1. The problem statement, all variables and given/known data Ted is lying down and attempts to stand up. However Ted stands up too fast, and experiences dizziness. To compensate for this effect, the vessels in Ted's head expand. Why does this dizziness happen and why does the body respond by expanding the vessels in Ted's head? 2. Relevant equations 3. The attempt at a solution I'm thinking it's because as Ted stands up, there isn't enough blood in his head, and therefore as the vessels expand, they create a difference in pressure, causing more blood to rush up to the head, also causing the dizziness. Is this right? Am I way off? Thanks in advance!