1. The Circulatory System

2. The human circulatory system consists of the heart, a series of blood vessels, and the blood that flows through them

3. The Heart A hollow organ composed mostly of muscles About the size of a clenched fist The heart is enclosed in a protective sac called the pericardium The heart contracts roughly 72 times a minute, moving the blood (about 5 Liters) once around the body

4. The Heart (cont…) The heart is divided into two sides (left & right) by the septum. This prevents the mixing of O 2 poor blood with O 2 rich blood. Four valves in the heart prevent backflow

5. The heart functions as two separate pumps The left side pumps blood through the body and back to the heart, this pathway is known as systemic circulation The right side pumps blood to and from the lungs, this is known as pulmonary circulation

6. Blood moves from the heart to the lungs and back to the heart. Then it travels to all the cells of the body and returns again to the heart

7. The heart has 4 chambers Right Atrium Left Atrium Right Ventricle Left Ventricle

8. Blood flow through the heart 1. O 2 poor blood returns from the body to the Right Atrium, the Right Atrium pumps the blood to the Right Ventricle 2. The Right Ventricle pumps O 2 poor blood into the pulmonary arteries then to the lungs, where, the blood exchanges CO 2 for O 2

9. Blood flow through the heart 3. The pulmonary veins carry O 2 rich blood from the lungs back to the heart into the left atrium 3. The pulmonary veins carry O 2 rich blood from the lungs back to the heart into the left atrium 4. The left atrium pumps the O 2 rich blood into the left ventricle 4. The left atrium pumps the O 2 rich blood into the left ventricle 5. The left ventricle pumps O 2 rich blood into the aorta where it is sent to the entire body 5. The left ventricle pumps O 2 rich blood into the aorta where it is sent to the entire body

10. Follow the pathway……. Foot → de- oxygenated O 2 vein → right atrium → right ventricle → pulmonary arteries → lungs → gas exchange → oxygenated blood → pulmonary vein → left atrium → left ventricle → aorta → to body → to foot

12. Arteries: Blood vessels that direct blood away from the heart. They have thick elastic walls. Capillaries: The smallest blood vessels in your body. The allow nutrients, oxygen and other substances to diffuse through the capillary walls (which are one cell thick!) Veins: Blood vessels that direct blood back toward the heart. The veins have valves that keep the blood from backtracking.

13. Disorders of the Circulatory System

14. Artherosclerosis Fatty deposits called plaque build up on the walls of the arteries. If the deposits get too large, they obstruct blood flow Blood pressure increases (high blood pressure) Blood pressure increases (high blood pressure) Blood clots could form. If a clot breaks free, it can get stuck in an artery and obstruct blood flow Blood clots could form. If a clot breaks free, it can get stuck in an artery and obstruct blood flow

15. High Blood Pressure (Hypertension) Causes the heart to work harder May weaken or damage heart muscles and blood vessels Increases the risk for heart attack and stroke

16. Heart Attack Atherosclerosis in the coronary arteries may lead to a heart attack If one of these arteries becomes blocked, part of the heart muscle may begin to die due to lack of oxygen

17. Stroke A stroke occurs when blood clots (formed from atherosclerosis) break free and get stuck in one of the blood vessels leading to a part of the brain. Can also occur if a weakened artery in the brain bursts and fills the area with blood Strokes can cause paralysis, loss of speech or death