Cardiovascular system

4. react to abnormal levels of oxygen
5. sends electrical pulses to set the rate for heart contractions
13. septum between the ventricle
15. lines heart chambers and makes up the tissue of heart valves
19. slow pulse and heart rate
20. inner membrane of the heart
21. two saclike membranes that enclose the heart
22. how blood pressure is often measured
25. rapid pulse and heart beat
27. two receiving chambers
28. condition that develops when the cardiovascular system fails to deliver enough oxygen and nutrients to the cells
30. pumping chambers inferior to the atria

1. heart contractions
2. located on left side of the heart; only has 2 flaps and a mitral valve
3. returns blood from the head to neck
6. detects impulse transmission through the heart's conduction system
7. when the heart contracts rapidly/irregularly
8. clusters of neurons located in the major arteries of the heart and chest
9. outer membrane of the heart
10. enter organs and tissues then branch into capillaries
11. mass of tissue that longitudinally separates heart chambers
12. part of brain that helps regulate blood flow
14. extends from the heart to the lungs and back to the heart
16. largest artery in the body
17. located between the right atrium and ventricle; has 3 valves or cusps
18. relaxation period of the heart
23. circular muscles that open and close to regulate blood flow through capillaries
24. when pressure accumulates and the vein is dilated
26. irregular heart beat rhythms
29. merge with other venules to form a vein