Neurotransmitter Communication Quiz
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Questions and Answers

What benefit does the slight delay in neurotransmitter communication provide?

  • It enhances the speed of neurotransmitter release.
  • It allows for faster reflex actions.
  • It increases the energy expenditure of the postsynaptic cell.
  • It reduces the likelihood of receptor overload. (correct)

    • What can lead to receptor downregulation in a postsynaptic cell?

  • Increased release of neurotransmitters.
  • Inhibition of neurotransmitter reuptake.
  • Constant stimulation from neurotransmitters. (correct)
  • Decreased sensitivity of the synapse.

    • In the context of heart failure patients, what neurotransmitter depletion is commonly observed?

  • Dopamine depletion.
  • Catecholamine depletion. (correct)
  • Acetylcholine depletion.
  • Serotonin depletion.

    • What condition might lead to a similar neurotransmitter release pattern in older individuals?

    <p>Chronic illness with compensation.</p> Signup and view all the answers

    What phenomenon can occur if a postsynaptic cell is continuously stimulated?

    <p>Fatigue in neurotransmitter response.</p> Signup and view all the answers

    What is an example of a situation where postsynaptic facilitation is monitored?

    <p>When assessing neuromuscular blockade.</p> Signup and view all the answers

    What does fatigue in the postsynaptic cell often relate to?

    <p>Depletion of neurotransmitter stores.</p> Signup and view all the answers

    Which of the following best explains the relationship between receptor amounts and constant stimulation?

    <p>Cells may reduce receptors to cope with constant stimulation.</p> Signup and view all the answers

    What type of bonding typically occurs when a drug attaches to its receptor?

    <p>Hydrophobic bonding</p> Signup and view all the answers

    Why is it important for a pharmacologically active molecule to be uncharged?

    <p>It allows the molecule to be lipophilic.</p> Signup and view all the answers

    What happens when a drug molecule fits perfectly onto a receptor?

    <p>A conformational change occurs.</p> Signup and view all the answers

    Which of the following is considered an aceptor in the context of drug binding?

    <p>Beta globulins</p> Signup and view all the answers

    What is the key characteristic of hydrophobic and lipophilic molecules?

    <p>They are nonpolar.</p> Signup and view all the answers

    Which type of receptor is commonly associated with anesthetics?

    <p>G protein coupled receptors</p> Signup and view all the answers

    What role do aceptors like albumin play in relation to drugs in plasma?

    <p>They bind to drugs without eliciting a response.</p> Signup and view all the answers

    Which of the following statements about drug-receptor interaction is FALSE?

    <p>Lipophilic drugs are likely to interact with hydrophilic receptors.</p> Signup and view all the answers

    What primarily causes the repolarization of the cell membrane?

    <p>The efflux of potassium ions from the cell</p> Signup and view all the answers

    During the action potential, why is the repolarization process considered slow?

    <p>Potassium channels open slowly and close slowly</p> Signup and view all the answers

    What phenomenon occurs when the cell membrane becomes more negative than its resting membrane potential?

    <p>Hyperpolarization</p> Signup and view all the answers

    What role does the sodium-potassium pump play after hyperpolarization?

    <p>It exchanges sodium for potassium to restore balance</p> Signup and view all the answers

    How does the state of the sodium channel change after the action potential?

    <p>It becomes inactivated and cannot respond to stimuli</p> Signup and view all the answers

    What is the typical extracellular sodium concentration in a resting state?

    <p>140 mM</p> Signup and view all the answers

    What happens to potassium channels during the action potential after sodium influx?

    <p>They open slowly and take time to close, leading to hyperpolarization</p> Signup and view all the answers

    Which conformational state of the sodium channel prevents it from responding to stimuli after the action potential?

    <p>Inactivated state</p> Signup and view all the answers

    What is the primary characteristic of the non-polar tails of phospholipids?

    <p>They exhibit affinity towards each other.</p> Signup and view all the answers

    What does selectivity of a receptor indicate?

    <p>The receptor's ability to bind specific endogenous chemicals.</p> Signup and view all the answers

    Which of the following substances is likely to easily diffuse across the phospholipid bilayer?

    <p>Oxygen molecules.</p> Signup and view all the answers

    What aspect of receptors does sensitivity pertain to?

    <p>The concentration required for a cellular response.</p> Signup and view all the answers

    What role do calcium channels play in neurotransmitter release?

    <p>They cause vesicles to merge with the presynaptic membrane.</p> Signup and view all the answers

    What role do the proteins in the postsynaptic density play?

    <p>They maintain the integrity of that area.</p> Signup and view all the answers

    Which process involves the return of neurotransmitter components to the presynaptic cell?

    <p>Reuptake via transport pumps</p> Signup and view all the answers

    Which statement best describes specificity in relation to receptors?

    <p>It refers to the type of response elicited in different tissues.</p> Signup and view all the answers

    How does the postsynaptic cell generate an efferent action potential?

    <p>By neurotransmitters binding to receptors on the postsynaptic cell.</p> Signup and view all the answers

    Which type of molecules generally require channels to cross the phospholipid bilayer?

    <p>Ions and larger molecules.</p> Signup and view all the answers

    What is a critical feature of receptors that characterizes their interaction with ligands?

    <p>Receptors exhibit a spectrum of bond strengths with ligands.</p> Signup and view all the answers

    What is the term for the area beneath the postsynaptic membrane where receptors and proteins are located?

    <p>Postsynaptic density</p> Signup and view all the answers

    What is a key function of synaptic modulation?

    <p>To affect signal transmission between cells.</p> Signup and view all the answers

    What happens to neurotransmitters at the neuromuscular junction after release?

    <p>They are metabolized and reabsorbed.</p> Signup and view all the answers

    In which of the following scenarios would neurotransmitter reuptake be essential?

    <p>There is excessive neurotransmitter in the synapse.</p> Signup and view all the answers

    What initiates the process of vesicle merging with the presynaptic membrane?

    <p>Binding of calcium ions to proteins in the presynaptic membrane.</p> Signup and view all the answers

    What is the resting membrane potential of a neuron?

    <p>-70 mV</p> Signup and view all the answers

    Which ion channels open when the membrane potential reaches the threshold of -55 mV?

    <p>Na+ voltage-gated channels</p> Signup and view all the answers

    What happens during the inactivation of Na+ channels at +30 mV?

    <p>They close and become inactive.</p> Signup and view all the answers

    Which condition can lead to sustained muscle depolarization?

    <p>Hypocalcemia</p> Signup and view all the answers

    What effect does hypercalcemia have on a neuron's membrane excitability?

    <p>Decreases excitability by lowering Na+ permeability.</p> Signup and view all the answers

    What can result from prolonged hypokalemia in terms of resting membrane potential?

    <p>Increased resting membrane potential negativity</p> Signup and view all the answers

    Which statement best describes the neurotransmitter release process in synaptic transmission?

    <p>Neurotransmitter is released after membrane depolarization and calcium entry.</p> Signup and view all the answers

    What is the role of the postsynaptic density in a neuron?

    <p>It maintains synaptic homeostasis and receptor organization.</p> Signup and view all the answers

    During which process does the synapse become more responsive after a short rest period?

    <p>Post-tetanic facilitation</p> Signup and view all the answers

    How does an increase in pH affect neuronal excitability?

    <p>Increases excitability.</p> Signup and view all the answers

    Which condition is associated with decreased excitability due to low oxygen levels?

    <p>Hypoxia</p> Signup and view all the answers

    What mechanism is responsible for re-establishing the resting membrane potential after an action potential?

    <p>Na+/K+ ATPase activity</p> Signup and view all the answers

    Which component is critical for maintaining synaptic signal fidelity?

    <p>Neurotransmitter reuptake pumps</p> Signup and view all the answers

    What happens during repetitive stimulation of excitatory synapses leading to fatigue?

    <p>Decreased postsynaptic response.</p> Signup and view all the answers

    Study Notes

    Action Potential

    • Nerve cells have a resting membrane potential, about -70mV
    • Repolarization: Potassium leaves the cell, making it more negative
    • Hyperpolarization: Overshoots resting potential, more negative than normal
    • Sodium-potassium pump returns cell to resting state
    • Sodium channels open rapidly, sodium rushes in (depolarization)
    • Potassium channels open slowly, potassium leaves the cell (repolarization)

    Potassium Channels

    • Potassium channels are slower than sodium channels
    • Potassium channels open and close slowly, causing a longer duration of repolarization
    • Potassium channels are important for establishing the resting membrane potential

    Synaptic Transmission

    • Synapses are junctions between nerve cells
    • Neurotransmitters are released from the presynaptic neuron
    • Neurotransmitters bind to receptors on the postsynaptic neuron
    • Neurotransmitter release is triggered by calcium entry
    • Neurotransmitters diffuse across the synaptic cleft
    • Vesicles release neurotransmitters in response to Ca2+ influx, then merge with the membrane
    • Neurotransmitters bind to receptors on postsynaptic neuron
    • Neurotransmitters are removed or deactivated
    • Action potentials cause channels to open/close in both pre and postsynaptic neurons

    Receptors

    • Receptors are proteins that bind neurotransmitters
    • Receptors have specific shapes to bind specific neurotransmitters
    • Receptors can be intracellular or membrane-bound
    • Hydrophobic interactions allow neurotransmitters to bind to receptors
    • Receptors are responsible for the specificity of a biological response depending on the tissue

    Other important concepts

    • Neurotransmitters can have different effects or concentrations which can result in different responses or changes in function
    • Hypokalemia causes a more negative resting membrane potential
    • Hypoxia decreases excitability
    • Abnormal calcium levels affect membrane permeability to sodium - leading to decreased or increased excitability
    • Different receptors/channels can speed up or slow down the physiological response or the signal itself, leading to a unique response
    • Cell membrane is a phospholipid bilayer; mostly impermeable to water-soluble substances

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    Description

    Test your knowledge on neurotransmitter communication and its effects on synaptic transmission. This quiz covers concepts such as receptor downregulation, neurotransmitter depletion in heart failure, and the impact of continuous stimulation on postsynaptic cells.

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