httpslearn-us-east-1-prod-fleet02-xythos.content.blackboardcdn.com61aab133e7df2201495419X-Blackboard-S3-Bucket=learn-us-ea

Chapter 4: Histology

Introduction to Tissue

• Tissue: Consists of cells and extracellular matrix (ECM).

• Main components of tissue include cells and their surrounding matrix.

Types of Tissues

• Excitable Tissues: Not covered in detail here.

• Non-Excitable Tissues: Classifications based on cell density and matrix composition.

Tissue Decision Tree for Non-Excitable Tissues

• Tightly-packed cells with little to no matrix:

  • Indicates Epithelium.

• Fewer cells with a larger quantity of matrix:

  • Indicates Connective Tissue.

Types of Connective Tissue

• Fibroblast: Main cell type in connective tissue.

• Connective Tissue Proper vs Specialized Connective Tissue:

  • Connective Tissue Proper (CTP):

    • Contains fibroblasts as the primary cell type.

  • Specialized Connective Tissue:

    • Different characteristics and functions.

Matrix Composition

• Loose (Areolar) CTP:

  • More ground substance (GS), fewer fibers.

• Dense CTP:

  • Packed fibers, less ground substance.

Observational Note

• Tissue appearance:

  • Common observation: "But it all looks pink!"

  • Dark circles represent nuclei, indicating the presence of epithelium underneath which is connected to connective tissue.

  • Bright red cells without nuclei are identified as red blood cells indicating blood vessels in connective tissue.

Epithelial Tissue Classification

• Simple Epithelia: One layer of cells.

  • Includes:

    • Simple squamous epithelium

    • Simple cuboidal epithelium

    • Simple columnar epithelium

    • Pseudostratified columnar epithelium (is technically simple)

• Stratified Epithelia: Multiple cell layers.

  • Includes:

    • Stratified squamous epithelium

    • Transitional epithelium (also stratified)

Epithelial Cell Functionality

• Transport Across Simple Epithelia:

  • Highlights the specific function and utility of simple epithelial types.

Epithelial Cell Cancer

• Carcinoma: Refers to cancer developed in epithelial cells.

Summary of Connective Tissue Types

• Cells of Connective Tissue Proper include:

  • Loose (Areolar) Connective Tissue

  • Dense Irregular Connective Tissue

  • Dense Regular Collagenous Connective Tissue

  • Reticular Tissue

  • Adipose Tissue