The problem of electrical discontinuity caused in the normal heart by the connective tissue separating the atria from the ventricles is solved by

Options

A. (a) coordinating electrical activity in the atria with electrical activity in the ventricles by connecting them via the bundle of His
B. (b) having the A-V node function as a secondary pacemaker
C. (c) having an ectopic pacemaker
D. (d) coordinating electrical activity in the atria with electrical activity in the ventricles by connecting them via the vagus nerve

Answer

To solve the problem of electrical discontinuity in the heart caused by the connective tissue separating the atria from the ventricles, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Heart's Structure**:
- The heart consists of four chambers: the right atrium, right ventricle, left atrium, and left ventricle.
- There is connective tissue (atrioventricular septum) that separates the atria from the ventricles, which can cause electrical discontinuity.

2. **Role of the SA Node**:
- The sinoatrial (SA) node, located in the right atrium, is the primary pacemaker of the heart. It generates electrical impulses that initiate the heartbeat.

3. **Propagation of Action Potential**:
- The action potential generated by the SA node spreads through the atria, causing them to contract. This is facilitated by gap junctions in the muscle fibers of the atria.

4. **AV Node Function**:
- The action potential reaches the atrioventricular (AV) node, located between the atria and ventricles. The AV node serves as a critical relay point for the electrical signal.

5. **Bundle of His**:
- From the AV node, the action potential travels down the bundle of His, which is a pathway that connects the atria to the ventricles. This bundle is essential for coordinating the electrical activity between the two.

6. **Purkinje Fibers**:
- The bundle of His branches into Purkinje fibers that spread throughout the ventricular walls. This ensures that the action potential is rapidly distributed, leading to coordinated contraction of the ventricles.

7. **Conclusion**:
- The electrical discontinuity caused by the connective tissue is resolved by the conduction system of the heart, particularly through the bundle of His, which connects the electrical activity of the atria with that of the ventricles.

### Final Answer:
The problem of electrical discontinuity caused in the normal heart by the connective tissue separating the atria from the ventricles is solved by **coordinating electrical activity in the atria with the electrical activity in the ventricles by connecting them via the bundle of His** (Option A).

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