Parkinsons Flashcards
what age does parkinsons usually show symptoms
60
signs of parkinsons
rhythmic tremor-rolling a pill motion leaning forward and backward muscle rigidity- jerky difficulty rising from sitting shrinking of writing loss of spontaneous movements bradykinesia- slow movement
how is movement controlled
signlas form motor cortex to spinal cord go to muscles
corticospinal tracts
from motor cortex to spinal cord
makes up the pyramids in the medulla
extra pyramidal system
basal ganglia signals to the cortex
controls movement without corticospinal nerves
voluntary motor pathways
upper and lower motoneurons
corticospinal pathway
piramidal tracts
involuntary motor pathways
extrapiramidal system
basal ganglia
reticular and vestibular system
what is parkinsons caused by
loss of neurons in substantia nigra and thus loss of dopamine innervation of striatum
when do symptoms appear
when 70% of nigrostriatal neurons are lost
what happens to gaba neurons normally
inhibited by dopamine and sitmulated by acetylcholine
what happens to gaba in parkinsons
dopaminergic neurons die so excess acetylcholine (stimulatory)
what happens to gaba in huntingtons
gaba and some acetylcholine neurons die
etiology of parkinsons
metabolism of dopamine by MAO B
environmental toxin
dopamine itslef an axidant
genetic pathway
what do COMT and DDC do
convert l-dopa before it can cross the BBB
di receptor dopamine subfamily
Gs adn increase camp
d2 dopamine subfamily
Gi and decrease camp
striatum dopamine receptors
smooth muscle in periphery
dopamine agonists
pramipexole
ropinirole
first line therapy for parkinsons
levadopa
how does l-dopa distribute in the body
rapidly absorbed from SI by amino acid transport system
crosses the BBB
peak concentraiton an hour after ingestion with 1-3 hour half life
bioavailability issues with ldopa
metabolized in the intestine, blood, and periphery
only 1% actually enters the brain
therapeautic effects of ldope
reduces rigidity and bradykinesia
improves motor function and speech
return of facial expression
side effects of ldopa
anorexia hypotension adn cardiac arrhythmias dyskinesias (involuntary movements) on-off effect becuase wears off behavoiural changes insomnia confusion schizophrenia like behaviour
why is carbidopa used in adjuncts with ldopa
inhibits dopa decarboxylase so less ldopa converted outside the BBB thus reducing the amount required and the adverse effects
