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Biology > Neuronal Communication > Flashcards

Neuronal Communication Flashcards

1
Q

Where is the sensory receptor located and state its function

A

sense organ
specialised cells in our body that can detect a change in a stimuli

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2
Q

Define energy transducer

A

convert the stimulus (one form of energy) into another form = electrical energy.

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3
Q

Roles of the 3 neurons

A

Sensory = carry impulse from receptor to CNS
Motor = carry impulse from CNS to effector
relay = carry impulse from sensory to motor within the CNS

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4
Q

Dendron

A

conduct nerve impulses TOWARDS cell body.
dendrons sub divide = form many dendrites

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5
Q

Cell body

A

contains nucleus and other organelles
(many mitochondria and ribosomes)

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6
Q

Axon

A

conduct nerve impulses AWAY FROM cell body.
axons = thinner than dendrons + longer

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7
Q

What is a schwann cells

A

individual specialised cells that wrap around the neurone = 1-3 mm wide

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8
Q

Function of schwann cell

A

insulate the neurone, preventing ion movement through neurone membrane.

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9
Q

What is node of Ranvier

A

Junction between 2 adjacent schwann cells

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10
Q

What is a myelin sheath

A

A row of schwann cells wrapped along a neurone

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11
Q

2 specialised protein channels found in neurons

A

gated channel proteins
Na/K pump

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12
Q

What ions do gated channel proteins allow through

A

Na+ or K+

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13
Q

How does a Na/K pump work

A

requires ATP = active process
Na+ transported OUT of cell
K+ transported INTO cell
3 Na+ move OUT for every 2 K+ that move IN

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14
Q

When the Na+/K+ pump is running, what will happen to the ionic charge on the inside and outside of the membrane?

A

more +ve charge outside cell
(3K+)
less +ve charge inside cell (2K+),
= polarised cell membrane
Since, cell membrane has a different charge on either side of it

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15
Q

Resting potential of neuron

A

-60mV

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16
Q

A resting neurone

A

no nerve impulse is being sent, it’s ‘at rest‘
BUT remember - working to constantly respire provide ATP to run the Na+/K+ pump!

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17
Q

Depolarisation

A

loss of polarisation across the membrane due to movement of Na+ ions into the cell.
= change in pd from -60mv (resting potential) towards 0mv

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18
Q

Where would you find Pacinian corpuscle

A

skin and around tendons/ joints

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19
Q

Function of Pacinian corpuscle

A

detect changes in pressure

20
Q

How does Pacinian corpuscle detect pressure change

A

plasma cell membrane is flattened
force causes the stretch mediated sodium channel proteins to open.
Na+ diffuse quickly into the cell’s cytoplasm
depolarisation occurs

21
Q

Receptor potential

A

pd change from -60 to -50mV on csm due to depolarisation

22
Q

Can any level of stimulus cause depolarisation?

A

Small stimuli = only 1 or 2 Na+ channel proteins to open
So only a small change in pd occurs
Not enough to depolarise membrane.

23
Q

Threshold level

A

minimum change in pd required to cause depolarisation

24
Q

Threshold potential

A

-50mV

25
Q

All or nothing response

A

Anything less than threshold potential = no response

Anything greater = same size of action potential is generated, no matter the size of stimulus.

26
Q

Why do membranes need special transport proteins to enable the movement of ions?
.

A

Ions are charged particles = cannot diffuse through the phospholipid bilayer

27
Q

Explain why a neurone is active while it is said to be resting.

A

neurone = using ATP to pump ions. Na+ = pumped out as K+ pumped into cell.
= creates + maintains resting potential across csm .

28
Q

Role of the organic anions inside the membrane

A

ensure inside of cell remains -ve compared to outside.

29
Q

Another way to open the gated channels during the depolarisation process

A

voltage gated channels

30
Q

How does depolarisation occur

A

Influx of Na+ into cytoplasm

31
Q

How is an action potential generated

A
32
Q

Local current

A

influx of Na+ through membrane into cytoplasm at one point on membrane affecting Na voltage gated channel further along membrane

33
Q

Propagation of a nerve impulse in a NON myelinated sheath

A
34
Q

Refractory period

A

a time when areas of the axon/ dendron cannot be excited again until the Na/K pump has restored resting potential

35
Q

Why can an impulse only be propagated in one direction

A
36
Q

Saltatory conduction

A

local currents = elongated causing action potentials to “jump” between the nodes of ranvier.

37
Q

What effect does a myelin sheath have

A

action potential passes along myelinated neurone faster as it jumps from one node of ranvier to next

38
Q

Purpose of myelinated neurons

A

faster impulse of transmissions
energy efficient, as it reduces the amount of ATP required, as energy is required for active transport during repolarisation, as there are less instances where it is required
useful for longer distances

39
Q

Effect of larger axon diameter

A

increase rate of saltatory conduction as the ions face less resistance

40
Q

Effect of higher temp for saltatory conductions

A

increase rate of saltatory conduction as ions diffuse quicker at higher temperatures
above 40 degrees transport proteins denature = no change in potentials

41
Q

Synapse

A

junction between 2 or more neurones

42
Q

Where is ACh used

A

cholinergic synapses

43
Q

Pre-synaptic knot / knob

A

end swelling of the presynaptic neurone.
= located at the end of the axon.

44
Q

Function of sER in synaptic knob

A

metabolism of neurotransmitter
package of neurotransmitter into vesicles

45
Q

Function of mitochondria in synaptic knob

A

provide ATP for:
recycling the neurotransitter
vesicle production
exocytosis of vesicles

46
Q

How many ACh molecules fuse with receptor sites

A

2

47
Q

What happens after ACh binds to receptors

A

= Na+ channel open
influx of Na+ into postsynaptic neurone
creates excitatory
if threshold potential reached - new action potential created in postsynaptic neurone

Biology (24 decks)

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