Give an example each for (a) Artificial sweetening agents (b) Narcotic analgesics.

Hint :Natural sweeteners like sucrose and fructose give a substance sweetness, but they also include calories, which may be hazardous to humans if consumed in excess. Artificial sweeteners are calorie-free sugar replacements that are used to replace natural sugar (sucrose). They are known as powerful sweeteners because they are several times sweeter than conventional sugar.

Complete Step By Step Answer:
A sweetening agent must be soluble in water and easily attach to a receptor molecule on the tongue's surface in order to function correctly. When the sweetener attaches to the receptor, the G- protein dissociates, activating a neighbouring enzyme and triggering a series of processes in which the signals are relayed to and processed by the brain. The sweetness of an artificial sweetening agent is determined by the interaction between the receptor and the sweetener.
Saccharin is the oldest non-nutritive sweetener, having been discovered in 1879. Sucrose has a harsh aftertaste and is around 300 times less sweet than saccharin. It cannot be used in items that need baking since it becomes unstable when heated. It can, however, be used to sweeten candy, beverages, and toothpaste.
Opioids are compounds that elicit morphine-like effects by binding to opioid receptors. They are generally used in medicine for pain treatment, as well as anaesthetic. Other medical applications include diarrhoea suppression, opioid use disorder replacement treatment, reversing opioid overdose, cough suppression, and executions in the United States. Only veterinary usage is permitted for extremely powerful opioids like carfentanil. Non-medically, opioids are widely taken for their euphoric effects or to avoid withdrawal.
Narcotic analgesics include morphine, heroin, and codeine. They relieve pain by depressing the central nervous system. These substances lead to addiction.

Note :
Opioids work through binding to opioid receptors in the central and peripheral neurological systems, as well as in the gastrointestinal tract. Both the psychotropic and physical effects of opioids are mediated by these receptors. Partially agonists, such as loperamide, for anti-diarrhea, and antagonists, such as naloxegol for opioid-induced constipation, do not cross the blood-brain barrier but can prevent other opioids from binding to those receptors.