Chapter 17, Section 1 The Body’s Transportation System

1. Chapter 17, Section 1The Body’s Transportation System Monday, March 15, 2010 Pages 536 -- 542

2. Objectives • Describe the function of the cardiovascular system. • Describe the structure of the heart and explain its function. • Describe the origin of the heartbeat and why the heart rate changes during exercise. • Trace the path taken by blood through the circulatory system.

3. Cardiovascular system Heart Atrium Ventricle Valve Pacemaker Artery Capillary Vein Aorta Vocabulary Words

4. The Cardiovascular System • Also known as the Circulatory System. • Made up of: • Heart • Blood vessels • Blood • Carries needed substances to cells and carries waste products away from cells.

5. Movement of Materials • Substances that need to get from one part of the body to another are carried by the blood. • Wastes are also picked up and expelled through exhalation. • Transports cells that attack disease-causing microorganisms.

6. Cardiovascular System • Blood vessels reach the entire body. • RED represents arteries. Arteries are oxygen-rich. • BLUE represents veins. Veins are oxygen-poor.

7. The Heart • Hollow, muscular organ. • Pumps blood throughout the body. • Size of your fist. • Located in the center of your chest.

8. The Heart’s Structure • The heart has two sides: right and left. • Each side is completely separated from each other by a wall of tissue. • Each side has two compartments called chambers. • There is an upper and lower chamber on each side. • The upper chambers are called atria (atrium - singular). • The lower chambers are called ventricles.

9. The Heart

10. The Atrium • The atria are separated from the ventricles by valves. • Valves are flaps of tissue that prevents the backflow of blood. • The atria receive blood that comes into the heart.

11. The Ventricles • Located in the lower portion of the heart. • Pumps blood out of the heart.

12. How The Heart Works • Two main phases. • Heart muscles relax and the atria fill with blood. • The atria contract and fill the ventricles and the ventricles contract to pump blood forward. (The sound of your heartbeat is made by this pumping phase.) • This process happens in less than a second.

13. The Valve • It is a flap of tissue that prevents the backflow of blood.

14. Pacemaker • A group of cells located in the right atrium. • Constantly receives messages about the body’s oxygen needs. • Heart rate is adjusted to match needs.

15. Two Loops • Body has three kinds of blood vessels: • ARTERIES -- blood vessels that carry blood away from the heart. • CAPILLARIES -- substances are exchanged between the blood and body cells. • VEINS -- blood vessels that carry blood back to the heart

16. Two Loops -- cont’d • Blood flows through the body in a figure eight pattern. • The heart is at the center where the two loops cross.

17. Loop One • Blood travels from the heart to the lungs and then back to the heart. • Blood from the body flowing into the right atrium is oxygen-poor (low oxygen and high carbon dioxide) • Oxygen-poor blood is dark red.

18. Loop One -- cont’d • Flow of blood: • Right atrium ---> right ventricle ---> arteries towards the lungs ---> capillaries close to the lungs ---> picks up oxygen from the lungs (the blood is now oxygen-rich) ---> carbon dioxide moves from blood into the lungs (and carbon dioxide-poor) ---> blood (bright red now) flows to the left side to be pumped through Loop Two.

19. Loop Two • Blood flows to the body and back. • Left atrium fills with oxygen-rich blood coming from the lungs ---> left ventricle ---> aorta (largest artery in the body) ---> branching arteries and tiny capillaries in different parts of the body ---> oxygen moves out of the blood and into the body cells ---> carbon dioxide passes from the body cells into the blood ---> blood flows back to the right atrium through veins.

20. Homework • Workbook 17.1 (3/17) • Vocabulary quiz 17.1 (3/17)