Final answer:
d-Tubocurarine is a neuromuscular blocker that causes muscle relaxation and paralysis by competitively blocking acetylcholine at the neuromuscular junction, while the muscle fiber remains responsive to potassium ions and electrical stimulation.
Step-by-step explanation:
Type, Mechanism of Action, and Effect of Tubocurarine
d-Tubocurarine is a type of muscle relaxant that acts as a neuromuscular blocker. Its mechanism of action involves blocking the transmitter action of acetylcholine at the neuromuscular junction. When d-tubocurarine is present, it competes with acetylcholine for the nicotinic acetylcholine receptors at the motor end plate. This inhibits the transmission of motor nerve impulses, rendering the muscle fiber insensitive to acetylcholine and unable to contract. As a result, d-tubocurarine causes muscle relaxation and paralysis. This is particularly useful during surgical procedures where muscle stillness is required. It's important to note that the muscle fiber maintains its sensitivity to potassium ions and can still respond to direct electrical stimulation despite the presence of d-tubocurarine.