Synaptic communication Flashcards

1
Q

Why is it odd that sodium does not pass through potassium channels?

A
  • same charge when dissolved in water
  • k+ is bigger than sodium
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2
Q

How did they study the specificities of potassium channels?

A
  • mutated the nucleic acids in the ion channel proteins one by one and grew them on a frog cell
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3
Q

Why can Na+ not pass through potassium ion channels?

A
  • in water, ions gain a hydration shell that stabilizes them and makes them bigger
  • the micro-charges of the potassium channel are organized so that the potassium ion is more stable in the channel than in its hydration shell
  • it will therefore leave its shell to join the channel
  • BUT the Na+ ion is too small to have these ideal interactions with the carbonyle groups inside the pump. it keeps its shell and is therefore too big to enter the cell.
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4
Q

What is a promoter?

A

Region of DNA that initiates transcription of a particular gene

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5
Q

How does the action potential propagate?

A
  • by causing a chain reaction of depolarization of the axon by puchinf positive ions always furhter toward the axon terminal
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6
Q

What is particular about the types of potassium channels a human has?

A
  • there are more than 40 types of potassium channels
    the number of channel of each type per cell partly determines the function of the neuron
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7
Q

What are glial cells?

A

lipids that surround all the cells in the brain

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8
Q

What are the functions of glial cells?

A
  • help traffic nutrient
  • help maintain molecular stability in the extracellular space
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9
Q

What is the most abundant component of the brain?

A

Glial cells

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10
Q

What is the quantity proportions between glial cells and neurons in the brain?

A

between 2:1 and 5:1

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11
Q

What are the three types of glial cells?

A
  • Astrocytes
  • Microglia
  • Oligodendrocytes
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12
Q

Where are the glial cells situated?

A

Exclusively in the central nervous system

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13
Q

What are the roles of astrocytes?

A
  • physical support
  • cleans up debris in the brain and break it down
  • provides scaffolding for various cellular functions
  • control the chemical composition of the inter-neuronal space
  • helps nourish neurons
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14
Q

What is the role of microglia?

A
  • responsible for the immune system of the brain that is independent from that of the rest of the body
  • protect the brain from invading micro-organisms
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15
Q

What are the roles of oligodendrocytes?

A
  • create myelin sheath
  • can myelinize 50 neurons
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16
Q

What glial cell is the janitor of the cell?

A

Astrocytes

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17
Q

What glial cell is responsible for the brain’s immune system?

A

Microglia

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17
Q

What glial cell is responsible for myelination?

A

oligodendrocytes

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18
Q

How many axons can one oligodendrocyte myelinate?

A

50

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19
Q

What is the structure of the myelin sheath?

A
  • the myelination is 20 microns
  • the node of ranvier is 1 micron
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20
Q

What is saltatory conduction?

A
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21
Q

How is the action potential propagated through the axon?

A
  • through saltatory conduction
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22
Q

What is the impact of the presence of a sheath of lipids around the axon?

A
  • no electrostatic interaction with the environment is possible, as the axon is insulated. the transport is therefore faster.
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23
Q

What is the impact of the presence of nodes of ranvier in the myelin sheath?

A
  • allows the regeneration of the electric charge (the charge is renewed). The transport is therefore more efficient (no loss of charge)
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24
Q

Where does the axon enter in contact with extracellular fluid?

A

at the node of ranvier

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25
Q

On the axon, where are the ion channels?

A

At the node of Ranvier

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26
Q

What is a synapse?

A

Junction between the axon terminal of the sending neuron and the cell membrane of the receiving neuron

27
Q

What is decremental conduction?

A
  • as the stimuli passes through thw axon, there is a loss of charge, so there is a decrease in the stimuli
28
Q

What is a synaptic vesicle?

A

Fragments of cell membrane that contains molecules of neurotransmitters

29
Q

How do synaptic vesicles release neurotransmitters ?

A

Tie themselves to the presynaptic membrane and release neurotransmitters

30
Q

What is the space between the pre and post synaptic membrane?

A

synaptic cleft

31
Q

Where are neurotransmitters released?

A

Synaptic cleft

32
Q

Which type of receptor has the fastest impact on the cell’s activity?

A

Ionotropic

33
Q

What is the modus operandi of ionotropic receptors?

A

opens ion channels, either EPSP or IPSP

34
Q

What is the main modus operandi of metabotropic receptors?

A

G-protein coupled receptors
Can act indirectly on ion channels through intracellular signaling cascade

35
Q

How are vesicles released?

A

1) AP goes down the axon
2) VG calcium channels open
3) vesicles sense the entrance of calcium
4) the vesicles fuse with the pre-synaptic membrane

36
Q

What are the two types of neurotransmitter receptors?

A

Ionotropic and metabotropic

37
Q

What are the three types of synaptic receptors?

A
  • postsynaptic
  • presynaptic
  • extrasynaptic
38
Q

What is the purpose of a pre-synaptic neuron?

A

Will detect i the cell they are assoiated with is actually releasing the neurotransmitters it should be releasing

39
Q

What is a ligand?

A
  • signaling molecule that binds to the binding site of a receptor
40
Q

What is a binding site?

A

Location on a protein receptor to which a ligand binds

41
Q

What is an ionotropic receptor?

A
  • receptor that is an ion channel
  • the properties of its pore determine if it causes EPSPs or IPSPs
42
Q

What is a ligand-gated ion channel?

A
  • a receptor that is an ion channel
  • known as an ionotropic receptor
  • opens when the ligand binds to it
43
Q

How does a neurotransmitter activate an ionotropic channel?

A
  • as soon as the neurotransmitter binds itself to the recepor, it changes the shape of the receptor
44
Q

what are the two mechanisms that keep neurotransmitter signaling in the synapse brief?

A
  • Enzymatic deactivation
  • Reuptake
45
Q

What is enzymatic deactivation?

A
  • Destruction of a neurotransmitter by an enzyme after action
46
Q

What is reuptake?

A

Reentry of a neurotransmitter just liberated by a terminal button back through its membrane. Aided by reuptake proteins.

47
Q

What is postsynaptic potential?

A
  • alteration in the membrane potential of a post-synaptic neuron
48
Q

What causes post-synaptic potential?

A

neurotransmitter release into the synapse that causes receptor activation

49
Q

What are the types of post-synaptic potentials?

A
  • excitatory
  • inhibitory
50
Q

What is the impact of an Excitatory postsynaptic potential?

A

Leads to depolarization, which makes the initiation of an AP easier

51
Q

What mediates an EPSP?

A

Receptor proteins that open ion channels permeable to sodium

52
Q

What is the impact of an inhibitory postsynaptic potential?

A

Hyperpolarization of the post-synaptic membrane, making it harder to initiate an action potential

53
Q

What mediates an inhibitory postsynaptic potential?

A

Receptor proteins that open ion channels permeable to chloride ions

54
Q

What happens whe there is an influx of sodium in the neuron, but not enough to create an Action Potential?

A

an increased outflow of potassium via the leack channels counteracts the change in charge

55
Q

What are the caracteristics of a movement of ions that allow for the formation of an action potential?

A

sodium ions need to come in at a faster rate than potassium ions exit

56
Q

What part of the axon must reach the threshold of excitation to trigger an action potential?

A

the axon hillcock

57
Q

What is particular about the axon hillcock?

A

There is an important pool of sodium ions, that, when they reach the threshold of excitation, let in massive amounts of sodium ions

58
Q

What is neural integration?

A

Interaction of the excitatory and inhibitory synapses on a articular neuron

59
Q

What determines the type of postsynaptic potential?

A

The receptor to which the neurotransmitter binds (the cell determines how it interprets the stimuli/neurotransmitter by choosing which receptors to express)

60
Q

To what type of ions are excitatory postsynaptic potentials associated?

A

Na+

61
Q

To what type of ions are inhibitory postynaptic potentials associated?

A

Cl-

62
Q

What is an interneuron?

A
  • A neuron situated exclusively in the central nervous system
  • Acts as a relay between motor neurons and sensory neurons
63
Q

What is the role of an interneuron?

A
  • Links sensory and motor neurons
  • Allows humans to override their reflexes by using IPSPs
64
Q

What is an inhibitory neuron?

A

Neuron that causes IPSPs in downstream neurons