Transmission of a nerve impulse across a synapse
Synaptic Transmission Review Sheet
Key terms
Write the key terms next to the correct definition
Key term
Definition
An electrical impulse generate by the flow of ions
Protein channel that allows calcium ions to enter the axon terminal
Metal ions whose influx stimulate the movement of intracellular vesicles
A membranous pouch within an axon terminal that stores and releases neurotransmitter
A neurotransmitter(chemical) that is responsible for muscle contraction
The neuron before the synaptic cleft
The neuron after the synaptic cleft
The space between the axon terminal of one neuron and the post-synaptic membrane of
another neuron. About 20 nm wide.
Protein channel that allows sodium ions to enter the post synaptic neuron
Metal ions whose influx generate an action potential
An enzyme that breaks down acetycholine to choline and ethanoic acid so it can be
recycled
WORD BANK
Acetylcholine
Calcium ions
Post-synaptic neuron
Synaptic cleft
Sodium ions
Action potential
Vesicle
Cholinesterase
Presynaptic neuron
Calcium ion channel
Sodium ion channel
Reading exercise -Transmission across a synapse
Read the following passage carefully. When you are finished reading, use the words highlighted in bold to label the
following diagram.
1. When an action potential arrives at the axon terminal it opens calcium ion channels in the presynaptic
membrane, so calcium ions enter from the synaptic cleft.
2. This causes the vesicles (containing the neurotransmitter ACh) to attach themselves to the presynaptic
membrane and discharge their contents, through the membrane into the synaptic cleft.
3. A molecule of acetylcholine will diffuse across the synaptic cleft and bind to its complementary receptor site
on the post-synaptic membrane a Na+ channel opens.
4. As the sodium ions rush into the cytoplasm of the postsynaptic neurone, an action potential is generated in
the post-synaptic neuron.
5. The transmitter substance on the receptors is immediately inactivated by enzymes. Acetylcholine is
hydrolysed to choline and ethanoic acid by the enzyme cholinesterase.
6. These substances can then be absorbed by the presynaptic membrane and used to re-synthesise
acetylcholine using energy from ATP.
Transmission of a nerve impulse across a synapse
Transmission of a nerve impulse across a synapse
Write the correct statements into the space next to the correct diagram. The statements ARE NOT IN ORDER!
1.
Choose one of these
statements below
A new action potential is
generated
2.
An action potential reaches
the axon terminal.
Calcium channels open and
calcium ions (Ca2+) flood into
the axon terminal
3.
This stimulates vesicles
containing neurotransmitter
(ACh) to fuse with the
presynaptic membrane.
This releases ACh into the
synaptic cleft.
4.
Neurotransmitter
(acetylcholine) diffuses across
the synaptic cleft
Acetylcholine binds to
receptors on the postsynaptic membrane.
5.
When ACh binds to its
receptor it opens the sodium
ion channel
Sodium ions diffuse into the
post synaptic neuron through
sodium ion channels
Transmission of a nerve impulse across a synapse