Lecture 2 of Senior Seminar

Neurotransmitters

Chemical signaling molecules released from neurons are known as _______.

Neurotransmitters.

Where are neurotransmitters typically released from in a neuron?

The presynaptic terminal.

What determines the specific effect a neurotransmitter has on the postsynaptic cell?

The specific receptor to which it binds to.

Which synaptic structures are specifically filled with neurotransmitters?

Synaptic vesicles.

What type of molecules are stored inside secretory granules?

Peptides (large protein molecules).

How do secretory granules compare in size to synaptic vesicles?

They are larger containers than vesicles.

The site at which neurotransmitters are released to bind to the postsynaptic neuron is called the _____.

Active zone.

Which brain region is noted as being important for regulatory behaviors like eating and sleeping?

Hypothalamus.

Where are amino acids and amines typically stored within the synapse?

Synaptic vesicles.

Where are peptides stored within the synapse?

Secretory granules.

What determines the speed of synaptic transmission for a given neurotransmitter?

The types of receptors that the neurotransmitter binds to.

Relative to standard neurotransmitters, what is the production cost of peptides?

They take more time and effort to produce.

Which neurotransmitter is synthesized by neurons classified as 'GABAergic'?

GABA.

From what source do neurons obtain Glutamate and Glycine?

They are abundant from the diet and do not have to be made by neurons.

What molecule serves as the precursor for the synthesis of GABA?

Glutamate.

Which proteins tether synaptic vesicles to the active zone to facilitate neurotransmitter release?

SNARE proteins.

What event triggers the opening of voltage-gated Ca2+ channels at the presynaptic terminal?

The arrival of an action potential.

What specific ion influx causes the release of neurotransmitters from synaptic vesicles?

Ca2+.

The process of releasing neurotransmitters into the synaptic cleft at the active zone is called _____.

Exocytosis.

The process by which neurotransmitters or membranes are reuptaken and recycled back into the vesicle is called _____.

Endocytosis.

What type of proteins are responsible for moving neurotransmitters back into the synaptic vesicle during reuptake?

Transporter proteins.

What are the three potential fates of a neurotransmitter after it is released into the synaptic cleft?

Reuptake, diffusion, or enzymatic destruction.

What is the function of the enzyme Acetylcholinesterase (AChE)?

It destroys Acetylcholine (ACh) at the neuromuscular junction.

Chemicals not made by the human body are categorized as _____.

Exogenous chemicals.

What is a substance that mimics the actions of a naturally occurring neurotransmitter?

Agonist.

Give an example of an exogenous agonist for opioid receptors mentioned in the text.

Morphine.

What is a substance that acts as an inhibitor of a neurotransmitter?

Antagonist.

Which drug is mentioned as an antagonist for opioids?

Naltrexone.

What is the primary effect (excitatory or inhibitory) of Glutamate?

Excitatory.

What is the primary effect (excitatory or inhibitory) of GABA?

Inhibitory.

Nicotine acts as an agonist for Acetylcholine receptors located in _____ muscle.

Skeletal.

Muscarine acts as an agonist for Acetylcholine receptors located in the _____.

Heart (cardiac muscle).

Which specific receptor type mediates Nicotine's effects on skeletal muscle?

Nicotinic ACh receptors.

Which specific receptor type mediates Muscarine's effects on the heart?

Muscarinic ACh receptors.

True or False: A single neurotransmitter can bind to many different types of receptors.

True.

True or False: A single receptor can usually bind to many different types of neurotransmitters.

False.

Ligand-gated ion channels are also referred to as _____ ion channels.

Neurotransmitter-gated.

How does the selectivity of ligand-gated ion channels compare to voltage-gated channels?

They are less selective for ions.

Which ion entry is associated with the activation of ACh- and glutamate-gated channels (these are ligand-gated ion channels)?

Na+ (producing an excitatory postsynaptic potential or EPSP).

Which ion entry is associated with the activation of Glycine- and GABA-gated channels (these are ligand-gated ion channels)?

Cl− (producing an inhibitory postsynaptic potential or IPSP).

How does the speed of ligand-gated ion channels compare to G-protein-coupled receptors (GPCRs)?

They are MUCH faster.

AMPA receptors are permeable to K+ and Na+ but not to which specific ion?

Ca2+.

Which glutamate receptor is permeable to both Na+ and Ca2+ and features a voltage-dependent inward current?

NMDA receptors.

What medical condition can result from having too little GABA regulation in the central nervous system?

Seizures.

What medical condition can result from having excessive GABA activity?

Loss of consciousness or coma.

How do benzodiazepines specifically modify the function of GABAA​ receptors?

They increase the frequency of channel opening.

How do barbiturates specifically modify the function of GABAA​ receptors?

They increase the duration of channel opening.

What is another name for G-protein-coupled receptors (GPCRs)?

Metabotropic receptors.

Where are autoreceptors typically located on the neuron?

The presynaptic membrane.

What are the three subunits that make up a G-protein?

α, β, and γ.

In the resting state, which molecule is bound to the G-protein α subunit?

GDP.

What occurs when a GDP-bound G-protein bumps into a receptor that has a transmitter molecule bound to it?

The G-protein releases GDP and exchanges it for a GTP picked up from the cytosol.

Once activated by GTP, into which two functional parts does the G-protein split?

The Gα-GTP subunit and the βγ complex.

Which subunit of the G-protein eventually terminates its own activity by breaking down GTP into GDP?

The α subunit.

In G-protein signaling, what is the functional difference between Gs​ and Gi​?

How many subtypes of muscarinic metabotropic receptors exist for Acetylcholine?

Five.

What class of receptor do all serotonin receptors belong to?

Metabotropic receptors.

Why are G-protein-coupled receptors considered important for metabolic efficiency?

One neurotransmitter binding to one receptor can activate many enzymes all at once.

Metabotropic receptors tend to have _____ effects compared to ligand-gated receptors.

Longer-lasting (and more widespread).

Which glutamate receptor subtype has very little known about it according to the lecture notes?

Kainate receptors.