Tissues

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• Tissues
• Groups of cells similar in structure and function
• Histology-study of tissues
• Primary tissue types
• Epithelial tissue -Forms boundaries between
  different environments, protects, secretes,
  absorbs, filters
• Connective tissue -Supports, protects, binds
  other tissues together
• Muscle tissue - Contracts to cause movement
• Nerve tissue communication

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• Functions of epithelial tissue
• Protection-covers all exposed body surfaces and
  lines all body cavities
• Absorption
• Filtration
• Excretion
• Secretionforms endocrine and exocrine glands
• Sensory reception

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• Characteristics of Epithelial Tissue
• Cells have polarity an apical surface (upper or
  free surface) and basal surface (lower or
  attached surface)
• Cells near apical surface differ from those at
  basal surface
• Are composed of closely packed cells which are
  connected to each other and evenly spaced
• Continuous sheets held together by tight
  junctions and desmosomes (anchoring) junctions
• Supported by connective tissue
• Avascular but innervated-depends on diffusion of
  nutrients from basement membrane
• High rate of regeneration

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• Classification of Epithelial tissue
• Number of tissue layers
• Simple one layer of cells
• typically found where absorption and filtration
  occur and a thin epithelial barrier is desirable
• Stratified many layers of cells
• common in high-abrasion areas where protection is
  important i.e. lining of the mouth, skin surface
• May have specialized names
• Endotheliuminnermost lining
• Provides a slippery lining
• Mesotheliummiddle lining
• Found in serous membranes lining ventral body
  cavity and covering the organs

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• Classification of Epithelial Tissues
• Type of cell
• Simple
• Squamous-thin, flat cell
• Cuboidal-cube shaped cell
• Columnar tall, rectangular shaped cell
• Stratified
• named according to number of cell layers

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• Pseudostratified columnar epithelium appears
  stratified, typically with nuclei located in at
  least two more-or-less distinct levels.  But
  every cell actually rests on the basement
  membrane, so epithelium is technically "simple",
  despite appearances.

http//www.siumed.edu/dking2/intro/epith.htm
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• Glandular Epithelial Tissue
• A gland is one or more cells that makes and
  secretes a product called a secretion
• Classified by
• Site of product releaseinto duct (exocrine) or
  directly into bloodstream (endocrine)
• or number of cells forming glandunicellular
  (e.g., goblet cells) or multicellular

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• Endocrine Glands
• Ductless glands
• Secrete hormones that travel through lymph or
  blood to target organs
• Exocrine Glands
• More numerous than endocrine glands
• Secrete products into ducts
• Secretions released onto body surfaces (skin) or
  into body cavities
• Examples include mucous, sweat, oil, and salivary
  glands

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• Connective Tissue
• Most abundant and widely distributed tissue type
• Four classes
• Connective tissue proper
• Cartilage
• Bone tissue
• Blood
• Major Functions of Connective Tissue
• Binding and support
• Protection
• Insulation
• Transportation (blood)

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• Connective Tissue Characteristics
• Connective tissues have
• Varying degrees of vascularity
• Living cells separated by nonliving extracellular
  matrix (ground substance and fibers) cells are
  scattered and not attached to each other
• Allows tissue to be stronger

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• Structural Elements of Connective Tissue
• Ground substance or Matrix
• Medium through which solutes diffuse between
  blood capillaries and cells
• Components
• Interstitial fluid
• Adhesion proteins (glue)
• Proteoglycans
• Protein core large polysaccharides
• Trap water in varying amounts, affecting
  viscosity of ground substance

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• Structure Elements of Connective Tissue
• Three types of fibers
• Collagen (white fibers)
• Strongest and most abundant type
• Provides strength
• Elastic
• Networks of long, thin, elastin fibers that allow
  for stretch (elasticity)
• Reticular
• Short, fine, highly branched collagenous fibers
• Cells
• Mitotically active and secretory cells blasts
• Mature cells cytes

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• Areolar Connective Tissue
• Gel-like matrix with fibroblasts, macrophages,
  mast cells, and some white blood cells.
• Function Wraps and cushions organs macrophages
  phagocytize bacteria plays important role in
• inflammation
• Location Widely distributed under epithelial
  tissues e.g.,packages organs surrounds
  capillaries.
• Adipose Connective Tissue
• Description Matrix sparse nucleus of closely
  packed adipocytes pushed to the side by large fat
  droplet.
• Function reserve fuel insulates against heat
  loss supports and protects organs.
• Location Under skin in hypodermis around
  kidneys and eyeballs within abdomen in breasts

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• Reticular Connective Tissue
• Description Network of reticular fibers in a
  loose ground substance reticular cells lie on
  network.
• Function Fibers form a soft internal skeleton
  that supports other cell types including white
  blood cells, mast cells, and macrophages.
• Location lymph nodes, bone marrow, and spleen
• Dense, Regular Connective Tissue
• Description parallel collagen fibers with few
  elastic fibers major cell type is fibroblast.
• Function Attaches muscles to bones or to
  muscles attaches bones to bones withstands
  great tensile stress when pulling force is
  applied in same direction as fibers.
• Location Tendons, most ligaments, aponeuroses.

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• Dense Irregular Connective Tissue
• Description irregularly arranged collagen
  fibers some elastic fibers major cell type is
  fibroblast.
• Function Able to withstand tension exerted in
  many directions provides structural strength.
• Location Fibrous capsules of organs and joints
  dermis of the skin submucosa of digestive tract.

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• Cartilaginous Connective Tissue
• Three types of cartilage
• Hyaline cartilage
• Elastic cartilage
• Fibrocartilage
• Hyaline Cartilage
• Description firm matrix of collagen fibers
  chondroblasts produce the matrix when mature,
  (chondrocytes) lie in lacunae.
• Function Supports and reinforces has cushioning
  properties resists compressive stress.
• Location embryonic skeleton covers ends of long
  bones forms costal cartilages of ribs
  cartilages of nose, trachea, and larynx.

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• Elastic Cartilage
• Description Similar to hyaline cartilage, but
  more elastic fibers in matrix.
• Function Maintains structure shape while
  allowing
• great flexibility.
• Location external ear (pinna) epiglottis.
• Fibrocartilage
• Description Matrix similar to but less firm than
  hyaline cartilage thick collagen fibers
  predominate.
• Function Tensile strength with the ability to
  absorb
• compressive shock.
• Location Intervertebral discs pubic symphysis
  discs of knee joint.

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• Osseous Tissue-Bone
• Description Hard, calcified matrix containing
  many collagen fibers osteocytes lie in lacunae.
  Very well vascularized.
• Function supports and protects provides levers
  for muscles stores calcium and other minerals
  and fat marrow inside bones is site for blood
  cell formation (hematopoiesis).
• Location Bones
• Blood
• Description Red and white blood cells in a fluid
  matrix
• (plasma).
• Function Transport of respiratory gases,
  nutrients, wastes, and other substances
• Location Contained within blood vessels.

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• Muscle Tissue
• Skeletal Muscle
• Description Long, cylindrical, multinucleate
  cells striated
• Function Voluntary movement locomotion
  manipulation of environment facial expression
  voluntarily controlled
• Location skeletal muscles attached to bones or
  to skin.
• Cardiac Muscle
• Description Branching, striated, uninucleate
  cells that connect at specialized
  junctions-intercalated discs
• Function As it contracts, it propels blood into
  the
• circulation involuntary control.
• Location walls of heart

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• Smooth Muscle
• Description Spindle-shaped cells with central
  nuclei no
• striations cells arranged closely to form
  sheets.
• Function Propels substances or objects
  (foodstuffs, urine,
• a baby) along internal passage-ways involuntary
  control.
• Location walls of hollow organs.
• Nervous Tissue
• Description Neurons are branching cells cell
  processes
• may be quite long extend from nucleus-containing
  cell body contributing to nervous tissue are
  nonirritable supporting cells
• Function Transmit electrical signals from
  sensory receptors to effectors (muscles and
  glands) which control their activity
• Location Brain, spinal cord, and nerves.

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• Epithelial Membranes
• covering and lining tissue composed of an
  epithelial layer bound to an underlying
  connective tissue
• Cutaneous membrane (skin)
• Consists of keratinized stratified squamous
  epithelium (epidermis) attached to a layer of
  dense irregular connective tissue (dermis)

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• Epithelial Membranes
• Mucous membranes
• Line body cavities open to exterior (e.g.,
  digestive and respiratory tracts)
• Are moist
• Directly underneath it is loose connective tissue
  called the lamina propria

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• Epithelial Membranes
• Serous Membranes
• Moist membranes in closed ventral body cavity
• Made of simple, squamous epithelium resting on
  areolar connective tissue
• Secretes thin, clear serous liquid that
  lubricates facing surfaces of parietal and
  visceral layers so there is no friction as they
  move
• Parietal serosa line internal body walls
• Visceral serosa cover internal organs

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• LAB TO DO
• 1. State the four basic tissue categories and the
  different tissues in each category.
• 2. ID microscope slides and models of each type
  of tissue covered in lab and give examples of
  where it is found and its function.
• Epithelial simple squamous, simple cuboidal,
  simple columnar
• pseudostratified (ciliated) columnar
• stratified squamous
• Connective Areolar,
• adipose, hyaline cartilage
• dense regular bone