ICPP - Changing Membrane Potential Flashcards Preview

CJ: UoL Medicine Semester One (ESA1) > ICPP - Changing Membrane Potential > Flashcards

Flashcards in ICPP - Changing Membrane Potential Deck (19)
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1
Q

What is depolarisation?

A

A decrease in the size of the membrane potential from its normal value - the cell interior becomes less negative.

2
Q

What is hyperpolarisation?

A

An increase in the size of the membrane potential from its normal value - cell interior becomes more negative.

3
Q

True or false - increasing membrane permeability for a particular ion moves membrane potential away from that ion?

A

False - it moves it towards

4
Q

What is the main way that changes in the membrane potential can be caused?

A

Changes in the activity of ion channels

5
Q

What is the Goldman-Hodgkin-Katz equation used to calculate?

A

Membrane permeability for each ion

6
Q

Why are nicotinic acetylcholine receptors viewed as less specific?

A

When 2 ACh molecules bind, the ion channels opens which lets through both Na+ and K+ (not anions though).

7
Q

What are the three types of ion channel gating?

A
  • Ligand gating (opens due to binding of ligand eg ACh)
  • Voltage gating (opens due to changes in membrane potential eg action potential changes)
  • Mechanical gating (opens due to membrane deformation)
8
Q

What sort of gated ion channel is present in the inner ear?

A

Mechanical gating

9
Q

How does the mechanical gating in the inner ear work?

A
  • pressure from sound waves makes K+ channel close
  • membrane depolarises
  • Ca2+ channel opens
  • vesicles containing neurotransmitter fuse with basement membrane
  • neurotransmitter binds to receptor and generates action potential
10
Q

Give some examples of places where synaptic transmission takes place.

A

Nerve cell - nerve cell
Nerve cell - muscle cell
Nerve cell - gland cell
Nerve cell - sensory cell

11
Q

What is different about the receptor protein in fast synaptic transmission?

A

It is also an ion channel, and transmitter binding causes it to open

12
Q

What do excitatory synapses do?

A

Open ligand-gated channels that cause membrane depolarisation.

13
Q

What is the change in membrane potential caused by excitatory synapses called?

A

Excitatory post-synaptic potential

14
Q

Give some examples of excitatory transmitters.

A

Acetylcholine, glutamate, dopamine

15
Q

What do inhibitory transmitters do?

A

Open ligand-gated channels that cause hyperpolarisation. Eg. Glycine, GABA

16
Q

What are the two patterns of slow synaptic transmission?

A
  • direct G-protein gating (rapid, localised)

- gating via an intracellular messenger (throughout cell, amplification by cascade)

17
Q

Give two factors other than action potentials that can influence membrane potential.

A
  • changes in ion concentration

- electrogenic pumps (Na/K-ATPase)

18
Q

Give three properties of cardiac ion channels.

A
  • selectivity (only permeable to single type of ion)
  • voltage sensitive gating
  • time dependence
19
Q

Explain the stages of action potential of cardiac muscles

A

Phase 4 - resting potential of cardiomyocyte is -90mV
Phase 0 - action potential triggers Na+ channels to open and cell depolarises rapidly. At -40mV, long-opening Ca2+ channels open.
Phase 1 - K+ flows out and repolarises to 0 mV.
Phase 2 - MP is maintained at plateau
Phase 3 - Ca2+ channels deactivated, pumps return normal ionic concentration gradients

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