Human Biology Body Systems

8. circulation: The circulation of blood between the heart and lungs.
10. Air-filled spaces in the skull that help to lighten the skull and produce mucus.
14. circulation: The circulation of blood from the heart to the body and back.
15. The phase of the cardiac cycle when the heart contracts.
16. Oxygen deficiency in the body's tissues.
18. Small veins that receive blood from capillaries.
19. Abnormally slow heart rate.
20. pressure: The force of blood against the walls of arteries.
22. Abnormally fast heart rate.
23. A diagnostic test that records the electrical activity of the heart.
25. Muscle that separates the chest cavity from the abdominal cavity and plays a major role in breathing.
26. Small artery that leads to capillaries.
27. Abnormally high blood pressure.
29. Abnormally low blood pressure.
32. Blood vessels that carry oxygen-depleted blood back to the heart.
33. Breathing in, or the intake of air into the lungs.
34. Tiny blood vessels where exchange of gases, nutrients, and waste occurs.
35. Inflammation of the pericardium, often causing chest pain and discomfort.
36. The upper chambers of the heart that receive blood from the body or lungs.

1. Increased depth and rate of breathing.
2. Breathing out, or the expulsion of air from the lungs.
3. The main airways that branch off from the trachea and lead to the lungs.
4. A specialized group of cells that regulate the heart's rhythm.
5. volume: Volume within the lungs.
6. Narrowing of blood vessels, increasing blood pressure.
7. points: Areas where arteries are close to the surface and can be compressed to control bleeding.
9. Openings through which air enters the nasal cavity.
11. The rhythmic expansion and contraction of arteries caused by the heartbeat.
12. The phase of the cardiac cycle when the heart relaxes.
13. cycle: The complete sequence of events in the heart during one heartbeat.
17. Blood vessels that carry oxygen-rich blood away from the heart.
18. The lower chambers of the heart that pump blood out to the body or lungs.
21. The muscular middle layer of the heart wall responsible for pumping blood.
22. The windpipe, which connects the larynx to the bronchi.
24. Rapid breathing that leads to decreased levels of carbon dioxide in the blood.
28. The double-layered sac surrounding the heart, providing protection and lubrication.
30. Membranes that surround the lungs and line the chest cavity.
31. Tiny air sacs in the lungs where gas exchange occurs.