Flashcards in ICPP - Changing Membrane Potential Deck (19):
What is depolarisation?
A decrease in the size of the membrane potential from its normal value - the cell interior becomes less negative.
What is hyperpolarisation?
An increase in the size of the membrane potential from its normal value - cell interior becomes more negative.
True or false - increasing membrane permeability for a particular ion moves membrane potential away from that ion?
False - it moves it towards
What is the main way that changes in the membrane potential can be caused?
Changes in the activity of ion channels
What is the Goldman-Hodgkin-Katz equation used to calculate?
Membrane permeability for each ion
Why are nicotinic acetylcholine receptors viewed as less specific?
When 2 ACh molecules bind, the ion channels opens which lets through both Na+ and K+ (not anions though).
What are the three types of ion channel gating?
- 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)
What sort of gated ion channel is present in the inner ear?
How does the mechanical gating in the inner ear work?
- 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
Give some examples of places where synaptic transmission takes place.
Nerve cell - nerve cell
Nerve cell - muscle cell
Nerve cell - gland cell
Nerve cell - sensory cell
What is different about the receptor protein in fast synaptic transmission?
It is also an ion channel, and transmitter binding causes it to open
What do excitatory synapses do?
Open ligand-gated channels that cause membrane depolarisation.
What is the change in membrane potential caused by excitatory synapses called?
Excitatory post-synaptic potential
Give some examples of excitatory transmitters.
Acetylcholine, glutamate, dopamine
What do inhibitory transmitters do?
Open ligand-gated channels that cause hyperpolarisation. Eg. Glycine, GABA
What are the two patterns of slow synaptic transmission?
- direct G-protein gating (rapid, localised)
- gating via an intracellular messenger (throughout cell, amplification by cascade)
Give two factors other than action potentials that can influence membrane potential.
- changes in ion concentration
- electrogenic pumps (Na/K-ATPase)
Give three properties of cardiac ion channels.
- selectivity (only permeable to single type of ion)
- voltage sensitive gating
- time dependence