Final answer:
Neuromuscular blocking agents like d-tubocurarine are used during surgery to cause muscle relaxation and flaccid paralysis by inhibiting the action of acetylcholine at the neuromuscular junction. General anesthesia involves the use of such drugs to relax respiratory muscles, requiring artificial ventilation support. The effects are reversible post-surgery, allowing for return of muscle control.
Step-by-step explanation:
The drug that is commonly used during surgery to cause muscle relaxation is a type of neuromuscular blocking agent. It works by interfering with the transmission of electrical signals from nerves to muscles at the neuromuscular junction. Specifically, the agent, such as d-tubocurarine, competitively inhibits the action of the neurotransmitter acetylcholine. This leads to muscle cells becoming insensitive to motor-nerve impulses and direct applied acetylcholine; however, the muscle can still respond to direct electrical stimulation.
Such agents inhibit the release of acetylcholine from neurons, which results in flaccid paralysis. For more severe toxins like Botulinum toxin (BONT), it binds irreversibly to presynaptic membranes and prevents release of acetylcholine, leading to muscle relaxation and paralysis. This is different from local anesthetics, which block nerve conduction but have a reversible action and do not cause paralysis.
During general anesthesia, these drugs are used not only for muscle relaxation but also to ensure that the patient's respiratory muscles are relaxed enough to require artificial ventilation, such as with endotracheal intubation. Post-surgery, as the effects of the anesthetics wear off, the patient's muscle control, including that of the respiratory muscles, slowly returns.