"Develop an attitude of gratitude, and give thanks for everything that happens to you, knowing that every step forward is a step toward achieving something and better than your current situation." .......Brian Tracy Words are not enough to thank my guide I take this opportunity to acknowledge the guidance and encouragement of my guide Dr. V.K. Deshpande, Dean, JNMC and Professor department of Physiology. I have been inspired by his meticulousness, his attention to detail and his energetic application to any problem. I value his concern and support at all times, good and bad. Among the many blessings that have come into my life as a result of his teachings, is an ever-deepening sensitivity to the vibrations of words. Some special words of gratitude go to Dr D.A. Biswas, Professor and head, department of Physiology who have always been a major source of support when things would get a bit discouraging. I have learnt several good things from her and highly indebted to her. Her continuous support, encouragement and appreciation have been extremely valuable to me. My sincere thanks to late Dr S.R. Johrapurkar, without his blessings and grace, the work would not have been possible.