Autonomic reflexes help regulate blood pressure. For example, numerous sympathetic neurons transmit a low but relatively constant frequency of action potentials that stimulate blood vessels throughout the body, keeping them partially constricted. If the vessels constrict further, blood pressure increases; if they dilate, blood pressure decreases. Thus, altering the frequency of action potentials delivered to blood vessels along sympathetic neurons can either raise or lower blood pressure. Important sensory receptors that monitor blood pressure are located in arteries in the chest above the heart and in arteries in the head.
1. How do the sympathetic reflexes that control blood vessels respond when an individual changes position? How do the sympathetic reflexes that control blood vessels respond to maintain cerebral perfusion when an individual suddenly stands up after crouching for a short time?
2. Why is it important to have both parasympathetic and sympathetic divisions of the ANS even though they affect many of the same organs?
3. What are some of the effects of an imbalance in the ANS?