PBL 2

Question 1

what is the function of the cerebellum?

Answer 1

smooths and coordinates contraction of skeletal muscles, it also regulates posture and balance and may have a role in cognition and language processing

Question 2

what is the function of the basal ganglia?

Answer 2

selection and initiation of voluntary movements.

Question 3

where is the substantia nigra?

Answer 3

one either side of the midbrain

Question 4

what are the 2 regions of the substantia nigra?

Answer 4

pars compacta and pars reticulata

Question 5

where does the substantia Nigra get its dark colouring from?

Answer 5

the large number f dopamine neurones as they express a dark pigment called neuromelanin

Question 6

which neurones are found in the substantia nigra pars reticulata and pars compacta?

Answer 6

pars compacta- dopamine

pars reticulata- GABA

Question 7

what is the basal ganglia?

Answer 7

a group of subcortical structures found deep within the white matter of the brain.

Question 8

what are the 5 pairs of nuclei found in the basal ganglia?

Answer 8

caudate nucleus, putamen, globus pallidus, subthalamic nucleus and substantia nigra

Question 9

describe the structure of the caudate nucleus?

Answer 9

it has a large head connected to a smaller tail by a long body

Question 10

what is the striatum?

Answer 10

the caudate nucleus and the putamen

Question 11

what are the 2 parts of the globus pallidus?

Answer 11

internal and external segment

Question 12

what are the functions of the basal ganglia?

Answer 12

control of movement, selection of voluntary movements, surpasses inappropriate movements, modulates movements, cognition/memeory/attention

Question 13

describe the synthesisation of dopamine?

Answer 13

amino acid tyrosine is converted to L-dopa. Then L-DOPA is decarboxylated to form dopamine.

Question 14

where are dopamine neurones most concentrated?

Answer 14

in the substantia nigra

Question 15

generally, how can we treat parkinsons symptoms?

Answer 15

by increasing levels of dopamine and decreasing levels of ACh.

Question 16

why would taking dopamine orally be useless in parkinsons?

Answer 16

because dopamine cannot cross the blood-brain barrier

Question 17

what is L-DOPA?

Answer 17

A precursor of dopamine which boost the dopamine levels in the substantia nigra neurons that are still alive

Question 18

what do dopamine agonists do?

Answer 18

Stimulate postsynaptic dopamine D2 receptors in the striatum

Question 19

what are some side effects of L-DOPA?

Answer 19

drug resistance, dyskinesia (involuntary movements) and psychosis

Question 20

what are some side effects of dopamine agonists?

Answer 20

sudden sleepiness

Question 21

how can foetal cell transplants be useful in parkinsons disease?

Answer 21

Transplantation of stem cells into the putamen basal ganglia

Question 22

how can deep brain stimulation help parkinsons disease?

Answer 22

Implanted electrode to inactivate the globus pallidus or subthalamic nucleus using high frequency stimulation, removes inhibitory effects of movement

Question 23

what is parkinsons disease?

Answer 23

is a progressive disorder of the CNS that typically affects its victims around age 60.

Question 24

what is the pathophysiology of parkinsons disease?

Answer 24

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.

Question 25

what are the effects of a reduction in D1 and D2 receptors?

Answer 25

• Leads to reduced excitation of the direct (D1) pathway

* Leads to reduced inhibition of the indirect (D2) pathway

Question 26

what are the clinical symptoms of parkinsons disease?

Answer 26

Tremor of hands
Rigidity of muscles
Akinesia (loss or impairment of the power of voluntary movement)
Postural problem