Final answer:
The parasympathetic nervous system uses nitric oxide as a transmitter, and it directly controls the digestive system along with the enteric nervous system. Drugs that affect both autonomic divisions target nicotinic receptors. The central nervous system consists of the brain and spinal cord.
Step-by-step explanation:
The branch of the autonomic nervous system that uses nitric oxide (NO) as a neurotransmitter is the parasympathetic nervous system. Nitric oxide is known to act as a vasodilator, which means it helps widen blood vessels, and it is involved in many other processes in the body. The enteric nervous system also utilizes NO but in the context of regulating gastrointestinal function.
Regarding the direct control of the digestive system, it is primarily under the control of the parasympathetic nervous system, which helps stimulate digestion through the release of certain neurotransmitters and hormones. However, the enteric nervous system can operate independently and is sometimes considered the 'second brain' due to its complexity.
A drug that affects both divisions of the autonomic system is likely to bind to, or block, nicotinic receptors since these are common to both the sympathetic and parasympathetic nervous systems.
The central nervous system is comprised of the brain and spinal cord, which serve as the main control centers for all nervous system activities, including the coordination of muscle movements and the processing of sensory information.