The Circulatory System

1. The Circulatory System Transporting nutrients, waste, dissolved gases and other chemicals to and from the cells of the body. For warm blooded organisms - also helps maintain body temperature.

2. Organisms without a circulatory system • Single celled organisms – in direct contact with their environment • Simple multi-cellular organisms – thin layers of cells, thus diffusion is enough to transport nutrients and waste.

3. Components • All circulatory systems have: • A fluid to carry dissolved particles • Tubes for the fluid to flow • A pump that pushes the fluid through the tubes

4. Types of Circulatory Systems - OPEN • Found in most invertebrates • Fluid – hemolymph (blood and tissue fluid) • One or more hearts pump the hemolymph through vessels then empties into sinuses where it bathes the tissues directly • When the heart(s) relax hemolymph returns to the heart

5. Types of Circulatory Systems- Closed • Found in all vertebrates and some invertebrates (ex. earth worms) • Fluid usually blood • Blood is pumped by one or more hearts and is always contained in vessels • thus to get to cells particles have to diffuse across the blood vessel through the extracellular fluid and across the cell membrane

6. Various Hearts • 2,3 and 4 chambered hearts • Atria always receive blood from the body • Ventricles always pump blood to the body • Chambers are separated by a wall of tissue called a septum

7. Types of Circulatory Sytems-Closed – Two Circuit • Circulation to lungs, separate from circulation to the rest of the body • Pulmonary Circuit – heart to lungs and back • Systemic Circuit – heart to all other body tissues and back

8. HWK • Read 11.1 pg 478-481 • Questions pg 481 #1-6