1. Sarin is a synthetic, volatile neurotoxin that can enter the body through the
ID: 3514911 • Letter: 1
Question
1. Sarin is a synthetic, volatile neurotoxin that can enter the body through the eyes, skin, lungs, and Gl tract. Early symptoms of sarin exposure include watery eyes and constricted pupils. Later, more severe symptoms include skeletal muscle paralysis and difficulty breathing. If not treated, paralysis of respiratory muscles leads to death. a) Does sarin affect effectors of the somatic nervous system, autonomic nervous system, neither, or both? Explain. (2 pts) b) Briefly describe the mechanism of action of sarin. (3 pts) c) Explain how sarin causes each: watery eyes, constricted pupils. (4 pts) d) Explain how sarin affects the movement of Nat into a skeletal muscle cell. (2 pts) e) Explain how sarin affects the concentration of Ca2+ in the cytosol of a skeletal muscle cell. (2 pts) f) In a myofibril, how would sarin affect the position of thin filaments relative to thick filaments? Explain. (2 pts) 2. Describe the changes that occur within the left ventricle throughout the course of the cardiac cycle, including changes in (a) pressure, (b) volume, (c) position of the left AV valve (bicuspid), and (d) the aortic semilunar valve. Begin at the onset diastole (relaxation period). (5 pts)Explanation / Answer
Ans. a) Considering the symptoms such as watery eyes, constricted pupil, skeletal muscle paralysis and difficulty in breathing which are modulated by the effectors of both the somatic and autonomous nervous system. It is evident that Sarin effects the effectors of the somatic nervous system by considering the symptoms such as skeletal muscle paralysis which is associated with somatic nervous system whereas the pupil constriction are governed by the autonomous nervous system. The voluntary activities are controlled by the somatic nervous system. The non voluntary ones governed by the autonomous nervous system.
Ans. b) Sarin is an inhibitor of the enzyme acetylcholinesterase. These enzyme degrades acetylcholine after it is released in the synaptic cleft. Due to improper control of this neurotransmitter it would result in improper control of the voluntary action and on numerous muscles such as respiratory muscle paralysis would result in breathing difficulty, skeletal muscle paralysis.
Ans. c) Watery eyes and pupil constriction are associated with the release of acetylcholine in the synaptic cleft. As the ezyme acetylcholinesterase are inhibited resulting in excess levels of acetylcholine and trigerring the parasympathetic activity of pupil constriction. It is considered as the muscarinic action of acetylcholine.
Ans. d) Sarin would increase the amount of Na+ going into the cell as it is constantly stimulated.
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