Neurophisiology 2: synapes and integration

Question 1

How do you call what binds to a receptor?

Answer 1

Ligand

Question 2

Can one label a neurotransmitter as inhibitory or excitatory?

Answer 2

No

Question 3

To what does the effect of a neurotransmitter depend?

Answer 3

To receptors

Question 4

Types of receptors (2)

Answer 4

Ionotropic, Metabotropic

Question 5

How does a ionotropic receptor work?

Answer 5

The Neurotransmitter binds to it, channel opens, ions (per questo di chiama ionotropic) flow in.

Question 6

How does a metabotropic receptor work?

Answer 6

The Neurotransmitter binds to membrane protein which releases a activating protein which can trigger different responses - including ion channels opening- in the post-synaptic membrane

Question 7

The five steps of synaptic transmission (explained)

Answer 7

The transfer of information across a synapse is called synaptic transmission. Here’s a
preview of the steps:
1. The action potential traveling down the axon arrives at the axon terminal.
2. This depolarization opens voltage-gated calcium channels in the membrane of
the axon terminal, allowing calcium ions (Ca2+) to enter the terminal.
3. The Ca2+ causes synaptic vesicles filled with neurotransmitter to fuse with the
presynaptic membrane and rupture, releasing the transmitter molecules into the
synaptic cleft.
4. Transmitter molecules cross the cleft to bind to special receptor molecules in the
postsynaptic membrane, leading to the opening of ion channels in the postsynaptic
membrane.
5. This ion flow creates a local EPSP or IPSP in the postsynaptic neuron.

Question 8

One postsynaptic potential can lead to the creation of an action potential (V/F)

Answer 8

False. You need hundreds of thousand postsynptic potentials creted by just as many neurotrasmitter in order to trigger or inhibit and action potential in the postsynaptic membrane.

Question 9

Definition of EPSP

Answer 9

Excitatory Postsynaptic Potential - potential with a depolarizing (making less negative ) effect on the postsynaptic membrane. -> makes the action potential more probable

Question 10

Definition of IPSP

Answer 10

Inhibitory Postsynaptic Potential - potential with a hyperpolarizing (making more negative) effect on the postsynaptic membrane.-> makes the action potential less probable.

Question 11

What happens to the Neurotransmitter that does not bind to receptors? (3 possible ways)

Answer 11

It is either:

• Taken by autoreceptors in the presynaptic membrane, which are there to tell the cell: look, the job is done, the neurotrasmitter was released!
• Taken back up and RECYCLED for a new transmission by TRANSPORTER proteins in the presynaptice membrane
• Inactivated (degraded) by enzimes in the synaptic cleft.

Question 12

the two types of potential, by their effect on the postsynaptic neuron (and not on behaviour)

Answer 12

Inhibitory postsynaptic potential -> hyperpolarizes, makes it less likely to reach threshold
Excitatory postsynaptic potential -> depolarizes, makes it more likely to reach threshold

Question 13

What do we mean by graded potential?

Answer 13

It means that its quality is not all-or-nothing, reaching always the same voltage and leading to the same effect. On the contrary, it can have a voltage of variable intensity/entity -> because of summation

Question 14

What do we intend by summation?

Answer 14

The sum (and subtraction) of potentials at the postsynaptic membrane coming from multiple neurotrasmitters.

Question 15

2 types of summation (profumo)

Answer 15

Spatial and temporal

Question 16

How many different types of synapses are there?

Answer 16

6: axosecretory, axoaxonic, axodendritic, axoextracellular, axosomatic, axosynaptic