Physiological Psychology Exam 2

What event triggers the fusion of synaptic vesicles with the presynaptic membrane during transmission?

The influx of Ca2+ ions through voltage-gated calcium channels.

Define an 'endogenous' ligand.

A substance produced naturally within the body that binds to a receptor.

Define an 'exogenous' ligand.

A substance originating from outside the body, such as a drug, that binds to a receptor.

What is the primary functional difference between ionotropic and metabotropic receptors?

Ionotropic receptors open ion channels directly, while metabotropic receptors activate G proteins to open channels or cause cellular changes.

Approximately how many receptor types have been identified for serotonin?

14 types.

How many receptor types are typically associated with dopamine?

5 types.

What phenomenon occurs when a single neuron contains and releases more than one type of neurotransmitter?

Co-localization or co-existence.

In what cellular location are small-molecule neurotransmitters, such as amines and amino acids, typically synthesized?

In the cytoplasm of the axon terminal.

Where are large-molecule neuropeptides synthesized within the neuron?

In the cell body (soma).

How are neuropeptides transported from the soma to the axon terminal?

Via kinesin along microtubules through axonal transport.

Contrast the release patterns of small-molecule versus large-molecule neurotransmitters.

Small-molecule transmitters are released with each action potential, while large-molecule transmitters are released gradually in response to multiple potentials.

Which neurotransmitter is considered the most common excitatory amino acid in the brain?

Glutamate.

Which amino acid neurotransmitter is the primary inhibitory signal in the brain?

GABA (Gamma-aminobutyric acid).

Name the three main ionotropic glutamate receptors.

AMPA, NMDA, and Kainate receptors.

What ion normally blocks the NMDA receptor channel at resting membrane potential?

Magnesium (Mg2+).

What two conditions are required to release the magnesium block from an NMDA receptor?

Partial depolarization of the membrane and co-activation by glutamate and glycine.

How is glutamate primarily cleared from the synaptic cleft?

Via Excitatory Amino Acid Transporters (EAATs) located on astrocytes and neurons.

Which enzyme breaks down glutamate within the cytoplasm of astrocytes?

Glutamine synthase.

What is the metabolic precursor for the synthesis of GABA?

Glutamic acid (glutamate).

Which enzyme catalyzes the conversion of glutamate into GABA?

Glutamic acid decarboxylase (GAD).

Describe the ion flow associated with the activation of ionotropic GABA-A receptors.

An influx of chloride (Cl−) ions occurs.

What is the main mechanism of action for the metabotropic GABA-B receptor?

It opens potassium (K+) channels for ion efflux.

Where are ionotropic GABA-C receptors primarily located?

In the retina.

Which enzyme is responsible for the degradation of GABA in the cytoplasm?

GABA aminotransferase.

What type of ion channel is controlled by the ionotropic glycine receptor?

A chloride (Cl−) channel.

Name the toxin that acts as a glycine receptor antagonist, leading to over-excitation.

Strychnine.

Which bacteria-produced toxin blocks the release of glycine and GABA, causing tetanus?

Tetanus toxin.

What was the first neurotransmitter to be identified?

Acetylcholine (ACh).

What term describes neurons that utilize acetylcholine as their primary neurotransmitter?

Cholinergic.

The loss of cholinergic neurons in the brain is a hallmark of which neurodegenerative disease?

Alzheimer’s disease.

Which enzyme synthesizes acetylcholine from Acetyl CoA and choline?

Choline acetyltransferase (ChAT).

Which enzyme breaks down acetylcholine in the synaptic cleft?

Acetylcholinesterase (AChE).

Name the two major cholinergic nuclei found in the basal forebrain.

The nucleus basalis and the medial septal nucleus.

Contrast the fast excitatory effects of nicotinic ACh receptors with the slower effects of muscarinic receptors.

Nicotinic receptors are ionotropic and flux Na+ and K+, while muscarinic receptors are metabotropic and G protein-coupled.

Which cholinergic antagonist is known for causing paralysis by blocking nicotinic receptors at the neuromuscular junction?

Curare.

In the autonomic nervous system, which neurotransmitter is used by all preganglionic neurons?

Acetylcholine.

List the three neurotransmitters categorized as catecholamines.

Dopamine, norepinephrine, and epinephrine.

What amino acid serves as the dietary precursor for all catecholamines?

Tyrosine.

Describe the Mesolimbocortical pathway for dopamine.

It originates in the Ventral Tegmental Area (VTA) and projects to the nucleus accumbens, cortex, and hippocampus.

Which dopaminergic pathway originates in the Substantia Nigra and is affected in Parkinson's disease?

The Nigrostriatal (or mesostriatal) pathway.

Which brain structure is the primary source of norepinephrine in the CNS?

The locus coeruleus.

What behavioral state is most strongly associated with the release of norepinephrine from the locus coeruleus?

Vigilance or attentiveness to environmental events.

What are axonal varicosities?

Swellings along an axon that release neurotransmitters without traditional synaptic junctions, enabling volume transmission.

How is norepinephrine primarily removed from the synapse?

Via the norepinephrine transporter (NET) and degradation by Monoamine oxidase (MAO) or COMT.

What is the dietary precursor for the synthesis of serotonin (5-HT)?

Tryptophan.

Where are the cell bodies of the brain's serotonergic neurons primarily located?

In the raphe nuclei.

Which serotonin receptor subtype is unique because it is ionotropic?

The 5−HT3​ receptor.

Which anxiolytic drug selectively targets the 5−HT1A​ receptor subtype?

BuSpar.

How are neuropeptides terminated after release, given they have no reuptake mechanisms?

They are destroyed by extracellular enzymes.

List the three main families of endogenous opioid peptides.

Endorphins, enkephalins, and dynorphins.

What is the primary function of endogenous opioids in the spinal cord and periaqueductal gray (PAG)?

The reduction of pain (analgesia).

Identify two characteristics of Nitric Oxide (NO) that distinguish it from classic neurotransmitters.

It is produced on demand (not stored) and can act as a retrograde transmitter by diffusing through membranes.

Define 'Neuropharmacology'.

The scientific study of compounds that selectively affect the functioning of the nervous system.

How does a 'competitive' ligand differ from a 'noncompetitive' ligand?

A competitive ligand binds to the orthosteric site, while a noncompetitive ligand binds to an allosteric modulatory site.

What is the function of an 'inverse agonist' at a receptor?

It initiates the reverse of the normal effect of the endogenous transmitter.

Define 'binding affinity'.

The propensity of molecules of a drug to bind to a specific receptor.

Define 'efficacy' in the context of neuropharmacology.

The ability of a bound ligand to activate the receptor and initiate a cellular response.

What does a dose-response curve (DRC) represent?

The relationship between the dose of a drug and the strength of the resulting response.

How is the 'Therapeutic Index' of a drug calculated?

By comparing the effective dose 50% (ED50​) with the lethal dose 50% (LD50​) or toxic dose 50% (TD50​).

What does 'bioavailability' refer to?

The amount of a drug that is free to act on its target tissue.

Which route of drug administration typically yields the fastest effect?

Intravenous (IV) injection or inhalation.

What physiological barrier prevents many large drug molecules from entering the brain?

The blood-brain barrier (BBB).

Define 'functional tolerance'.

A decrease in drug effectiveness due to changes in receptor density (up-regulation or down-regulation).

What receptor change typically occurs in response to chronic exposure to an agonist?

Down-regulation (a decrease in the number of receptors).

What receptor change typically occurs in response to chronic exposure to an antagonist?

Up-regulation (an increase in the number of receptors).

Define 'sensitization' as it relates to repeated drug administration.

An increase in the effectiveness of a drug with repeated use.

Why do withdrawal symptoms often resemble the opposite of a drug's primary effects?

They are caused by compensatory mechanisms the body established to maintain homeostasis during chronic drug use.

How does the drug Reserpine impact neurotransmitter production?

It interferes with the storage of transmitters by blocking their packaging into vesicles.

How does Tetrodotoxin (TTX) prevent synaptic transmission?

By blocking voltage-gated Na+ channels, preventing the conduction of nerve impulses.

What is the mechanism of action for Botox (botulinum toxin)?

It disrupts the SNARE proteins that allow motor neuron vesicles to release ACh.

What is the primary role of presynaptic autoreceptors?

They monitor the amount of transmitter released to provide feedback and regulate further release.

How does caffeine increase the release of stimulatory neurotransmitters?

It acts as a competitive antagonist at presynaptic adenosine autoreceptors, blocking the inhibitory feedback loop.

How do drugs like cocaine and amphetamines prolong synaptic activity?

By inhibiting the reuptake mechanisms (transporters) that clear neurotransmitters from the cleft.

What is the mechanism of Monoamine oxidase (MAO) inhibitors?

They block the enzymes that degrade monoamines, allowing transmitters to remain active longer.

Name a drug that acts as an antagonist at postsynaptic dopamine D2​ receptors.

Haloperidol (an antipsychotic).

What is the mechanism of the mood stabilizer lithium?

It modulates intracellular signals, such as second messengers, leading to changes in gene expression.

Which amino acid is present at lower concentrations and has a controversial role as a neurotransmitter compared to glutamate?

Aspartate.

What are the behavioral effects of norepinephrine release in the CNS?

It is generally excitatory, increasing vigilance and attentiveness.

Which neuropeptide acts at the kidneys to retain fluid and in the brain to promote thirst?

Angiotensin.

What is 'cross-tolerance'?

A condition where tolerance to one drug results in tolerance to another drug in the same chemical class.

Which enzyme converts serotonin into melatonin?

Not explicitly named, but melatonin is listed as the subsequent indoleamine in the serotonin family.

Define 'metabolic tolerance'.

A type of tolerance where the body (usually the liver) becomes more effective at clearing or metabolizing a drug.

What does the abbreviation 'ADME' stand for in pharmacokinetics?

Absorption, Distribution, Metabolism, and Excretion.

Which drug inhibits tryptophan hydroxylase, preventing the synthesis of serotonin?

Para-chlorophenylalanine.

Which drug impairs the maintenance of microtubules, thereby blocking axonal transport?

Colchicine.

Contrast 'partial agonists' with full agonists regarding efficacy.

Partial agonists produce only a moderate maximal response, regardless of the dose administered.

What is a 'nonmonotonic' dose-response curve?

A curve where the drug response reverses after a certain dose, often due to binding at secondary, lower-affinity sites.

Where are α and β adrenergic receptors found besides the CNS?

In many other tissues of the body, including the sympathetic nervous system target organs.

What is the role of 'retrograde transmitters' like Nitric Oxide in the brain?

They diffuse from the postsynaptic neuron back to the presynaptic neuron to modulate synaptic plasticity.

Which neuropeptide is co-released with glutamate by C-fiber pain afferents during significant pain?

Substance P.

How do cannabinoids communicate in the nucleus accumbens according to the provided schematic?

They are shown acting as part of the complex neuronal communication network involving reinforcement.

What is the effect of Carbon Monoxide (CO) on cerebral blood flow?

It acts as a vasodilator, increasing blood flow.

In the Nigrostriatal pathway, how can dopamine be both excitatory and inhibitory?

Because it acts on different receptor subtypes, such as D1​ (excitatory) and D2​ (inhibitory).

Name the two specific nuclei in the pons/midbrain that form a main cholinergic projection system.

Pedunculopontine nucleus and laterodorsal tegmental nucleus.

Which specific brain region is associated with dopamine's role in reinforcement and reward?

The nucleus accumbens (NAc).

What is the relationship between dietary tryptophan and brain serotonin levels?

The amount of tryptophan in the diet directly determines the amount of 5−HT available in the brain.

What is 'orthosteric' binding?

Binding that occurs at the same site on a receptor as the endogenous neurotransmitter.

Define 'allosteric' binding.

Binding that occurs at a modulatory site on the receptor complex, distinct from the primary transmitter site.

Why is the therapeutic index of Lorazepam (Ativan) considered better than that of Phenobarbital?

Lorazepam has a wider separation between its effective dose (ED50​) and lethal dose (LD50​).

The electrochemical process where neurons communicate via chemical messengers is called _____.

Synaptic Transmission