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Anatomy M1T2 > Membrane Potential > Flashcards

Membrane Potential Flashcards

1
Q

thin layer that encloses intracellular contents, is a mechanical barrier, controls movement of waste, and maintains different concentrations

A

plasma membrane

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2
Q

Why are cells from muscle and nervous tissue excitable?

A

because they produce electrical signals when excited,

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3
Q

What’s membrane potential?

A

separation of opposite charges across the membrane in ECF and ICF. Slight excess of negative charges

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4
Q

What’s resting membrane potential?

A

potential that exists when an excitable cell is at rest and not responding to an electrical stimulus, is stable, negative, and influenced by leaky K+

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5
Q

What is resting membrane potential in neurons, skeletal muscle, and cardiac?

A

-60 to -70, -85 to -95, -80 to -90

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6
Q

What are two types of gradients?

A

electrical - produced by unequal charged particles
chemical - produced by unequal distribution of ions

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7
Q

What 3 factors contribute to resting membrane potential?

A

Ionic concentration gradient, caused by K+ and Na+ diffusion. Selective membrane permeability, and sodium potassium pump.

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8
Q

What happens to resting membrane potential when NA/K+ pump inhibited?

A

depolarization

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9
Q

How is K+/Na+ diffusion different than K+ leaky channels?

A

K+ and Na+ channels are ion specific whereas the K+ leaky channels usually permit K+ but sometimes Na+ can sneak through

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10
Q

Small water filled passageways, formed from proteins, highly selective, and let ions transport passively

A

channels

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11
Q

Membrane proteins that can undergo reversible changes in shape to expose specific binding sites, bind with and transfer substances unable to cross plasma membrane

A

transporter - example is Na+ K+ pump

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12
Q

Potential that exists when concentration gradient for given ions counterbalances for no net movement

A

equilibrim potential

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13
Q

Nerst Equation

A

Equilibrim potential for a given ion with differing concentrations across a membrane

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14
Q

What’s equilibrium potential of K+?

A

-90

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15
Q

What’s equilibrium potential for Na+

A

+60

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16
Q

True or false: If concentration out is greater than concentration in than the log will be positive

A

True

17
Q

Ion Movements based on Driving force

A

Cations:
If VDF is (+), then the ion is moving OUTof the cell.
If VDF is (-), then the ion is moving INTO the cell.
If VDF = 0, then there is NO net movement of the ion
Anions:
If VDF is (+), then the ion is moving INTO the cell.
If VDF is (-), then the ion is moving OUT of the cell.
If VDF = 0, then there is NO net movement of the ion.

18
Q

When membrane potential becomes less polarized inside and less negative than resting

A

Depolarization

19
Q

When membrane returns to resting potential after being depolarized

A

Repolarization

20
Q

When membrane becomes more polarized inside becomes more negative than at resting potential

A

Hyperpolarization

21
Q

Local changes in membrane potential that signal over short distances, usually produced from triggering event, can initiate AP

A

Graded potential

22
Q

Brief, quick changes in membrane potential that signal over long distances, reverses membrane potential so inside cell is more positive

A

Action potential

23
Q

What is different between voltage gated sodium channels and potassium channels?

A

Sodium channels have activation and inactivation gates leading to 3 conformations of closed open, and inactive. Whereas potassium channels are only closed or open

24
Q

8 ion fluxes during action potential?

A
  1. Resting - Na+ and K+ voltage are closed and Na+ inactivation gate is open
  2. Threshold potential - Na+ activation gates open which leads to 3. Rapid depolarization.
  3. End of depolarization - Na+ inactivation gates close, K+ activation gates open which leads to 5. Repolarization - K+ efflux
  4. Resting membrane potential Nat+ activation closed and inactivation gates open
  5. Hyperpolarization - K+ activation gates close
  6. Resting potential - K+ activation gates close so cell can go back to RMP
25
Q

AP cannot be initiated to ensure one way propagation of AP in neurons to limit frequency this is due to…

A

Refractory period

26
Q

What are the two types of refractory periods?

A
  1. Absolute - activated patch of membrane where AP cannot initiate no matter the strength
  2. Relative - when another AP can be triggered with a greater than normal stimulus
27
Q

What are 5 steps of AP in cardiac contractile cells?

A
  1. Rapid depolarization - activates voltage Na+ channels for fast influx
  2. Brief repolarization - Na+ channels close and K+ open
  3. Plateau - closure of K+, activates slow L Ca2+ channels which cause slow calcium influx and low K+ efflux
  4. Repolarization - inactivation of Ca2+ channels, activation of K+ channels
  5. Resting potential K+ channels close and leaky ones stay open
28
Q

These cells initiate cardiac contraction, possess intrinsic automaticity, and are composed of conduction tissue

A

pacemaker cells

29
Q

How does pacemaker self induce an action potential?

A
  1. Influx of sodium through funny channels, decreased K+ efflux, and activation of T type calcium channels causing influx
  2. Self induced AP
  3. Rising phase - activated L - type calcium channels causing influx
  4. Falling phase - activate K+ channels and closure of L-type channels causing efflux
30
Q

What does conduction velocity depend on?

A

depends on size of inward current during AP upstroke, correlates with dV/dT, does not depend on AP duration

31
Q

How does autonomic nervous system affect heart rate?

A

Sympathetic causes increases depolarization and SA node depolarizes more frequently. Parasympathetic decreases depolarization and increases threshold potential

32
Q

Properties of nerve and muscle APs

A

Anatomy M1T2 (18 decks)

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