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Physl > Nervous System 1 - Membrane Potential > Flashcards

Nervous System 1 - Membrane Potential Flashcards

1
Q

What is plasticity?

A

The changing of the connectivity and physiological strength of synapses

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2
Q

What are the 4 specialized sub regions for receiving/integrating inputs?

A
  • Dendrites
  • Cell body
  • Axon
  • Synaptic terminals
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3
Q

What is Hyperpolarization?

A

Moving to a more negative potential

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4
Q

What is Depolarization?

A

Going from resting potential to a more positive value

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5
Q

What is repolarization?

A

Returning to a resting potential

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6
Q

What is Vo?

A

Extracellular Voltage = 0 mV

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7
Q

What is Vi?

A

Intracellular voltage

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8
Q

What is Vm?

A

Membrane potential

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9
Q

What is Vrest?

A

Resting potential

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10
Q

What is Inward current?

A

Cations flowing into the cell or anions flowing out of the cell

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11
Q

What is Outward current?

A

Cations flowing out of the cell and anions flowing in

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12
Q

What is the sign of inward current?

A

Negative

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13
Q

What is the sign of outward current?

A

Positive

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14
Q

What is the charge of of cells at rest?

A

At rest the inside has a negative charge relative to the outside

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15
Q

What is the Resting charge of cells due to?

A

Difference in ion concentrations and permeabilities across the membrane

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16
Q

What cation is permeable to the cell at rest?

A

K+

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17
Q

How is K+ permeable to the cell at rest?

A

It has leakage channels that are open at resting potential allowing it to leak out

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18
Q

How are concentration gradients in a resting cell maintained?

A

By the active transport of K+ and Na+

19
Q

How must ions pass through the lipid bilayer?

A

Through ion channels

20
Q

What can gated channels open and close in response to?

A

Changes in the membrane voltage

21
Q

What are electrical signalling a result of?

A

Ions moving through ion channels

22
Q

What are the two ways channel activation can occur?

A
  • Binding of a chemical ligand

* Changes in membrane potential (Vm)

23
Q

What are the two ways a Ligand can open a channel?

A

It binds to the protein or a phosphate group binds to the channel opening it

24
Q

How do voltage gated channels work?

A

When membrane potential becomes depolarized the channel can open and allow ions to cross the membrane

25
Q

How can channel inactivation (closure) occur?

A

Prolonged depolarization can cause the membrane to close

26
Q

What are the characteristics of Voltage dependant Na+ channels at rest?

A

The channels are closed because the activation gate within the channel is closed blocking sodium ions from entering the cell

27
Q

What is the state of Voltage dependant Na+ channels when the membrane is depolarized?

A

The activation gate is opened allowing sodium ions to flow into the cell down its concentration gradient

28
Q

When the cell is at rest where is the greater concentration of sodium ions?

A

Outside the cell

29
Q

When the cell is at rest where is the greater concentration of potassium ions?

A

Inside the cell

30
Q

What is the state of voltage dependant Na+ channels after 1 msec of depolarization?

A

The inactivation gate is closed preventing sodium from flowing into the cell

31
Q

What are Channelopathies?

A

Diseases arising from mutation of genes encoding ion channel subunits

32
Q

What could happen if a channel remains open for too long?

A

Cells become hyperexcitable

33
Q

What is the concentration of calcium ions relative to the cell?

A

Ca2+ ions are kept in extremely low concentration inside the cell

34
Q

What direction is the concentration gradient for Ca2+?

A

Ca2+ gets pushed into the cell

35
Q

What direction is the concentration gradient for Cl-?

A

It tends to get pushed into the cell

36
Q

What are the two driving forces on ions?

A

Chemical and Electrical driving forces

37
Q

What is the magnitude of chemical driving forces on ions proportional to?

A

The concentration gradient

38
Q

What is the electrical driving force on ions provided by?

A

Membrane potential

39
Q

What is Conductance (g)?

A

The ease with which ions flow across the membrane

40
Q

What is the equilibrium potential for ion x?

A

The membrane potential at which the current carried by ion x is 0

41
Q

What is the formula for the driving force on an ion?

A

Membrane potential - Equilibrium potential of ion

42
Q

What is the rule about membrane potential?

A

It will always move towards the equilibrium potential of the ion whose conductance increases

43
Q

What is the equation for calculate the Equilibrium potential for an ion?

A

Ex= (58/x) log [(conc. outside the cell)/(conc. inside the cell)

44
Q

Why is the resting membrane potential close to Ek?

A

Because the membrane is highly permeable to K+ and much less permeable to Na+

Physl (94 decks)

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