What is structure A called?

Where is the body's blood-pumping organ normally located?

Which statement correctly compares heart muscle with the muscles used to lift your arm?

Blood returning from most of the body first enters which chamber?

Which chamber pumps blood toward the lungs?

On the diagram, where does blood arrive immediately after returning from the lungs?

Why must chamber D squeeze more forcefully than the other chambers?

What is the main job of parts A and B?

What is vessel A called?

From chamber C, blood passes next into which chamber?

Which wall type suits vessels carrying blood away from the pumping organ under high pressure?

In which direction does blood flow through vessel C?

What happens mainly between body cells and the tiny vessels marked D?

Which blood component carries most of the oxygen delivered to body cells?

Bacteria enter Lito's body. Which blood component includes cells that can surround and destroy the invading bacteria?

Carlo scrapes his knee, and a clot begins to form. Which blood component helps start this process?

Which blood component makes up a little more than half of its total volume?

To find the radial pulse, where should Ana place two fingertips?

Compared with sitting quietly, how will Miguel's pulse usually change after one minute of jumping?

Which regular activity most directly improves the heart's ability to supply working muscles during sustained exercise?