1. Respiration and Circulation Part 2 Biology 155 Krilowicz Spring 2010

2. II. Circulation: A. Components- 1. The cardiovascular system = heart + blood vessels Function = Circulates the blood to and from the tissues Fig. 23.3A

3. 2. The lymphatic system = lymph vessels + lymph nodes Functions – -immune defense - returns some fluid from the tissues Fig. 24.3

4. Return of excess fluid from the tissues via the immune system

5. B. Functions of the Circulatory System 1.Transport – oxygen, carbon dioxide, nutrients, wastes and hormones in blood 2.Blood clotting – to seal breaks in vessels, uses platelets and clotting proteins 3.Protection – internal defense using the white blood cells and the lymphatic system

6. C. Types of Circulatory Systems 1.None – a.Only used by small animals and/or those with low rates of oxygen use b.Circulation occurs due to simple diffusion through the body tissues

7. Examples of Animals That Lack a Circulatory System sponges (not shown) jellyfish flatworms sea stars

8. 2. 3. (Pump) Few vessels (Tissue sinuses) Few vessels Blood leaves vessels, loses pressure, thus low flow, low oxygen demand system large vessels (arteries, arterioles) Capillaries in tissues for exchange (pump) large vessels (veins) Blood stays in vessels, thus high pressure, high flow system for high oxygen demand Fig. 23.1

9. Examples of Animals with an Open Circulatory System clams Crayfish, shrimp, lobsters (not shown) insects as exception to low oxygen use rule (remember the tracheal system)

10. Examples of Animals with a Closed Circulatory System vertebrates from fish to mammals

11. D. The Vertebrate Circulatory System - 1.Blood consists of– a.Plasma = fluid with dissolved substances (examples – nutrients, hormones and most carbon dioxide) b.Cells and cell fragments – 1)White blood cells – defense 2)Red blood cells – oxygen transport 3)Platelets – blood clotting

12. 2. Vertebrate hearts and circulatory patterns - Note that the evolution of the four-chambered heart of the mammals and birds allows blood to be returned to the heart after exchanging gases at the lungs and to be pumped a second time before traveling to the tissues, needed for high oxygen demand associated with high body temperatures

13. Mammals and aorta Vena cava Atrium = receiving chamber Ventricle = pump Two-chambered heart with blood pumped once; lower pressure, lower flow system And thus blood is pumped twice for a higher pressure, higher flow system arteries (Pressure declines) CO 2 O2O2 O2O2 Pulmonary artery Pulmonary vein aorta Vena cava Left atrium Right ventricle Right atrium CO 2 O 2 CO 2 O 2 Fig. 23.2

14. 3. Generation of the heart beat – note that all cardiac cells are autorhythmic and contract on their own Pacemaker (fastest rate of contraction) = Electrical signals = action potentials pass due to intercalated discs (Holds signal before passing to ventricles, connective tissue between atria and ventricles prevents immediate passage of signal Fig. 23.5A