Final answer:
The cardiac cycle, driven by pressure gradients and electrochemical signals, involves the contraction and relaxation of heart chambers to pump blood efficiently through the body.
Step-by-step explanation:
The cardiac cycle consists of a series of contractions and relaxations of the heart chambers, which drive the flow of blood through the body. The cycle can be broken down into several key phases:
- Cardiac diastole: This is a phase of relaxation where all heart chambers are relaxed, allowing blood to flow into the heart.
- Atrial systole: This is when the atria contract, pushing blood into the ventricles.
- Ventricular systole: This occurs after atrial diastole, where the ventricles contract, forcing blood out of the heart.
This cycle repeats, with each phase being carefully regulated and coordinated to ensure efficient blood pumping. Pressures and flow within the heart are governed by pressure gradients, which are the prime drivers of this cycle. The atria and ventricles each undergo periods of systole (contraction) and diastole (relaxation), with blood flow from regions of higher pressure to regions of lower pressure.
Electrochemical signals are the driving force behind the cardiac cycle. These signals originate at the heart's pacemaker cells and spread across the atria and ventricles, inducing contractions. Additionally, the closing of valves during these phases produces the characteristic 'lub' and 'dub' heart sounds.