Brain and Cognition 1 – Tutorial: Neural Transmission
Answer Sheet
Tutorial aims:
- Understanding the concepts of charge and potential (in particular membrane potentials).
- Understanding why membrane potentials are generally non-zero, and how they can change.
- Learning the most important and common neurotransmitters.
- Understanding the difference between excitatory an inhibitory synapses and how they are
implicated in neural communication.
- Understanding the mechanism that generates an action potential.
Preparation (before study group)
- Prepare all questions before the meeting.
- Please take with you to the study group meeting: the handbook, a printed version of the answer
sheets (available on blackboard) and headphones (to be able to listen to auditory information in
the movies).
Product
- Answers to the questions in this tutorial.
Page 1 of 7
, Question 1
Consider two equally sized compartments separated by a membrane. Left and right Left Right
of the membrane there is a different concentration of particles X, Y and Z. All these X 100 15
particles have no charge (i.e. are neutral, and therefore they are not ions) and are Y 20 30
not able to cross the membrane. See the table here on the right. Z 20 20
a. Which way will the particles Y start to flow when a channel is placed in the membrane that allows Y
particles to move through it? Why will this happen?
Y will flow from right to left. This will happen because the concentration is higher in the right
compartment and particles will move from high to low concentration. = diffusie
b. The same question as a but now the channel permits both Y and X particles to move through it.
Where will the Y particles flow and what happens to the concentration of X particles now?
Y will still move from right to left. But the X particles will move from left to right because 100>15.
Diffusie. Totdat ze allebei verdeeld zijn.
c. If we place channels in the membrane that let all particles (X, Y and Z) move through and you
wait long enough, will there be a concentration difference or not? Explain your answer.
No, because diffusion means that eventually both compartments are the same concentraits.
Page 2 of 7
Answer Sheet
Tutorial aims:
- Understanding the concepts of charge and potential (in particular membrane potentials).
- Understanding why membrane potentials are generally non-zero, and how they can change.
- Learning the most important and common neurotransmitters.
- Understanding the difference between excitatory an inhibitory synapses and how they are
implicated in neural communication.
- Understanding the mechanism that generates an action potential.
Preparation (before study group)
- Prepare all questions before the meeting.
- Please take with you to the study group meeting: the handbook, a printed version of the answer
sheets (available on blackboard) and headphones (to be able to listen to auditory information in
the movies).
Product
- Answers to the questions in this tutorial.
Page 1 of 7
, Question 1
Consider two equally sized compartments separated by a membrane. Left and right Left Right
of the membrane there is a different concentration of particles X, Y and Z. All these X 100 15
particles have no charge (i.e. are neutral, and therefore they are not ions) and are Y 20 30
not able to cross the membrane. See the table here on the right. Z 20 20
a. Which way will the particles Y start to flow when a channel is placed in the membrane that allows Y
particles to move through it? Why will this happen?
Y will flow from right to left. This will happen because the concentration is higher in the right
compartment and particles will move from high to low concentration. = diffusie
b. The same question as a but now the channel permits both Y and X particles to move through it.
Where will the Y particles flow and what happens to the concentration of X particles now?
Y will still move from right to left. But the X particles will move from left to right because 100>15.
Diffusie. Totdat ze allebei verdeeld zijn.
c. If we place channels in the membrane that let all particles (X, Y and Z) move through and you
wait long enough, will there be a concentration difference or not? Explain your answer.
No, because diffusion means that eventually both compartments are the same concentraits.
Page 2 of 7
