Which term describes exterior sources that affect the heart?

• A. Extrinsic Cardiac Factors
• B. Intrinsic Cardiac Factors
• C. Endocardial Factors
• D. Pericardial Fluid

Answer: (A)

Exterior sources that influence how the heart works are described as Extrinsic Cardiac Factors. This term captures influences outside the heart itself, such as autonomic nervous system input and circulating hormones that speed up or slow down rate and force of contraction. In contrast, intrinsic cardiac factors are those inside the heart, like the conduction system (SA node, AV node, Purkinje fibers) and the myocardium. Endocardial factors relate to the inner lining of the heart, and pericardial fluid is simply the lubricating fluid in the pericardial space, not a category of external influences. So the best answer is Extrinsic Cardiac Factors.