Question

If embryonic heart cells are separated into a Petri dish and kept alive, each is capable of generating its own electrical impulse followed by contraction. When two independently beating embryonic cardiac muscle cells are placed together, the cell with the higher inherent rate sets the pace, and the impulse spreads from the faster to the slower cell to trigger a contraction. As more cells are joined together, the fastest cell continues to assume control of the rate. A fully developed adult heart maintains the capability of generating its own electrical impulse, triggered by the fastest cells, as part of the _______________________.

Answer 1

A fully developed adult heart retains the ability to generate its own electrical impulses via the cardiac conduction system, orchestrated by the fastest pacemaker cells. Components of this system include the sinoatrial node, atrioventricular node, bundle of His, bundle branches, and Purkinje cells. Together, they ensure the heart beats in a coordinated and effective manner.

Step-by-step explanation:

When embryonic heart cells are maintained alive outside the body, each cell can generate its own electrical impulse, leading to contraction. When two beating embryonic cardiac muscle cells touch each other in a Petri dish, the cell with the higher beating rate synchronizes the beating of the other cell by setting the pace. Throughout development, the cell with the highest inherent rate will continue to control the heart rate. In an adult heart, the same principle applies; the cardiac conduction system is responsible for generating these impulses and coordinating the heart's rhythm.

The cardiac conduction system includes major components such as the sinoatrial node (SA node), the atrioventricular node (AV node), the atrioventricular bundle also known as the bundle of His, the bundle branches, and the Purkinje cells. These components work together to create and propagate electrical signals that result in the heart's synchronous contractions which pump blood effectively through the body.

The initial impulse starts at the SA node, which effectively acts as the heart's natural pacemaker. The SA node's pacing is influenced by both neural and hormonal signals. The electrical impulse then travels through the AV node, bundle of His, bundle branches, and finally, the Purkinje fibers, which leads to the contraction of the ventricles. This system ensures that the heart can maintain a consistent rhythm and properly circulate blood.