I learned something new at Shepherd MS Clinic....duh...every part of the body works together!
While suffering with leg spasms for a year or so and taking more meds, exercising, etc. They told me to try watching the digestive system. It can effect the leg spasms.
The basic rules, when filling with liquid it needs to travel on it's way out. I have been watching this more carefully and it has helped my leg spasms some.
When disease or age effects the perfection, I guess we learn to adjust. There is also aides to help the damaged parts of the body.
Did I ever wonder that God had not designed our bodies to work perfectly? Nah....
My opinion spiritually, I believe His body has been designed to work together also.