Final answer:
The systolic phase of blood pressure is when the left ventricle of the heart contracts and forces blood into the arteries, resulting in the maximum arterial pressure, typically around 120 mm Hg in a healthy adult.
Step-by-step explanation:
Blood Pressure and the Systolic Phase
The systolic phase of blood pressure represents the maximum arterial pressure during a heartbeat, more specifically during the contraction of the left ventricle of the heart. When the ventricles contract, this phase is also known as ventricular systole, propelling blood into the aorta and throughout the systemic circulation. The systolic pressure is the higher value in a blood pressure reading and is typically around 120 mm Hg in a healthy adult. It acts as a critical indicator for blood flow and is a vital measurement for assessing cardiovascular health. During this phase, the arterial walls stretch to accommodate the surge of blood resulting from the heart's contraction. This is distinct from the diastolic phase, which occurs when the heart muscle relaxes and the chambers of the heart fill with blood.
In the context of measuring blood pressure, the systolic value is always noted first, followed by the diastolic value, such as in a blood pressure reading of 120/80 mm Hg, where 120 represents the systolic blood pressure.