Please explain what does parkinson's disease do to the body?

Parkinsons symptoms: Parkinsons disease, when not treated, tends to cause slowing of movements, as if movement is inhibited. This can affect writing, buttoning, or speaking for example. Muscle tone may be increased with passive manipulation. People sometimes feel "frozen" when walking or lying in bed. Many people with Parkinsons have a tremor when the arms are at rest. This ceases with movement however.