Unit 1 - Neuron Action Potential Flashcards
earning all the information well enough to reproduce or copy it exactly (29 cards)
What is the axon?
The main highway of the neuron that carries signals passed from other neurons.
What are dendrites?
The receivers that catch signals from other neurons through neurotransmitters.
What is the soma?
The cell’s home base where all the organelles hang out.
What does the myelin sheath do?
Insulates the axon so signals travel faster and don’t get lost.
What are ion channels?
Protein pores in the neuron’s membrane that let specific ions flow in or out.
What do sodium channels (Na⁺) do?
Open to let sodium ions rush in, making the inside of the neuron more positive.
What do potassium channels (K⁺) do?
Open to let potassium ions flow out, helping bring the neuron back to its resting state.
What do calcium channels (Ca²⁺) do?
Trigger the release of neurotransmitters at the synapse.
What do chloride channels (Cl⁻) do?
Usually let chloride ions in to make the neuron more negative.
How does neuron firing start?
The neuron starts at rest, with the inside more negative than outside.
What happens when sodium channels open?
Sodium floods in, making the inside positive (depolarization).
What creates an action potential?
The electrical signal traveling down the axon after depolarization.
What happens when potassium channels open?
Potassium flows out, restoring the negative charge (repolarization).
What is the final state of the neuron after firing?
The neuron resets to resting state, ready to fire again.
How do neurotransmitters convert a chemical signal into an electrical signal in neurons?
They bind receptors on dendrites, opening ion channels that let charged ions flow in/out, turning chemical signals into electrical ones.
What happens when many dendrites’ inputs combine enough to change the neuron’s charge?
It triggers an action potential, an electrical signal racing down the axon.
What ions are typically higher outside vs inside the neuron?
Outside: Na⁺ (sodium), Cl⁻ (chloride), Ca²⁺ (calcium); Inside: K⁺ (potassium), A⁻ (negatively charged anions).
What is a ligand-gated ion channel?
An ion channel that opens in response to a ligand (neurotransmitter) binding, letting specific ions flow.
What is depolarization?
When positive ions (like sodium) flow into the neuron, making it less negative inside.
What causes an excitatory postsynaptic potential (EPSP)?
A net influx of positive ions into the neuron, making it more likely to fire.
What causes an inhibitory postsynaptic potential (IPSP)?
A net influx of negative ions (like chloride), making the neuron more negative and less likely to fire.
What triggers voltage-gated sodium channels to open at the axon hillock?
The membrane potential reaching a threshold of about -55 mV due to combined EPSPs.
What is unique about the voltage-gated sodium channel’s inactivation gate?
It blocks sodium influx shortly after opening and stays closed until the neuron repolarizes.
How do voltage-gated potassium channels affect the neuron after depolarization?
They open slower, letting potassium flow out to repolarize the cell and reduce the positive charge.
