1. Parkinson's disease destroys the substantia nigra of the brain and prevents it producing a neurotransmitter called dopamine.
a) What is meant by substantia nigra and where in the brain is it found?
b) How might dopamine affect the central nervous system and cause the symptoms of Parkinson's?
c) Name two other known neurotransmitters besides dopamine.
2. Draw a diagram of the human brain and label the parts which are concerned with speech, hearing, eyesight and co-ordination of body movements.
3. The average potential across a neuron is about 70mV. When a neuron "transmits", this potential is temporarily reduced to a threshold of about 50mV by movement of sodium ions into the neuron. Depolarisation then occurs involving a refractory period of about between 0.001-0.002 seconds in which time a second impulse will not "fire" the neuron.
a) Explain which part (inside or outside) of an unstimulated neuron
is negative?
b) How does depolarisation occur?
c) How many impulses per second can a neuron transmit?
d) What voltage is required to stimulate a neuron?
e) Why to control movement must some neurons be inhibited by the new treatment for Parkinson's?
