Question

Mr. L. works with pesticides and is accidentally exposed to a nicotinic agonist.

1. Focusing on motor output only, on which cell types would the nicotinic agonist work?
2. What effect would it have on somatic motor output? Why?
3. Where would it act to affect ANS motor output?  
4. Which division(s) would be affected? Explain your answer.
5. Describe a treatment that could be given to counteract the effect of the pesticide and justify your treatment by indicating how it would improve function.

Answer 1

* A nicotinic agonist is a drug that acts like acetylcholine at nicotine acetylcholine receptors. They act on nerve cells, musclee cells and other tissues too. Considering only the motor output, it can be said that nicotinic agonist act on muscle cells.

* When the nicotinic agonist attaches to the nicotinic receptors on somatic cells like the muscles, it induces the selective opening of the sodium ion channels. The influx of the positively charged Na+ ins triggers membrane depolarization. This opens channels for the flow of K+ ions into the cell. This causes repolarization.

* Unlike the somatic neurosystem, the autonomic nervous system or ANS, is a control system that acts unconciously and regulated bodily functions like the heart rate, digestion, respiratory rate, urination, sleep etc. etc. The ANS has two divisions- the sympathetic division and the parasympathetic division.

The sympathetic division is the 'action division' , that is , it prepares the body to put out energy and get ready to face the situation. Like, it will increase the heart rate and blood pressure, make more glucose for the blood so that energy can be released, increase breathing rate etc.

The parasympathetic division has just the opposite effect- it slows the heart and breathing rates, brings down the blood pressure, in fact, it does all the opposite things to the sympathetic division.

Nicotinic agonist act on the sympathetic division by stimulating the release of catecholamine and activating the adrenal medulla to release its hormone.

* First of all, the person will have to avoid physical contact with the pesticide. Also, to prevent inhalation of the pesticide, he will have to wear a mask at work. Certain drugs, like atropine or an oxime such as pralidoxime, can be used but under the strict supervision of a specialist and under close monitoring. The person will have to be in constant supervision of the doctor till the medication lasts.