Tissue Level of Organization

• Concept of Tissues - can be traced back to 1801 when it was introduced by Xavier Bichat
• Xavier Bichat - a French anatomist and pathologist
• Tissue - They form a cellular organizational level, intermediate between the cells and organ system.
• Histology - study of tissue
• Histopathology - study of disease-related to tissue
• Four Major Types of Tissue

  1. Epithelial
  2. Connective
  3. Nervous
  4. Muscle
• Epithelial Tissue - which are commonly referred to as epithelium
• Epithelial Tissue - It is involved in permeability: the movement of materials through the process of filtration, diffusion and secretion.
• Epithelial Cell Shape

  1. Squamos
  2. Cuboidal
  3. Columnar
  4. Transitional
• Squamous cell – are flattened irregularly round cells filled with cytoplasm possessing a small round nucleus at the center
• Cuboidal Cells – are tall as they are wide and are shaped like cubes or hexagons
• Columnar Cell – are much taller than they are wide, like columns and protect underlying tissue
• Transitional Cell – changes shape, from squamous to cuboidal and back, organs such as urinary bladder stretches (distend) to a larger size and the collapse to a smaller size
• Arrangement in Cell Layers

  1. Simple Epithelium
  2. Pseudostratified Epithelium
  3. Stratified Epithelium
• Three Types of Simple Epithelium

  1. Squamos
  2. Cuboidal
  3. Columnar
• Simple Epithelium - is composed of a single layer of cells which mainly make up the linings of ducts, tubes and other cavities in the body
• Squamous epithelium: It is a simple single-layered epithelium.
• Cuboidal epithelium - The tissue is made of cube-shaped cells.
• Columnar epithelium: It is composed of tall and slender, column-shaped.
• Pseudostratified Epithelium – made up of closely packed cells that appears to have multiple layer of cells because the cell nuclei lie at different levels and different sizes
• Stratified Epithelium – made up of two or more layers of cells that protect underlying tissues in locations where there is considerable wear and tear
• Connective Tissue - It is made up of cells, fibers, and a gel-like substance
• Types of Connective Tissues

  1. Aerolar
  2. Adipose
  3. Blood
  4. Bone
  5. Cartilage
• Connective Tissue - binds structures together, thus establishing a framework for the body and support organs as a whole
• Two Connective Tissue Proper

  1. Loose
  2. Dense
• Connective Tissue Proper – includes those with many types of cells and extracellular fibers and is divided into two
• Loose – fibers create loose, open framework
• Dense – fibers densely packed
• Loose Tissue

  1. Aerolar
  2. Adipose
  3. Reticular
• Areolar Tissue – serves as a reservoir of water and salts
• Adipose Tissue – found deep in the skin (flanks, breasts and buttocks) and around internal organs
• Reticular Tissue – creates and maintains the fine networks of fibers that provides support and resist distortion and serves as the framework for most lymphoid organs
• Dense Tissue

  1. Dense Regular
  2. Dense Irregular
  3. Elastic
• Dense regular – found in cords
• Dense irregular – has fibers not arranged in parallel bundle forming an interwoven meshwork in no consistent pattern
• Elastic – consist of fibroblasts and densely compacted parallel bundles of fibers
• Tendons - muscles to bone
• Ligaments - bone to bone
• Fluid Connective Tissues – have distinctive populations of cells suspended in a watery matrix that contains dissolved proteins
• Fluid Connective Tissues

  1. Blood
  2. Lymph