Hormones Of Heart Kidney And Gastrointestinal Tract

To solve the problem, we need to identify the correct structure that protects the heart from shocks.

1. Understanding the Function:
The heart is protected from mechanical shocks and friction by the presence of a fluid-filled space around it.

2. Evaluating the Options:
- Pericardial membranes: They form a double-layered protective covering around the heart but do not directly absorb shocks.
- Pericardial fluid: It is found between the two layers of pericardial membranes and acts as a cushion, protecting the heart from shocks and mechanical injury.
- Auricles and Ventricles: These are chambers of the heart involved in pumping blood, not in protection against shocks.

3. Identifying the Correct Answer:
The correct protective element is the pericardial fluid.

Final Answer:
The correct answer is option (B): Pericardial fluid.