32 Questions
Which major Ach producing nucleus is found in the brainstem?
Pedunculopontine nucleus
Which of these Ach receptor types is ionotropic?
Nicotinic
What role does Ach play in brain function?
Cognition
Which substance inhibits the vesicular acetylcholine transporter in a typical Ach synapse?
Vesamicol
Which 5HT receptor subtype is not metabotropic?
5HT3
Which drug is known as a 5HT3 antagonist?
Odansetron
What enzyme is responsible for converting glutamate to GABA?
Glutamic acid decarboxylase (GAD)
Which neurotransmitter is NOT a monoamine?
Acetylcholine
Which of the following substances inhibits the dopamine transporter leading to an increase in dopamine release?
Amphetamine
Which dopamine receptor is a part of the five DA receptors in the brain?
D₂
Which of the following is an antagonist to α₁ receptors in the noradrenergic system?
Prazosin
Which of the following inhibits the enzyme COMT?
Tropolone
What is the primary role of norepinephrine (NA) in brain function?
Arousal
Which major dopamine nucleus is located in the brainstem?
Substantia nigra
Which neurotransmitter is the major excitatory neurotransmitter throughout the nervous system?
Glutamate
What is the primary function of GABA in the brain?
Inhibition of neuronal activity
Which class of neurotransmitter does acetylcholine belong to?
Amines
Which of the following is NOT a class of GABA receptors?
GABA-D
What is one role of glutamate in brain function regarding health?
Enhances memory
What is the consequence of dysregulation of glutamate activity?
Excessive excitability of neurons leading to seizures
Which of the following is not one of the glutamate receptors?
GABA-R
Which enzyme converts glutamine to glutamate?
Glutaminase
What is required for optimal brain function?
Both electrical and chemical signals between neurons
Where are neurotransmitters typically stored?
Synaptic vesicles
Which of the following is NOT a criterion for a chemical to be classified as a neurotransmitter?
It must be synthesized in the postsynaptic neuron
What is the role of mitochondria in the presynaptic terminal?
Provide energy for synaptic transmission
What is the function of the synaptic vesicles?
They package and protect neurotransmitters
What are secondary messengers?
Biochemical pathways initiated following neurotransmitter binding to receptors
What is the main difference between agonists and antagonists?
Agonists activate receptors while antagonists do not
What happens when neurotransmitters bind to receptors?
The postsynaptic neuron undergoes either excitation or inhibition
Where do neurotransmitters have their effect?
On the receptors of the postsynaptic region
Which organelles in the presynaptic terminal are responsible for packaging neurotransmitters?
Synaptic vesicles
Study Notes
Neurotransmitters
- Neurotransmitters are chemicals that transmit signals between neurons.
- For optimal brain function, neurons need to communicate with each other using electrical and chemical signals.
Classification of Neurotransmitters
- A chemical must meet three criteria to be considered a neurotransmitter:
- Be synthesized and stored in presynaptic neurons
- Be released by presynaptic axon terminals
- Produce responses in postsynaptic cells
Structure of a Typical Synapse
- Presynaptic terminal: the end of an axon that forms the synapse
- Mitochondria: provides energy for synaptic transmission
- Secretory granules: contain chemicals (usually neuropeptides) released from the axon terminal to activate receptors on surrounding neurons
- Synaptic cleft: the area between the presynaptic terminal and the postsynaptic regions
- Synaptic vesicles: small organelles in which neurotransmitters are packaged
- Active zone: the part of the presynaptic region where synaptic vesicles dock and are released
- Postsynaptic density: a region of the postsynaptic membrane enriched with receptors
Glutamate
- The major excitatory neurotransmitter throughout the nervous system
- Expressed in almost all brain regions
- Binds to its receptors, causing excitation of neurons
- Two classes of Glutamate receptors:
- Ionotropic (NMDA, AMPA, Kainate)
- Metabotropic (mGluR, with 8 subclasses)
- Important for learning, memory, and cognition
- Dysregulation can lead to excessive neuronal excitability, seizures, and excitotoxicity
GABA
- The major inhibitory neurotransmitter in the brain
- Binds to its receptors (GABA-R), resulting in the inhibition of neuronal activity
- Three classes of GABA receptors:
- GABA-A
- GABA-B
- GABA-C
Dopamine
- Synthesized from tyrosine
- Has five receptors: D1, D2, D3, D4, and D5
- Important for:
- Motor coordination
- Motivation
- Reward seeking
- Cognition
- Nausea and vomiting
- Hormonal regulation
- Receptors are metabotropic, causing excitation or inhibition depending on the G-proteins they are coupled to
Noradrenaline (NA)
- Synthesized from tyrosine
- Has three types of receptors: Alpha 1 & 2, and Beta 1, 2, and 3
- Important for:
- Arousal
- Memory and cognition
- Stress response
- Receptors are metabotropic, causing excitation or inhibition depending on the G-proteins they are coupled to
Acetylcholine (ACh)
- Synthesized from choline
- Has two classes of receptors:
- Nicotinic (ionotropic)
- Muscarinic (metabotropic)
- Important for:
- Cognition
- Motor activity
- Mood
- Receptors are either ionotropic or metabotropic, causing excitation or inhibition depending on the G-proteins they are coupled to
Serotonin (5-HT)
- Synthesized from tryptophan
- Has seven subclasses of receptors
- Important for:
- Sleep
- Pain
- Emotion
- Receptors are metabotropic, causing excitation or inhibition depending on the G-proteins they are coupled to
Understand the synthesis of GABA, monoamine neurotransmitters, and their characteristics in the brain. Learn about the enzymes involved and the differences between them.
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