The heart comprises distinct layers: the inner endocardium and the outer epicardium. While *myofibrils* and *myofilaments* are components found within muscle fibers, they are not considered separate layers of the heart itself.
| List - I | List – II | ||
| A. | Epinephrine | i. | Hyperglycemia |
| B. | Thyroxine | ii. | Smooth muscle contraction |
| C. | Oxytocin | iii. | Basal metabolic rate |
| D. | Glucagon | iv. | Emergency hormone |