Final answer:
Parkinson's disease is a neurodegenerative disorder that affects the elderly and causes tremors and debilitation. It is characterized by the loss of dopamine neurons in the substantia nigra, leading to symptoms such as tremor, slowed movement, and rigid muscles.
Step-by-step explanation:
Parkinson's disease is a neurodegenerative disorder that affects the elderly and causes tremors and eventual debilitation. It is characterized by the loss of dopamine neurons in the substantia nigra, a midbrain structure that regulates movement. This loss of neurons leads to symptoms such as tremor, slowed movement, speech changes, balance problems, and rigid muscles. Patients with Parkinson's disease may also develop psychological symptoms such as dementia.