Electricity and neural function: resting membrane potential, action potential, synaptic transmission Flashcards Preview

Nervous system > Electricity and neural function: resting membrane potential, action potential, synaptic transmission > Flashcards

Flashcards in Electricity and neural function: resting membrane potential, action potential, synaptic transmission Deck (34)
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1
Q

What is membrane potential?

A

Difference in charge between extracellular and intracellular fluid of the cell

2
Q

What are the three main ionic contributors to membrane potential?

A

Na+, K+, A-

3
Q

What is A-?

A

Organic anions

4
Q

Can A- cross cell membranes?

A

No

5
Q

Sodium concentration outside cell

A

150

6
Q

Sodium concentration inside cell

A

15

7
Q

Potassium concentration outside cell

A

5

8
Q

Potassium concentration inside cell

A

150

9
Q

A- concentration outside cell

A

0

10
Q

A- concentration inside cell

A

65

11
Q

Equation for equilibrium potentials

A
E = 61log (c0/ci)
61 = RT/zF
12
Q

What is C0?

A

Outside concentration

13
Q

What is Ci?

A

Inside cell concentration

14
Q

What is R?

A

Gas constant

15
Q

What is z?

A

Valence of ion

16
Q

What is F?

A

Electrical constant

17
Q

If the membrane was impermeable to Na+ and K+, what would the potential be?

A

-90mV

18
Q

What is the resting potential?

A

-70mV

19
Q

What is depolarisation?

A

Membrane becomes positively charged - caused by influx of sodium

20
Q

What is repolarisation?

A

Voltage changes from +40mV to negative again - caused by efflux of potassium

21
Q

What is the threshold potential?

A

-55mV

22
Q

What happens to activation gates when the threshold potential is reached?

A

They open, allowing extracellular particles to enter
Very quickly reverses intracellular concentration of sodium so potential is now positive
When threshold potential reached, inactivation gate activated
Sodium leaks into cell

23
Q

At what potential will voltage gated potassium channels open?

A

+30mV

24
Q

In which direction does the sodium concentration gradient point?

A

Outside cell

25
Q

When is inactivation of voltage-gated sodium channels activated?

A

-55mV

26
Q

When do potassium channels open?

A

Activated at -55mV but open at +30mV

27
Q

How does GABA work?

A

By triggering a hyper-polarization of the post-synaptic membrane when it binds to receptors. It does this by stimulating an efflux of K+

28
Q

What is an ionotropic receptor?

A

Membrane bound receptor that contains an ion channel

29
Q

What is temporal summation?

A

A single action potential in the presynaptic neuron releases low levels of neurotransmitter that are not high enough to trigger an action potential in the postsynaptic neuron. However, two or more action potentials in neuron 1 in quick succession release enough neurotransmitter to trigger an action potential in neuron 2

30
Q

What is spatial summation?

A

Release of neurotransmitter from each of the presynaptic neurons does not trigger an action potential in the postsynaptic neuron. However, when neurons simultaneously release neurotransmitter, an action potential is triggered

31
Q

In what direction does the electrical gradient for potassium go?

A

Into the cell

32
Q

In what direction does the concentration gradient for potassium go?

A

Out of cell

33
Q

In what direction does the electrical gradient for sodium go?

A

Out of the cell

34
Q

In what direction does the concentration gradient for sodium go?

A

Into cell