Connective Tissue

Connective Tissue Overview

  • Main Functions:

    • Connects structures

    • Provides support and protection

    • Fills spaces, stores fat, transports blood cells

    • Located deep to epithelial tissues, supplying nutrients due to epithelial avascularity

Characterization of Connective Tissue

  • Components:

    • Cells: Fibroblast is the most prevalent type

    • Extracellular Matrix (ECM):

    • Composed of ground substance (mostly water, minimal protein visible)

    • Contains fibers:

      • Collagen fibers: Thick bundles (stain pink, typically visible in various slides)

      • Elastic fibers: Thin, do not bundle (stain purple)

Classes of Connective Tissue

  • 1. Connective Tissue Proper:

    • Loose Connective Tissue:

    • Less fiber, more cells and ground substance

    • Includes areolar and adipose tissue

    • Dense Connective Tissue:

    • More fibers, less ground substance and cells

    • Includes dense regular (fibers in same direction) and dense irregular (fibers in multiple directions)

  • 2. Specialized Connective Tissue:

    • Includes blood, lymph (fluid), bone, and cartilage

    • Cartilage Types:

    • Hyaline Cartilage: Smooth, glassy, found at rib ends, contains chondrocytes in lacunae

    • Elastic Cartilage: Flexible, contains elastic fibers, found in epiglottis

    • Fibrocartilage: Contains dense collagen fibers for shock absorption, found in intervertebral discs

Specific Tissue Characteristics

  • Areolar Connective Tissue:

    • Fibroblasts, collagen, and elastic fibers in ground substance

  • Dense Regular Connective Tissue:

    • Fibroblasts' nuclei squished by collagen bundles

  • Adipose Tissue:

    • Stores fat, adipocytes with peripheral nuclei due to fat vacuole

  • Hyaline Cartilage:

    • Lacunae with chondrocytes, smooth ECM appearance

  • Elastic Cartilage:

    • Lacunae with chondrocytes, elastic fibers present

  • Fibrocartilage:

    • Many collagen fibers, found in intervertebral discs

Key Terms and Definitions

  • Fibroblast: main connective tissue cell

  • Extracellular Matrix (ECM): network providing support, made of ground substance and fibers

  • Lacunae: small spaces in cartilage where chondrocytes reside

  • Adipocyte: fat-storing cell in adipose tissue

  • Chondrocyte: cartilage cell

  • All connective tissues share an ECM that is crucial for their function, whether supporting, storing, or connecting different parts of the body.