Body Tissues

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Chapter 3

• Body Tissues

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• Epithelial (epithelium) Tissue
• Epithet laid on, covering
• Lining, covering, glandular
• Functions protection, absorption, filtration,
  secretion
• Characteristics
• Fit closely forming continuous sheets
• Apical surface 1 free surface exposed to
  bodys exterior/interior
• Lower surface rests on basement membrane
  secreted by the cells
• Avascular no blood supply of their own
• Depend on diffusion
• Regenerate

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• 2 names based on of layers and cell shape
• Simple epithelia one layer
• Simple squamous (fish scale)
• Allow rapid diffusion air sacs, capillaries
• Produce serous membranes (serosae) line ventral
  body cavity
• Simple cuboidal (cube shaped)
• Glands and their ducts salivary, pancreas
• Kidney tubule walls
• Ovary surface

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• Simple columnar (columns)
• Goblet cells produce lubricating mucus
• Line digestive tract
• Mucus membranes (mucosae) line body cavities
  that open to exterior
• Pseudostratified columnar
• Different heights
• Line respiratory tract
• May have cilia

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• Stratified epithelia 2 or more cell layers
• Stratified squamous
• Most common
• Esophagus, mouth, outer skin (friction areas)
• Free edge squamous
• Basement membrane cuboidal or columnar

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• Stratified cuboidal Stratified columnar
• Rare
• Ducts of large glands
• Transitional
• Modified stratified squamous allow much
  stretching
• Urinary bladder, ureters, part of urethra

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• Glandular epithelium
• Glands 1 or more cells that make and secrete a
  particular product
• Endocrine glands
• Ductless glands
• Secretions diffuse directly into blood vessels
• Ex. thyroid, adrenals,
• pituitary
• Exocrine glands
• Have ducts
• Secretions empty directly on epithelial surface
• Ex. sweat, oil, liver, pancreas

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• Connective tissue
• Most abundant
• Protection, support, binding
• Characteristics
• Variation in blood supply lower supply slower
  healing

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• Extracellular matrix nonliving substance bound
  outside cell produced by connective tissue
• 2 main elements
• 1.Ground substance
• Water, adhesion proteins, polysaccharides
• Fluid, gel-like, rock hard
• Adhesion proteins glue attaches connective
  tissue to matrix fibers
• Absorbs large amounts of water reservoir
• 2. Fibers
• Collagen white high tensile strength
• Elastic yellow stretch/recoil
• Reticular internal skeleton of soft organs
  (spleen)

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• Functions forms soft packing tissue, bears
  weight, w/stand stretching/abrasions
• Ex. Fat tissue many cells soft matrix
• Ex. Bone/cartilage few cells hard matrix
• Types based on differences in fiber type and
  fiber
• Bone osseous tissue
• Bone cells in cavities (lacunae)
• Surrounded by hard matrix w/ calcium salts and
  lots of collagen
• Support, protection

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• Cartilage
• Hyaline cartilage
• Most widespread
• Abundant collagen, rubbery matrix
• Ex. Surrounds larynx, attaches ribs to
  breastbone, covers ends of bones
• Prenatal skeleton replaced by bone by birth
• Fibrocartilage cushioning disks of spinal cord
• Elastic cartilage elasticity ear

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• Dense connective tissue (dense fibrous tissue)
• Collagen fibers
• Tendons attach muscles to bone
• Ligaments attach bone to bone
• Dermis lower layer of skin

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• Loose connective tissue
• More cells and fewer fibers
• Areolar tissue
• Most widely distributed connective tissue
• Cushions/protects body organs
• Universal packing tissue
• Glues internal organs together
• Lamina propria under
• all mucous membranes
• Water/salt reservoir
• Edema swelling caused by collecting excess
  fluid
• Phagocytes

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• Adipose tissue (fat)
• Signet ring cells contain large oil droplet
  that pushes nucleus to side
• Subcutaneous tissue under skin
• Insulates/protects
• Fat deposits hips, breasts

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• Reticular connective tissue
• Forms stroma (bed) in lymph nodes, spleen, bone
  marrow

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• Blood (vascular tissue)
• Blood cells surrounded by nonliving, fluid matrix
  (plasma)
• Fibers are only seen during clotting

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• Muscle tissue
• Contract and shorten
• Skeletal muscle
• Attached to skeleton
• Voluntary control
• Pulls on bone or
• skin movement
• Multinucleate
• Striations
• Cells aka muscle fibers because their elongated

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• Cardiac muscle
• Only in heart
• Involuntary control
• Uninucleate
• Striations
• Intercalated disks where branching cells fit
  together contain gap junctions

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• Smooth muscle (visceral muscle)
• No striations
• Spindle shaped
• Found in walls of hollow organs stomach, blood
  vessels
• Contraction cavity smaller
• Relaxation cavity larger
• Ex. Peristalsis small intestines

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• Nerve tissue
• Neurons nerve cells
• 2 characteristics irritability and conductivity
• Cytoplasm drawn into long processes

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Tissue Repair

• Inflammation nonspecific attempts to prevent
  further injury
• Immune responses attacks specific invaders
• Repair (healing)
• Regeneration replacement of cells
• Fibrosis repair by fibrous connective tissue
  scar tissue
• Type of repair determined by
• Type of tissue damaged
• Severity of damage

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• Process
• Capillaries become permeable
• Allow clotting to occur
• Stop blood loss, holds wound edges, walls of
  injured area
• Granulation tissue forms
• Composed largely of new capillaries
• Contain phagocytes dispose of clot and scar
  tissue
• Surface epithelium regenerates
• Grows under scab
• Scar may be visible depends on severity of
  wound
• Epithelial and connective tissues regenerate
  well.
• Muscle and nervous may not regenerate at all.

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Tissue Development

• Neoplasm loss of control over cell division
• May be benign or malignant
• Hyperplasia cells multiply due to an irritant
  or condition
• Ex. Breast enlargement due to pregnancy
• Atrophy decrease in size not used or loses
  nerve supply