1) How is the nervous system transmitted along the axon of a nerve cell?
2) How does the transmission across the junction between one neurone and the next happen?
3) How is the impulse transmitted across a neurone?
4) How does the impulse cross the synapse?
5) What happens along the axon and at a synapse?
a) What happens at the end of one neuron?
b) What happens in the synapse itself?
c) What happens in the second neuron?
1) The nervous system transmits signals along the axon of a nerve cell through the propagation of action potentials. An action potential is generated when the voltage of a nerve cell exceeds a certain threshold, causing ion channels to open and allowing positive ions to flow into the cell. This flow of ions continually moves along the axon towards the synaptic terminals, transforming the electrical signal into a chemical one at the synapse.
2) Transmission across the junction between one neuron and the next occurs through the release of neurotransmitters. Once the action potential reaches the end of the axon, it triggers the release of neurotransmitter molecules from vesicles in the presynaptic neuron. These neurotransmitters then diffuse across the synaptic cleft and bind to specific receptors on the postsynaptic neuron, leading to the opening or closing of ion channels and the generation of a new action potential or inhibition of one.
3) Impulses are transmitted across a neuron through the propagation of action potentials, as mentioned above. An initial stimulus causes a change in membrane potential, and if this change exceeds the threshold value, voltage-gated ion channels open. This allows an influx of positively charged ions into the neuron, leading to the generation and propagation of an action potential along the axon.
4) The impulse crosses the synapse through the release of neurotransmitters from the presynaptic neuron, which then interact with receptors on the postsynaptic neuron. This neurotransmitter-receptor interaction causes the opening or closing of ion channels on the postsynaptic neuron, ultimately leading to either the generation of a new action potential or the inhibition of a potential.
5) a) At the end of one neuron (the presynaptic neuron), an action potential causes the release of neurotransmitters from synaptic vesicles into the synaptic cleft.
b) In the synapse itself, neurotransmitters diffuse across the synaptic cleft and bind to specific receptors on the second (postsynaptic) neuron.
c) In the second (postsynaptic) neuron, the binding of neurotransmitters to their receptors causes the opening or closing of ion channels. This can either excite or inhibit the postsynaptic neuron, leading to the generation of a new action potential or the suppression of one.