Anatomy and Physiology of the Nervous System: Neurophysiology

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What is the value of the resting membrane potential in a neuron?

-90 mV

-50 mV

-110 mV

-70 mV (correct)

What is the main reason for the electrical polarization of the plasma membrane in a resting neuron?

Equal permeability of the membrane to sodium and potassium

More potassium leak channels than sodium leak channels (correct)

More sodium leak channels than potassium leak channels

The presence of anions in the cytosol

What is the role of trapped anions in the resting membrane potential?

They increase the permeability of the membrane to sodium

They facilitate the inward flow of sodium ions

They help to expel potassium ions from the neuron

They cannot follow potassium ions out of the neuron (correct)

What are the two factors that determine the membrane potential?

Ion concentration gradient and ion permeability Signup and view all the answers

What is the state of the neuron when the resting membrane potential is measured?

Inactive and not transmitting a signal Signup and view all the answers

What is the term for the electrical polarization of the plasma membrane in a resting neuron?

Electrical polarization Signup and view all the answers

What is the direction of an action potential in a neuron?

Unidirectional Signup and view all the answers

What is the purpose of the myelin sheath in saltatory conduction?

To act as a good electrical insulator Signup and view all the answers

What is the effect of lower temperature on the speed of nerve impulses?

It slows down the speed Signup and view all the answers

What is the advantage of electrical synapses in neuronal communication?

Faster communication and synchronization Signup and view all the answers

What is the location of voltage-gated ion channels in a myelinated axon?

Nodes of Ranvier Signup and view all the answers

What determines the speed of nerve impulses in an axon?

Temperature, axon diameter, and myelin sheath Signup and view all the answers

What is the main function of the presynaptic neuron in a chemical synapse?

To convert an electrical signal into a chemical signal Signup and view all the answers

What is the result of an excitatory synapse on the postsynaptic cell?

It depolarizes the local membrane potential of the postsynaptic cell Signup and view all the answers

What is the relationship between the strength of the stimulus and the frequency of action potentials?

The frequency of action potentials increases as the stimulus strength increases until a maximum frequency is reached. Signup and view all the answers

Where are neurotransmitters synthesized in the neuron?

In the cytoplasm of the cell body Signup and view all the answers

What is the sequence of events in an action potential?

Depolarization, repolarization, refractory period, and after-hyperpolarization. Signup and view all the answers

What is the function of the synaptic cleft in a chemical synapse?

To separate the presynaptic and postsynaptic neurons Signup and view all the answers

What is the result of an inhibitory synapse on the postsynaptic cell?

It hyperpolarizes the local membrane potential of the postsynaptic cell Signup and view all the answers

During which phase of the action potential is the membrane potential restored to the resting state?

Repolarization phase Signup and view all the answers

What is the role of neurotransmitters in a chemical synapse?

To act as chemical messengers between neurons Signup and view all the answers

What is the function of the sodium-potassium pump in the action potential process?

To restore the initial ionic condition after repolarization Signup and view all the answers

What is the result of the action potential on the adjacent portions of the membrane?

The action potential causes an electric current that stimulates adjacent portions of the membrane. Signup and view all the answers

What is the duration of the absolute refractory period?

From the beginning of the action potential until the end of repolarization Signup and view all the answers

What is the function of the electrogenic Na+–K+ ATPase in terms of ion transport?

It expels 3 Na+ ions for every 2 K+ ions imported Signup and view all the answers

What is the characteristic of a graded potential in terms of its spatial extent?

It is confined to a localized region of the plasma membrane Signup and view all the answers

What is the significance of the threshold stimulus in generating an action potential?

It is necessary for the generation of an action potential Signup and view all the answers

What is the difference between graded potentials and action potentials in terms of summation?

Graded potentials can summate, but action potentials cannot Signup and view all the answers

What is the location where an action potential is primarily generated?

Neuron axons Signup and view all the answers

What is the sequence of events during an action potential?

Depolarization followed by repolarization Signup and view all the answers