Session 3 - Resting Membrane Potential Flashcards
How do we measure a membrane potential?
- Use a micro-pippette to penetrate cell membrane
- Micro-electrode then used to measure voltage inside relative to the voltage outside of the cell
Give the range of values in which an animals cells membrane potentials lie in
-20mV to -90mV
Which tissues have the highest membrane potential in animal cells?
Skeletal and Cardiac muscle
What is the range of values that a nerve cells membrane potential will lie?
-50mV to -75mV
How does a membrane acheived selective permeability?
Differing types of ion channels which specific to one or a few ions that are open or closed allowing the membrane to be selectively permeable
Name the concentrations of sodium intra and extracellularly
Intra - 10mM
Extra - 145mM
Name the concentration of Potassium ions intra and extracellularly
Intra - 160mM
Extra - 4.5mM
Name the concentration of Chloride ions intra and extracellularly
Intra - 3mM
Extra - 114mM
Name the concentration of Anions intra and extracellularly
Intra - 167mM
Extra - 40mM
What is the equilibrium potential for an ion?
The membrane potential at which the ions are at an equilibrium between their electrochemical and diffusing gradients
Define Depolarisation
A decrease in membrane potential, so that the inside of the cell becomes less negative
Define Hyperpolarisation
Increase in membrane potential, such that the inside of the cell become more negative
What is the usual result of opening Sodium or Calcium ions?
Depolarisation
What is the usual result of opening Potassium or Chloride ion channels?
Hyperpolarisation
What are ligand-gated channels?
Channel is open or closed by the binding of a chemical ligand either extra or intracellularly
What are Voltage-gated channels?
Channels that open of close in response to a change in membrane potential
What is fast synaptic transmission?
The receptor is also a ligand-gated channel?
What is an Excitatory Postsynaptic Potential (EPSP)?
When transmitters such as Sodium and Calcium enter a cell causing depolarisation and excitation of the cells
What is an Inhibitory Postsynaptic Potential (IPSP)?
When the entrance of transmitters such as Potassium of Chloride into a cell causes inhibition and hyperpolarisation
What is Slow Synaptic Transmission?
When the receptor is not an ion channel, involving the use of a GTP binding protein
Name the two types of Slow synaptic transmission
- Within a membrane (G-protein diffuses laterally and binds to ion channel)
- Intracellular messenger (G-protein binds to an enzyme causing a signalling cascade
What is a membrane potential?
The electrical potential difference across a plasma membrane
