neurons Flashcards

1
Q

neuron dendrites function

A

receive electrical input

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2
Q

neuron cell body function

A

passively conducts electrical signals

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3
Q

neuron axon hillock/initial segment/trigger zone function

A

initiates action potentials

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4
Q

neuron axon function

A

propagates action potentials

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5
Q

neuron axon terminal function

A

releases chemical signals across synapse

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6
Q

how much more negative are neuron cytosol compared to extracellular fluid

A

50 to 70mV more negative

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7
Q

how are intracellular potentials measured today?

A

1.)microelectrode recording technique

2.) patch clamp technique

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8
Q

what affects Resting Membrane Potential (RMP)

A

1.) unequal concentrations of ions inside and outside of cell resulting in electrochemical gradient

2.) unequal membrane permeability to these ions

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9
Q

two main types of ion channels in neurons

A

leak channels - open at rest (many K+, fewer Na+ leak channels)
gated channels - closed at rest, (voltage, mechanical, ligand stimuli)

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10
Q

1:40 is the ratio of….

A

ratio of sodium to potassium leak channels/ratio of membrane permeability of sodium to potassium ions

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11
Q

nernst equation calculates…

A

-equilibrium potential for one type of ion

-considers only concentration of ion inside and outside of cell

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12
Q

equilibrium potential for K+ and Na+

A

K+ = -80mV

Na+ = +60mV

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13
Q

nernst equation application to neurons and glial cells

A

-only applies when membrane is permeable only to one ion

-applicable to glial cells because they’re only permeable to K+ so RMP is -80mV

-NOT applicable to neurons as they’re permeable to more than one ion type

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14
Q

goldmans equation calculates…

A

resting membrane potential (-65mV)

considers concentration gradient AND relative permeability of resting membrane to K+ and Na+ ions

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15
Q

factors in nernst equation

A

ion concentration extracellular and intracellular

faradays

gas constant

temperature

valence of ion

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16
Q

threshold value required to generate AP

A

approx -55mV

17
Q

4 phases of action potentials

A

stimulus, fast depolarisation, repolarisation, after hyperpolarisation

18
Q

absolute vs relative refractory period

A

absolute during fast depolarisation and repolarisation - no stimulus can cause another AP

relative during the end of repolarisation and after hyperpolarisation - stimulus can only cause another AP if larger than the original threshold

19
Q

fast depolarisation caused by

A

stimulus reaching threshold activates voltage-gated Na+ channels letting sodium into the cell (relative permeability of Na+ to K+ now 20:1 so more permeable to Na+)

20
Q

repolarisation caused by

A

quick inactivation of Na+ voltage gated channels and activation of voltage gated K+ channels

21
Q

after hyperpolarisation caused by

A

membrane permeability of K+ to Na+ really large 100:1

22
Q

Na+ voltage gated channel mechanism during repolarisation and after hyperpolarisation

A

repolarisation when Na+ gated channel INACTIVATES due to inactivation gate shuts (ball and chain)

after hyperpolarisation (back at RMP) when Na+ gated channel AT REST due to activation gate shut and inactivation gate open

23
Q

what causes passive current to dissipate

A

leak channels

24
Q

receptor potential

A

graded depolarisation

25
Q

end plate/neuromuscular junction

A

motorneuron with axon forming synpase on muscle fibre

26
Q

end plate potential is always

A

suprathreshold meaning an action potential is always triggered

27
Q

factors determining synaptic action

A

1.) type of neurotransmitter/ neuromodulator
2.) type 3.) and amount of receptor

28
Q

long term potentiation vs long term depression

A

LTP = stimulating multiple times leads to more receptors expressed

LTD = stimulating multiple times leads to less receptors expressed

29
Q

why can only neurons and muscle fibres SUDDENLY change their membrane potential

A

because of voltage gated ion channels allowing them to be excitatory