Explain how an understanding of the nervous system can us find ways to alleviate disease and pain.

By moderating your attention degree to the pain/disease stimuli, you can feel more or less pain sensation. When you pay attention to a certain stimulation, it starts to govern your behavior towards the stimulus, and your thalamus is more active. While distracted, the pre-frontal cortex region is more active, and this region is responsible for diminishing the pain feeling. Understanding how some regions of the nervous system work can, thus, help on alleviate those sensations.

Explanation:

The nervous system comprehends the brain, the spinal marrow and a complex web of cells and nerves. The main function of the nervous system is to carry messages from the brain and to the brain.  

The nervous system can be divided in two; the central nervous system (brain and spinal marrow) and the peripheral system (nervous web that links the rest of the body with the central nervous system).  

The nerves are part of the peripheral system. There are two types; sensitive nerves and movement nerves - although the majority of them are a mix. One of the functions of the nerves is to transport sensory signs like pain into the central nervous system.  

A direct relation presents itself involving knowledge of the central nervous system and pain. The more we know about the variables of the nervous system, the more we understand how pain is produced, transported and interpreted. When we understand those variables, we are able to control them and, reduce or stop a stimulus like pain.  

A disease can be defined as an abnormal functioning of a component of the human body. This abnormal functioning can be cause by external agents (pathogens) or internal causes. As presented above, a direct relation can be established between the understanding of the nervous system and disease. The more we know about the way our body interprets pathogens and stimulus, the more we can controlled them.  

b tumor cells have a cell wall instead of a membrane

explanation:

tumor cells different from normal cells because tumor cells have a cell wall instead of a membrane.