Final Answer:
Cholinesterase inhibitors lead to prolonged activation of cholinergic receptors by preventing the breakdown of acetylcholine, causing its accumulation and extended stimulation of the receptors.
So, C) Prolonged activation of cholinergic receptors is correct option.
Step-by-step explanation:
Cholinesterase inhibitors are substances that block the action of the enzyme cholinesterase, responsible for breaking down acetylcholine (ACh) in the synaptic cleft. When cholinesterase is inhibited, ACh cannot be effectively degraded, leading to its accumulation at the synapse. This excess ACh continuously stimulates cholinergic receptors, causing prolonged activation.
As a result, the effects of ACh, such as increased muscle contractions or heightened activity in the nervous system, are prolonged, leading to the observed symptoms of poisoning with a cholinesterase inhibitor.
The inhibition of cholinesterase prevents the breakdown of ACh, but it doesn't influence its synthesis or release. Instead, it impacts the duration of its action by allowing ACh to persist in the synaptic cleft. This prolonged stimulation of cholinergic receptors causes a variety of symptoms, depending on the affected receptors and their locations.
Symptoms may include muscle twitching, increased secretions, blurred vision, and in severe cases, respiratory distress or convulsions due to excessive cholinergic activity.
Understanding the mechanism of action of cholinesterase inhibitors is crucial in both toxicology and medicine. In cases of pesticide or nerve agent poisoning (such as organophosphates or certain insecticides), these inhibitors can cause significant health issues by overwhelming the cholinergic system.
Conversely, in medicine, some cholinesterase inhibitors are used therapeutically to increase ACh levels in conditions like myasthenia gravis or Alzheimer's disease, aiming to improve neuromuscular transmission or cognitive function.
So, C) Prolonged activation of cholinergic receptors is correct option.