Final answer:
The apical pulse is often checked in pediatric patients for a more accurate measure of the heart rate. In healthy young adults, cardiac output tends to decrease when the heart rate exceeds 160 bpm due to inadequate ventricular filling.
Step-by-step explanation:
When a medical assistant observes that a provider is taking a patient's apical pulse, it is often related to the need for a more accurate measurement of the heart rate compared to a peripheral pulse. This method is frequently used in pediatrics since young children and infants have small vessels that can make peripheral pulses difficult to palpate accurately. Thus, the apical pulse is much reliable for assessing their cardiac function. In regards to the effect of an increased heart rate on cardiac output in a healthy young adult, when the heart rate rises above 160 beats per minute (bpm), it can lead to a decrease in the cardiac output. This occurs because at such a high rate there is not enough time for the heart chambers to fill with blood before the next contraction, reducing the volume of blood ejected with each heartbeat.