Neural Communication and Receptor Types

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Questions and Answers

What is the primary function of receptors in neural communication?

To transport neurotransmitters across the synapse

To bind neurotransmitters and initiate a cellular response (correct)

To decompose neurotransmitters into inactive forms

To generate action potentials within the neuron

Which neurotransmitter is often associated with inhibitory functions?

GABA (correct)

Dopamine

Serotonin

Glutamate

What occurs when an action potential reaches the axon terminal?

The neuron undergoes apoptosis

Ions are absorbed back into the axon

Dendrites generate new receptors

Neurotransmitters are released into the synapse (correct)

Which of the following neurotransmitter systems is most directly involved in mood regulation?

Serotonin system Signup and view all the answers

How do neurotransmitters achieve their effects on target cells?

By binding to receptors and altering ion channel permeability Signup and view all the answers

What role does dopamine NOT play in the brain's functions?

Recovery from stress Signup and view all the answers

Which statement best describes norepinephrine?

It is both a hormone and a neurotransmitter. Signup and view all the answers

How do the VTA (DA) neurons respond to unexpected rewards?

They fire initially for unexpected rewards. Signup and view all the answers

What is the primary effect of propranolol as it relates to PTSD?

It acts as a norepinephrine receptor antagonist. Signup and view all the answers

Which neurotransmitter is most closely linked to the effects of stress and emotion enhancement in memory?

Norepinephrine Signup and view all the answers

What is NOT a function associated with serotonin?

Development of PTSD Signup and view all the answers

SSRIs impact serotonin levels primarily by affecting what?

Blocking serotonin adsorption Signup and view all the answers

What is a characteristic of serotonin receptors?

Almost all are metabotropic. Signup and view all the answers

What type of ion channel is associated with ligand-gated receptors?

Ionotropic receptors Signup and view all the answers

Which of the following is the primary excitatory neurotransmitter in the brain?

Glutamate Signup and view all the answers

What is the main characteristic of metabotropic receptors compared to ionotropic receptors?

They operate slower and have longer-lasting effects. Signup and view all the answers

Which of the following is NOT a method of neurotransmitter clean-up?

Storage in vesicles Signup and view all the answers

Which drug is an antagonist of glutamate?

Ethanol Signup and view all the answers

What type of postsynaptic effect do excitatory neurotransmitters like glutamate generally produce?

Depolarization (EPSPs) Signup and view all the answers

How many primary types of glutamate receptors are identified?

Three ionotropic types and eight metabotropic types Signup and view all the answers

What type of effect do ionotropic receptors produce?

Fast and transient effects Signup and view all the answers

What is the primary function of GABA in the brain?

Inhibitory neurotransmitter Signup and view all the answers

Which of the following substances are classified as GABA agonists?

Chloroform Signup and view all the answers

Which of the following neurotransmitters is not a catecholamine?

Serotonin Signup and view all the answers

Where in the brain is dopamine primarily produced?

Tegementum Signup and view all the answers

Which statement about dopamine receptors is true?

Dopamine receptors can be both positive and negative modulatory. Signup and view all the answers

What was the conclusion of Olds and Milner's research regarding dopamine?

Dopamine is related to pleasure and motivation. Signup and view all the answers

How do addictive drugs influence dopamine transmission?

They indirectly enhance dopamine transmission. Signup and view all the answers

Which of the following statements regarding metabotropic receptors is accurate?

They modulate neurotransmitter activity. Signup and view all the answers

What is the primary action of SSRIs like Prozac?

Block serotonin from being reabsorbed Signup and view all the answers

What was found about the efficacy of SSRIs in treating mild to moderate depression?

SSRIs have no better effect than placebos Signup and view all the answers

Which neurotransmitter is primarily associated with wakefulness and attention?

Acetylcholine Signup and view all the answers

What is the role of endocannabinoids in neurotransmission?

Weaken connections between two cells at a synapse Signup and view all the answers

Which substance is known to be a cannabinoid receptor agonist?

THC Signup and view all the answers

What are endogenous opioids also known as?

Endorphins Signup and view all the answers

What characteristic is notable about adenosine?

It is a byproduct of ATP metabolism. Signup and view all the answers

What implication is suggested about psychedelics like LSD and psilocybin?

They can lead to radical changes in perception. Signup and view all the answers

Study Notes

Introduction to Neural Communication Between Cells

Neurons communicate via synapses.
Axon terminals contain vesicles filled with neurotransmitters.
Action potentials trigger neurotransmitter release into the synapse.
Dendrites contain receptors that bind to neurotransmitters.

Receptor Types

Ionotropic receptors are ligand-gated ion channels that open when neurotransmitters bind.
- They produce fast, transient effects.
- They can be excitatory (depolarizing) or inhibitory (hyperpolarizing).
Metabotropic receptors are G-protein-coupled receptors that modulate cell signalling.
- They have slower, longer-lasting effects.
- They activate signal cascades.

Receptor Locations

Postsynaptic receptors are located on the postsynaptic cell.
Presynaptic receptors are located on the presynaptic cell.
- Autoreceptors regulate the release of the same neurotransmitter.
- Heteroreceptors regulate the release of a different neurotransmitter.

Neurotransmitter Clean-up

Diffusion: Neurotransmitters diffuse away from the synapse.
Enzymatic degradation: Enzymes break down neurotransmitters.
Re-uptake: Neurotransmitters are transported back into the presynaptic cell or glial cells (e.g., astrocytes).

Drug Action

Agonists mimic the effects of neurotransmitters by binding to receptors.
Antagonists block the effects of neurotransmitters by binding to receptors.
Other drug actions include:
- Transporter blockers prevent reuptake of neurotransmitters.
- Reuptake inhibitors block the reuptake of neurotransmitters.
- Enzyme inhibitors block the breakdown of neurotransmitters.

Amino Acid Neurotransmitters

Glutamate: The primary excitatory neurotransmitter.
- Involved in learning, memory, and synaptic plasticity.
- Receptors include AMPAR, NMDAR, Kainate receptors, and mGluR 1–8.
GABA: The primary inhibitory neurotransmitter.
- Involved in anxiety reduction, sleep, and motor control.
- Receptors include both ionotropic and metabotropic types.

Monoamine Neurotransmitters

Dopamine (DA):
- Originates in the substantia nigra pars compacta and ventral tegmental area.
- Involved in movement, motivation, reward, and attention.
- Five receptor subtypes (D1R-D5R / D1-D5) are all metabotropic.
- NOT the “pleasure molecule.”
Norepinephrine (NE):
- Also known as noradrenaline.
- Originates in the locus coeruleus.
- Involved in arousal, attention, and memory.
- Plays a role in stress responses.
- Two main receptor types (⍺1-2, β1-3) with subtypes and sub-subtypes are all metabotropic (GPCRs).
Serotonin (5-HT):
- Originates in the raphe nuclei.
- Involved in mood, sleep, appetite, and cognition.
- Fifteen receptor subtypes, almost all metabotropic.
- NOT simply the “mood molecule.”

Other Small Neurotransmitters

Acetylcholine:
- The first discovered neurotransmitter.
- Involved in muscle contraction, learning, and memory.
Endocannabinoids:
- Two neurotransmitters (anandamide and 2-arachidonoylglycerol).
- Involved in pain perception, appetite, and mood.
- Two receptors (CB1 and CB2) are both GPCRs.
Adenosine:
- A byproduct of ATP.
- Involved in sleep, wakefulness, and energy metabolism.
Endogenous Opioids:
- Also known as endorphins.
- Giant peptide neurotransmitters involved in pain perception, reward, and mood.
- Receptors are all GPCRs.

Drugs Affecting Neurotransmitter Systems

Glutamate antagonists:
- Barbiturates
- Nitrous oxide
- Ketamine
- Ethanol
GABA agonists:
- Benzodiazepines
- Ethanol
- Chloroform
- Ether
Dopamine drugs:
- Addictive drugs increase dopamine transmission.
Norepinephrine antagonists:
- Propranolol (beta blocker) is used in PTSD treatment.
Serotonin agonists:
- Hallucinogens (LSD, DMT, psilocybin) affect perception and thoughts.
- SSRIs (e.g., Prozac) are used for depression by blocking serotonin reuptake.
Acetylcholine agonists:
- Nicotine
Endocannabinoid agonists:
- THC (cannabis)
Endogenous opioid agonists:
- Heroin
- Fentanyl
- Naloxone (antagonist)

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Description

Explore the fascinating world of neural communication between cells. This quiz covers key concepts such as neurotransmitter release, types of receptors, and their functions in synaptic transmission. Test your knowledge on ionotropic and metabotropic receptors as well as their locations.