Noradrenaline is a neuro-transmitter which plays an crucial role in mood changes. If any person has low level of noradrenaline, then the message transfer process becomes slow and the person feeling of depression.

Antiseptics and disinfectants both are antimicrobials. Antiseptics prevent or destroy development or inhibit the pathogenic action of microbes. They are safe to be applied on living tissues.

On the other hand, disinfectants also kill microorganisms but are not safe to be applied on living tissues. They are generally applied on non-living objects such as drains, toilets, floors and living rooms infected with bacteria and disease carrying germs.

Magnesium hydroxide $\left[\mathrm{Mg}(\mathrm{OH})_2\right]$ is a better antacid because being insoluble it does not allow the pH to increase above neutrality. On the other hand, sodium hydrogen carbonate being soluble and its excess amount can make the stomach alkaline and trigger the production of even more acid.

Analgesics reduce or abolish pain without causing impairment of consciousness, mental confusion, incoordination or paralysis or some other disturbances of nervous system. These are classifieds in two categories

(i) Non-narcotic (non-addicitive) analgesics - Aspirin and paracetamol belong to the class of non-narcotic analgesics.

(ii) Narcotic analgesics-Morphine and many of its homologues, when administered in medicinal doses, relieve pain and produce sleep. In poisonous doses, these produce stupor, coma, convulsions and ultimately death. Morphine narcotics are sometimes referred to as opiates, since they are obtained from the opium poppy.

Narcotic analgesics (morphine and many of its homologous) when administered in medicinal doses, relieve pain and produce sleep. Since, these drugs relieve pain and produce sleep, therefore are chiefly used for the relief of postoperative pain, cardian pain and pains of terminal cancer, and in child birth.