Cell Differentiation, Tissues, and Cancer Notes

Cell Differentiation, Tissues, and Cancer
  • Learning Outcomes
    • D2.1: Describe the relationships of organs to tissues to cells.
    • D2.2: Explain the function of epithelial cells within organs.
    • D2.3: Explain why epithelial cells are particularly vulnerable to carcinogens.
    • D2.4: Explain why most cancers originate from epithelial cells.
Normal Cells
  • Understanding what constitutes a "normal cell" is essential in defining cancer.
Levels of Organization
  • Cells: Simplest unit of organization.
  • Tissues: Groups of similar cells.
  • Organs: Collections of tissues functioning together.
  • Organ Systems: Comprise various organs working collectively.
  • Organism: Complete living entity made of organ systems.
Epithelial Tissues
  • Composition: Various shapes and sizes of epithelial cells arranged in single or multiple layers.
  • Function: Lines and covers internal and external body surfaces (e.g., cavities and organs), with roles in protection, secretion, and absorption.
Specialized Epithelial Cells
  • Glandular Epithelium:
    • Location: Glands.
    • Function: Secretes substances like hormones and proteins.
  • Olfactory Epithelium:
    • Location: Nasal cavity.
    • Function: Contains cilia that detect odor molecules.
Types of Epithelial Cells - Arrangement
  • Simple: One layer of cells.
  • Stratified: More than one layer.
  • Pseudostratified: Appears stratified due to varying cell heights but is a single layer.
Types of Epithelial Cells - Shape
  • Squamous: Flat and sheet-like.
  • Cuboidal: Cube-like.
  • Columnar: Column-like.
Squamous Epithelial Cells
  • Function: Provide cover and protection.
  • Location: Skin, lining of throat, esophagus, lungs.
Cuboidal Epithelial Cells
  • Function: Secretion.
  • Location: Breasts (milk, hormones) and ovaries (hormones).
Columnar Epithelial Cells
  • Function: Absorption.
  • Location: Intestines and stomach.
Transitional Epithelial Cells
  • Function: Allow for organ stretching.
  • Location: Bladder and genital tracts.
Specialized Cell Functions
  • Organs consist of specialized cells forming tissues for specific functions necessary for organ operations.
Organ Systems and Functions
  • Epithelial Tissue Types:
    • Epithelial, muscular, nervous, connective tissues constitute all organs.
    • Each organ contains at least two of these four tissue types.
Organ Structure: Parenchyma and Stroma
  • Parenchyma: Main functional tissue of an organ.
  • Stroma: Supporting tissue of an organ.
Examples of Organs and their Tissues
  • Heart: Muscle, blood vessels, nerves.
  • Lung: Epithelial cells, blood vessels, connective tissue.
  • Breast: Epithelial cells, blood vessels, nerves.
  • Skin: Epithelial cells, blood vessels, nerves.
Vulnerability of Epithelial Cells to Carcinogens
  • Cancer Statistics: 85% of all cancers involve epithelial cells.
  • Epithelial cells have high turnover rates.
  • Mutations accumulate, leading to cancer development.
Carcinomas
  • Definition: Cancers that originate from epithelial cells.
  • Types of Carcinomas:
    • Squamous cell carcinoma
    • Cuboidal cell adenocarcinoma
    • Columnar cell adenocarcinoma
    • Transitional cell carcinoma
  • Note: Sarcomas are cancers of stromal cells. Only carcinoma arises from epithelial cells.
Conclusion
  • Understanding the function and structure of epithelial cells is crucial in cancer studies, specifically why most cancers arise from them due to their vulnerability to carcinogens.