Lecture Exam 3 Flashcards
(12 cards)
What happens when chemically-gated Cl⁻ channels open?
Chloride ions (Cl⁻) enter the cell, causing hyperpolarization of the membrane.
What is an inhibitory postsynaptic potential (IPSP)?
An IPSP makes it less likely for the neuron to reach threshold and generate an action potential.
What is summation in neurons?
Summation is the process of integrating incoming excitatory postsynaptic potentials (EPSPs) and IPSPs to determine whether an action potential will be generated.
What are the two types of summation?
- Spatial Summation: Multiple presynaptic neurons fire simultaneously at different synapses on the same postsynaptic neuron.
- Temporal Summation: A single presynaptic neuron fires multiple times in quick succession.
What triggers an action potential?
If a graded potential (typically an EPSP) reaches the axon hillock and is large enough to reach the threshold potential.
What occurs during the depolarization phase of an action potential?
Voltage-gated Na⁺ channels open, allowing Na⁺ to rush into the neuron, causing rapid depolarization.
What happens during the repolarization phase?
Na⁺ channels close and voltage-gated K⁺ channels open, allowing K⁺ ions to exit the cell, restoring the negative charge inside the neuron.
What is hyperpolarization?
It occurs when K⁺ channels stay open longer than necessary, making the membrane more negative than the resting membrane potential (RMP).
What is a property of the action potential regarding propagation?
Self-Propagating: Once initiated at the axon hillock, the action potential continues down the axon.
What does unidirectional mean in the context of action potentials?
The action potential moves in one direction because after a voltage-gated Na⁺ channel closes, it enters a refractory period.
What is the all-or-none principle?
The action potential either occurs fully if the threshold is reached or not at all if the threshold is not met.
How do neurons encode information?
The frequency of action potentials conveys the intensity of a stimulus.
