The circulatory system functions to deliver needed materials to cells, remove waste from cells, and fight off infections. It consists of the heart with four chambers that pump blood through two pathways - the pulmonary circuit which sends blood to the lungs to exchange gases and the systemic circuit which pumps oxygenated blood to the body. Blood vessels including arteries, veins, and capillaries transport blood and allow for the exchange of materials between blood and body cells. The heart beat and pulsing blood flow are controlled to maintain healthy blood pressure levels, while diseases can occur if the circulatory system is compromised.

1. Circulatory System 6th Grade Science

2. I. Function A. Deliver needed materials to cells B. Removing waste from cells C. Fighting off infection

3. II. Parts Heart 1. Muscle to pump blood 2. Four chambers i. 2 Atrium (top) ii. 2 Ventricle (bottom) 3. Valves to separate flow

4. 4. Pathway From Body From Lung RA LA RV LV To Lung To Body

6. 4. Pathway ii. Pulmonary Circuit a. Send CO2 blood from right side heart to lungs b. Lungs remove CO2 and replace with O2 c. Return to left side of heart

7. 4. Pathway iii. Systemic Circuit a. Send O2 blood from left side heart to body b. Cells remove O2 and replace with CO2 b. Return to right side of heart

8. 5. Heart Beat i. Top heart contracts together a. Valves close (Lub) ii. Bottom heart contracts together a. Larger Valves close (Dub)

9. B. Blood Vessels Arteries Carry blood away from heart Veins Carry blood toward the heart Capillaries i. Where body exchanges materials

10. 4. Controlling blood flow i. Pulsing blood flow a. Heart beats (high number) - top b. Heart relaxes (low number) – bottom c. Healthy numbers 120/80

11. ii. Veins a. Valves to help return blood b. Muscles help return blood

12. III. Diseases A. Atherosclerosis B. Heart Attack C. Hypertension 140/90