chapter 3 : Biological basis of behaviour (2)

Question 1

What is the primary way neurons commmunicate with other neurons?

Answer 1

Synaptic transmission.

Question 2

What is the brief process involved when two neurons communicate?

Answer 2

Each neuron makes a chemical and stores it in the terminal buttons.

When a neuron is sufficiently stimulated, an action potential causes the chemical to be released into very tiny gaps between the neuron and adjacent neurons (synaptic cleft).

This chemical that is released can cling to specialized areas of these adjacent neurons and stimulate them. If this stimulation, combined with the stimulation from chemicals released from hundreds of other cells, is sufficient, these adjacent neurons may have their own action potential.

Question 3

What are the 8 steps of synaptic transmission?

Answer 3

1. Synthesis
2. Transportation &storage
3. Release
4. Binding
5. Deactivation
6. Autoreceptor activation
7. Reuptake
8. Degradation.

STacy RELEASED Blind Ducks At the Red Dance

Question 4

Explain the 1st step of synaptic transmission.

Answer 4

Synthesis : Chemicals, or at least parts of them,
are made in the cell body of each neuron. These
chemicals, known as neurotransmitters, transmit
information from one neuron to another

Question 5

Explain transportation and storage .

Answer 5

Transportation and storage. When molecules of
the neurotransmitter are made, they are transported
from the cell body to the axon terminal where they
are stored. They are stored in small bead-like containers called synaptic vesicles.

Question 6

Explain the 3rd step of the synaptic transmission.

Answer 6

Release : When an action potential in the
neuron reaches the axon terminal, the synaptic vesicles melt into the cell membrane (presynaptic membrane), causing the release of the neurotransmitter into the synapse.

Question 7

Explain the process of binding.

Answer 7

Binding : The released molecules of neurotransmitter float across the gap and some bind with the membrane of the cell after the synapse.

The molecules bind to specialized proteins called receptors. These receptors allow the molecules to influence whether this next cell, the postsynaptic cell, will have its own action potential.

A specific neurotransmitter can bind only to receptor sites that its molecular structure will fit into, much like a key must fit a lock

Question 8

Explain the 5th step of synaptic transmission.

Answer 8

Deactivation. One type of neurotransmitter
(acetylcholine) can be destroyed by an enzyme in the synapse. This prevents the neurotransmitter from having a never-ending influence on the postsynaptic cell.

Question 9

Explain what autoreceptor activation is.

Answer 9

Autoreceptor activation : Some neurotransmitters bind to receptors on the same neuron that released it. This type of receptor is called an autoreceptor.

Binding on these presynaptic receptors can regulate Steps 1 and 3. For example, this binding can decrease the synthesis and release of the neurotransmitter.

Question 10

Explain the process of reuptake and what are its two side effects?

Answer 10

Reuptake : Leftover and excess neurotransmitter molecules can be brought back in to the presynaptic region of the cell. By taking the extra molecules
out of the synapse, this can stop the effect of the neurotransmitter on the postsynaptic cell and reduce the amount of neurotransmitter that the presynaptic cell must make.

Question 11

What is the last step of the synaptic transmission?

Answer 11

Degradation. Given that you are continually
synthesizing neurotransmitters (Step 1) and recycling used neurotransmitters (Step 7), there needs to be a mechanism to ensure that you don’t end up with
too much.

Enzymes in the presynaptic region break
down excess neurotransmitter molecules, which are
then eliminated.

Question 12

What is graded potential?

Answer 12

The trigger that takes a neuron from its resting
potential to an action potential.

Question 13

What are the two changes that the cell membrane undergoes when neurotransmittors bind to the receptors?

Answer 13

1. . One type of change is that the channels in the cell membrane open, allowing the cell to become less negative. ( For example, sodium ions, which are positive, enter the cell through sodium channels)
2. The second type of change is that the channels in the membrane open, allowing the cell to become more negative. For example, potassium ions, which are also positive, may leave the cell through potassium channels. When potassium ions leave the cell, the cell becomes more negative.

Question 14

What is it called when a cell is more negative?

Answer 14

Hyperpolarization

Question 15

What is it called when a cell is more positive?

Answer 15

Depolarization.

Question 16

Differentiate between the inhibitory postsynaptic potential and excitory postsynaptic potential.

Answer 16

Activity at some synapses causes the postsynaptic membrane to become more negative. These changes are called inhibitory postsynaptic potential,as they inhibit or decrease the chance of an action potential.

Some synapses cause the postsynaptic membrane to become less negative. These changes are called excitatory postsynaptic potentials, as they increase the chance of an action potential.

Question 17

What is spatial summation?

Answer 17

This process of combining excitatory and inhibitory inputs at different, but very close, branches of a dendrite is called spatial summation.

Question 18

What determines the if the IPP or EPP to begin the action potential?

Answer 18

If it reaches -50 Millivolt, an action potential will begin.

Question 19

What is temporal summation?

Answer 19

This process of combining excitatory and inhibitory inputs that arrive at the dendrites in rapid succession is called temporal summation.