PP13 Tissue Structure and Organization 1

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PP13Tissue Structure and Organization 1

• Chapter 2 pg 7-18
• ANS 3043
• University of Florida
• Dr. Michael J. Fields

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Introduction

• Cells
• Living structural units within the body
• Contain properties that allow them to function in
  a specific manner
• Aggregates of cells form tissues
• Tissues
• Groups of closely related cells that act
  synergistically to perform specific functions
• Muscle, Connective, Nervous, Epithelial

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Tissues

• Epithelium (Figure 2.1 Table 2.1)
• Location Thin tissue layer that covers all free
  surfaces of body
• External and Internal
• Positioned tightly together and possess minimal
  extracellular substances
• Function Protection of exposed surfaces
• Dermis of skin, oral and nasal cavities
• Lining of digestive and respiratory tracts
• Sensory communication with nervous system (taste
  and sight)
• Nerves associated with surface epithelium

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Tissues

• Endothelium
• Location Covers innermost areas of capillaries
• Function Nutrients cross and enter adjacent
  tissues
• Cellular metabolites diffuse across and re-enter
  circulation
• Secretory Cells
• Function Package and transport products to cell
  surface for release
• Enzymes (proteins) in digestive tract
• Lubricants (CH20) like mucous to reduce friction

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Classification

• Related to function
• Epithelial Tissue
• Structure (Cell Stratification)
• Simple Single layer of cells located where
  maximal secretion and absorption are needed
• In well protected areas
• Stratified multiple layers of cells located
  where there is friction
• Skin
• Extremities of digestive tract

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Classification

• Cell Shape
• Squamous thin and flat cells in one dimension
  but broad in other two
• Cuboidal box-like structure where all
  dimensions are equal
• Columnar slender, elongated cells with nucleus
  at base of cell
• Transitional Epithelium resembles stratified
  cuboidal but changes dramatically with distension
  of tissue (bladder, urinary tract)

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Digestive
Thyroid
Vagina
Endothelium
Bladder
Skin
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Classification

• Ciliation
• Improves absorptive and secretory abilities by
  increasing surface area
• Aides in movement of material along border
• GI tract, Oviduct, Vas Efferens

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Thyroid
Digestive
Endothelium
Bladder
Vagina
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Examples of Types of Epithelium
only found here
cells take abuse
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Connective Tissue

• (Figure 2.2)
• Contains a rich extensive extracellular matrix
  that contains few active cells to provide
  structural framework for cell, tissues and organs

Helps to stretch
Secretes collagen
Breaks down cells
Secretes histamine
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Connective Tissue

• Connective Tissue Proper
• Extracellular Substance
• Ranges from a semi-solid glue like substance to a
  rigid amorphous material that contains various
  fibers and cells
• Ground Substance consist of proteoglycans
  (proteins Carbohydrates)
• Hyaluronic acid viscous substance found in
  synovial fluid

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Connective Tissue

• Cell Types
• Macrophages ameboid cells that consume damaged
  cells and foreign substances
• Fibroblasts anchored to connective tissue
  matrix and are responsible for production of
  fibrous proteins that reinforce the amorphous
  structure of the cell

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Connective Tissue

• Types of Connective Tissue Fibers
• Collagen Fibers (Collagen) most abundant
  protein in the body (20-30)
• Primary sequence is in alpha chain
• Contains multiple repeating units of amino acids
• x glycine proline hydroxyproline glycine
  X
• (x any amino acid)
• Represents helical part of molecule and provides
  stability
• Non-helical part on ends, which allow alignment
  of alpha chains

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Connective Tissue

• Collagen
• Synthesized from fibroblasts
• Procollagen three alpha helices linked by
  disulfide bonds in the non-helical portion of
  molecule
• Cross linking of collagen molecules gives it
  strength
• Types of Collagen (11 Known)
• Designated by which alpha helical chain comprises
  the triple helical molecule
• Differences in amino acid sequence (Affects
  structural strength and functionality of
  different collagens)
• Type 1 Comprises 80 of total collagen in skin
  and muscle tissue

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Collagen Types and Location in Animal Tissues
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Connective Tissue

• Reticular Fibers
• Formed similar to collagen but without large
  bundles
• Small (35 nm) and delicate with abundant ground
  substance
• Location in body
• Found in parenchyma surrounding many organs

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Connective Tissue

• Elastic Fibers (Elastin)
• Figure 2.7
• Very elastic and capable of reversibly stretching
  to twice their length
• Composed primarily of desmosine and isodesmosine
  (special amino acids)
• Synthesized from fibroblasts
• Secreted as a precursor molecule (tropoelastin)
• Cross linked after secretion
• Location Blood vessels, Ligaments, Lungs and
  Skin

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Elastic Connective Tissue of Aorta
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Connective Tissue Location in Body Tissues