Transport Mechanism

• • Transport Mechanisms: Animals have evolved various mechanisms for material transport within their bodies.
  • Sponges and Diploblasts: Depend on their aquatic environment for transport.
• • Acoelomate Flatworms: Survive with a short body distance, allowing efficient diffusion for waste and respiratory gases.
  • Circulatory Systems: Essential for larger or more active animals.
• • Annelid Worms: Exhibit a closed circulatory system with a pump, arterial distribution, capillaries, venous reservoirs, and return system.
  • Hemocoel: Open circulatory system in invertebrates, replacing blood capillaries in insects and some mollusks.
• • Closed System vs. Open System: Closed system found in annelids, cephalopod mollusks, and vertebrates; open system in many invertebrates.
  • Heart in Arthropods: Located in the hemocoel, with ostia for blood entry and a limited arterial system.
• • Respiratory Systems: Insects and some arthropods have a separate respiratory system (tracheal system or book lungs).
  • Closed Circulation in Mammals and Birds: Blood confined within channels for effective gas and nutrient exchange.
• • Components of Closed Circulation System: Atria, ventricles, AV valves, semilunar valves, papillary muscles, chordae tendineae, coronary arteries, coronary veins, aorta, pulmonary artery, pulmonary veins.
  • Single Circulation vs. Double Circulation: Types of closed circulatory systems.
• • Single Circulation Example: Fishes with a two-chambered heart, where blood flows in a single pathway.
  • Double Circulation Example: Birds and mammals with a four-chambered heart, having two separate pathways for pulmonary and systemic circulation.
• • Double Circulation Characteristics: Oxygenated and deoxygenated blood do not mix in the heart.