Chp 3.2: Synaptic Transmission

Question 1

How do neurons communicate? (2)

Answer 1

• Communicate with chemicals

- The firing (presynaptic) neuron releases chemicals called neurotransmitters into the synaptic cleft

Question 2

Where is the synaptic cleft located between 2 neurons?

Answer 2

between the axon terminal of one neuron and the dendrite of the next neuron

Question 3

Synapse

Answer 3

-a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron (or its target)

Question 4

Neurotransmitters (4)

Answer 4

-Chemicals produced by neurons
-Synthesized (made) inside neurons
-
-Stored in synaptic vesicles
-Released by presynaptic neuron

• Bind to receptor sites in postsynaptic neuron, where they produce a chemical reaction that is either excitatory or inhibitory
• Neurotransmitters bind only to specific sites

Question 5

Synaptic Vesicles

Answer 5

Chambers that molecules are stored in within the axon terminal

Question 6

Receptor Sites

Answer 6

protein molecules on neurons’ dendrites or soma that are specially shaped to accommodate a specific neurotransmitter molecule

Question 7

What are the five steps of chemical communication?

Answer 7

synthesis, storage, release, binding, and deactivation

Question 8

Where are neurotransmitters stored?

Answer 8

Synaptic vesicles

Question 9

Describe how neurotransmitters are communicated between neurons? (3)

Answer 9

• neurotransmitters are released by presynaptic neuron
• bind to receptor sites in postsynaptic neuron
• neurotransmitters bind only to specific sites

Question 10

What are the 2 types of neurotransmitters?

Answer 10

• Excitation

- Inhibition

Question 11

Describe the five steps of chemical communication.

Answer 11

1) Synthesis - The chemical molecules are formed inside the neuron.
2) Storage - Then get stored in the synaptic vesicles within the axon terminals.
3) Release - When action potential comes down the axon, the vesicles move to the surface of the axon terminal and release the chemical neurotransmitter into the fluid-filled space between the axon of the sending (presynaptic) neuron and the membrane of the receiving (postsynaptic) neuron.
4) Binding - The molecules of neurotransmitter cross the synaptic space and bind to receptor sites (the receptor sites each have a specially shaped surface that fits a specific transmitter molecule). Once the neurotransmitter has bound to a receptor site, it can have an effect.
5) Deactivation - Deactivation through reuptake or breakdown.

Question 12

Excitatory neurotransmitters (3)

Answer 12

• depolarises neurons
• stimulate flow of Na+
• Increase likelihood of action potential

Question 13

Inhibitory neurotransmitters (3)

Answer 13

• hyperpolarizes neuron
• Stimulates K+ to flow out
• Decrease likelihood of action potential

Question 14

Does a successful binding of a neurotransmitter to postsynaptic neuron cause an action potential?

Answer 14

It does not necessarily trigger an action potential.

Question 15

What are the 2 methods of deactivation?

Answer 15

Breakdown

Reuptake

Question 16

Define breakdown (deactivation)

Answer 16

Other chemicals in the synapse break down neurotransmitters into their chemical components

Question 17

Define reuptake (deactivation)

Answer 17

Neurotransmitters are taken back into presynaptic axon terminal

Question 18

Glutamate (glutamic acid)

Answer 18

Excitatory; found throughout the brain; involved in the control of all behaviours, especially important in learning and memory

Question 19

GABA (gamma-aminobutyric acid)

Answer 19

Destruction of GABA-producing neurons in Huntington’s disease produces tremors and loss of motor control, as well as personality changes

Question 20

Acetylcholine (ACh)

Answer 20

Memory loss in Alzheimer’s disease (undersupply)
Muscle contractions, convulsions (oversupply)

Question 21

Norepinephrine

Answer 21

Depression (undersupply)
Stress and panic disorders (oversupply)

Question 22

Serotonin

Answer 22

Depression, sleeping, and eating disorders

Question 23

Dopamine

Answer 23

Parkinson’s disease and depression (undersupply)
Schizophrenia (oversupply)

Question 24

Endorphins

Answer 24

Insensitivity to pain (oversupply)
Pain hypersensitivity, immune problems (undersupply)

Question 25

neuromodulators

Answer 25

neurotransmitter substances that are released by neurons and circulate within the nervous system to affect the sensitivity of many neurons to their natural transmitter substances