Neuroscience Receptor Potential Quiz

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Questions and Answers

What is the initial effect of energy from the environment on sensory receptors?

No change in membrane potential

Depolarization of the membrane (correct)

Hyperpolarization of the membrane

Inhibition of ion channel activity

What occurs when a receptor protein changes shape after receiving specific energy?

It only opens potassium channels

It stops the transmission of nerve signals

It modifies the membrane permeability (correct)

It immediately generates an action potential

Which second messenger can be activated via G-protein coupling in sensory receptors?

Acetylcholine

Cyclic AMP (cAMP) (correct)

Serotonin

Dopamine

What is the term for the change in membrane potential due to the reception of a sensory cue?

Receptor potential Signup and view all the answers

In what way do photoreceptors differ from other sensory receptors in response to stimuli?

They hyperpolarize in response to light Signup and view all the answers

What is the primary role of the receptor potential in sensory cells?

It allows for vesicle release without generating an action potential. Signup and view all the answers

Which type of adaptation is characterized by a receptor potential that is sustained for the duration of a stimulus?

Slowly Adapting Signup and view all the answers

How does habituation differ from adaptation in sensory response?

Habituation involves progressively weaker responses to repeated identical stimuli. Signup and view all the answers

What limits the impulse frequency in sensory systems after reaching a certain threshold?

The refractory period. Signup and view all the answers

What occurs when the intensity of a stimulus increases?

More transmitter is released. Signup and view all the answers

What characterizes rapidly-adapting receptors?

They decrease their response quickly to a constant stimulus. Signup and view all the answers

What is a key function of exocytosis in sensory cells?

To release neurotransmitter vesicles. Signup and view all the answers

During sensory transmission, where does the depolarizing current primarily travel to generate an action potential?

At the branch point of the membrane. Signup and view all the answers

In the context of sensory systems, what does the term 'coding of stimulus intensity' refer to?

Proportional relationship between stimulus intensity and receptor potential. Signup and view all the answers

What happens to the receptor potential if the stimulus remains constant over time?

It decays to zero. Signup and view all the answers

What initiates the production of 2nd messengers in sensory cell transmission?

Binding of a chemical stimulus to a metabotropic receptor Signup and view all the answers

Which best describes the role of G-protein in signal amplification?

It activates multiple enzyme molecules leading to more 2nd messengers. Signup and view all the answers

How do olfactory receptors contribute to signal transmission?

By activating G-proteins that lead to the production of cAMP. Signup and view all the answers

What is the relationship between cAMP and ion channels in sensory cells?

cAMP directly binds to ion channels and promotes cation influx. Signup and view all the answers

What occurs at the trigger zone of a sensory cell?

Collection of receptor potentials to reach the action potential threshold. Signup and view all the answers

What happens to the depolarizing current once it is generated?

It travels down the membrane to the axon terminal. Signup and view all the answers

How does the sensory cell release vesicles during signal transmission?

As a result of depolarization at the spiking zone. Signup and view all the answers

Which stage of cAMP production amplifies the signal in sensory cells?

The simultaneous activation of multiple G-proteins. Signup and view all the answers

Study Notes

Receptor Potential

Change in membrane potential (MP) due to external sensory cues.
Environmental energy interacts with membrane proteins, usually causing depolarization.
Photoreceptors are an exception; they hyperpolarize.
Receptor proteins in sensory cell membranes change shape upon receiving specific energy.
Shape change either directly opens ion channels (e.g., cation channels leading to depolarization) or activates enzymes via G-protein coupling, producing second messengers (cAMP, cGMP, IP3) to amplify the signal.
First patch of excitable membrane is usually at the branch point; receptor potential must travel and summate there to reach threshold for an action potential (AP).

Sensory Cell Transmission

Sensory cells either generate an AP at a spike-generating zone or release vesicles when depolarized; impulses are then generated in the postsynaptic neuron.

Transmission of Signal (Vesicles)

Depolarizing current doesn't produce APs; it travels to the other end of the membrane. Sufficient depolarization causes Ca++ influx and triggers vesicle exocytosis. The sensory cell releases vesicles without producing an AP. This is seen in taste receptors.

Transmission of Signal (AP)

Occurs at the axon terminal (e.g., in sensory axons in the skin). Receptor potential travels to the branch point to summate and reach threshold for an AP.

Adaptation

Membrane potential decays over time, even with a constant stimulus. This is known as adaptation.
Slow Adaptation: Receptor potential sustained throughout the duration of the stimulus; concerned with overall stimulus magnitude.
Rapid Adaptation: Receptor potential elicited by stimulus change; decays to zero with a constant stimulus; concerned with stimulus velocity.

Habituation

Repeated identical stimuli elicit progressively weaker responses over time. The degree of habituation varies among cells.

Coding of Stimulus Intensity

Receptor potential varies directly with stimulus intensity.
Stronger stimuli cause greater receptor depolarization (graded potential), leading to more transmitter release and/or higher AP frequency.
Greater depolarization speeds the membrane's recovery from hyperpolarization to generate new spikes.
AP frequency is limited by the refractory period, leading to a ceiling effect for high intensity coding. Mechanisms for coding beyond the refractory limit are not described.

Coding of Modality

There is no specific information provided on coding of modality (type of stimulus).

Receptive Field

There is no specific information provided on receptive fields in this text.

Axon Reflex

There is no specific information provided on axon reflex in this text.

Olfactory Receptor

Specific receptor proteins bind specific odorants, activating G-proteins. This activates adenylyl cyclase, producing cAMP. cAMP binds to ion channels, allowing cation (Na+ and Ca++) influx and membrane depolarization. The depolarizing current travels to the axon's trigger zone. Signal amplification occurs.

Stages of Amplification (Olfactory Receptor)

G-protein activates multiple enzyme molecules, each producing numerous cAMP molecules. This results in significant signal amplification from a single stimulus molecule.

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Description

Explore the processes involved in receptor potentials and sensory cell transmission through this quiz. Understand how environmental cues interact with membrane proteins to elicit changes in membrane potential. This quiz also delves into action potentials and the role of second messengers in amplifying signals.