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
end plate/neuromuscular junction
motorneuron with axon forming synpase on muscle fibre
26
end plate potential is always
suprathreshold meaning an action potential is always triggered
27
factors determining synaptic action
1.) type of neurotransmitter/ neuromodulator 2.) type 3.) and amount of receptor
28
long term potentiation vs long term depression
LTP = stimulating multiple times leads to more receptors expressed LTD = stimulating multiple times leads to less receptors expressed
29
why can only neurons and muscle fibres SUDDENLY change their membrane potential
because of voltage gated ion channels allowing them to be excitatory