NWCA Medical Assistant Practice Exam

Decreased blood pressure happens when there isn’t enough circulating blood volume. Dehydration lowers plasma volume, so there is less blood in the vessels. With less blood returning to the heart, the preload drops, which reduces the amount the heart can eject with each beat (stroke volume). That lowers cardiac output and, as a result, arterial pressure falls. The body may compensate by raising heart rate, but the underlying issue is reduced circulating volume from fluid loss. Other factors listed don’t fit as the primary cause: lack of sleep can affect blood pressure in the short term but doesn’t directly reduce circulating volume; obesity is typically associated with higher blood pressure due to increased vascular resistance and related factors; increasing arterial blood volume would raise, not lower, blood pressure.