Heart block is a condition in which the SA node is properly functioning but the atria and ventricles are contracting out of synch. Which of the following statements explains why this happens?
A) The SA node is working extra hard to make the ventricles catch up.
B) The AV node is not sending signals to the ventricles as it should.
C) The coronary arteries are not delivering blood to the heart.
D) The heart valves are allowing blood to flow backward through the heart.

Question

Quizplus · Accepted Answer

In heart block, the problem lies in the AV node, which is responsible for transmitting electrical signals from the atria to the ventricles. When the AV node is not sending signals properly or at all, the atria and ventricles will contract out of synch, causing heart block. Option A is incorrect because the SA node is working properly in this condition. Option C is incorrect because inadequate blood flow to the heart can cause heart attack or angina, but not heart block. Option D is incorrect because backflow of blood through the heart valves is known as valvular insufficiency and would not cause heart block.

Heart Block Is a Condition in Which the SA Node