Local Potentials and Action Potentials Quiz

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Which one of these is a type of local potential?

Endplate potential

Synaptic potential (correct)

Generator potential

Action potential

What is the main characteristic of local potentials?

They initiate action potentials

They are graded phenomena (correct)

They result from opening/closing of ion-permeable channels

They have longer duration than action potentials

Which one of these is an example of a local potential in neurons?

Synaptic potentials (correct)

Endplate potentials

Generator potentials

All of the above

What happens if synaptic potentials depolarize the postsynaptic cell?

They elicit action potentials Signup and view all the answers

What is the ionic basis for EPSPs and IPSPs?

Permeability to Na+ and K+ Signup and view all the answers

What is the typical value for ECl?

-70 mV Signup and view all the answers

What is the main function of IPSPs in the postsynaptic cell?

To inhibit production of action potentials Signup and view all the answers

What is the main characteristic of temporal summation?

It occurs with time Signup and view all the answers

What is the main characteristic of spatial summation?

It occurs with distance Signup and view all the answers

What are the three general types of local potentials?

Synaptic potentials, endplate potentials, and generator potentials Signup and view all the answers

Which type of potential is depolarizing and results from the activation of sodium and potassium channels in the endplate of skeletal-muscle fibers?

Endplate potentials (EPPs) Signup and view all the answers

What is the region of membrane in skeletal-muscle fibers where a motor neuron innervates the muscle fiber at the neuromuscular junction (NMJ)?

Endplate Signup and view all the answers

What triggers muscle contraction in a muscle fiber?

Action potential (AP) Signup and view all the answers

Where does inhibition of muscle contraction occur?

Neural synapses Signup and view all the answers

What term is used to describe the local potential that generates trains of action potentials (APs) in sensory receptors?

Generator (or receptor) potential Signup and view all the answers

Which type of receptor is well studied and detects pressure (touch) stimuli in the palms, fingers, and other regions?

Pacinian corpuscle Signup and view all the answers

What type of ion channels does the Pacinian corpuscle have?

Stretch-sensitive ion channels Signup and view all the answers

What is the term used to describe the amount of depolarization in a receptor potential that is proportional to the intensity of pressure?

Graded Signup and view all the answers

What encodes the stimulus intensity in a receptor potential?

Frequency of action potentials (APs) Signup and view all the answers

What is the term used to describe the concept that each action potential (AP) arriving in the central nervous system has the same amplitude, while the number of APs per second (frequency) encodes the stimulus intensity?

Frequency encoding Signup and view all the answers

Which of the following is true about the soma?

The soma lacks rapidly activating Na+ channels Signup and view all the answers

What is the role of the soma in neural integration?

The soma sums up the effects of all EPSPs and IPSPs Signup and view all the answers

What is the main reason why the depolarization caused by individual potentials does not sum up algebraically?

The individual potentials have different locations Signup and view all the answers

What is the result of repetitive stimulation of a single synapse?

Temporal summation leading to larger depolarizations Signup and view all the answers

What can lead to an action potential at the axon hillock?

Depolarization to threshold Signup and view all the answers

What can cancel the effects of excitatory postsynaptic potentials (EPSPs)?

Inhibitory postsynaptic potentials (IPSPs) Signup and view all the answers

What can produce no change in membrane potential but still effectively counter an EPSP?

Silent IPSPs resulting from gCl Signup and view all the answers

What is the significance of neural inhibition?

Roughly half of all neural synapses are inhibitory Signup and view all the answers

What is the effect of tetanus toxin on inhibitory synapses?

Tetanus toxin irreversibly blocks inhibitory synapses Signup and view all the answers

What is the main cause of death in tetanus infections?

Asphyxiation due to muscle contractions Signup and view all the answers