Cell Signaling and Neurotransmission Quiz

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Questions and Answers

What distinguishes neurotransmission from neuromodulation based on their signaling speed?

Neurotransmission is a slower signaling process, whereas neuromodulation is faster.
The speed of neurotransmission and neuromodulation is solely determined by the type of ligand involved.
Neurotransmission is a faster signaling process, whereas neuromodulation is slower. (correct)
Neurotransmission and neuromodulation operate at comparable speeds.

Which of the following receptor types directly forms an ion channel as part of its structure?

Metabotropic receptor
Ligand-gated receptor (correct)
Neurotransmitter receptor
G protein-coupled receptor

What is the primary mechanism by which metabotropic receptors initiate intracellular signaling?

Modulating gene expression directly within the nucleus.
Directly opening ion channels to alter membrane potential.
Activating G proteins upon ligand binding. (correct)
Releasing neurotransmitters into the synaptic cleft.

Considering the scope of signaling, how does endocrine signaling differ from paracrine signaling as described in the content?

Endocrine signaling occurs in the bloodstream, while paracrine signaling is local within tissue. (B) Signup and view all the answers

Which of the following receptor types is exemplified by the nicotinic acetylcholine receptor (nAchR)?

Ionotropic receptor (C) Signup and view all the answers

What is the primary distinction in the mechanism of action between ionotropic and metabotropic receptors?

Ionotropic receptors directly alter the membrane potential through ionic flux, while metabotropic receptors initiate intracellular signaling cascades. (D) Signup and view all the answers

During G protein activation in metabotropic signaling, which event directly follows ligand binding to the receptor?

Dissociation of the G protein trimer after the alpha subunit binds GTP. (B) Signup and view all the answers

In the cyclic AMP signaling system, what is the immediate consequence of adenylyl cyclase activation?

Production of the second messenger cyclic AMP (cAMP). (A) Signup and view all the answers

Which of the following is a second messenger produced by phospholipase C in the phosphatidylinositol signaling system?

Diacyl glycerol (DAG). (A) Signup and view all the answers

Phosphorylation of target proteins by protein kinases, a downstream effect of metabotropic receptor activation, can directly modulate the function of which cellular component?

Ion channels, pumps, and receptors. (C) Signup and view all the answers

What is the primary effect of muscarinic acetylcholine receptors (mAchR) on cardiac muscle?

Inhibition of muscle contraction (C) Signup and view all the answers

Which type of receptor is directly linked to an ion channel and mediates fast synaptic transmission?

Ionotropic receptor (A) Signup and view all the answers

In cardiac muscle, activation of muscarinic acetylcholine receptors (mAchR) leads to:

Potassium ion efflux and hyperpolarization (C) Signup and view all the answers

Which of the following is a characteristic of metabotropic receptors?

They involve second messenger systems. (D) Signup and view all the answers

Curare is known to block nicotinic acetylcholine receptors (nAChR). What would be the expected physiological effect of curare?

Muscle relaxation and paralysis (B) Signup and view all the answers

In sympathetic ganglia, muscarinic acetylcholine receptors (mAchR) activation leads to a slow EPSP by:

Closing "M" type potassium channels (D) Signup and view all the answers

Atropine is an antagonist for muscarinic acetylcholine receptors (mAchR). Which of the following effects would be consistent with atropine administration?

Increased heart rate and bronchodilation (A) Signup and view all the answers

Nicotine acts as an agonist at nicotinic acetylcholine receptors (nAChR). Where would nicotine primarily exert its agonistic effects?

Skeletal muscle (D) Signup and view all the answers

Which form of synaptic plasticity is characterized by changes occurring at the same synapse where the activity modification originates?

Homo-synaptic potentiation (A) Signup and view all the answers

According to the 'residual calcium hypothesis', what is the primary mechanism underlying homo-synaptic facilitation?

Increased levels of calcium in the nerve terminal from prior action potentials enhancing neurotransmitter release. (B) Signup and view all the answers

Long-term potentiation (LTP), a form of homo-synaptic plasticity associated with learning and memory, is prominently observed in which brain structures?

Hippocampus and cerebral cortex (D) Signup and view all the answers

Activation of NMDA glutamate receptors in the post-synaptic neuron leads to an influx of $Ca^{2+}$. What is a downstream effect of this calcium influx in the context of synaptic plasticity?

Activation of calmodulin and kinases, initiating pathways for retrograde signaling. (D) Signup and view all the answers

Hetero-synaptic plasticity is defined by synaptic changes resulting from activity at:

A different synapse than where the initiating activity occurs. (C) Signup and view all the answers

In pre-synaptic facilitation, an interneuron modulates neurotransmitter release by:

Releasing neurotransmitter that enhances neurotransmitter release from the pre-synaptic terminal. (B) Signup and view all the answers

Enkephalin, released by pre-synaptic interneurons in the spinal cord, modulates pain pathways by what mechanism of hetero-synaptic plasticity?

Pre-synaptic inhibition of substance P release. (D) Signup and view all the answers

Hetero-synaptic inhibition, leading to a reduction in neurotransmitter release, can be mediated by:

Decreased duration of the pre-synaptic action potential due to increased $I_{K^{+}}$. (D) Signup and view all the answers

Flashcards

Ionotropic Receptors

Receptors that directly open or close ion channels upon ligand binding, leading to rapid changes in membrane potential. Think of them as a direct gatekeeper for ions.

Metabotropic Receptors

Receptors that activate a separate signaling pathway involving G proteins and second messengers, leading to slower, more complex changes in cell activity. They're like signal amplifiers!

G Protein-Coupled Receptors (GPCRs)

A type of metabotropic receptor that is linked to a G protein. These receptors are involved in a variety of cellular functions and are often targets for drugs.

Second Messengers

A class of signaling molecules that act as messengers within cells. These molecules are involved in a wide range of cellular processes, including metabolism, growth, and differentiation.