What changes in blood pressure after the subject stood up for 3 minutes?

After standing up for 3 minutes, the blood pressure typically undergoes the following changes:

1. Initial Drop (Orthostatic Hypotension): When a person suddenly stands up from a seated or lying position, there is a transient decrease in blood pressure. This is known as orthostatic hypotension. It occurs due to the pooling of blood in the lower extremities, which leads to a reduction in the volume of blood returning to the heart.

2. Reflexive Increase: The body's autonomic nervous system quickly responds to the drop in blood pressure by activating compensatory mechanisms. The heart rate increases, and blood vessels in the body constrict (vasoconstriction) to maintain blood pressure.

3. Stabilization: After the initial drop and subsequent increase, blood pressure usually stabilizes at a level that is slightly higher than the original seated blood pressure. This elevated blood pressure helps maintain adequate blood flow to the brain and other vital organs despite the change in body position.

It's important to note that the magnitude and duration of these blood pressure changes can vary among individuals and may be influenced by factors such as age, physical fitness, underlying medical conditions, and medications. In some cases, individuals may experience more pronounced orthostatic hypotension or may not fully compensate for the drop in blood pressure, resulting in symptoms like dizziness or fainting (syncope).