Overview
This lecture covers the structure, function, and types of connective tissue, highlights the genetic disorder Marfan Syndrome, and explains how connective tissue abnormalities can affect the body.
Flo Hyman & Marfan Syndrome
- Flo Hyman was a professional volleyball player whose death at 31 was caused by Marfan Syndrome.
- Marfan Syndrome is a genetic disorder weakening connective tissue, often resulting in tall, thin individuals with long limbs and flexible joints.
- The disorder can cause serious issues in joints, eyes, lungs, and especially the heart and aorta.
Functions and Diversity of Connective Tissue
- Connective tissue is the most abundant and diverse tissue in the body.
- It supports, binds, protects organs, insulates, stores energy, and transports materials (like blood).
- Four main classes: connective tissue proper, cartilage, bone, and blood.
- Fat (adipose tissue) insulates, stores fuel, and helps hold organs in place.
Structure of Connective Tissue
- All connective tissue develops from embryonic mesenchyme.
- Vascularity varies: some have many blood vessels, others (like cartilage) have none.
- Majority of connective tissue is the extracellular matrix, not living cells.
Components of the Extracellular Matrix
- Ground substance: a flexible, watery material filled with proteins and starches, mainly proteoglycans and glycosaminoglycans (GAGs).
- Fibers: three main types—
- Collagen (strong, abundant, provides toughness),
- Elastic fibers (stretchy, allow flexibility),
- Reticular fibers (delicate, form networks for support).
Connective Tissue Cells
- Immature cells (ending in -blast, e.g., osteoblasts, chondroblasts) build matrix.
- Mature cells (ending in -cyte, e.g., osteocytes, chondrocytes) maintain the matrix.
- Some cells can revert to the blast stage for repair.
- Immune cells in connective tissue include macrophages (engulf invaders) and leukocytes (white blood cells fighting infection).
Marfan Syndrome and Connective Tissue Dysfunction
- Marfan Syndrome weakens elastic fibers, especially in the aorta, causing risk of rupture.
- Most patients develop heart and artery problems as the matrix loses support.
Key Terms & Definitions
- Connective tissue — Tissue supporting, binding, protecting other tissues/organs, storing energy, transporting substances.
- Mesenchyme — Embryonic tissue from which all connective tissues develop.
- Extracellular matrix — Nonliving material between cells, comprising ground substance and fibers.
- Proteoglycans — Protein molecules in ground substance anchoring GAGs.
- Glycosaminoglycans (GAGs) — Starchy strands that trap water and provide cushioning.
- Collagen fibers — Strong, flexible protein fibers providing structural support.
- Elastic fibers — Protein fibers that stretch and recoil.
- Reticular fibers — Thin, branching fibers supporting soft organs.
- -blast cells — Immature, matrix-secreting connective tissue cells.
- -cyte cells — Mature, matrix-maintaining connective tissue cells.
- Macrophages — Immune cells that engulf pathogens and debris.
- Leukocytes — White blood cells involved in immune defense.
- Marfan Syndrome — Genetic disorder weakening connective tissue, especially elastic fibers.
Action Items / Next Steps
- Review the four types of connective tissue and their functions.
- Prepare for next week’s lesson on connective tissue subtypes.
- Be ready to discuss how connective tissue abnormalities affect health.