12.4 Neuron Electricity? Flashcards
What is the resting membrane potential of a typical neuron?
-70 mV
True or False: The resting membrane potential is primarily determined by the concentration of sodium ions inside the cell.
False
Fill in the blank: The primary ions involved in generating the action potential are _____ and _____.
sodium, potassium
What is the threshold potential required to trigger an action potential?
-55 mV
Which ion channels open first during the depolarization phase of an action potential?
Sodium channels
What is the term for the period during which a neuron cannot fire another action potential?
Refractory period
True or False: During the repolarization phase, potassium channels open and sodium channels close.
True
What is the role of myelin in neuronal conduction?
To increase the speed of action potential propagation
Define depolarization.
A decrease in the membrane potential, making the inside of the cell more positive.
What is the function of the sodium-potassium pump?
To maintain the resting membrane potential by pumping sodium out and potassium in.
Fill in the blank: The all-or-nothing principle states that an action potential either occurs or _____ when the threshold is reached.
does not occur
What is the typical duration of an action potential?
1-2 milliseconds
Which phase of the action potential is characterized by a rapid influx of sodium ions?
Depolarization phase
What is hyperpolarization?
An increase in the membrane potential, making the inside of the cell more negative.
True or False: Action potentials can vary in amplitude.
False
What type of synapse involves the direct transfer of ions between cells?
Electrical synapse
What is the main neurotransmitter released at the neuromuscular junction?
Acetylcholine
Fill in the blank: An excitatory postsynaptic potential (EPSP) _____ the likelihood of an action potential.
increases
What is the role of calcium ions in neurotransmitter release?
They trigger the fusion of neurotransmitter vesicles with the presynaptic membrane.
Define graded potential.
A change in membrane potential that varies in size and can summate.
True or False: Graded potentials can lead to action potentials if they reach the threshold.
True
What is the term for the time between the arrival of an action potential at the axon terminal and the release of neurotransmitters?
Synaptic delay
What type of ion channel opens in response to a change in membrane potential?
Voltage-gated ion channel
What is the role of inhibitory neurotransmitters?
To decrease the likelihood of an action potential in the postsynaptic neuron.
Fill in the blank: The process of converting an electrical signal into a chemical signal is called _____ transmission.
chemical
What is the function of the axon hillock?
To integrate incoming signals and determine whether to fire an action potential.
True or False: All neurons release the same type of neurotransmitter.
False
What is the effect of myelin on capacitance in neurons?
It decreases capacitance, allowing for faster signal transmission.
What is the primary effect of local anesthetics on neurons?
They block sodium channels to prevent action potentials.
What occurs during the after-hyperpolarization phase?
The membrane potential becomes more negative than the resting potential.
Fill in the blank: The _____ potential is the change in membrane potential caused by synaptic activity.
postsynaptic
What is the significance of the nodes of Ranvier?
They allow for saltatory conduction, increasing the speed of action potentials.
Which structure in the neuron receives incoming signals?
Dendrites
True or False: Neurotransmitters can be either excitatory or inhibitory.
True
What is the typical threshold for excitatory postsynaptic potentials (EPSPs)?
-55 mV
Fill in the blank: The _____ phase of the action potential is characterized by the efflux of potassium ions.
repolarization
What happens to the membrane potential during an action potential?
It rapidly depolarizes and then repolarizes.
True or False: The frequency of action potentials can encode information about stimulus intensity.
True
What is the primary role of astrocytes in the nervous system?
To support neurons and maintain the blood-brain barrier.
Fill in the blank: The _____ is the site of action potential initiation.
axon hillock
What is the consequence of a failure in the sodium-potassium pump?
Disruption of the resting membrane potential and potential cell death.
What is the primary effect of potassium channel blockers on neurons?
Prolonged action potentials.
Fill in the blank: The action potential travels along the axon through _____ conduction.
saltatory
Which type of receptor responds to neurotransmitters and opens ion channels?
Ionotropic receptors
What is the role of metabotropic receptors?
To activate intracellular signaling pathways that can affect ion channel activity.
True or False: Action potentials are graded responses.
False
What is the effect of the depolarization of the postsynaptic membrane?
It can lead to an excitatory postsynaptic potential (EPSP).
Fill in the blank: The _____ is the gap between two neurons at a synapse.
synaptic cleft
What is the significance of the absolute refractory period?
It ensures that action potentials are unidirectional and prevents overlapping.
What is the role of neurotransmitter reuptake?
To terminate the action of neurotransmitters in the synaptic cleft.
True or False: Neurons can regenerate action potentials indefinitely.
True
What determines the speed of action potential conduction?
Axon diameter and myelination
