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.