Skin and Body Membranes

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Skin and Body Membranes

• Human Anatomy and Physiology

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General Characteristics of Body Membranes

• Cover surfaces of body/ line body cavities
• Form protective and often lubricating sheets
  around organs
• 2 major groups
• Epithelial
• Cutaneous/ Mucous/ Serous Membranes
• Connective
• Synovial Membranes

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Epithelial Membranes covering lining membranes

• Cutaneous (skin)
• Mucous (lines body cavities that open to
  exterior)
• Serous (lines body cavities closed to exterior)
• Remember all include both epithelial tissue AND
  an underlying layer of connective tissueso these
  membranes are actually simple organs

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Cutaneous Membrane

• Epidermis on outside
• Stratified squamous
• Keratinizing
• Dermis under epidermis
• Dense (fibrous) connective tissue
• Cutaneous membrane is exposed to air so its
  considered a dry membrane

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Mucous Membranes (mucosa)

• Lines body cavities opening to outside
  respiratory/ digestive/ urinary/ reproductive
  tracts
• Epithelium resting on loose connective tissue
• wet membranes
• Adapted for absorption or secretion

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Serous Membranes (serosa)

• Line body cavities that are not exposed to
  outside
• Simple squamous epithelium resting on thin
  areolar connective tissue
• Occurs in pairs parietal and visceral
• Peritoneum abdominal cavity
• Pericardium around heart
• Pleura around lungs

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Parietal layer lines the wall of ventral body/
Visceral layer covers the outside of the organ in
that cavity
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Connective Tissue membranes Synovial

• No epithelial cells
• Soft areolar connective tissue
• Line fibrous capsules surrounding joints
• Cushion organs rubbing against each other
• Secrete lubricating fluid
• Also line bursae

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The Integumentary System (your skin!)

• List 4 important functions of the integumentary
  system, and explain how these functions are
  accomplished.
• Label a diagram of the skin recognizing the
  following epidermis, dermis (papillary and
  reticular layers), hair and hair follicle,
  sebaceous gland, and sweat gland
• Describe the distribution and function of
  sebaceous glands, sweat glands and hair

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The Integumentary System (continued)

• Name the factors that determine skin color and
  describe the function of melanin
• Describe syndromes/ infections/ allergic
  reactions in skin
• Differentiate first, second and third degree
  burns
• Explain the importance of the rule of nines
• Summarize the characteristics of basal cell
  carcinoma, squamous cell carcinoma and malignant
  melanoma

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What specifically is the integumentary system?

• Cutaneous membrane
• All its derivatives
• Sweat glands
• Oil glands
• Hair
• Nails

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Functions of the Skin

1. Controls internal body temperature
2. Heat loss activates sweat glands and allows
   blood to flush into skin capillary beds so heat
   can radiate from skin surface
3. Heat retention not allowing blood to flush to
   skin capillary beds
4. Aids in excretion of urea and uric acid
   perspiration by sweat glands
5. Synthesizes vitamin D modified cholesterol
   molecules in skin

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Functions of Skin (cont.)

• Protects deeper tissue from
• Mechanical damage physical barrier, keratin,
  fat cells, pressure receptors to stimulate
  movement
• Chemical damage impermeable keratin,
  chemoreceptors, nociceptors
• Bacterial damage skin secretions
• Ultraviolet radiation melanin
• Thermal damage thermoreceptors/ nociceptors
• Desiccation water proofing glycolipid and
  keratin

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Integumentary system provides a wealth of sensory
data

• Receptors are classified by the following
• Stimulus type
• Location
• Structural complexity

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Classification by Stimulus Type

• Mechanoreceptorsrespond to touch, pressure,
  vibration, stretch, and itch
• Thermoreceptorssensitive to changes in
  temperature
• Photoreceptorsrespond to light energy (e.g.,
  retina)
• Chemoreceptorsrespond to chemicals (e.g., smell,
  taste, changes in blood chemistry)
• Nociceptorssensitive to pain-causing stimuli
  (e.g. extreme heat or cold, excessive pressure,
  inflammatory chemicals)

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Classification by Location

• 1.Exteroceptors
• Respond to stimuli arising outside the body
• Receptors in the skin for touch, pressure, pain,
  and temperature
• Most special sense organs
• 2. Interoceptors (visceroceptors)
• Respond to stimuli arising in internal viscera
  and blood vessels
• Sensitive to chemical changes, tissue stretch,
  and temperature changes
• 3. Proprioceptors
• Respond to stretch in skeletal muscles, tendons,
  joints, ligaments, and connective tissue
  coverings of bones and muscles
• Inform the brain of ones movements

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Classification by Structural Complexity

• 1. Complex receptors (special sense organs)
• Vision, hearing, equilibrium, smell, and taste
  (Chapter 15)
• 2. Simple receptors for general senses
• Tactile sensations (touch, pressure, stretch,
  vibration), temperature, pain, and muscle sense
• Unencapsulated (free) or encapsulated dendritic
  endings

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Unencapsulated Dendritic Endings

• Thermoreceptors
• Cold receptors (1040ºC) in superficial dermis
• Heat receptors (3248ºC) in deeper dermis
• Nociceptors
• Respond to
• Pinching
• Chemicals from damaged tissue
• Temperatures outside the range of thermoreceptors
• Capsaicin
• Light touch receptors
• Tactile (Merkel) discs
• Hair follicle receptors

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Table 13.1
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Encapsulated Dendritic Endings

• All are mechanoreceptors
• Meissners (tactile) corpusclesdiscriminative
  touch
• Pacinian (lamellated) corpusclesdeep pressure
  and vibration
• Ruffini endingsdeep continuous pressure
• Muscle spindlesmuscle stretch
• Golgi tendon organsstretch in tendons
• Joint kinesthetic receptorsstretch in articular
  capsules

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Table 13.1
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Skin (Integument)

• Consists of three major regions
• Epidermissuperficial region
• Dermismiddle region
• Hypodermis (superficial fascia)deepest region
• Subcutaneous layer deep to skin (not technically
  part of skin)
• Mostly adipose tissue

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Epidermis

• Keratinized stratified squamous epithelium
• Cells of epidermis
• Keratinocytesproduce fibrous protein keratin
• Melanocytes
• 1025 of cells in lower epidermis
• Produce pigment melanin
• Epidermal dendritic (Langerhans)
  cellsmacrophages that help activate immune
  system
• Tactile (Merkel) cellstouch receptors

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Keratin

• Fibrous protein that helps give the epidermis its
  protective properties
• Found not only in skin, but also hair, nails,
  claws, horns, scales, shells, feathers, even
  baleen plates of whales
• Strong, waterproof, contains sulfur

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Melanocytes

• Spider-shaped cells found in stratum basale.
• Produce pigment melanin which accumulates in
  granules called melanosomes
• Melanosomes are taken up by keratinocytes where
  they accumulate on the sunny side of the nucleus

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Layers of the Epidermis Stratum Basale (Basal
Layer)

• Deepest epidermal layer firmly attached to the
  dermis
• Single row of stem cells
• Also called stratum germinativum cells undergo
  rapid division
• Journey from basal layer to surface
• Takes 2545 days

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Stratum corneum Most superficial layer 2030
layers of dead cells represented only by flat
membranous sacs filled with keratin. Glycolipids
in extracellular space.
Stratum granulosum Three to five layers of
flattened cells, organelles deteriorating
cytoplasm full of lamellated granules (release
lipids) and keratohyaline granules.
Stratum spinosum Several layers of keratinocytes
unified by desmosomes. Cells contain thick
bundles of intermediate filaments made of
pre-keratin.
Stratum basale Deepest epidermal layer one row
of actively mitotic stem cells some newly formed
cells become part of the more superficial
layers. See occasional melanocytes and
epidermal dendritic cells.
(a)
Dermis
Figure 5.2a
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Layers of the Epidermis Stratum Spinosum
(Prickly Layer)

• Cells contain a weblike system of intermediate
  prekeratin filaments attached to desmosomes
• Abundant melanin granules and dendritic cells

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Keratinocytes
Stratum corneum Most superficial layer 2030
layers of dead cells represented only by flat
membranous sacs filled with keratin. Glycolipids
in extracellular space.
Stratum granulosum Three to five layers of
flattened cells, organelles deteriorating
cytoplasm full of lamellated granules (release
lipids) and keratohyaline granules.
Stratum spinosum Several layers of keratinocytes
unified by desmosomes. Cells contain thick
bundles of intermediate filaments made of
pre-keratin.
Stratum basale Deepest epidermal layer one row
of actively mitotic stem cells some newly
formed cells become part of the more superficial
layers. See occasional melanocytes and epidermal
dendritic cells.
Dermis
Desmosomes
Sensory nerve ending
Melanin granule
Epidermal dendritic cell
Melanocyte
Tactile (Merkel) cell
(b)
Figure 5.2b
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Layers of the Epidermis Stratum Granulosum
(Granular Layer)

• Thin three to five cell layers in which the
  cells flatten
• Keratohyaline and lamellated granules accumulate

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Stratum corneum Most superficial layer 2030
layers of dead cells represented only by flat
membranous sacs filled with keratin. Glycolipids
in extracellular space.
Stratum granulosum Three to five layers of
flattened cells, organelles deteriorating
cytoplasm full of lamellated granules (release
lipids) and keratohyaline granules.
Stratum spinosum Several layers of keratinocytes
unified by desmosomes. Cells contain thick
bundles of intermediate filaments made of
pre-keratin.
Stratum basale Deepest epidermal layer one row
of actively mitotic stem cells some newly formed
cells become part of the more superficial
layers. See occasional melanocytes and
epidermal dendritic cells.
(a)
Dermis
Figure 5.2a
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Layers of the Epidermis Stratum Lucidum (Clear
Layer)

• In thick skin
• Thin, transparent band superficial to the stratum
  granulosum
• A few rows of flat, dead keratinocytes

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Layers of the Epidermis Stratum Corneum (Horny
Layer)

• 2030 rows of dead, flat, keratinized membranous
  sacs
• Three-quarters of the epidermal thickness
• Functions
• Protects from abrasion and penetration
• Waterproofs
• Barrier against biological, chemical, and
  physical assaults

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Keratinocytes
Stratum corneum Most superficial layer 2030
layers of dead cells represented only by flat
membranous sacs filled with keratin. Glycolipids
in extracellular space.
Stratum granulosum Three to five layers of
flattened cells, organelles deteriorating
cytoplasm full of lamellated granules (release
lipids) and keratohyaline granules.
Stratum spinosum Several layers of keratinocytes
unified by desmosomes. Cells contain thick
bundles of intermediate filaments made of
pre-keratin.
Stratum basale Deepest epidermal layer one row
of actively mitotic stem cells some newly
formed cells become part of the more superficial
layers. See occasional melanocytes and epidermal
dendritic cells.
Dermis
Desmosomes
Sensory nerve ending
Melanin granule
Epidermal dendritic cell
Melanocyte
Tactile (Merkel) cell
(b)
Figure 5.2b
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Dermis

• Strong, flexible connective tissue
• Cells include fibroblasts, macrophages, and
  occasionally mast cells and white blood cells
• Two layers
• Papillary
• Reticular

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Hair shaft
Dermal papillae
Subpapillary vascular plexus
Epidermis
Papillary layer
Pore
Appendages of skin
Dermis
Reticular layer
Eccrine sweat gland
Arrector pili muscle
Sebaceous (oil) gland
Hypodermis (superficial fascia)
Hair follicle
Nervous structures
Hair root
Sensory nerve fiber
Cutaneous vascular plexus
Pacinian corpuscle
Adipose tissue
Hair follicle receptor (root hair plexus)
Figure 5.1
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Layers of the Dermis Papillary Layer

• Papillary layer
• Areolar connective tissue with collagen and
  elastic fibers and blood vessels
• Dermal papillae contain
• Capillary loops
• Meissners corpuscles
• Free nerve endings
• Epidermal ridges lie atop deeper dermal papillary
  ridges to form friction ridges of fingerprints

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Friction ridges
Openings of sweat gland ducts
(a)
Figure 5.4a
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(b)
Figure 5.4b
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Layers of the Dermis Reticular Layer

• Reticular layer
• 80 of the thickness of dermis
• Collagen fibers provide strength and resiliency
• Elastic fibers provide stretch-recoil properties
• Collagen fibers arranged in bundles form
  externally invisible cleavage (tension) lines
• Incisions made parallel to cleavage lines heal
  more readily

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Skin Color

• Three pigments contribute to skin color
• Melanin
• Yellow to reddish-brown to black, responsible for
  dark skin colors
• Produced in melanocytes migrates to
  keratinocytes where it forms pigment shields
  for nuclei
• Freckles and pigmented moles
• Local accumulations of melanin
• Carotene
• Yellow to orange, most obvious in the palms and
  soles
• Hemoglobin
• Responsible for the pinkish hue of skin

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Erythema

• Redness of the skin
• caused by embarrassment, fever, hypertension,
  inflammation, allergyor even massage, acne
  medicine, waxing, lyme disease
• 30-50 erythema of unknown cause

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Pallor or Blanching

• Caused by fear, anger, certain emotional stress
• Often a symptom of anemia or low blood pressure
• Raynauds syndrome

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JaundiceYellow cast

• Can be a result of a liver disorder in which
  yellow bile pigments, bilirubin, accumulate in
  the body
• Also could be a result of eating a lot of
  carotenecarotenemia

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Albinism

• Absence of pigment in the skin, hair and eyes.
• Melanocytes are present but melanin not produced
  because of missing or disabled enzyme

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Black and Blue marksBruising

• Bruise can also be called a contusion
• Where blood has escaped from the circulation and
  clotted beneath the skin
• Mild Hematoma

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Cyanosis

• When hemoglobin is poorly oxygenated both the
  blood and often the skin appear blue
• Skin become cyanotic during heart failure and
  severe respiratory disorders
• Not as evident in darker skinned people

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Blue Fugates of Troublesome Creek, Kentucky

• Genetic Disorder that was amplified in a small
  Appalachain community from a French descendant
• Form of hemoglobin, methemoglobin cannot be
  recycled back into hemoglobin because of an
  enzyme deficiency

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Part 2 Skin Appendages

• Compare the structure and locations of sweat and
  oil glands and their secretions.
• Compare and contrast eccrine and apocrine glands.
• List the parts of a hair follicle. Describe
  functional relationship of arrector pili muscles
  to the hair follicle.
• Name the regions of a hair and explain the basis
  of hair color.
• Describe the structure of nails.

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Sweat Glands

• Two main types of sweat (sudoriferous) glands
• Eccrine (merocrine) sweat glandsabundant on
  palms, soles, and forehead
• Sweat 99 water, NaCl, vitamin C, antibodies,
  dermcidin (microbe killing peptide), metabolic
  wastes (urea, uric acid and ammonia)
• pH from 4-6
• Ducts connect to pores
• Function in thermoregulation

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Multicellular Exocrine Glands

• Multicellular exocrine glands are composed of a
  duct and a secretory unit
• Classified according to
• Duct type (simple or compound)
• Structure of their secretory units (tubular,
  alveolar, or tubuloalveolar)

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Compound duct structure (duct branches)
Simple duct structure (duct does not branch)
Tubular secretory structure
Simple tubular
Simple branched tubular
Compound tubular
Example Intestinal glands
Example Stomach (gastric) glands
Example Duodenal glands of small intestine
Alveolar secretory structure
Simple alveolar
Simple branched alveolar
Compound alveolar
Compound tubuloalveolar
Example Mammary glands
Example No important example in humans
Example Sebaceous (oil) glands
Example Salivary glands
Surface epithelium
Duct
Secretory epithelium
Figure 4.5
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Modes of Secretion

• Merocrine
• Products are secreted by exocytosis (e.g.,
  pancreas, sweat and salivary glands)
• Holocrine
• Products are secreted by rupture of gland cells
  (e.g., sebaceous glands)

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What type of Secretion is each picture?
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Eccrine Sweat Glands are also called merocrine
sweat glands

• Sweating is regulated by the sympathetic division
  of the autonomic nervous system
• Major role is to prevent overheating of body
• Heat induced sweating begins on forehead and
  spreads inferiorly over body
• Emotionally induced sweating begins on palms,
  soles and axillae then spreads to other areas of
  body

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Sweat pore
Eccrine gland
Sebaceous gland
Duct
Dermal connective tissue
Secretory cells
(b) Photomicrograph of a sectioned eccrine
gland (220x)
Figure 5.5b
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Sweat Glands (cont.)

• Apocrine sweat glandsconfined to axillary and
  anogenital areas
• Sebum sweat fatty substances and proteins so
  secretion is yellow or whitish
• Ducts connect to hair follicles
• Functional from puberty onward (as sexual scent
  glands?)/ basis of body odor
• Also merocrine glands as opposed to other
  apocrine glands (3rd type of gland not seen in
  humans)
• Specialized apocrine glands
• Ceruminous glandsin external ear canal secrete
  cerumenear wax!
• Mammary glands

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Sebaceous (Oil) Glands

• Widely distributed, large on face, neck and upper
  chest
• Most develop from hair follicles
• Become active at puberty
• Sebum
• Oily holocrine secretion
• Bactericidal
• Softens hair and skin

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Sweat pore
Sebaceous gland
Dermal connective tissue
Eccrine gland
Sebaceous gland duct
Hair in hair follicle
Secretory cells
(a) Photomicrograph of a sectioned sebaceous
gland (220x)
Figure 5.5a
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What is Acne?

• Whitehead When a sebaceous gland duct is
  blocked by accumulated sebum.
• If sebum oxidezes and dries blackhead
• Cradle Cap (seborrhea) is from overactive
  sebaceous glands
• pores on face are external outlet of hair
  follicles, where sebaceous glands empty

• Acne is active inflammation of sebaceous lands
  accompanied by pimples which are pustules or
  cysts on skin
• Acne is usually caused by bacterial infection,
  often staphylococcus.

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Hair

• Functions in Humans
• Alerting the body to presence of insects on the
  skin
• Guarding the scalp against physical trauma, heat
  loss, and sunlight
• As opposed to other mammal hair functions like
  trapping body heat
• Distribution
• Entire surface except palms, soles, lips,
  nipples, and portions of external genitalia

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Hair

• Consists of dead keratinized cells
• Contains hard keratin more durable than soft
  keratin of skin (and doesnt flake off)
• Three layers medulla, cortex and cuticle
• Hair pigments melanins (yellow, rust brown,
  black) produced by melanocyctes at base of hair
  follicle amd transferred to cortical cells
• Gray/white hair decreased melanin production,
  increased air bubbles in shaft
• Red hair due to iron containing pigment

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Follicle wall
Connective tissue root sheath Glassy
membrane External epithelial root sheath
Internal epithelial root sheath
Hair shaft
Hair
Cuticle Cortex Medulla
Arrector pili
(a) Diagram of a cross section of a hair
within its follicle
Sebaceous gland
Hair root
What is the role of hair conditioners?
Hair bulb
Figure 5.6a
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Follicle wall
Connective tissue root sheath
Glassy membrane
External epithelial root sheath
Internal epithelial root sheath
Hair
Cuticle
Cortex
Hair shaft
Medulla
Arrector pili
(b) Photomicrograph of a cross section of a
hair and hair follicle (250x)
Sebaceous gland
Hair root
Hair bulb
Figure 5.6b
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Hair Follicle

• Extends from the epidermal surface into dermis
• Two-layered wall outer connective tissue root
  sheath, inner epithelial root sheath
• Hair bulb expanded deep end
• Hair papilla of dermal tissue protrudes into the
  hair bulb
• Contains a knot of capillaries that provide
  nutrients to growing hair

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Hair Follicle

• Hair follicle receptor (root hair plexus)
• Sensory nerve endings around each hair bulb
• Stimulated by bending a hair
• Arrector pili
• Smooth muscle attached to follicle
• Responsible for goose bumps

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Hair shaft
Arrector pili
Sebaceous gland
Follicle wall
Hair root
Connective tissue root sheath
Hair bulb
Glassy membrane
External epithelial root sheath
Internal epithelial root sheath
Hair root
Cuticle
Cortex
Medulla
Hair matrix
Hair papilla
Melanocyte
Subcutaneous adipose tissue
(c)
Diagram of a longitudinal view of the expanded
hair bulb of the follicle, which encloses the
matrix
Figure 5.6c
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Follicle wall
Connective tissue root sheath
Hair shaft
Glassy membrane
External epithelial root sheath
Internal epithelial root sheath
Arrector pili
Hair root
Cuticle
Sebaceous gland
Cortex
Medulla
Hair root
Hair matrix
Hair bulb
Hair papilla
Subcutaneous adipose tissue
(d) Photomicrograph of longitudinal view of
the hair bulb in the follicle (160x)
Figure 5.6d
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Types of Hair

• Velluspale, fine body hair of children and adult
  females
• Terminalcoarse, long hair of eyebrows, scalp,
  axillary, and pubic regions (and face and neck of
  males)
• Hair growth and density influenced by nutrition,
  hormones and local blood flow (that can be
  increased by physical irritation)

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Hirsutism excessive hairiness (particularly in
women)
May result in an adrenal gland or ovarian tumor
that secretes abnormally large amounts of
androgens.
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Types of Hair

• Hair Growth
• Growth rate averages 2.5 mm per week
• Each follicle goes through growth cycles
• Growth phase (weeks to years) followed by
  regressive stage and resting phase (13 months)
• Growth phase varies (610 years in scalp, 34
  months in eyebrows)
• During regressive stage, hair falls out. After
  resting phase, cycling starts again and new hair
  is formed to replace one that fell out
• Loose an average of 90 scalp hairs daily

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Hair Thinning and Baldness

• Alopeciahair thinning in both sexes after age 40
• True (frank) baldness
• Genetically determined and sex-influenced
  condition
• Male pattern baldness is caused by follicular
  response to DHT
• Until recently, the only cure for male pattern
  baldness was to inhibit testosterone
  productionproblems with this?
• By accident, minoxidil to reduce HBP, also
  stimulates hair regrowth

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Structure of a Nail

• Scalelike modification of the epidermis on the
  distal, dorsal surface of fingers and toes
• Made of hard keratin
• Each nail has free edge, body and proximal root
• Nail matrix at proximal root responsible for
  nail growth
• Normally appear pink/ region over thick nail
  matrix looks like half moon (lunule)

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Lateral nail fold
Lunule
(a)
Eponychium (cuticle)
Body of nail
Free edge of nail
Proximal nail fold
Nail bed
Root of nail
Nail matrix
(b)
Hyponychium
Phalanx (bone of fingertip)
Figure 5.7
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Nail Basics

• Proximal and lateral borders of nail are
  overlapped by skin folds called nail folds
• Proximal nail fold is the eponychium (aka
  cuticle)
• Region beneath the free edge of the nail where
  dirt and debris accumulate is the hyponychium
  (quick)

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Functions of the Integumentary System

• Protectionthree types of barriers
• Chemical
• Low pH secretions (acid mantle) and defensins
  retard bacterial activity
• Physical and Mechanical
• Keratin and glycolipids block most water and
  water- soluble substances
• Limited penetration of skin by lipid-soluble
  substances, plant oleoresins (e.g., poison ivy),
  organic solvents, salts of heavy metals, some
  drugs
• Biological barriers
• Dendritic cells, macrophages, and DNA

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Functions of the Integumentary System

• Body temperature regulation
• 500 ml/day of routine insensible perspiration
  (at normal body temperature)
• At elevated temperature, dilation of dermal
  vessels and increased sweat gland activity
  (sensible perspirations) cool the body
• Cutaneous sensations
• Temperature, touch, and pain

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Functions of the Integumentary System

• Metabolic functions
• Synthesis of vitamin D precursor and collagenase
• Chemical conversion of carcinogens and some
  hormones
• Blood reservoirup to 5 of bodys blood volume
• Excretionnitrogenous wastes and salt in sweat

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Part Three Homeostatic Imbalances of Skin

• Summarize the characteristics of three major skin
  cancers
• Explain why serious burns are life threatening.
  Describe how to determine the extent of a burn
  and differentiate first, second and third degree
  burns.
• Discuss various common homeostatic imbalances
  from acne to psoriasis.
• ID effects of tattoo on skin

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Homeostatic Imbalances of Skin Infections
Allergies

• Skin can develop more than 1000 different
  conditions and ailments.
• Objectives
• Describe cause of several common skin disorders .
• Summarize the characteristics of the three major
  types of skin cancers.
• Explain why serious burns are life threatening.
  Describe how to determine the extent of a burn
  and differentiate first, second and third-degree
  burns.

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Burns

• When skin is burned, 2 life threatening problems
  result
• body loses supply of fluids containing proteins
  and electrolytes. Dehydration and electrolyte
  imbalance can lead to kidney shut down and
  circulatory shock (inadequate blood flow to
  body)
• After 24 hours, infection is important
  threatleading cause of death in burn victims.
• Rule of Nines way to determine volume of fluid
  lost by burns

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Rule of Nines

• Divides the body into 11 areas each representing
  9 of total body area, with genitals accounting
  for remaining 1
• This is obviously only an approximation

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Classification of Burns

• First Degree
• Only the epidermis is damaged
• Red and swollen
• Heals in 2-3 days
• Sunburn
• Second Degree
• Injury to epidermis and upper region of dermis
• Red, painful, blisters
• Care to protect from infection

• Third Degree
• Destroys entire thickness of skin
• Full thickness burn
• Appears blanched (gray-white) or blackened
• Nerve endings are destroyed/ not painful
• Regeneration not possible/ skin grafting necessary

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Skin Cancer

• The single most common type of cancer in humans
• 1 in 5 Americans will develop skin cancer
• Most important risk factor overexposure
  ultraviolet radiation in sunlight
• Damages DNA bases (pyrimidines C and T)
• UV light disables tumor suppressor gene p53
• Most skin neoplasms are benign and do not
  metastasize. For example a wart
• There are three types of malignant skin neoplasms

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Basal Cell Carcinoma

• Least malignant
• Most common skin cancer/ 80
• Skin cells no longer honor boundary between
  epidermis and dermis/ cannot form keratin
• Shiny domed shaped nodules
• Slow growing
• Surgically removed, full cure in 99 cases

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Squamous Cell Carcinoma

• Lesion is scaly, reddened, small and rounded that
  gradually forms an ulcer
• Arises from keratinocytes
• Most often occurs on scalp, ears, dorsum of
  hands, lower lip
• Grows rapidly
• Sun induced
• Chance of cure good if caught removed early

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Malignant Melanoma

• Cancer of melanocytes
• Metastasizes rapidly (50 survival rate if
  metastasized)
• Resistant to chemotherapy
• Forms wherever there is pigment, sometimes moles
• ABCD(E) rule Asymmetry/ Border irregular/
  Colors/ Diameter larger than 6mm/ elevation above
  skin

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Your epidermal cells scream for sunscreen!

• Sunscreens are currently rated for their ability
  to prevent sunburn but not for their ability to
  protect against DNA damage.
• SPF Sun Protection Factor
• Research levels of radiation not strong enough
  to burn still affect DNA

93
Ultraviolet Light

• UVA (ultraviolet-A) long- wave solar rays of
  320-400 nanometers (billionths of a meter).
  Although less likely than UVB to cause sunburn,
  UVA penetrates the skin more deeply, and is
  considered the chief culprit behind wrinkling,
  leathering, and other aspects of "photoaging."
  The latest studies show that UVA not only
  increases UVB 's cancer-causing effects, but may
  directly cause some skin cancers, including
  melanomas.
• UVB (ultraviolet-B) short-wave solar rays of
  290-320 nanometers. More potent than UVA in
  producing sunburn, these rays are considered the
  main cause of basal and squamous cell carcinomas
  as well as a significant cause of melanoma.

94
Suncreens

• Sunblocks and sunscreens Sunscreens chemically
  absorb UV rays, sunblocks physically deflect
  them. Sunscreen has long blocked UVB effectively,
  but until recently provided less UVA protection.
  New ingredients such as octylcrylene and the
  benzophenones have improved sunscreen's defenses
  against shorter UVA rays, and the revolutionary
  chemical avobenzone (Parsol 1789) works against
  all UVA wavelengths.
• Sunblocks have also markedly improved. New
  preparations such as micronized titanium dioxide
  are less conspicuous on the skin and offer
  substantial protection against both UVA and UVB.
• SPF (sun protection factor) measures the length
  of time a product protects against skin reddening
  from UVB, compared to how long the skin takes to
  redden without protection. If it takes 20 minutes
  without protection to begin reddening, using an
  SPF 15 sunscreen theoretically prevents reddening
  15 times longer -- about 5 hours. (Actually, it
  may take up to 24 hours after sun exposure for
  redness to become visible.) To maintain the SPF,
  reapply sunscreen every two hours and right after
  swimming.

95
Look for new DNA protecting Sunscreen

• Contains enzymes in liposomes that initiate
  repair of DNA, particularly at the pyrimidines
  that have fused together.