Circulatory System 2

1. Circulatory System 2 11.3 & 11.4

2. Blood Vessels • arteries • arterioles • capillaries • venules • veins

3. Arteries • carry blood away from the heart toward body tissues • the aorta • elasticity of the walls ensures constant flow of blood

5. Arterioles • smallest arteries • smooth muscles in arterioles can cause vasoconstriction or vasodilation • diverts blood flow toward areas of need, e.g., during exercise, cold temperatures, etc.

6. Capillaries • smallest blood vessels • no body cell is further than 2 cells away from a capillary • site of gas, nutrient, waste exchange

8. Venules & Veins • carry blood toward the heart • Smooth muscle layer not as thick (not as elastic) • valves & skeletal muscles ensure blood flow

9. The Lymphatic System

11. Circulatory Functions • lymphatic system helps ensure that blood volume is maintained • collects excess tissue fluids (lymph) and returns it to the blood

12. Immune System Functions • removes bacteria & other harmful components from blood • lymph nodes are enlargements where leukocytes gather • spleen is a filtering station & reservoir of erythrocytes & leukocytes • Animation: http://kids.britannica.com/lm/animations/olympha001d4/product.html

13. The Heart

16. Structures… • septum • pericardium • semilunar valves • atrioventricular valves

18. Cardiac Cycle • diastole = ventricles relaxed (blood fills ventricles) • systole = ventricles contracted (blood is pumped from the ventricles) • sounds of heartbeat caused by the valves closing (AV valves during systole & semilunar valves during diastole)

19. Animation • Heartbeat animation: • http://www.nhlbi.nih.gov/health//dci/Diseases/hhw/hhw_pumping.html