1. Copy and complete: The blood from the lungs enters the ______ ______. Then it gets moved down to the _______ _____. Then it gets squeezed out to the ______ _____. The blood from the body cells enters the _______ _______. Then it gets moved down to the _______ _______. Then it gets squeezed out to the _______.

2. The heart as a pump

3. The circulatory system

6. Artery The blood vessel that carries blood away from the heart. They have very thick walls. thick outer wall thick inner layer of muscle and elastic fibres narrow central tube (lumen)

7. Vein The blood vessel that takes blood into the heart. They have valves. thin outer wall thin inner layer of muscle and elastic fibres wide central tube (lumen)

8. Valves When blood is flowing against gravity, or when a vein is squeezed by muscle action, there is a risk that blood will flow in the wrong direction. Veins have valves to prevent backflow. blood to the heart backflow prevented vein valve open vein valve closed

10. The heart as a pump

11. The three types of blood vessels Arteries – take the blood away from the heart. They have very thick walls. Veins – take the blood into the heart. They have valves.

12. Capillary The blood vessel that carries blood through the body cells. The wall is only one cell thick. They are extremely narrow and they connect the arteries to the veins. wall only one cell thick

18. Capillaries – carry blood through the body cells. The wall is only one cell thick. They are extremely narrow and they connect the arteries to the veins.

19. Blood vessels very thick wall narrow tube thin wall wide tube wall only one cell thick ARTERY VEIN CAPILLARY extremely narrow tube

20. Blood vessels

21. Compare & Contrast 1.Thick walls 2.Have valves 3.Connect arteries to the veins 4.Carry blood away from the heart 5.Carry blood to and from the body cells 6.Walls only one cell thick 7.Thin walls 8.Low pressure 9.High pressure 10.Carry blood into the heart