1. Circulation - The Body’s Transport System The Cardiovascular System The cardiovascular system carries needed substances to cells and carries waste products away from cells. In addition, blood contains cells that fight disease.

2. Circulation - The Body’s Transport System The Heart The heart is a hollow, muscular organ that pumps blood throughout the body. The right side of the heart is completely separated from the left side by a wall of tissue called the septum. Each side has an upper chamber, or atrium, and a lower chamber, or ventricle.

3. Circulation - The Body’s Transport System The Heart As blood flows out of the heart and toward the lungs, it passes through a valve like the one here.

4. Circulation - The Body’s Transport System Two Loops Blood circulates through the body in two loops, with the heart at the center. In the first loop, blood travels from the heart to the lungs and then back to the heart. In the second loop, blood is pumped from the heart throughout the body and then returns to the heart.

5. Circulation Sequencing As you read, make a cycle diagram like the one below that shows the path that blood follows as it circulates throughout the body. Write each step of the pathway in a separate circle. Pathway of Blood Right side of heart Lungs Left side of heart Body - The Body’s Transport System

6. Circulation - A Closer Look at Blood Vessels Artery and Vein In this photo, you can compare the wall of an artery with the wall of a vein.

7. Circulation Blood VesselFunctionStructure of Wall Comparing and Contrasting As you read, compare and contrast the three kinds of blood vessels by completing a table like the one below. Artery Carries blood away from the heart Thick wall consisting of three cell layers with thick muscle in the middle layer Capillary Exchange of materials between the blood and body cells Thin walls consisting of one cell layer Vein Carries blood back to the heart Thick walls consisting of three cell layers with thin muscle in the middle layer - A Closer Look at Blood Vessels

8. Circulation - Blood and Lymph Blood Blood consists of liquid plasma and three kinds of cells—red blood cells, white blood cells, and platelets.

9. Circulation - Blood and Lymph The Lymphatic System The lymphatic system is a network of veinlike vessels that returns the fluid to the bloodstream.

10. Circulation Identifying Main Ideas As you read the section titled “Blood,” write the main idea in a graphic organizer like the one below. Then write four supporting details that give examples of the main idea. Blood is made up of four components. Plasma is the liquid part of blood. Red blood cells take up oxygen and deliver it to cells in the body. White blood cells fight disease. Main Idea Platelets help form blood clots. Detail - Blood and Lymph

11. Circulation Graphic Organizer Loop Right side Loop One Loop Two Side of Heart Where Loop Starts Where Blood Flows to Where Blood Returns to Left side LungsLeft atrium BodyRight atrium