PBL 2 Flashcards
what is the function of the cerebellum?
smooths and coordinates contraction of skeletal muscles, it also regulates posture and balance and may have a role in cognition and language processing
what is the function of the basal ganglia?
selection and initiation of voluntary movements.
where is the substantia nigra?
one either side of the midbrain
what are the 2 regions of the substantia nigra?
pars compacta and pars reticulata
where does the substantia Nigra get its dark colouring from?
the large number f dopamine neurones as they express a dark pigment called neuromelanin
which neurones are found in the substantia nigra pars reticulata and pars compacta?
pars compacta- dopamine
pars reticulata- GABA
what is the basal ganglia?
a group of subcortical structures found deep within the white matter of the brain.
what are the 5 pairs of nuclei found in the basal ganglia?
caudate nucleus, putamen, globus pallidus, subthalamic nucleus and substantia nigra
describe the structure of the caudate nucleus?
it has a large head connected to a smaller tail by a long body
what is the striatum?
the caudate nucleus and the putamen
what are the 2 parts of the globus pallidus?
internal and external segment
what are the functions of the basal ganglia?
control of movement, selection of voluntary movements, surpasses inappropriate movements, modulates movements, cognition/memeory/attention
describe the synthesisation of dopamine?
amino acid tyrosine is converted to L-dopa. Then L-DOPA is decarboxylated to form dopamine.
where are dopamine neurones most concentrated?
in the substantia nigra
generally, how can we treat parkinsons symptoms?
by increasing levels of dopamine and decreasing levels of ACh.
why would taking dopamine orally be useless in parkinsons?
because dopamine cannot cross the blood-brain barrier
what is L-DOPA?
A precursor of dopamine which boost the dopamine levels in the substantia nigra neurons that are still alive
what do dopamine agonists do?
Stimulate postsynaptic dopamine D2 receptors in the striatum
what are some side effects of L-DOPA?
drug resistance, dyskinesia (involuntary movements) and psychosis
what are some side effects of dopamine agonists?
sudden sleepiness
how can foetal cell transplants be useful in parkinsons disease?
Transplantation of stem cells into the putamen basal ganglia
how can deep brain stimulation help parkinsons disease?
Implanted electrode to inactivate the globus pallidus or subthalamic nucleus using high frequency stimulation, removes inhibitory effects of movement
what is parkinsons disease?
is a progressive disorder of the CNS that typically affects its victims around age 60.
what is the pathophysiology of parkinsons disease?
Neurons that extend form the substantia nigra to the putamen and caudate nucleus, where they release dopamine, degenerate. The imbalance of neurotransmitter (too little dopamine, too much ACh) is thought to cause most of the symptoms. Both cause increased inhibition of the thalamus and decreased excitation of the motor cortex resulting in a reduction of movement.
what are the effects of a reduction in D1 and D2 receptors?
- Leads to reduced excitation of the direct (D1) pathway
* Leads to reduced inhibition of the indirect (D2) pathway
what are the clinical symptoms of parkinsons disease?
Tremor of hands
Rigidity of muscles
Akinesia (loss or impairment of the power of voluntary movement)
Postural problem
