What are the 5 structures that enable the heart to contract (cardiac conduction) a. Which chambers of the heart contact?

sinoatrial node

Explanation:

impulses starts in small bundles of specialized cells which are located in the right atrium which is known as the SA node. The electrical activity tends to spread through the walls of the atria and then causes it to contract. however, forcing the blood into ventricles.

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igneous rock formed from below the surface would have more crystals because

answer: because magma cools more slowly than lava

if you add everything up correctly you should get 69 i got this because 50 plus 19 is it