During which phase of the cardiac cycle is the pressure in the arteries highest?

The pressure in the arteries reaches its peak during the systolic phase of the cardiac cycle. This phase occurs when the heart's ventricles contract to pump blood out into the arteries. As the ventricles contract, they generate high pressure to overcome the resistance of the arteries and propel blood forward to the lungs and the rest of the body. This high pressure is specifically known as systolic blood pressure, and it is measured when the heart beats.

In contrast, during the diastolic phase, the heart muscle relaxes and fills with blood, leading to a decrease in arterial pressure as blood is not being actively pumped into the arteries. The resting phase is not a recognized phase within the typical cardiac cycle terminology; it can refer to the overall state of the heart when it is between beats. The refractory phase pertains to the electrical activity of the heart muscle following a contraction and does not directly relate to pressure within the arteries.

Thus, the systolic phase is critical for understanding arterial pressure dynamics, highlighting its role in determining systolic blood pressure as the highest point of pressure during the cardiac cycle.