Flashcards in Membrane Potential (session 4) Deck (30):
Which cells have the largest resting potentials? (2)
Cardiac and skeletal muscle cells (-80 to -95 mV)
Which two factors are important for the generation of a membrane potential?
Asymmetric distribution of ions across the plasma membrane
Selective ion channels in the plasma membrane
What dominates the resting membrane permeability?
Open K+ channels
What is depolarisation?
Decrease in size of membrane potential from its normal value, cell interior becomes less negative (-70mV to -50mV)
What is hyperpolarisation?
Increase in size of membrane potential from its normal value, cell interior becomes more negative (-70mV to -90mV)
What is the equilibrium potential of K+? (Ek)
What is the equilibrium potential of Na+? (ENa)
What is the equilibrium potential of Cl-?
What is the equilibrium potential of Ca2+?
The opening of which channels causes hyperpolarisation?
K+ or Cl-
The opening of which channels causes depolarisation?
Na+ or Ca2+
True or false: nicotinic acetylcholine receptors open by binding to ACh
When do ligand-gated channels open?
In response to the binding of a chemical ligand
When do voltage-gated channels open?
In response to changes in membrane potential
When do mechanical-gated channels open?
In response to membrane deformation
True or false: in fast synaptic transmission, receptor proteins are also ion channels
What do excitatory transmitters do?
Open ligand-gated channels that cause membrane depolarisation
What does EPSP stand for and what is it?
Excitatory post-synaptic potential - Change in membrane potential at a excitatory synapse
What are the features of an EPSP? (2)
Longer time course than action potential
Graded with amount of transmitter
Which transmitters are used in an excitatory synapse? (3)
What do inhibitory transmitters do?
Open ligand-gated channels that cause hyperpolarisation
Which ions are excitatory synapses permeable to?
Na+ and Ca2+
Which ions are inhibitory synapses permeable to?
K+ and Cl-
Which transmitters are used in inhibitory synapses? (2)
Gamma-aminobutyric acid (GABA)
Which other two factors can influence the membrane potential?
Changes in ion concentration
Define membrane potential
Magnitude of electrical charge that exists across a plasma membrane and is always expressed as a potential inside the cell relative to the extracellular solution
What is [K+]o?
What is [K+]i?
What is the difference between fast and slow synaptic transmission?
In fast, the receptor protein is also an ion channel whereas in slow, the receptor and channel are separate proteins