Final answer:
Parkinson's Disease is a degenerative disorder that affects the central nervous system and causes symptoms such as muscle tremor, rigidity, slowness of movement, and postural instability.
Step-by-step explanation:
Parkinson's Disease is a degenerative disorder of the central nervous system that mainly affects the muscular system and movement. Four motor signs and symptoms are considered defining Parkinson's disease: muscle tremor (shaking), muscle rigidity, slowness of movement, and postural instability. Tremor is the most common and obvious symptom, and it most often occurs in a limb at rest, so it disappears during sleep or when the patient moves the limb voluntarily. Difficulty walking eventually develops, and dementia is common in the advanced stages of the disease. Depression is common, as well.