Human Histology (Lecture)

• Histology


  The science that deals with the study of normal tissues
• Histology


  • Prelude to pathology
  • Prerequisite to Histopathology
• Observation


  Key to identifying cell types through microscope
• Pathology


  The study of abnormal tissues with altered structure and function of the body, organs, tissues, and cells
• Tissues


  Groups of cells that have similar structure and intercellular materials interrelated to perform a specific function
• Cytology


  The study of cells
• Cells


  The basic unit of life, composed of all living things
• Mitosis


  The division of a cell into two daughter cells that are genetically identical to the parent cell
• Meiosis


  The division of germ cells resulting in four daughter cells which are not identical to the parent cell
• Anton Von Leeuwenhoek - first person to observe and describe living cells using his handheld microscope


  16th Century
• Robert Hooke - English microscopist and physicist who observed a slice of cork under a microscope and discovered many small compartments like honeycomb structures, which he called cells


  17th Century
• Marcelo Malphigi - Italian anatomist, the true father of histology, who first described true units forming animal tissues using simple lenses

  17th Century
• Anton Von Leeuwenhoek - developed compound lenses and was the first to describe the nucleus while examining the red blood cells of salmon


  17th Century
• Robert Brown - introduced the nucleus, observing small dense centers in plant cells but their function was yet unknown


  17th Century
• Marie Francois Bichat - French pathologist who termed tissues as textures, different groups of cells


  18th Century
• Matthias Schleiden - proposed cell theory for plants


  18th Century
• Theodor Schwann - described that animals are made of cells and discovered cells that form the sheath surrounding nerves


  18th Century
• Friedich Gustav Jacob Henle - published the first human histology


  18th Century
• Max Schultze - first described cells as mass of nucleated protoplasm


  19th Century
• Rudolf Virchow - described human body as "Cell state" and that all diseases involved changes in normal cells


  19th Century
• Gross Anatomy


  Division of Anatomy
• Microscopic Anatomy


  Division of Anatomy, including Cytology, Histology, and Organology
• Three elements that compose the human body

  • Cells
  • Intercellular Substances
  • Body fluid
• Eukaryotic cells


  Cells with true nucleus, nuclear envelope, histones, and numerous membrane-limited organelles
• Prokaryotic cells


  Cells without true nucleus, nuclear envelope, histones, and membrane-limited organelles (usually absent)
• Cell Membrane/Plasmalemma


  Regulates entrance and exit of nutritive and excretory substances, acts as a selective barrier
• Protoplasm


  All that is inside the cell membrane, including organelles, inclusion bodies, and nucleus
• Cytoplasm


  All contents outside the nucleus, containing organelles and inclusion bodies, and a matrix embedding them
• Physiologic properties of protoplasm

  • Irritability
  • Contractility
  • Conductivity
  • Respiration
  • Absorption/Endocytosis
  • Exocytosis
  • Growth and Reproduction
• Chemical composition of cytoplasm

  • 75% water
  • 1% salt
  • 3% lipids
  • 1% carbohydrates in the form of glycogen
  • 20% CHON
  • Cations: Na, K, Ca, Mg
  • Anions: phosphates, bicarbonates, chlorine
• Cytoplasmic organelles


  • Mitochondria
  • Lysosome
  • Centrosome
  • Golgi Apparatus/Dictyosome
  • Endoplasmic Reticulum
  • Ribosome
  • Fibrils
  • Microtubules
  • Microbodies/Peroxisome
• Cytoplasmic inclusion bodies


  • Vacuoles/Vesicles
  • Lipid/Fat Droplet
  • Glycogen Granules
  • Pigment Granule
  • Secretory/Zymogen Granules
  • Mucigen Droplets
• Nucleus


  Stains blue, basophilic, unifies, controls, and integrates cell function, controls biochemical reactions and reproduction, repository of complete set of heredity
• Parts of a nucleus

  • Nuclear Membrane
  • Nucleoplasm/Karyoplasm
  • Nuclear Chromatin/Chromatin Granules
  • Nucleolus
• Eukaryotic cell cycle periods

  • G1: Initial Gap
  • S Stage: Synthetic Stage
  • G2: Second Gap
  • Mitosis
• Cells have limited life cycle, with RBC life cycle of 120 days
• Cell division occurs in all adult cells except the cells of the central nervous system
• Cell division involves both Cytokinesis and Karyokinesis
• Nuclear envelope


  Skin around nucleus, selective barrier between cytoplasm and nucleoplasm
• Nucleoplasm/Karyoplasm


  Base material of the nucleus where nuclear chromatin and nucleolus are suspended