ECG: What Do You Know About Cardiac Cycle? Trivia Quiz

The QRS-complex occurs during ventricular depolarization. This is the phase in which the electrical activity spreads through the ventricles, causing them to contract and pump blood out of the heart. The QRS-complex is a visual representation of this depolarization on an electrocardiogram (ECG). It consists of three waves: Q, R, and S, which correspond to different parts of the ventricular depolarization process. Therefore, the correct answer is "Ventricular depolarization."

The statement is false because the atria do need to contract in order to facilitate ventricular filling. During the cardiac cycle, the atria contract to push blood into the ventricles, which is known as atrial systole. This contraction helps to complete the filling of the ventricles before they contract (ventricular systole) to pump blood out of the heart. Therefore, the atria play an active role in the filling of the ventricles and their contraction is necessary for proper cardiac function.

The superior and inferior vena cava supply the right side of the heart with blood. The vena cavae are large veins that carry deoxygenated blood from the body back to the heart. The superior vena cava collects blood from the upper body, including the head, neck, and upper extremities, while the inferior vena cava collects blood from the lower body, including the abdomen, pelvis, and lower extremities. This deoxygenated blood is then pumped into the right atrium of the heart, where it is then sent to the right ventricle and eventually to the lungs for oxygenation.

The left ventricle is responsible for pumping oxygenated blood to the rest of the body, so it experiences the highest rate of increased pressure during systole when it contracts to push blood out into the aorta. This is because the left ventricle has thicker and more muscular walls compared to the right ventricle, allowing it to generate greater force and pressure. The right ventricle, on the other hand, pumps blood to the lungs, which have lower resistance and pressure, resulting in a lower rate of pressure increase. The atria, both right and left, primarily receive blood and do not generate as much pressure as the ventricles.

The beginning of ventricular systole is actually when the ventricles contract, causing the semilunar valves to open and blood to be pumped out of the heart. The closing of the semilunar valves occurs at the end of ventricular systole, when the ventricles relax and blood begins to flow back toward them. Therefore, the statement is false.

When the pressure in the ventricles becomes lower than the pressure in the atria, it indicates that the ventricles are in the diastole phase of the cardiac cycle. During this phase, the atrioventricular valves open, allowing blood to flow from the atria into the ventricles. This is necessary for the ventricles to fill with blood before they contract during the systole phase. Therefore, the correct answer is that the atrioventricular valves open.

During the QRS complex in an electrocardiogram, the ventricles of the heart contract, which is known as ventricular systole. This contraction allows the ventricles to pump blood out of the heart and into the arteries. The QRS complex represents the depolarization of the ventricles, which leads to their contraction. This is an important phase of the cardiac cycle as it ensures that oxygenated blood is efficiently pumped to the rest of the body.

During ventricular systole, the ventricles contract, causing the tricuspid and mitral valves to close. This prevents blood from flowing back into the atria. At the same time, the pulmonary and aortic valves open, allowing blood to be pumped out of the ventricles. In this case, blood flows from the ventricles to the pulmonary arteries, which carry deoxygenated blood to the lungs for oxygenation.

The correct answer is "recoil of the blood against closure of the semilunar valves." When the semilunar valves close, the blood flowing back towards the heart experiences resistance and creates a recoil effect. This recoil causes a sound known as "dup." The other options listed do not directly relate to the sound produced by the closure of the semilunar valves.

During a normal cardiac cycle, the atria contract during atrial systole, while the ventricles relax during ventricular diastole. Atrial systole is the contraction of the atria, which pushes blood into the ventricles. Ventricle diastole is the relaxation of the ventricles, allowing them to fill with blood. Atrial systole takes a shorter time compared to ventricle diastole because the atria have a smaller volume to contract and push blood into the ventricles, while the ventricles have a larger volume to relax and fill with blood. Therefore, atrial systole takes the shortest time.