2.1.5 Nerve impulses Flashcards
(21 cards)
What is an action potential?
A wave of electrical change that passes rapidly along an axon membrane.
What does it mean for a membrane to be polarised?
There is a difference in positive and negative charge between the two sides.
What maintains the resting potential of a neuron?
Sodium-potassium pumps.
What is the resting potential of a neuron approximately?
~-70mV.
What is depolarisation in the context of nerve transmission?
A change in the potential of the axon membrane causing a more positive charge.
What happens during the propagation phase of an action potential?
A burst of electrical charge passes along the axon in one direction.
What occurs during repolarisation?
Potassium channels open, K+ ions move out, restoring the positive charge outside.
What is hyperpolarisation?
A temporary overshoot of the resting electrical gradient, making the inside more negative.
What restores the resting potential after an action potential?
Sodium/potassium pump actively pumping Na+ out and K+ back in.
What is the threshold potential for an action potential to occur?
-55mV.
True or False: An increase in stimulus size increases the size of the action potential.
False.
What is the all-or-nothing response in nerve impulses?
The action potential occurs fully or not at all, regardless of stimulus size.
What is synaptic transmission?
The process of transmitting information from one neuron to another via neurotransmitters.
What happens when the action potential reaches the axon terminal?
Vesicles full of neurotransmitter move to the end and release their contents through exocytosis.
What is the role of neurotransmitters in synaptic transmission?
They diffuse across the synapse and bind to receptors on the next neuron.
What are the two types of synaptic effects?
- Excitatory (depolarisation) * Inhibitory (increases negativity)
What is a reflex arc?
An unlearned, automatic rapid response that does not travel to the brain for processing.
Fill in the blank: The _______ is a gap between neurons where neurotransmitters diffuse.
synapse.
What is the relative refractory period?
The time taken for the membrane to restore its resting potential after hyperpolarisation.
What can prevent neurotransmitter release at the synapse?
Drugs and poisons like botulism.
What is the significance of the sodium-potassium pump?
It maintains the resting potential and restores ion balance after an action potential.
