Body Tissues rev 9-11

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Body Tissues rev 9-11

• 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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• Epithelial Tissue
• sheet of cells that covers a body surface or
  lines a body cavity
• helps form boundaries between different body
  environments
• protects underlying tissues
• reduces friction because it is smooth
• absorbs
• secretes

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• Forms glands
• 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

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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
• many layers--stratified epithelium
• second name describes the shape of the cells

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• 4. Cells occur in 3 types
• squamous--thin and flat cells
• cuboidal--cube or rounded cells
• columnar--cylindrical cells
• these tissues may also have microvilli, cilia, or
  goblet cells

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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.
• Epithelial cells can also be attached to each
  other by different types of cell junctions
• 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
• Adhesion junctions (also called spot desmosomes)
  are looser in structure and allow for some
  movement between cells so the tissues can stretch
  and bend
• Gap junctions are connecting protein channels
  that permit the movement of ions or water between
  2 adjacent cells

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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

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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
• Collagen fibers--provides strength and slight
  flexibility
• Elasticthin and very flexible coiled elastic
  fibers made from the protein elastin
• 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
  (called the matrix)
• It contains many types of cells including fat
  cells, mast cells, various WBC, and fibroblasts.

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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 muscles,
  and around blood vessels, muscles 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

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• Elastic Connective Tissue
• Surrounds organs that have to reguarly change
  shape or size
• 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
• Because there are no blood vessels, mature cells
  obtain nutrients by diffusion through the ground
  substance.
• Maintains the shape of certain body parts
• Protects and cushions joints cartilagenous disks
  cushion the vertebrae, forms the tough covering
  of bones at joints

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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
• White blood cells (WBC) 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)
• Primary role is insulation and cushioning stores
  energy forms a protective layer around internal
  organs

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Muscle 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.
• Neuron specialized nervous system cell which
  generates and transmits impulses.
• Structural components cell body, dendrites, axon
• Glial cells support neuron cells and supplies
  with nutrients

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INTEGUMENTARY SYSTEM (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
• 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.
• 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
• When cells are dead and water has evaporated,
  keratin forms a tough barrier
• Provides protection from abrasion, cells can be
  rubbed off and will be replaced also protects
  our body from drying out

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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.

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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. Sweat helps in
  temperature regulation and contains an antibiotic
  called dermicidin.
• Arrector pili muscles which make our hair stand
  up
• Blood vessels supply nutrients, remove waste,
  assist in temperature regulation
• Nails a scale like modification of the epidermis
• 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
• 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
• 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 to 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
  if 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