Nerve Impulses Flashcards
What is a nerve impulse?
A nerve impulse is an electrical signal that travels along the axon of a neuron, enabling communication within the nervous system.
What is the resting potential of a neuron?
The resting potential is the difference in charge across the membrane of a neuron when it is not transmitting an impulse. It is typically around -70mV.
What is the role of sodium-potassium pumps in neurons?
Sodium-potassium pumps actively transport 3 sodium ions out of the neuron and 2 potassium ions into the neuron, maintaining the resting potential.
What is depolarization?
Depolarization is the process by which the membrane potential becomes less negative (more positive) due to the influx of sodium ions (Na⁺) when sodium channels open.
What is repolarization?
Repolarization is the return of the membrane potential to its resting state, caused by potassium ions (K⁺) leaving the neuron through potassium channels.
What is an action potential?
An action potential is a rapid, temporary change in membrane potential that occurs when the neuron depolarizes and then repolarizes, allowing the nerve impulse to travel.
What is the threshold potential?
The threshold potential is the critical level of depolarization that must be reached for an action potential to be initiated, typically around -55mV.
What is the all-or-nothing principle?
The all-or-nothing principle states that once the threshold potential is reached, an action potential will occur at full strength, or not at all.
What is the role of voltage-gated sodium channels?
Voltage-gated sodium channels open when the membrane potential reaches the threshold, allowing sodium ions to flood into the neuron, causing depolarization.
What is the role of voltage-gated potassium channels?
Voltage-gated potassium channels open after depolarization, allowing potassium ions to exit the neuron, leading to repolarization.
What is the refractory period?
The refractory period is the brief period following an action potential during which the neuron cannot fire another action potential, ensuring unidirectional impulse flow.
How do myelinated axons affect nerve impulse transmission?
Myelinated axons transmit nerve impulses faster due to saltatory conduction, where the impulse jumps between nodes of Ranvier, increasing speed.
What is saltatory conduction?
Saltatory conduction is the process by which action potentials jump from one node of Ranvier to the next, allowing faster nerve impulse transmission in myelinated axons.
What is the function of the nodes of Ranvier?
The nodes of Ranvier are gaps in the myelin sheath where action potentials are regenerated, enabling saltatory conduction.
How do neurotransmitters transmit signals between neurons?
Neurotransmitters are released from the presynaptic neuron and bind to receptors on the postsynaptic neuron, triggering a response in the next neuron.
What is the role of calcium ions in synaptic transmission?
Calcium ions enter the presynaptic terminal when an action potential arrives, causing vesicles containing neurotransmitters to fuse with the membrane and release their contents.
What is synaptic transmission?
Synaptic transmission is the process by which an electrical signal is converted into a chemical signal at a synapse, allowing communication between neurons.
What is the difference between excitatory and inhibitory neurotransmitters?
Excitatory neurotransmitters stimulate the postsynaptic neuron to generate an action potential, while inhibitory neurotransmitters make it less likely to fire an action potential.
How is an action potential propagated along an axon?
An action potential is propagated along the axon by a wave of depolarization and repolarization, where the influx of sodium ions causes adjacent areas of the membrane to depolarize.
What is the role of the axon hillock in generating an action potential?
The axon hillock is the region where the action potential is initiated if the membrane potential reaches the threshold potential
