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Chapter 7 Body Systems

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Title: Chapter 7 Body Systems Author: Linda Honeycutt Last modified by: Nicole.Bourgeois Created Date: 1/16/2005 5:28:53 PM Document presentation format – PowerPoint PPT presentation

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Title: Chapter 7 Body Systems


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Introduction- Chapter 6
  • Skin (integument) is bodys largest organ
  • Approximately 1.6 to 1.9 m2 in average-sized
    adult
  • Integumentary system describes the skin and its
    appendages the hair, nails, and skin glands

4
Structure of the Skin
  • Skin classified as a cutaneous membrane
  • Two primary layersepidermis and dermis joined
    by dermal-epidermal junction
  • Hypodermis lies beneath dermis

5
Structure of the Skin
  • Thin and thick skin
  • Thin skincovers most of body surface
  • 1 to 3 mm thick
  • Thick skinsoles and palms
  • 4 to 5 mm thick
  • Makes fingerprints
  • No hair

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Structure of the Skin
  • Epidermis
  • Cell types
  • Keratinocytes
  • Melanocytes
  • Langerhans cells

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Keratinocytes
  • constitute over 90 of cells present
  • principal structural element of the outer skin
  • Arranged in strata, or layers

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Melanocytes
  • pigment-producing cells (5 of the total)
  • contribute to skin color
  • filter ultraviolet light decrease the amount of
    UV light that can penetrate into the deeper
    layers of the
  • skin

9
Langerhans cells
  • they play a role in immune response
  • Originate in the bone marrow
  • Function with specialized leukocytes called
    helper T cells, to trigger immune response

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Structure of the Skin
  • Epidermis
  • Cell layers- 5 Layers (deep ? superficial)
  • Stratum germinativum (growth layer)describes the
    stratum spinosum and stratum basale together
  • Stratum basale (base layer)
  • Stratum spinosum (spiny layer)
  • Stratum granulosum (granular layer)
  • Stratum lucidum (clear layer)
  • Stratum corneum (horny layer)

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Structure of the Skin
  • Epidermis
  • The cells form in the basale layer and degenerate
    and fill with keratin as they move up to the
    surface
  • This is keratinization

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section reveals epidermis containing basal,
spinous, granular keratinocytes and stratum
corneum. Dermis contains numerous viable
fibroblasts. 400X)
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1. Stratum basale (base layer- deepest)
  • single layer of columnar cells
  • only these cells undergo mitosis
  • ? migrate through the other layers until they
    are shed
  • The renewal of the human
  • epidermis takes
  • about 3 to 4 weeks.

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2. Stratum spinosum (spiny layer)
  • cells arranged in 8 to 10 layers with desmosomes
    (bridges) that pull cells into spiny shapes
  • cells rich in RNA ? protein synthesis to produce
    keratin

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3. Stratum granulosum (granular layer)
  • cells arranged in two to four layers
  • filled with granules ? makes keratin
  • contain high levels of lysosomal enzymes ?
    theyre starting to degenerate
  • Nuclei absent
  • May not be in regions of thin skin

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4. Stratum lucidum (clear layer)
  • Closely packed and clear keratinocytes
  • cells filled with eleidin (ay lee din) ? blocks
    water penetration or loss (eventually makes
    keratin)
  • absent in thin skin (in thick skin- hands and
    feet)
  • Nuclei absent

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5. Stratum corneum (horny layer)
  • Dead, squamous cells
  • most superficial layer
  • dead cells filled with keratin ? water-repellent
    protein
  • Cell membranes are thick and chemically resistant
  • Also called barrier area because it functions to
    prevent water loss

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Structure of the Skin
  • Thick Skin
  • Thin Skin

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Wrinkled Fingers and Toes
  • FYI
  • dead cells in stratum corneum absorb water
  • (deeper layers do NOT)
  • When swollen water-filled cells expand over the
    normal sized cells below, the skin wrinkles

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Structure of the Skin
  • Epidermis
  • Epidermal growth and repair
  • Turnover or regeneration time refers to time
    required for epidermal cells to form in the
    stratum basale and migrate to the skin surface
    about 35 days
  • Shortened turnover time will increase the
    thickness of the stratum corneum and result in
    callus formation

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Structure of the Skin
  • Epidermal growth and repair continued
  • Normally 10 to 12 of all cells in stratum
    basale enter mitosis daily
  • Each group of 8 to 10 basal cells in mitosis with
    their vertical columns of migrating keratinocytes
    is called an epidermal proliferating unit, or EPU

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Structure of the Skin
  • Dermal-epidermal junction
  • Definite basement membrane
  • glues the epidermis to the dermis below
  • Partial barrier to the passage of some cells and
    large molecules

Specific staining of the indicated protein is
displayed as a red band localized at the
dermal/epidermal junction.
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Blisters
  • FYI
  • Caused by injury to cells in epidermis OR
  • From separation of dermal-epidermal junction

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Structure of the Skin
  • Dermis (corium)
  • Sometimes called true skinmuch thicker than
    the epidermis and lies beneath it
  • Gives strength to the skin

Sunburn cell formation in EpiDerm-FT following
solar UV-irradiation. HE stained paraffin
sections were prepared from EpiDerm-FT 24 hr
after irradiation. Sunburn cells are indicated by
arrows.
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Structure of the Skin
  • Dermis (cont.)
  • Contains various structures
  • Arrector pili muscles and hair follicles
  • Sensory receptors
  • Sweat and sebaceous glands
  • Blood vessels
  • Rich vascular supply plays a critical role in
    temperature regulation? homeostasis

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Structure of the Skin
  • Dermis (cont.)
  • 2 Layers of dermis
  • Papillary layer
  • Reticular layer

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Dermis-Papillary Layer
  • composed of dermal papillae that project into the
    epidermis
  • ? fingerprints- used for grasping and gripping
    tools
  • contains loose connective and elastic fibers
  • contains the dermal-epidermal junction
  • Like egg crate foam mattress pad

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Dermis- Reticular Layer
  • contains interlacing collagenous fibers and
    elastic fibers
  • ? make the skin tough yet stretchable
  • when processed from animal skin, produces leather
  • Attachment point for muscle fibers (smooth and
    skeletal)
  • Contains arrector pili muscles

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Arrector pili muscles
  • Bundle of smooth muscles on each hair follicle
  • Makes the hair stand on end
  • Occurs due to fright or cold
  • Causes erection of nipples and elevation of testes

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  • Where are the arrector pili?
  • Where is the adipose tissue?
  • Is adipose deep or superficial to the stratum
    lucidum?

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Dermis
  • Dermal growth and repair
  • The dermis does NOT continually shed and
    regenerate
  • During wound healing, begins forming a dense mass
    of new connective fibers ? scar
  • If elastic fibers in dermis stretch too much,
    they TEAR and form ? stretch marks
  • Eventually lose color- NOT due to cocoa butter

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FYI
  • If an incision cuts across cleavage lines
    (Langers lines), stress tends to pull the cut
    edges apart and may retard healing.
  • Surgical incisions parallel to cleavage lines are
    subjected to less stress and tend to heal more
    rapidly.

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Hypodermis
  • Also called subcutaneous layer or superficial
    fascia
  • Deep to the dermis
  • forms connection between the skin and other
    structures
  • NOT part of the skin

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Skin Color
  • Melanin
  • Basic determinant of skin color
  • Melanin formed by melanocytes
  • Albinism
  • congenital
  • absence of
  • melanin

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Functions of the Skin (Table 6-1 Page 171)
  • Protection
  • Physical barrier
  • Prevents dehydration
  • Sensation
  • Pain
  • Heat and cold
  • Pressure and touch

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Functions of the Skin contd (Table 6-1 Page 171)
  • Movement growth
  • Imagine moving without elastic skin
  • Endocrine (hormones)
  • vitamin D production
  • Excretion (minor role)
  • Water Urea/ammonia/uric acid

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Functions of the Skin contd (Table 6-1 Page 171)
  • Immunity
  • Phagocytic cells (phago- to eat) (-cyte-
    cell)
  • Langerhans cells
  • Temperature Regulation
  • Heat loss or retention

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Temperature Regulation- Vasodilation
  • Heat lossapproximately 80 of heat loss occurs
    through the skin
  • Increased blood flow to epidermis
  • Decreased blood flow to organs
  • Redness after exercise

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Temperature Regulation- Vasoconstriction
  • Heat retention
  • Decreased blood flow to skin
  • Increased blood flow to organs
  • Turning white
  • Vasoconstriction

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How do we sense touch?
  • MANY receptors in our skin (mostly dermis) allow
    for different touch stimuli
  • Meissners corpuscle- detects light touch-
    superficial dermis
  • Pacinian corpuscle- detects pressure- deep dermis
  • ?Receptors send signals to the brain (those
    signals were called?)

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Somatosensory Cortex in Brain
  • Receptors send action potentials to specialized
    part of brain ? somatosensory cortex (soma-
    body) (cortex- outermost, superficial)
  • Each part of the body
  • corresponds with a
  • particular area in the
  • cortex
  • Also a corresponding
  • Motor cortex

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Homunculi (Page 394)
  • Both sensory motor cortex have homunculi
    (little man)
  • Hands and face- large part of cortical area
  • Most important for survival

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Two point discrimination
  • The density of receptors varies
  • If the hands and the face have the most cortical
    area, where do you think the densest area of
    receptors will be?

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Skin Glands
  • 3 Types
  • Sweat (2 types)
  • Sebaceous
  • Ceruminous

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Skin Glands- Sweat Glands
  • Eccrine glands
  • Most numerous sweat glands very small
  • Distributed over total body surface except a few
    places (ear
  • canal, lips)
  • Simple, coiled, tubular glands
  • Secrete sweat ? constant
  • core temperature

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Skin Glands- Sweat Glands
  • 2. Apocrine glands
  • Located deep in subcutaneous layer
  • Limited distributionaxilla (armpit), areola of
    breast, and around anus
  • Large (gt 5 mm in diameter)
  • Connected to hair follicle
  • Begin to function at puberty

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Skin Glands
  • Sebaceous glands
  • Secrete sebum (oil)
  • Hair and skin
  • prevents excessive water loss from the skin
  • antifungal activity
  • dermis except in palms and soles
  • Secretion increases in adolescence
  • Oxidated sebum accumulations ? blackheads

Stages of acne. (A) Normal follicle (B) open
comedo (blackhead) (C) closed comedo
(whitehead) (D) (E) pustule v
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Blackhead
Whitehead
Papules
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Skin Glands
  • Ceruminous glands (se ROO mi nus)
  • Modified apocrine sweat glands
  • Mixed secretions of sebaceous and ceruminous
    glands called cerumen (wax)
  • protects from dehydration

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Cycle of Life Skin
  • Children
  • Skin is smooth, unwrinkled, and characterized by
    elasticity and flexibility
  • Few sweat glands
  • Rapid healing

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Cycle of Life Skin
  • Adults
  • Development and activation of sebaceous and
    sweat glands
  • Increased sweat production
  • Body odor
  • Increased sebum production
  • Acne

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Cycle of Life Skin
  • Old age
  • Decreased sebaceous and sweat gland activity
  • Wrinkling
  • Decrease of bodys ability to cool itself

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The Big Picture Skin and the Whole Body
  • Skin is a major component of the bodys
    structural framework
  • Skin defines the internal environment of the
    body
  • Primary functions are support and protection
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