Synapse Flashcards
What is a synapse
It is a junction between 2 cells where electrical changes in 1 cell cause a signal to be passed to another
What is the synaptic cleft
It is the gap
What is a bouton
A swelling formed by the terminal of the presynaptic cell
Describe synaptic vesicle docking
Synaptic vesicles move toward and attach to the presynaptic membrane near the synaptic cleft
Describe synaptic vesicle fusion
- When an action potential arrives at the presynaptic terminal, it causes voltage-gated calcium channels to open
- Calcium ions (Ca²⁺) enter the cell and trigger the fusion of the synaptic vesicle with the presynaptic membrane
Describe exocytosis
- The fusion of the vesicle with the membrane results in the vesicle releasing its neurotransmitters into the synaptic cleft through exocytosis
- This is the process of neurotransmitter release.
Describe how vesicles are charged with neurotransmitter
- Neurotransmitters are synthesized and transported into synaptic vesicles by specific vesicular transporters located in the vesicle membrane
- This loading is facilitated by the vesicle maintaining a proton gradient across their membrane created by a vesicular H+ ATPase pump
Describe the role of membrane recycling in the neuron
- After vesicles fuse with the presynaptic membrane and release neurotransmitters, the vesicle membrane is retrieved by the process of endocytosis, where it is pinched off and internalized
- The recycled vesicular membrane is then refilled with neurotransmitters and reused in future synaptic transmission, ensuring the neuron can continue to communicate effectively. This recycling process helps maintain the neuron’s membrane integrity and vesicle pool
What are ionotropic receptors
Ligand gated ion channels that produce rapid and short lived changes in membrane potential
What are metabotropic receptors
G protein couple receptors that when activated by a neurotransmitter, initiate intracellular signalling through G-proteins and second messengers which may modulate ion channels
What is EPSP
It is caused by the binding of excitatory neurotransmitters to postsynaptic receptors, leading to the opening of ion channels
What is the effect of EPSP
Depolarizes the postsynaptic membrane (makes it less negative), increasing the likelihood of an action potential
What is IPSP
Caused by the binding of inhibitory neurotransmitters to postsynaptic receptors, leading to the opening of ion channels
What is the effect of IPSP
Hyperpolarises the postsynaptic membrane, decreasing the likelihood of an action potential
What is the effect of dendritic morphology on dendritic integration
- More branches or complex dendritic structures increase the area available for synaptic connections, enhancing signal integration
- Changes in spine number or shape can modulate the efficiency and plasticity of synaptic transmission
What is the effect of synapse distribution on dendrite integration
- Synapses located near the dendritic root (closer to the soma) have more direct influence on the neuron’s output, while synapses farther out on dendritic branches (distal synapses) may have less immediate impact
- Synapses located on different parts of the dendrite can have varying effects on the overall response, depending on the temporal and spatial summation of inputs, with distal inputs requiring more synchronous activation to influence the soma
What is long term potentiation
A long lasting increase in synaptic strength following high frequency stimulation of one neuron by another
What is an example of LTP
In the hippocampus, repeated stimulation of a presynaptic neuron can lead to a long-lasting increase in the postsynaptic neuron’s response, which is thought to be crucial for learning and memory
What is synaptic plasticity
It refers to the ability of synapses to change their strength in response to activity
What is the simple reflex arc
A basic, automatic response to a stimulus, often involving a sensory neuron and a motor neuron, with minimal or no involvement of the brain
What is a converging circuit
Multiple inputs from different neurons converge onto a single postsynaptic neuron, allowing integration of information from various sources
What is a diverging circuit
One presynaptic neuron sends signals to multiple postsynaptic neurons, allowing the signal to spread and affect many different targets
What is a reverberating circuit
Neurons are arranged in a loop, allowing signals to be repeatedly transmitted, leading to sustained activity or feedback
What is a parallel after discharge circuit
An initial signal is split into parallel pathways, each with different lengths or delays, converging onto the same postsynaptic neuron
