Please tell me which one is TRUE or FALSE for the statements below:
1. During the cardiac cycle the pressure in the left ventricle and right ventricle are approximately equal.
2. During isovolumetric contraction the left ventricular pressure continues to increase and eventually reaches a point where it exceeds the aortic pressure.
3. The aortic valve opens when left ventricular pressure equals aortic pressure.
4. In the absence of other influences the intrinsic rate of the sinoatrial node is between 80 and 85 beats per minute.
5. The QRS complex represents the wave of ventricular depolarisation that precedes the contraction of the ventricles.
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To determine the truth or falsity of the statements, we can consult reliable sources such as medical textbooks or trusted websites. Here's a breakdown of each statement:
1. During the cardiac cycle, the pressure in the left ventricle and right ventricle are approximately equal.
Explanation: To verify this statement, we can refer to medical literature or physiology textbooks. During the cardiac cycle, the pressure in the left ventricle and right ventricle is not exactly equal but is relatively close. However, it is important to note that the left ventricle generally has higher pressures due to its role in pumping blood to the systemic circulation. Therefore, this statement is FALSE.
2. During isovolumetric contraction, the left ventricular pressure continues to increase and eventually reaches a point where it exceeds the aortic pressure.
Explanation: Isovolumetric contraction refers to the phase in which the ventricles are contracting, and all the valves between the chambers are closed. During this phase, the ventricular pressure increases until it exceeds the pressure in the aorta. Hence, this statement is TRUE.
3. The aortic valve opens when left ventricular pressure equals aortic pressure.
Explanation: To determine the accuracy of this statement, we need to consider the sequence of events during the cardiac cycle. The aortic valve opens when the left ventricular pressure exceeds the pressure in the aorta. Therefore, this statement is FALSE.
4. In the absence of other influences, the intrinsic rate of the sinoatrial node is between 80 and 85 beats per minute.
Explanation: The intrinsic rate of the sinoatrial (SA) node, the natural pacemaker of the heart, refers to the rate at which it generates electrical impulses without any external influences. The average intrinsic rate of the SA node is around 60 to 100 beats per minute. However, the specific rate may vary among individuals due to factors such as age, fitness level, and health conditions. Hence, in the absence of other influences, the intrinsic rate of the SA node can fall within the range of 80 to 85 beats per minute. Therefore, this statement is TRUE.
5. The QRS complex represents the wave of ventricular depolarization that precedes the contraction of the ventricles.
Explanation: The QRS complex is an electrical pattern observed on an electrocardiogram (ECG) and represents the depolarization (contraction) of the ventricles. The QRS complex comes after the P wave, which represents the depolarization of the atria. Therefore, this statement is TRUE.
It is always recommended to cross-reference information from reliable sources or consult a medical professional for accurate and up-to-date information regarding cardiac physiology.