Structure and Function of Synapses 2 Flashcards
What is an inhibitory synapse?
A synapse that reduces the likelihood of an action potential in the postsynaptic neurone
How do inhibitory synapses function?
The presynaptic neurone releases a neurotransmitter that binds to chloride ion protein channels on the postsynaptic neurone, causing them to open
What happens when chloride ion channels open?
Chloride ions move into the postsynaptic neurone by facilitated diffusion, making the inside more negative
What effect does the neurotransmitter have on potassium channels?
It causes potassium channels to open, allowing potassium ions to move out of the postsynaptic neurone into the synapse
How does the movement of chloride and potassium ions affect the membrane potential?
The inside of the postsynaptic membrane becomes more negative due to chloride ions moving in and potassium ions moving out
What is hyperpolarisation, why does it inhibit an action potential?
Hyperpolarisation is when the membrane potential becomes more negative than resting potential.
This means a larger influx of sodium ions is needed to reach the threshold and trigger an action potential
What is the primary function of synapses?
To transmit information from one neurone to another, acting as junctions for nerve impulses
How synapses allow a single impulse to create multiple responses?
A single impulse can initiate new impulses in multiple neurones at a synapse, leading to simultaneous responses
How do synapses allow multiple impulses to be combined?
They can integrate multiple impulses from different neurones allowing nerve impulses from different stimuli to contribute to a single response
Where is the neurotransmitter produced?
Only in the presynaptic neurone, not in the postsynaptic neurone
Where is the neurotransmitter stored before release?
In synaptic vesicles within the synaptic knob of the presynaptic neurone
What happens when an action potential reaches the synaptic knob?
The vesicles fuse with the presynaptic membrane, releasing the neurotransmitter into the synaptic cleft
What happens after the neurotransmitter is released into the synaptic cleft?
It diffuses across and binds to specific receptor proteins on the postsynaptic neurone
What is the result of neurotransmitter binding to receptor proteins?
It triggers a new action potential in the postsynaptic neurone
What are synapses called if they trigger a new action potential?
Exitatory synapses
