Final answer:
The ultimate cause of Parkinson's disease is the degeneration of the dopamine-releasing neurons of the substantia nigra.
Step-by-step explanation:
The ultimate cause of Parkinson's disease is the degeneration of the dopamine-releasing neurons of the substantia nigra.
Parkinson's disease is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta (SNC) projecting to the corpus striatum. This leads to a reduction in dopaminergic innervation and a deficiency of dopamine in the brain.
These degenerative changes in the dopamine-releasing neurons result in the motor symptoms associated with Parkinson's disease, such as tremors, slowed movement, balance problems, and rigid muscles.