Body Tissues rev 12-12

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Body Tissues rev 12-12

• Tissue group of cells that are similar in
  structure and perform a common function
• 4 primary tissue groups
• Epithelial
• Connective
• Muscle
• Nervous

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• Tissues combine to form organs
• Organs combine to form organ systems
• Organ systems combine to form the organism
  (humans)

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• Epithelial Tissue
• sheet of cells that covers a body surface or
  lines a body cavity
• helps form boundaries between different body
  environments
• examples skin, lining of mouth, lining of
  digestive tract, etc.
• protects underlying tissues

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• reduces friction because it is smooth
• lines blood vessels and helps blood flow more
  easily
• absorbs
• secretes

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• Forms glands
• glands are epithelial tissues that are
  specialized to synthesize and secrete a product
• Characteristics of Epithelial Tissue
• 1. Cells are packed closely together
• 2. One surface of the tissue is free while the
  other surface is attached to the underlying
  connective tissue by the basement membrane

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• 3. Epithelial tissues are typically given 2
  names--first name indicates the number of cell
  layers present
• one layer of cells is called simple epithelium
• typically found where absorption and filtration
  occur and a thin epithelial layer is adapted for
  diffusion across barriers
• many layers--stratified epithelium
• common in high-abrasion areas where protection is
  important i.e. lining of the mouth, skin surface
• second name describes the shape of the cells

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• 4. Cells occur in 3 types
• squamous--thin and flat cells
• forms the thinnest possible layer for diffusion
  filtration line vessels
• look like a pancake when viewed from the side
• mostly found in air sacs of lungs, kidney
  glomeruli, lining of vessels

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Classification of Epithelia

• Squamous

Figure 4.1b
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• cuboidal--cube or rounded cells (about as tall as
  are wide)
• major function is secretion but may also be
  involved in absorption
• line the ducts of many glands
• has round shaped nucleus which stains very darkly

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Classification of Epithelia

• Cuboidal

Figure 4.1b
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• columnar--cylindrical cells (tall and column
  shaped)
• tall cell with oval shaped nucleus
• mostly associated with absorption, secretion of
  enzymes and mucus, and movement of materials
  (ciliated cells)
• line the stomach, small and large intestines and
  a few ducts
• these tissues may also have microvilli, cilia, or
  goblet cells (secrete mucus to lubricate tissues
  and trap bacteria, viruses and irritating
  particles)
• line small bronchi, uterine tubes

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Classification of Epithelia

• Columnar

Figure 4.1b
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Basement Membrane

• Underneath the cells of epithelial tissue is a
  supporting non-cellular layer called the basement
  membrane and beneath that is typically a layer of
  connective tissue.
• The basement membrane anchors the epithelial
  layer to the stronger connective tissue
  underneath.
• Epithelial cells can also be attached to each
  other by different types of cell junctions made
  up of proteins Tight junctions, Adhesive
  junctions, Gap junctions

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• Tight junctions seal plasma membranes of
  adjacent cells so tightly that nothing can pass
  between the cells
• These are very important in epithelial layers
  that must control the movement of substances into
  or out of the body?digestive tract, bladder,
  kidney tubules

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• Adhesion junctions (also called spot desmosomes)
  are looser in structure and allow for some
  movement between cells so the tissues can stretch
  and bend i.e. skin

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• Gap junctions are connecting protein channels
  that permit the movement of ions or water between
  2 adjacent cells i.e. liver, heart, some muscle
  tissue

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Connective Tissue

• found everywhere in the body
• Major functions
• 1. Binding or connecting of body parts
• 2. Support of organs against gravity
• 3. Protection
• 4. Cushioning, insulation energy storage fat
  storage
• 5. Produces blood cells
• 6. Transportation
• Has comparatively few cells and a lot of matrix
  (non-living extracellular matter) which is made
  by connective tissue cells and released into the
  space between them. The strength of the
  connective tissue comes from the matrix, not from
  the living cells themselves

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• Matrix is composed of water stabilized by
  carbohydrates, glycoproteins, minerals. This
  provides mechanical and nutritional support to
  the cells. It permits free diffusion of
  nutrients and metabolites.

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• Types of Connective tissue
• Fibrous-connects various body parts provides
  strength, support and flexibility
• consists of several types of fibers and cells
  embedded in a gel-like ground substance (matrix)
• Collagen fibers--provides strength and slight
  flexibility
• Elasticthin and very flexible coiled elastic
  fibers made from the protein elastin can stretch
  without breaking
• Reticularmade of thinner collagen fibers which
  interconnect with each other serves as internal
  framework for some organs fiber flexibility is
  between elastic and collagen fibers

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• The various fibers are set in a ground substance
  made of water, polysaccharides and proteins that
  range in consistency from gel to rubbery.
• It contains many types of cells including fat
  cells, mast cells (immune cells that detect
  foreign substances in tissue spaces and initiate
  an inflammatory response), various WBC, and
  fibroblasts (the cells responsible for producing
  and secreting the proteins that compose the
  collagen, elastic and reticular fibers).

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• Fibrous connective tissues are subclassified
  according to the density and arrangement of their
  fibers
• Loose Areolar connective tissue
• most common type
• contains collagen fibers and elastic fibers in a
  loose irregular pattern is very flexible but
  not strong
• usually found below the skin, between and around
  muscles, and around blood vessels, and organs.
• Spaces between fibers are good storage areas.

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• Dense (Regular) Connective Tissue
• fibers are densely packed and run in the same
  direction
• is very strong when stress is in the same
  direction as the fibers run
• has few blood vessels and takes a long time to
  heal
• functions to bind, protect and connect
• primarily attaches muscles to bones or to other
  muscles, bones to bones
• usually found in tendons, ligaments and joint
  capsules

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• Elastic Connective Tissue
• Surrounds organs that have to reguarly change
  shape or size
• Stomach, bladder, vocal cords
• Contains a high proportion of elastic fibers
• Reticular connective Tissue
• Also called lymphoid tissue
• Serves as the internal framework of soft organs
  such as the liver, lymphatic system organs
• Is made up of thin, branched reticular fibers

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• Specialized connective tissues
• Cartilage is the transition tissue from which
  bone develops
• Produced by chondroblasts which become trapped
  and enclosed in areas called lacunae no blood
  vessels, high collagen fiber and water content
  (this is why it functions as a cushion)
• Because there are no blood vessels, mature cells
  obtain nutrients by diffusion through the ground
  substance (matrix).

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• Maintains the shape of certain body parts i.e.
  tip of your nose
• Protects and cushions joints cartilagenous disks
  cushion the vertebrae, forms the tough covering
  of bones at joints (and helps reduce friction)

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• Bone connective tissue which contains only a few
  living cells
• inorganic matrix with calcium and phosphate salts
  for hardness
• Blood cells are suspended in a fluid matrix
  called plasma. Considered a connective tissue
  because all blood cells derive from earlier stem
  cells located within bone.
• Red blood cells transport oxygen and nutrients to
  body cells and carry away the waste products.
• White blood cells function in the immune system
• Platelets help to form blood clots following an
  injury.

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• Adipose (Fat) tissue specialized for fat storage
• has few connective tissue fibers and almost no
  ground substance primarily made up of adipocytes
  (fat cells) (large, round cells which look empty
  but really contain an oil droplet which takes up
  most of the cell and pushes the nucleus to one
  side)
• Primary role is insulation and cushioning stores
  energy forms a protective layer around internal
  organs
• Found below skin, around various organs, and
  around certain muscles
• The number of adipocytes you have is partly
  determined by genetics

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Other Tissue TypesMuscle Tissue Contracts for
Movement

• Muscle tissue is made up of tightly packed cells
  called muscle fibers. The muscle fiber cytoplasm
  contains proteins which allow the cell to
  contract
• 3 types of muscle tissue
• Skeletal muscle moves body parts.
• Is connected to tendons which are connected to
  bones.
• Voluntary, multinucleated

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• Cardiac muscle
• Found only in the heart
• Individual cells are shorter than skeletal, have
  single nucleus
• Cells are arranged parallel to each other
• Have intercalated disks which function as gap
  junctions for direct electrical contact with
  neighboring cells. This allows one cell to
  activate all its neighbors so the heart can
  contract in a coordinated way.
• Involuntary muscle

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• Smooth muscle
• Surrounds hollow organs and tubes i.e. blood
  vessels, digestive tract
• Smaller cells than skeletal muscles have a
  single nucleus
• Cells arranged parallel to each other
• Have gap junctions between cells so that it works
  in a coordinated fashion
• Involuntary muscle

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Nervous Tissue Transmit Impulses

• Nervous tissue is made up of cells which are
  specialized for generating and transmitting
  electrical impulses. It is a rapid communication
  network for the body.
• Is located in the brain, spinal cord and nerves
• Neuron specialized nervous system cell which
  generates and transmits impulses.
• Structural components cell body, dendrites, axon
• Glial (Neuroglial) cells support neuron cells
  and supplies with nutrients

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INTEGUMENTARY SYSTEM(also known as SKIN)

• Functions --outer covering of the body
• protects from dehydration
• protects from injury
• protects against invasion by microorganisms
  (bacteria and viruses)
• helps regulate body temperature
• synthesizes vitamin D
• Sensory awareness receptors for touch,
  vibration, pain and temperature provide
  information about the environment

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• Skin consists of
• epidermis outermost layer of stratified
  squamous epithelial tissue no blood vessels
• is made up of 5 sub-layers stratum corneum,
  stratum lucidum, stratum granulosum, stratum
  spinosum, and stratum basale layers

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• Innermost layer stratum basale undergoes almost
  continuous mitosis. Cells are pushed upward by
  the production of new cells beneath them and
  create new skin
• Melanocytes are found here they produce melanin,
  a brown pigment.
• Primary reason for differences in skin color is
  the activity (not number) of melanocytes. In
  darker races, melanocytes are always active in
  lighter skinned people, the melanocytes are
  activated by UV radiation.
• Stratum spinosum thickest layer cells switch
  from a mitotic role to producing keratin.
• Keratin is a waterproofing protein which also
  toughens the outer surface of the skin.
• Macrophages (phagocytes which protect us from
  infection) are also present throughout this skin
  layer

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• Stratum granulosum acts as a protective shield
  to the layers below it.
• Stratum lucidum thin layer with keratin
  production occurring
• Stratum corneum outermost and toughest layer of
  epidermis
• Outermost layers of epidermis are made up of
  dead, dried out epithelial cells which contain
  keratin (a fibrous protein, also a component of
  fingernails and hair)
• When cells are dead and water has evaporated,
  keratin forms a tough barrier which
  microorganisms generally have a tough time
  entering
• Provides protection from abrasion, cells can be
  rubbed off and will be replaced also protects
  our body from drying out
• Skin continually being renewed throughout our life

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• The dermis is primarily dense connective tissue
  with collagen, elastic and reticular fibers in a
  ground matrix.
• The fibers allow the skin to stretch when we move
  
• give it strength to resist abrasion and tearing.
  
• Our skin becomes less flexible and more wrinkled
  as we age because the number of fibers in the
  dermis decreases.

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• composed of two sub-layers
• this layer binds the body together
• richly supplied with nerve fibers, blood vessels,
  hair follicles, sebacious (oil) glands, sweat
  glands and lymphatic vessels
• Sensory nerve endings for heat, cold, touch,
  deep pressure, vibration provide information
  about the outside environment
• Nerve fibers
• Meissners corpuscles-light touch
• Pacinian corpuscles-deep pressure. Free nerve
  endings-pain

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• There are 2 types of sweat glands
• Eccrine which are throughout the body and
• Apocrine which are primarily in the groin and
  underarm (axillary) areas. Because of the waste
  products of bacteria who live off of apocrine
  sweat glands, we can have an odor in these areas.
• Sweat helps in temperature regulation and
  contains an antibiotic called dermicidin
• Arrector pili muscles which make our hair stand
  up produce goose bumps
• Blood vessels supply nutrients, remove waste,
  assist in temperature regulation

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• Nails a scale like modification of the epidermis
  that forms a clear protective covering on the
  dorsal surface of the ends of fingers and toes
• Ceruminous or wax gland

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• Hypodermis supportive layer consisting of loose
  connective tissue containing fat cells
• also called subcutaneous tissue or superficial
  fascia
• anchors the skin to underlying structures
  (primarily muscles)
• is flexible so the skin can move and bend
• its fat cells insulate against excessive heat
  loss and cushion against injury

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Diseases of the Skin

• Impetigo
• A contagious, superficial infection in bullous
  (blister like) and nonbullous forms
• Usually occurs on face, around the mouth and nose
• ITCHY!
• Causes
• Staph aureus usually causative organism
• When blister breaks, liquid (exudate) can cause
  more lesions on rest of body

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• Treatment
• Antibiotics (penicillin, cephalosporin,
  zithromax)
• Anti-itch creamitching spreads impetigo
• Frequent washing of lesions with antibacterial
  soap
• Patient has own towels, bedding, etc
• Caretaker must wash hands carefully and
  frequently

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• Tinea (Skin Fungus) infections
• can occur directly (through contact with infected
  lesions) or indirectly (through contact with
  contaminated articles-shoes, towels, or shower
  stalls)

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• Tinea capitis
• Small, spreading blister like rash on scalp
  causing patchy hair loss and scaling
• Usually affects children in babies called
  cradle cap
• Tinea corporis (also known as ringworm)
• produces flat lesions on the skin which, as they
  get bigger, have healed centers and look like a
  ring
• Tinea pedis (Athletes foot)
• Scaling and blisters between the toes

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• Tinea cruris (Jock itch)
• Produces red, raised, sharply defined, itchy
  lesions in the groin that can extend to the
  buttocks, inner thighs, and the external
  genitalia.
• Warm weather and tight clothing encourage fungal
  growth
• Treatment for all Tineas
• Usually topical creams
• Continue applying cream for 2 weeks after lesions
  heal
• Observe for secondary infections
• Expose areas (when possible) to air

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• Scabies
• Infection by the itch mite which causes a
  sensitivity reaction
• Occurs primarily in areas with overcrowding and
  poor hygiene
• Very contagious transmitted through skin or
  sexual contact
• Mite lives in the skin. Female burrows into the
  skin to lay her eggs. The larvae emerge to
  copulate and then reburrow under the skin

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• Causes itching which intensifies at night and can
  lead to a secondary bacterial infection
• Lesions are usually excoriated, threadlike, about
  3/8 inch long and typically seen between fingers,
  on flexor surfaces of wrist, on elbows, underarm,
  at the waistline, and can be seen in genitalia
• Treatment
• Cream over entire skin surface and left on for
  8-12 hours for 5 days (depending on the specific
  type of cream)
• Application usually repeated in 1 week
• Oral antihistamine
• Wash clothes and bedding in very hot water or
  dryclean

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• Lice or Pediculosis
• Pediculus capitis (head lice)
• Pediculus corporis (body lice)
• Pediculus pubis (crab lice)
• Lice feed on human blood and lay their eggs
  (nits) in body hairs or clothing fibers
• After nits hatch, lice must feed within 24 hours
  or die. Mature in 2-3 weeks
• When louse bites it injects a toxin into the skin
  that produces irritation and a purpuric spot
  (spot containing leaked blood).

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• Causes itching which can cause skin breakdown,
  swollen lymph glands, rash
• Treatment
• Special shampoo, creams
• Shampoo applied and washed off after 5-10 minutes
  (depending on specific shampoo) repeat in 7-10
  days
• After this, all nits should be combed out of hair
  with a metal nit comb
• Wash clothing and bedding

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• Psorias
• Chronic disease marked by epidermal
  proliferation skin is covered by scales
• Life cycle of normal skin is 28 days and then
  it sloughs off life cycle of psoriatic skin is 4
  days so the cell cant mature resulting in thick,
  flaky skin
• Has remissions and exacerbations
• Tendency to develop this is genetic
• Symptoms itching dry, cracked skin lesions
  which can cause pain.
• Lesions commonly appear on scalp, chest, elbows,
  knees, shins, back, and buttocks

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• Treatment
• No permanent cure exists
• Lotions or tar preparations to help soften the
  scales which then can be scrubbed off gently
  ultraviolet light to retard rapid cell
  production
• Steroid creams to control disease
• Antihistamines to relieve itching
• Not contagious

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• Eczema
• Chronic inflammatory response often associated
  with allergies, irritating chemicals, temperature
  and humidity, skin irritation (i.e. tight
  clothing), and emotions.
• Lesions generally begin as raised areas on skin
• Typically flares and subsides repeatedly
• During flareups, itching and scratching can
  cause edema, crusting and scaling
• Treatment eliminate allergens and irritations
• Antihistamines to relieve itching, steroid
  creams Hydrate skin Short baths/showers in cool
  water