Tissue

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Tissue

• The Living Fabric

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Tissues are

• Groups of cells that are similar in structure and
  function
• They are specialized groups of cells and
  non-living materials (fibers, gels, fluids) which
  perform specific functions

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Histology

• Is the study of tissues

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Four generalized types of tissue

• Epithelial for lining or covering
• Connective for support
• Muscle for movement
• Nervous for control

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Epithelial tissue is used for

• Lining,
• Covering
• glandular

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Functions of the epithelials

• Protection
• Absorption
• Filtration
• Secretion
• All substances given off by body must go
  through epithelial cells

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Lets take it from the top

• Apical surface
• Exposed to bodys exterior or to internal organ
  cavity.
• Can be slick and smooth
• Can have cilia or microvilli
• Avascular

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All the way to the bottom

• Basement membrane
• Lower surface of an epithelium rests on this
• Nutrients are supplied through this membrane by
  diffusion

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Epithelial classification. They have two names.

• Number of layers
• Simple, one very thin layer, little protection
• Stratified, two or more layers
• Shape can vary in different layers therefore
  they are named by cells in the apical surface
• Squamous-flat
• Cuboidal cube shaped
• Columnar tall closely packed
• Transitional changes from cuboidal to squamous

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Naming a cell

• Simple squamous
• Stratified squamous
• Simple columnar
• Stratified columnar

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Simple squamous

• One layer
• Rests on basement layer
• Usually forms membranes where filtration or
  exchange of substances by rapid diffusion occurs
• Form serous membranes which line the ventral body
  cavity and its organs.

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Simple cuboidal

• One layer of cuboidal cells
• Rest on basement membrane
• Common in glands (salivary and pancreas)
• Forms walls of kidney tubules and ovary surfaces

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Simple columnar

• Made up of single layer of tall cells that fit
  closely together
• Have goblet cells which produce lubricating mucus
• Found in digestive tract
• Mucosa are mucus membranes

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Pseudostratified ciliated columnar epithelials

• All rest on basement membrane
• Some are shorter than others and do not go to
  surface
• Pseudo because it only gives the appearance of
  being stratified
• In the respiratory tract are pseudostratified
  ciliated columnar epithelials

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Suffixes for cells

• Blast immature stage in cellular development
  before the appearance of the definitive
  characteristics
• Matrix ground work on which anything is cast

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Connective Tissue

• Connects body parts
• Most abundant tissue type in body found
  everywhere in the body
• Protect, support, bind together, transport of
  substances within the body
• Made up of widely scattered cells that lie within
  a large amount of matrix (non living material)

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More connective

• Composed of intercelluar matrix, fiber and cells.
  The largest majority is matrix
• Matrix is the link that connects all types of
  connective tissue.
• Matrix is created by a blast cell. The different
  types of connective tissues are distinguished by
  changing matrix

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Matrix

• Extracellular matrix is a non living substance
  outside of the cells

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Matrix function

• Forms packing tissue around organs
• Allows organs to bear weight and withstand
  stretching and abuse
• Can be soft as in fat
• Bone and cartilage has large amounts of hard
  matrix making them strong

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To sum this all up All connective tissue

• Consists of living cells surrounded by a matrix
• Their major differences reflect fiber type and
  the number of fibers in the matrix

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Types of connective tissue

• Cartilage
• Bone
• Loose connective tissue few fibers, more cells
• Dense connective tissue
• Areolar tissue
• Adipose
• Reticular connective
• Blood

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Areolar

• Soft, pliable, cobwebby. Universal packing
  material
• Cushions and protect the body organ it wraps
• Acts like a glue, but allows movement.
• Body cells get nutrients from and release wastes
  into this tissue fluid
• When inflammation occurs, it soaks up excess
  fluid like a sponge, swells up and becomes puffy
  (edema)

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Adipose

• Also known as fat.
• Signet ring cells
• Forms subcutaneous layer Insulating padding
  between organs, shock absorber
• As mature cells they cannot reproduce
• Store energy as fat
• Matrix is gooey and slimy in abdomen, hips,
  behind eyeball

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Reticular connective

• 3D web appearance. Purpose, like a spider web,
  to catch something
• Stroma is the internal supporting framework which
  can support many free blood cells in lymphoid
  organs such as tonsils, spleen, lymph nodes and
  bone marrow

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Blood components

• Consists of
• A non living fluid matrix called plasma
• Red blood cells
• White blood cells
• Platelets
• Blood carries nutrients, wastes, respiratory
  gases and other substances through out the body.

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Cartilage types

• Hyaline most common type
• Larynx, ends of bones at joints, skeleton of a
  fetus
• Fibrous (intervertebral disks vertebra)
• Elastic external ear, end of nose
• Costal connect ribs to sternum

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Dense Connective

• Tendons attach skeletal muscle to bone
• Ligaments connect bone to bone

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Bone

• Made of osseous tissue
• Bone cells sitting in cavities called lacunae
• Haversian system supplies blood
• Hardness prevents osmosis
• Bone cells are called osteocytes
• Matrix is hard, calcified, minerals and salts
• Canalculi means small canals

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Muscle Tissue

• Primary function is to contract
• Three types
• Skeletal
• Cardiac
• Smooth

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Skeletal muscle

• Attached to the skeleton
• Voluntary muscles
• Cells are long, cylindrical, multinucleate with
  obvious striations.

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Cardiac muscle

• Found only in the heart
• Uni-nucleate
• Fit together at junctions called intercalated
  disks
• Involuntary muscle

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Smooth muscle

• Smooth, no striations
• Uninucleate
• Found in hollow organs, such as stomach, bladder,
  uterus and blood vessels
• Moves usually by peristalsis

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Nervous tissue

• Usually called neurons
• Two major functions are irritability and
  conductivity
• Make up nervous system brain, spinal cord and
  nerves