Lect3 BIOSCI

Lecture 3: Connective Tissues

  • Instructor: Anthony Phillips

  • Course: BioSci 107

  • Date: 2025

The Functions of Connective Tissue

  • Binding and Support:

    • Connective tissue (CT) binds, supports, and strengthens other tissues in the body.

  • Transport System:

    • Blood, a type of connective tissue, serves as a major transport system for the body.

  • Energy Reservoir:

    • Adipose tissue (fat) acts as a significant energy reserve.

Features of Connective Tissue

  • Differences from Epithelia:

    • CT is not found on body surfaces (e.g., bones, cartilage, blood).

    • Can be highly vascularized, unlike cartilage which is avascular and tendons with minimal blood supply.

  • Similarities to Epithelia:

    • CT is supplied by nerves (except cartilage).

Composition of Connective Tissue

  • Connective tissue is made up of:

    • Extracellular Matrix (ECM): The non-cellular component.

    • Cells: Various specialized cells that function within the ECM.

Extracellular Matrix (ECM)

  • Components:

    • Composed of a ground substance (GS) and protein fibers.

    • Ground Substance: Includes water, proteins, and polysaccharides.

  • Protein Fibers: Three major types:

    1. Collagen Fibers: Strong and flexible support.

    2. Reticular Fibers: Form neetworks for support (thin, branching structure).

    3. Elastic Fibers: Allow tissues to stretch and return to shape.

  • Function of ECM: Dictates the properties of the various types of connective tissue (e.g., cartilage is firm and rubbery).

Ground Substance Composition

  • Key Ingredients:

    • Water

    • Proteins (e.g., gelatin)

    • Polysaccharides (e.g., glycosaminoglycans, or GAGS)

  • Types of GAGS:

    • Mucopolysaccharides that bind to core proteins forming proteoglycans.

Types of Glycosaminoglycans (GAGS)

  • Sulphated GAGs:

    • Examples include dermatan sulfate, heparin sulfate, keratan sulfate, and chondroitin sulfate.

  • Non-Sulphated GAGs:

    • Hyaluronic acid, responsible for water retention in the ground substance.

Applications of GAGS

  • Hyaluronic Acid:

    • Lubricates joints, maintains eye shape, and aids in cell binding.

  • Chondroitin Sulphate:

    • Provides support in cartilage, bone, skin, blood vessels.

  • Keratan Sulphate:

    • Present in cartilage, corneas, and bone.

Connective Tissue Cell Types

  • Fibroblasts:

    • Primary cells that secrete matrix components.

  • Adipocytes:

    • Store energy in the form of fat.

  • Macrophages:

    • Phagocytic cells that help in immune response.

  • Plasma Cells:

    • Derived from B lymphocytes; produce antibodies.

  • Mast Cells:

    • Release histamine to mediate inflammatory responses.

  • Leukocytes:

    • White blood cells that play key roles in immunity.

Classification of Connective Tissue

  • Types:

    • Embryonic Connective Tissue: Mesenchyme and mucous tissue.

    • Mature Connective Tissue:

      • Connective Tissue Proper: Loose and dense connective tissues.

      • Fluid Connective Tissue: Blood and lymph.

      • Supporting Connective Tissue: Cartilage and bone.

Types of Mature Connective Tissue

  • Loose Connective Tissue:

    • Includes areolar, adipose, and reticular tissues.

  • Dense Connective Tissue:

    • Divided into dense regular, dense irregular, and elastic tissues.

  • Cartilage Types:

    • Hyaline, elastic, and fibrocartilage.

  • Bone Types:

    • Compact and spongy bones.

Bone Structure

  • Compact Bone:

    • Composed of tightly packed units called osteons.

  • Spongy Bone:

    • Porous structure found beneath compact bone, lacking osteons.

Cellular Components of Bone

  • Osteogenic Cells:

    • Stem cells that develop into bone-forming cells.

  • Osteoblasts:

    • Responsible for bone formation.

  • Osteocytes:

    • Mature bone cells that maintain bone tissue.

  • Osteoclasts:

    • Cells involved in bone resorption.

Structure of Osteons

  • Parts:

    • Lamellae: Concentric rings of minerals and collagen.

    • Lacunae: Spaces containing osteocytes.

    • Canaliculi: Tiny canals facilitating nutrient exchange.

    • Central canal: Houses blood vessels, lymphatic vessels, and nerves.

Healing Process in Bone

  • Depicts stages from injury, through inflammation, callus formation, to remodeling.

Liquid Connective Tissue: Blood

  • Composed of blood plasma and formed elements (red blood cells, white blood cells, and platelets).

  • Function of Blood Cells:

    • Red blood cells transport gases; white blood cells are involved in immune responses.

Conclusion

  • Connective tissue is essential for binding, supporting, and protecting other tissues and organs in the body. It plays a critical role in transportation, energy storage, and storage of key Components.