question

1. Once she turned 21, Amanda expected good times ahead. So why could she barely manage to climb the two flights of steps to her chemistry class? When she started experiencing weakness in her left hand, Amanda consulted a physician. After conducting numerous tests, Amanda’s physician told her she had multiple sclerosis (MS), a condition in which the myelin sheaths of motor and sensory neurons within the central nervous system are gradually destroyed. By combining what you learned about the histology, physiology, and gross anatomy of the muscular system with new information about nervous tissue organization in this chapter, explain why MS made it difficult for Amanda to walk up stairs and also led to her hand weakness. Also, predict how Amanda’s condition is likely to change over the next several years.

2. How many times had Javier told his kids not to leave their toys lying around on the floor? While walking down a dark hallway in the middle of the night, Javier stepped on a tiny race car with his right foot. He immediately withdrew his foot from the painful stimulus, but then stepped on a second car with his left foot. Fortunately, he was able to shift his weight back to his other foot not to fall down. After reading this chapter, explain the spinal reflexes that kept Javier on his feet. Describing those reflexes will require your knowledge of nervous system organization.