eventually shed from the body

    Skin Color

    • Melanocytes are located deep in the epidermis
    • Responsible for skin color
    • All humans have the same number of melanocytes
    • Variation in skin color is due to the amount of melanin produced and distributed, not the number of melanocytes

    Dermis

    • Mainly composed of adipose tissue, elastic and fibrous connective tissue
    • Lipocytes produce fat that provides padding to protect deeper tissues and insulation for temperature regulation

    Accessory Structures of the Integumentary System

    • Include: sweat glands, sebaceous glands, nails, hair and hair follicles
    • Most are located in the dermis and protrude through the epidermis

    Accessory Structures - Sweat Glands

    • Also called sudoriferous glands
    • Consist of a small tube originating as a coil in the deep dermis
    • Coiled portion is lined with sweat-secreting cells
    • Sweat is carried out of the skin by tubes called pores that open at the skin surface
    • Made up of 99% water and salts, including sodium chloride
    • Normal acidic pH of between 4 and 6

    Accessory Structures - Sweat Glands

    • Contains dermicidin, a peptide that kills microbes
    • Sweating, starting on the forehead, prevents overheating
    • Cold sweating, caused by nervousness or fright, starts on palms, axillae, and soles
    • Sweat has no odor, but bacteria degrade substances in the sweat into chemicals that give off strong smells

    Accessory Structures - Sweat Glands

    • The skin contains two types of sweat glands: merocrine (eccrine) glands and apocrine sweat glands
    • Merocrine glands: predominant type, 2-5 million in adults, found all over the skin, important in temperature regulation
    • Apocrine sweat glands: active at puberty, ~2,000 in number, mostly found in the groin, anal region, and armpits, produce smell in contact with skin bacteria, believed to act as sexual attractants

    Accessory Structures - Sebaceous Glands and Follicles

    • Also called oil glands
    • Primarily located near hair follicles, largest on the face, neck, and upper chest
    • Secrete sebum, a mixture of fatty material and cell debris
    • Sebum is secreted through small hair follicle ducts
    • Functions of sebum: keeps hair and skin pliable and waterproof, inhibits bacterial growth, lubricates hair and skin

    Accessory Structures - Sebaceous Glands and Follicles

    • Sebaceous follicles are large sebaceous glands, with ducts discharging sebum directly onto the epidermis
    • Found on the face, chest, nipples, back, and external genitalia
    • Overactive sebaceous glands, usually on the scalp, can lead to inflammation known as seborrheic dermatitis, a common cause of dandruff

    Accessory Structures - Nails

    • Protect the ends of fingers and toes
    • Consist of a nail plate above a skin surface called nail bed
    • A modification of the epidermis that contains hard keratin
    • Part of the nail plate that grows most actively is covered by a whitish, half-moon-shaped lunula
    • Nails appear pink due to underlying capillaries, with the white crescent-shaped lunula above the nail matrix

    Accessory Structures - Hairs and Hair Follicles

    • Approx. 2.5 million hairs on the human body, over 75% on the body surface
    • Hairs project above the skin surface over most of the body, except for soles of the feet, palms of the hands, sides of fingers and toes, lips, and parts of the external genitalia
    • Consist of a large amount of dead keratinized cells, dominated by hard keratin
    • Structures produced in organs called hair follicles

    Burns

    • Two factors assess the degree of damage: depth and total surface of skin damaged
    • Depth refers to the layers of skin affected

    First Degree Burn

    • Involves only the epidermis, most common type
    • Symptoms include redness, pain, and swelling (edema)
    • Pain subsides in 2-3 days and usually does not leave scars
    • Most sunburns are first-degree burns

    Second Degree Burn

    • Also called partial-thickness burn
    • Involves the entire depth of the epidermis and a portion of the dermis
    • May appear red, tan, or white with blisters
    • Symptoms include redness, pain, and blistering
    • Very painful, slow healing and may leave scars

    Second Degree Burn

    • Extent of blistering depends on the depth of the burn
    • Blisters heal within 10-14 days without complications, but deeper burns take 1-3.5 months
    • Scarring is common in second degree burns

    Third Degree Burn

    • Also termed full-thickness burns
    • Affects all three layers of the skin; epidermis and dermis are completely destroyed, deeper tissue is damaged
    • Skin can only repair itself from the edges of the wound

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    Description

    Test your knowledge on the structure and function of the epidermis, the outermost layer of skin. This quiz explores the role of keratinocytes, the process of keratinization, and the factors affecting skin color, including the role of melanocytes. Challenge yourself to understand these essential concepts in skin biology.

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