Glycosaminoglycans and Hyaluronic Acid Quiz

Ground Substance

• Composed of a mixture of water, proteins (e.g., gelatin), and polysaccharides (sugars)
• Glycosaminoglycans (GAGS) join with core proteins to form proteoglycans
• GAGS are long, unbranched polysaccharides with repeating disaccharide units
• Amino sugar examples: N-acetylglucosamine, Uronic sugar examples: glucuronic acid

Hyaluronic Acid

• A glycosaminoglycan (GAG) that is not sulfated or covalently bound to a core protein
• Forms a viscous, slippery substance that binds cells together, lubricates joints, and maintains the shape of the eyeball
• Hyaluronidase breaks down hyaluronic acid, making the ground substance more liquid

Applications of GAGS

• Hyaluronic acid: lubricates joints, maintains eyeball shape, and binds cells together
• Chondroitin sulfate: provides support and adhesive features in cartilage, bone, skin, and blood vessels
• Keratan sulfate: found in bone, cartilage, and cornea of the eye
• Dermatan sulfate: found in skin, tendons, blood vessels, and heart valves

Abnormal ECM and Thyroid Disease

• Exophthalmos (bulging eyes) is associated with abnormal ECM deposition and thyroid disease (goiter)
• Autoimmune over-activation of thyroid gland and autoimmune action on fibroblasts in ECM of the eye

Connective Tissue and Extracellular Matrix

• CT = ECM + Cells
• ECM = GS + Fibers
• ECM is composed of ground substance and fibers
• Ground substance is composed of water, proteins, and polysaccharides (GAGS)

Bone Structure

• Osteon structure consists of lamellae, lacunae, canaliculi, and central (Haversian) canal
• Lamellae: concentric rings of mineral salts and collagen for hardness and tensile strength
• Lacunae: small spaces between lamellae that contain mature bone cells (osteocytes)
• Canaliculi: minute canals that radiate from lacunae and provide routes for oxygen, nutrients, and waste
• Central (Haversian) canal: contains blood, lymph, and nerves

Mature Connective Tissues

• Blood: liquid connective tissue composed of plasma (ECM) and formed elements (red cells, white cells, and platelets)
• Erythrocytes transport oxygen and carbon dioxide, while leukocytes combat disease through phagocytosis

Test your knowledge about glycosaminoglycans (GAGs) and hyaluronic acid, including their functions and properties in the body. Explore the role of hyaluronic acid in lubricating joints, binding cells together, and maintaining the shape of the eyeball.