Cardiovascular I

2. Organelles that are more numerous in cardiac muscle tissue than other types of muscle tissue.
4. Coronary arteries receive blood from this major vessel.
5. The last part of the conduction pathway that receives the action potential before the ventricle contract.
8. The slow depolarization seen in cardiac conduction cells of the heart, due to slow opening sodium channels.
10. 1% of cells have these structures to allow them to drift gradually to threshold without nervous system input.
12. The AV valves open when pressure is higher in the ____.
15. These valves close when the heart ventricles first begin to contract.
16. Cardiac veins empty into this special vessel on the heart.
18. The phase of the action potential in contractile cells caused by calcium ions flowing into cells.
19. Term for when the atria or ventricles are contracting.

1. Special structures in cardiac muscle that allow it to act as a unit (functional synctium)
3. Gap junctions and desmosomes are found here.
6. Ion that prolongs depolarization of contractile cells in the heart to allow the heart to eject blood.
7. These valves close when the ventricles relax.
9. Special term for the relaxation of atria or ventricles.
11. The ion channels that open to cause the heart to relax.
13. Arteries that supply blood to the myocardium of the heart
14. The rate of action potentials at this conduction structures is 100bmp without autonomic nervous system influence.
17. Ion that causes the sharp rise of the action potential in autorhythmic cells.
18. This portion of the ECG represents atrial depolarization.