1b. Refer to the diagram above of the cardiovascular system and explain how blood flows through the heart.

Blood flows through the heart in a systematic manner, following a specific path through its chambers and associated valves. Here is an overview of the process:

1. Deoxygenated Blood Enters the Heart: Blood that is low in oxygen returns from the body to the heart through two large veins: the superior vena cava (from the upper body) and the inferior vena cava (from the lower body).

2. Right Atrium: The deoxygenated blood enters the right atrium of the heart. As the atrium fills, it contracts, pushing the blood through the tricuspid valve.

3. Right Ventricle: Blood flows into the right ventricle, which is located just below the right atrium. When the right ventricle contracts, it pumps the deoxygenated blood through the pulmonary valve into the pulmonary artery.

4. Pulmonary Arteries: The pulmonary artery carries the deoxygenated blood to the lungs. Here, carbon dioxide is exchanged for oxygen in the capillaries surrounding the air sacs (alveoli) in the lungs.

5. Oxygenated Blood Returns to the Heart: Once oxygenated, the blood returns to the heart through the pulmonary veins, entering the left atrium.

6. Left Atrium: As the left atrium fills with oxygen-rich blood, it contracts and pushes the blood through the mitral (or bicuspid) valve into the next chamber.

7. Left Ventricle: Blood enters the left ventricle, which is the strongest chamber of the heart. Upon contraction, it pumps oxygenated blood through the aortic valve into the aorta.

8. Aorta: The aorta distributes the oxygen-rich blood to the rest of the body through a network of arteries, ensuring that all tissues receive the oxygen and nutrients they need.

Summary

The flow of blood through the heart is a continuous cycle where deoxygenated blood is received, sent to the lungs for oxygenation, and then pumped out to the body as oxygen-rich blood. The heart's structure with its four chambers (right atrium, right ventricle, left atrium, left ventricle) and valves (tricuspid, pulmonary, mitral, and aortic) plays a crucial role in directing blood flow efficiently.