Action and resting potential Flashcards
What do neurones transmit?
Neurones transmit electrical impulses which travel along the neurone cell surface membrane from one end of a neurone to the other.
How is an impulse defined in neurones?
An impulse is a momentary reversal in the electrical potential difference across the neurone cell surface membrane.
What is the resting potential of a neurone?
The resting potential of a neurone is usually about -70 mV.
What factors contribute to establishing resting potential?
- The active transport of sodium ions and potassium ions. 2. A difference in membrane permeability to sodium and potassium ions.
What do sodium-potassium pumps do?
Sodium-potassium pumps actively transport sodium ions out of the axon and potassium ions into the axon.
What is depolarisation?
Depolarisation is the reversal of the electrical potential difference across the membrane.
What is the threshold potential?
The threshold potential is around -55 mV, and it is the level that must be reached to initiate an action potential.
What happens during repolarisation?
During repolarisation, potassium ions diffuse out of the axon, causing the inside of the axon to become negatively charged again.
What is hyperpolarisation?
Hyperpolarisation is a short period during which the membrane potential is more negative than resting potential.
What is the all-or-nothing principle?
Action potentials are either generated or not generated depending on whether the threshold potential is reached; there is no such thing as a small or large action potential.
What is saltatory conduction?
Saltatory conduction is the process where action potentials appear to ‘jump’ from one node of Ranvier to the next, increasing the speed of impulse transmission.
How can impulse transmission be prevented?
Medications can prevent impulse transmission by binding to sodium ion channels, preventing them from opening and thus preventing depolarisation.
