Chapte 15 Mammalian nervous system ( Synapses )
The functions of synapses
A synapse is a junction where information is transferred from one neurone to another neurone or to
an effector cell. Synapses are designed to allow transmission in only one direction: from presynaptic
neurones to postsynaptic neurones or effector cells.
Synapses play several key roles in neural communication:
1. They transmit information through the release of neurotransmitter chemicals.
2. A single impulse from a presynaptic neurone can initiate impulses in multiple postsynaptic
neurones or effector cells.
3. Impulses from several presynaptic neurones can be combined into a single postsynaptic
response.
If a synapse is weakly stimulated, it might not release enough neurotransmitter to reach the
threshold necessary for an action potential to be generated in the postsynaptic neurone or effector
cell. Summation is a process that combines these inputs to make the generation of an action
potential in a postsynaptic neurone or effector cell more likely.
The structure of synapses
Synapses are crucial for connecting neurones and coordinating activities in the nervous system.
The key structures in a synapse include:
1. Presynaptic neurone - This neurone releases neurotransmitters into the synapse.
2. Synaptic knob - The section at the end of the presynaptic neurone that contains the
organelles needed for neurotransmitter production, like mitochondria to release energy.
3. Synaptic vesicles - These sacs within the synaptic knob store neurotransmitters until they
are released.
The functions of synapses
A synapse is a junction where information is transferred from one neurone to another neurone or to
an effector cell. Synapses are designed to allow transmission in only one direction: from presynaptic
neurones to postsynaptic neurones or effector cells.
Synapses play several key roles in neural communication:
1. They transmit information through the release of neurotransmitter chemicals.
2. A single impulse from a presynaptic neurone can initiate impulses in multiple postsynaptic
neurones or effector cells.
3. Impulses from several presynaptic neurones can be combined into a single postsynaptic
response.
If a synapse is weakly stimulated, it might not release enough neurotransmitter to reach the
threshold necessary for an action potential to be generated in the postsynaptic neurone or effector
cell. Summation is a process that combines these inputs to make the generation of an action
potential in a postsynaptic neurone or effector cell more likely.
The structure of synapses
Synapses are crucial for connecting neurones and coordinating activities in the nervous system.
The key structures in a synapse include:
1. Presynaptic neurone - This neurone releases neurotransmitters into the synapse.
2. Synaptic knob - The section at the end of the presynaptic neurone that contains the
organelles needed for neurotransmitter production, like mitochondria to release energy.
3. Synaptic vesicles - These sacs within the synaptic knob store neurotransmitters until they
are released.
