What system is not affected by nerve agents?

The respiratory system is not directly affected by nerve agents, as these agents primarily target the nervous system by inhibiting the enzyme acetylcholinesterase, leading to an accumulation of acetylcholine at synapses. However, nerve agents can indirectly impact respiratory function due to muscle paralysis and convulsions, which may affect breathing. In contrast, the circulatory system can be influenced by nerve agents, particularly through changes in heart rate and blood pressure. Overall, while the respiratory system may not be the primary target, it can still be compromised as a result of the overall effects of nerve agents.