8.3 Movement Disorders Flashcards
Main symptoms of Parkinson’s disease are ____, ____ ____, ____ ____, and difficulty initiating physical and mental activity.
rigidity, muscle tremors, slow movements,
Brain disorders that impair ____ also impair mood, memory, and cognition.
movement
Parkinsons strikes about ___ to ___ of people over age 65.
1% to 2%
In addition to the motor problems, patients are slow on ____ ____, such as imagining events or actions, even when they don’t have to do anything.
cognitive tasks
A loss of ____ is often an early symptom of Parkinson’s, and sometimes the first symptom.
olfaction
____ and ____ ____ are also common symptoms of Parkinsons, beginning early in the course of the disease.
Depression and memory loss
People with Parkinson’s disease are not paralysed or weak. The basal ganglia have cells specialised for learning to start or stop a ____ ____ of ____. Those cells are impaired in Parkinson’s disease, and the result is a difficulty with spontaneous movements in the absence of stimuli to guide their actions.
voluntary sequence of motions
The immediate cause of Parkinson’s disease is a gradual progressive death of neurons, especially in the ____ ____, which sends dopamine-releasing axons to the caudate nucleus and putamen. People with Parkinsons disease lose these axons and therefore dopamine.
substantia nigra
- The main route, known as the direct pathway, is this follows: axons from the substantia nigra release ____ that excites the cordate nucleus and putamen.
dopamine
- The caudate nucleus and putamen inhibit the globus pallidus, which in turn inhibits part of the ____.
thalamus
- For people with Parkinson’s disease, decreased output from the substantia nigra means less ____ of the caudate nucleus and putamen, and therefore less ____ of the globus pallidus.
excitation : inhibition
- The globus pallidus, freed from inhibition, increases its (inhibitory) output to the thalamus. So the net result is ____ activity in the thalamus, and therefore also in parts of the cerebral cortex.
decreased
- In summary, a loss of dopamine activity in the ____ ____ leads to less stimulation of the motor cortex and slow onset of movements.
substantia nigra
Genes only ____ influence the risk of late-onset Parkinson’s disease.
weakly
A toxin that could be responsible for Parkinsons symptoms is ____, a chemical that the body converts to MPP+, which accumulates in, and then destroys, neurons that release dopamine.
MPTP
One hypothesis for Parkinson onset is that people are sometimes exposed to ____ ____ in herbicides and pesticides, many of which damage cells of the substantia nigra.
hazardous chemicals
Parkinson’s disease is more common than average among ____ and others who have had years of exposure to herbicides and pesticides.
farmers
One factor that stands out consistently with Parkinsons is ____ ____ and ____: people who smoke cigarettes or drink coffee have less chance of developing Parkinson’s disease.
cigarette smoking and coffee
Animal research indicates that decaffeinated coffee works just as well as regular coffee, and the nicotine-free tobacco works as well as full tobacco, so the effective chemicals are something other than ____ and ____.
caffeine and nicotine
Parkinson’s disease probably results from a mixture of causes. What they have in common is damage to the ____.
mitochondria
When a neurons mitochondria begins to fail – because of genes, toxins, infections, or whatever – a chemical called _____ clots into clusters that damage neurons containing dopamine. Dopamine-containing neurons are especially vulnerable to damage.
a-synuclein
If Parkinson’s disease results from a dopamine deficiency, the logical goal is to ____ ____ ____. A dopamine pill would be ineffective because dopamine does not cross the blood-brain barrier.
restore missing dopamine
______, a precursor to dopamine, does cross the barrier. Taken as a daily pill, ______ reaches the brain, we neurons convert it to dopamine. ______ is the main treatment for Parkinson’s disease.
L-dopa
However, L-dopa is ____ in several ways. First, it is ineffective for some patients, especially those in the late stages of the disease. Second, it does not prevent the continued loss of neurons. Third, it produces unpleasant side-effects such as nausea, restlessness, sleep problems, low blood pressure, repetitive movements, hallucinations and delusions.
L-dopa is disappointing
____ disease is a severe neurological disorder that strikes about one person in 10,000 in the United States.
Huntington’s
