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Biology A2 Rafa > 5.3 Neuronal Communication > Flashcards

5.3 Neuronal Communication Flashcards

1
Q

What is a Pacinian corpuscule?

A

a pressure sensor found in the skin

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2
Q

Define sensory receptors

A

cells/sensory nerve endings that respond to a stimulus in the internal or external environment of an organism and can create action potentials

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3
Q

Define tranducer

A

a cell that converts one form of energy into another - in this case and electrical impulse

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4
Q

Define motor neuron

A

neutrons that can carry an action potential from the CNS to the effector

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5
Q

Define myelinated neuron

A

has an individual layer of myelin around it

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6
Q

Define on-myelinated neuron

A

has no individual layer of myelin

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7
Q

Define relay neurone

A

join sensory neutrons to motor neurons

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8
Q

Define sensory neurons

A

neurones that carry an action potential from the sensory receptor to the CNS

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9
Q

Define action potential

A

a brief reversal of the potential across a membrane of a neurone causing a peak of +40mV compared to a resting potential of -60mV

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10
Q

Define positive feedback

A

a mechanism that increases a change taking the system further away from the optimum

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11
Q

Define resting potential

A

The potential difference across the membrane while the neurone is at rest

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12
Q

Define cholinergic synapse

A

a synapse that uses acetylcholine as its neurotransmitter

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13
Q

Define neurotransmitter

A

A chemical used as a signalling molecule between two neurones in a synapse

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14
Q

What is summation?

A

occurs when the effects of several excitatory post-synaptic potentials (EPSPs) are added together

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15
Q

Which ion is higher outside

A

Na

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16
Q

Which ion is higher inside the cell

A

K

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17
Q

What is resting potential value

A

-60mV

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18
Q

What happens when sodium channels open

A

Cell is depolarised

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19
Q

What are Schwann cells

A

Insulate the electrical acitivity

unmyeinated cells are only loosely sheathed

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20
Q

Sodium potassium pump

A

3Na out

2K in

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21
Q

IS the inside of a cell more positive or negative inside at rest

A

Positive outside

Negative insdie

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22
Q

Stages of an action potential

A

1) Na channels opened by action of synapse and ions diffuse in. This is depolarising the cell
This is generator potential.
If it possesses the threshold of the cell, an action potential is created (if there are a lot of them)

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23
Q

Why is it called an all or nothing response?

A

If big enough to reach threshold, action potential will be created but it will always be the same

24
Q

How is creating action potentials an example of positive feedback?

A

Na depolarisation cause voltage gated sodium channels to open nearby which causes the cell to depolarise even more

25
what happens when na channels close in an action potential?
K channels open, | K ions leave by diffusion, this is repolarisaton, as the inside of the cell is more negative
26
What is hyper polarisation?
The refractory period - Na channels are closed so there are no ways to generate another generator potential - Na and K ions switched places and we need time for the sodium potassium pump to work
27
Gap between neurone name
Synaptic cleft
28
Why is there are lot of smooth endoplasmic reticulum in synapse
Put everything in vesicles
29
Describe acetyl choline receptor
Five subunits 2 contain acetylcholine binding sites need to acetylcholine molecules per ion channels
30
Describe trasmissione across. a synapse
- action potential arrives at the synaptic bulb - change in membrane potential causes voltage gated ca2+ channels to open - calciumionsdiffuse in to the presynaptic bulb - Ca2+ causes vesicles with acetylcholine to fuse with membrane and acetylcholine moves into the synaptic cleft
31
Role of acetylcholinesterase
It hydrolyses acetylcholine into ethnic acid and choline these diffuse into presynaptic bulb and are recombined to form acetylcholine using ATP This is stored in presynaptic vesicles
32
Temporal summation
several action potentials in the same presynaptic neuron
33
Spatial summation
action potentials arriving from several different pre-synaptic neurones
34
What does EPSP stand for
excitatory post-synaptic potential
35
What does IPSP stand for
Inhibitory post-synaptic potential
36
What do IPSPs do
inhibit EPSPs (e.g. can make cl- go into cell or k+ to leave)
37
What does the pacinian corpuscle look like?
concentric rings of connective tissue | response to CHANGES in pressure
38
What does a sodium potassium pump do?
Pumps 3 sodium out of cells and 2 potassium into cells
39
Where is there more sodium?
outside the cell
40
Where is there more potassium?
inside the cell
41
What is the value of resting potential?
-60mV
42
What carries impulse towards cell body?
dendron
43
What carries nerve impulse away from cell body?
axon
44
What are Schwann cells?
Insulate electrical activity Stop neurons touching each other Loose sheath
45
Which type of neuron has long dendrites?
Sensory
46
What are nodes of Ranvier and how long are they?
Bits between schwann cells that myelinate | 2-3 micrometeres
47
How long is a schwann cell that is myelinating a neurone?
1-3 mm
48
Which types of neuron are generally myelinated and why?
sensory and motor | because they are longer and need saltatory conduction
49
Is the inside or outside of the cell more negative and why?
inside is more negative 3 Na+ leave K+ leak channels mean K+ leave there are proteins inside the cytoplasm that are negatively charged
50
Potential of neuron when depolarised
+40mV
51
Why does the refractory period happen?
- Na+ are closed so no way to make a generator potential | - Na+ and K+ are in the wrong places and the Na/K pump must fix this
52
What do cholinergic synapses use as the neurotransmitter?
acetylcholine
53
Why is there a lot of smooth ER in pre-synaptic bulb?
Packaging neurotransmitters into vesicles
54
Describe the acetylcholine receptor
- it is an sodium ion channel - five units - has 2 acetylcholine receptor sites
55
Describe transmission across a synapse
- action potential at presynaptic bulb - voltage gated calcium channels open - vesicles move and fuse with presynaptic membrane - acetylcholine diffuses across cleft - binds to receptor channel and sodium channel open
56
What does acetylcholinesterase actually do?
hydrolyse acetylcholine into ethanoic acid and choline which reenter the presynaptic bulb and are recombined using ATP
57
How do IPSPs work?
different neurotransmitter causes Cl- channels to open and K+ channels to open -Cl- diffuses in -K+ diffuses out result in hyperpolarisation

Biology A2 Rafa (14 decks)

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