Title: Psychology / Biopsychology / 04_Synapses
Tags: Biopsychology::04_Synapses Biopsychology::Semester_1

Q: What are electrical synapses called?
A: Gap junctions

Q: How do gap junctions work?
A: Two adjacent cells can directly exchange ions by connecting two connexons to form an ion channel between the two cells.
electrical synapses

Q: What is the synaptic cleft?
A: A tiny bit of space between the terminal bouton and the next cell. These two do NOT touch!

Q: What is the difference between axondendritic, axonsomatic and axonaxonic synapses?
A: The location where they connect to the next cell (obvious from the names)

Q: What is another way of describing the receptors in a synapse?
A: They are neurotransmitter-gated ion channels.

Q: What 4 steps does a chemical synapse go through when an action potential arrives?
A: (Prev: Vesicles are docked at active zone)
1) Voltage gated Ca+ channels open
2) Ca+ leads to a fusion of the vesicles with the cell membrane (exocytosis)
3) neurotransmitters are released into the cleft, causing transmitter gated ion channels to open
4) the used vesicles get recycled (endocytosis)

Q: What does a synaptic vesicle do?
A: It stores neurotransmitters and has the ability to merge with the cell membrane to release said neurotransmitters.

Q: What does an influx of Ca+ ions generally mean?
A: Structural changes for elements inside the cell

Q: What is the difference between exocytosis and endocytosis?
A: Endocytosis is the process of capturing a substance or particle from outside the cell by engulfing it with the cell membrane, and bringing it into the cell.
Exocytosis describes the process of vesicles fusing with the plasma membrane and releasing their contents to the outside of the cell.

Q: What is the structural difference between excitatory and inhibitory synapses?
A: The kind of ion channels on the postsynaptic membrane!
Na+ channels for excitatory synapses
Cl- channels for inhibitory synapses

Q: What is the functional difference between excitatory and inhibitory synapses?
A: Excitatory drive the next cell towards triggering an action potential (depolarisation) by making the inside of the cell more positive
Inhibitory synapses make the triggering of an action potential in the next cell less likely by driving it towards inhibition (hyperpolarisation, making the cell more negative)

Q: What do IPSP and EPSP stand for?
A: Inhibitory PostSynaptic Potential
Excitatory PostSynaptic Potential

Q: What is the directional difference between chemical and electrical synapses?
A: Chemical: unidirectional
Electrical: bidirectional

Q: What 4 factors does the effectiveness of a synapse depend on?
A: Location of the synapse
Size of the synapse
What ion channels are activated by the neurotransmitters
What neurotransmitter is used

Q: How do chemical synapses switch between being inhibitory and excitatory?
A: They don't! A chemical synapse can either be excitatory OR inhibitory

Q: What are the 3 major categories of neurotransmitters?
A: Amino Acids (fast)
Amines
Peptides (sluggish)

Q: How many different kinds of neurotransmitters are usually found in a synapse?
A: Mostly ONE.

Q: Except for reuptaking neurotransmitters into the pre synapse, what other 2 ways of removing neurotransmitters from the synaptic cleft are there?
A: Certain enzymes help by breaking down neurotransmitters.
They diffuse away from the cleft or get taken up by astrocytes.

Q: How can the removal of the neurotransmitters in the synaptic cleft be manipulated in order to improve the efficiency of the neurotransmitters?
A: e.g. the reuptake of neurotransmitters can be inhibited to make the neurotransmitters stay in the cleft for longer.
alternatively, one could inhibit the neurotransmitter-breaking enzymes for a similar effect.

Q: What is the difference between spatial and temporal summation for synaptic integration?
A: spatial: multiple axons sending action potentials at the same time
temporal: one axon sending a quick succession of action potentials

Q: What is the ratio of excitatory to inhibitory synapses in the brain?
A: 85% excitatory
15% inhibitory

Q: Which type of synapse is usually closer to the axon hillok (i vs e)?
A: inhibitory synapses (making them more powerful overall)

Q: Why are inhibitory synapses so important?
A: Neurons are strongly interconnected, so an AP will go to every single cell connected to this neuron.
→ not every one of those neurons should generate an AP, so inhibition makes it so that only those neurons that get triggered by multiple other neurons generate an AP themselves

Q: What are gap junctions?
A: Electrical synapses

Q: What post synaptic potential can be found at synapses using chloride receptors (Cl)?
A: IPSP

Q: What are the big and plastic post synaptic areas on the dendrites called?
A: Dendritic spines