Synapse

Question 1

What is a synapse

Answer 1

It is a junction between 2 cells where electrical changes in 1 cell cause a signal to be passed to another

Question 2

What is the synaptic cleft

Answer 2

It is the gap

Question 3

What is a bouton

Answer 3

A swelling formed by the terminal of the presynaptic cell

Question 4

Describe synaptic vesicle docking

Answer 4

Synaptic vesicles move toward and attach to the presynaptic membrane near the synaptic cleft

Question 5

Describe synaptic vesicle fusion

Answer 5

• 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

Question 6

Describe exocytosis

Answer 6

• 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.

Question 7

Describe how vesicles are charged with neurotransmitter

Answer 7

• 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

Question 8

Describe the role of membrane recycling in the neuron

Answer 8

• 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

Question 9

What are ionotropic receptors

Answer 9

Ligand gated ion channels that produce rapid and short lived changes in membrane potential

Question 10

What are metabotropic receptors

Answer 10

G protein couple receptors that when activated by a neurotransmitter, initiate intracellular signalling through G-proteins and second messengers which may modulate ion channels

Question 11

What is EPSP

Answer 11

It is caused by the binding of excitatory neurotransmitters to postsynaptic receptors, leading to the opening of ion channels

Question 12

What is the effect of EPSP

Answer 12

Depolarizes the postsynaptic membrane (makes it less negative), increasing the likelihood of an action potential

Question 13

What is IPSP

Answer 13

Caused by the binding of inhibitory neurotransmitters to postsynaptic receptors, leading to the opening of ion channels

Question 14

What is the effect of IPSP

Answer 14

Hyperpolarises the postsynaptic membrane, decreasing the likelihood of an action potential

Question 15

What is the effect of dendritic morphology on dendritic integration

Answer 15

• 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

Question 16

What is the effect of synapse distribution on dendrite integration

Answer 16

• 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

Question 17

What is long term potentiation

Answer 17

A long lasting increase in synaptic strength following high frequency stimulation of one neuron by another

Question 18

What is an example of LTP

Answer 18

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

Question 19

What is synaptic plasticity

Answer 19

It refers to the ability of synapses to change their strength in response to activity

Question 20

What is the simple reflex arc

Answer 20

A basic, automatic response to a stimulus, often involving a sensory neuron and a motor neuron, with minimal or no involvement of the brain

Question 21

What is a converging circuit

Answer 21

Multiple inputs from different neurons converge onto a single postsynaptic neuron, allowing integration of information from various sources

Question 22

What is a diverging circuit

Answer 22

One presynaptic neuron sends signals to multiple postsynaptic neurons, allowing the signal to spread and affect many different targets

Question 23

What is a reverberating circuit

Answer 23

Neurons are arranged in a loop, allowing signals to be repeatedly transmitted, leading to sustained activity or feedback

Question 24

What is a parallel after discharge circuit

Answer 24

An initial signal is split into parallel pathways, each with different lengths or delays, converging onto the same postsynaptic neuron