Heart and Circulatory system

5. - A blood vessel that carries oxygenated blood away from the heart to the body.
6. - Red blood cells that transport oxygen throughout the body.
11. Cycle - The sequence of events in a single heartbeat, including phases of contraction and relaxation.
13. - A type of white blood cell that engulfs and digests bacteria and other harmful particles.
14. Node (Sinoatrial Node) - The heart's natural pacemaker, initiating each heartbeat and controlling heart rate.
17. - One of the two upper chambers of the heart that receives blood from the veins and pumps it into the ventricles.
18. - A blood vessel that carries deoxygenated blood toward the heart from the body.
19. Systole - The phase in the cardiac cycle where the ventricles contract, pushing blood out of the heart.
20. - The thin membrane that lines the inside of the heart chambers.

1. Artery - The artery that carries deoxygenated blood from the right ventricle to the lungs for oxygenation.
2. - Platelets involved in the blood clotting process.
3. - A type of white blood cell that produces antibodies to fight infections.
4. - The liquid component of blood that carries cells, nutrients, hormones, and waste products.
7. Valves - Valves located at the bases of the large arteries leaving the heart, preventing backflow into the ventricles.
8. - One of the two lower chambers of the heart that pumps blood out to the body or lungs.
9. - Small blood vessels where the exchange of substances between blood and tissues occurs.
10. - A protein in red blood cells that binds with oxygen and gives blood its red color.
12. - White blood cells that are part of the immune system, helping to fight infections.
15. Systole - The phase in the cardiac cycle where the atria contract, pushing blood into the ventricles.
16. - The muscular wall dividing the left and right sides of the heart.