Neuropeptides Functions and Synthesis

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Questions and Answers

Where are neuropeptides synthesized?

In the synapse and released into the extracellular space

In the cell body and transported to the axon terminal to be released (correct)

In the dendrite and released into the intracellular space

In the axon terminal and released immediately

What is the function of neuropeptides?

They are always excitatory and act on the same receptors as dopamine

They are involved in the regulation of serotonin levels

They are always inhibitory and act on their own receptors

They modify the effect of small molecule neurotransmitters and can be excitatory or inhibitory (correct)

What is the function of Substance P?

It is an inhibitory neuropeptide that reduces pain perception

It is involved in the regulation of insulin release

It is an excitatory neuropeptide that brings pain signals to the brain (correct)

It is a type of endogenous opioid

What is a characteristic of gaseous neurotransmitters?

They diffuse through membranes and interact with internal receptors to transmit information Signup and view all the answers

What is the function of agonists?

They boost the activity of a neurotransmitter Signup and view all the answers

What is the target of the drug Viagra?

Nitric oxide Signup and view all the answers

What is the primary function of serotonin in the regulation of bodily processes?

Regulating mood, sleep, and appetite Signup and view all the answers

Which type of neurotransmitter is not classified as a small molecule neurotransmitter?

Neuropeptides Signup and view all the answers

What is the primary pathway associated with dopamine's role in reward and emotion?

Reward and Emotion pathway: Midbrain to Limbic System Signup and view all the answers

Which of the following is a characteristic of dopamine's function?

Inhibitory and involved in regulating movement Signup and view all the answers

What is the precursor molecule used to synthesize indolamine neurotransmitters, such as serotonin and melatonin?

Tryptophan Signup and view all the answers

Which type of neurotransmitter is dopamine classified as?

Monoamine neurotransmitter Signup and view all the answers

What is the primary function of norepinephrine in the sympathetic nervous system?

Increasing arousal and vigilance Signup and view all the answers

What type of receptors do epinephrine and norepinephrine bind to?

Metabotropic receptors Signup and view all the answers

Where are most serotonergic neurons found in the brain?

Raphe nuclei of brainstem Signup and view all the answers

What type of receptors do most serotonergic receptors belong to?

Metabotropic Signup and view all the answers

What is the function of glutamates in the nervous system?

Excitatory neurotransmitter affecting learning and memory Signup and view all the answers

What type of receptors does GABA A belong to?

Ionotropic chloride channels Signup and view all the answers

Where can acetylcholine be found in the nervous system?

In the neuromuscular junction, autonomic nervous system, and central nervous system Signup and view all the answers

Study Notes

Neurotransmitters, Neuromodulators, and Neurohormones

Definition of a Neurotransmitter: Any chemical released by one cell at a synapse that produces a response in a target cell.

Types of Neurotransmitters

3 main types: Small Molecule Neurotransmitters, Neuropeptides, and Gaseous Neurotransmitters.

Small Molecule Neurotransmitters

Divided into Monoamines and Amino Acids.
Produced anywhere in the neurons.

Monoamines

Contain catecholamines (dopamine, norepinephrine, epinephrine) and indoleamines (serotonin + melatonin).
Catecholamines:
- Synthesized from a single precursor, tyrosine.
- Dopamine:
  - Controls movement, reinforcement, attention, memory, learning, emotion, and planning.
  - Mostly inhibitory.
  - Pathways: Motor Pathways (midbrain to basal ganglia) and Reward and Emotion pathway (midbrain to limbic system).
- Norepinephrine:
  - Increases arousal and vigilance in the central nervous system and sympathetic nervous system (fight/flight).
  - Affects mood.
  - Excitatory.
  - Major Pathway: Locus coeruleus (found within the pons) and projects to nearly every major brain area and spinal cord.
- Epinephrine:
  - Adrenergic receptors are metabotropic receptors that bind to both epinephrine and norepinephrine.
Indolamines:
- Synthesized from the precursor tryptophan.
- Serotonin:
  - Acts as a neurotransmitter in the regulation of mood, sleep, and appetite.
  - Inhibitory.
  - Pathways: Most are found in raphe nuclei of brainstem; their projections travel to spinal cord, cerebellum, limbic system, and neocortex.

Amino Acids

Contain glutamates and GABA.
Glutamates:
- Affects learning and memory.
- Most frequently used excitatory neurotransmitter in the central nervous system.
- Multiple Subtypes (receptors): NMDA, kainate, AMPA.
GABA:
- Major inhibitory neurotransmitter of central nervous system.
- Two subtypes (receptors): GABA A (ionotropic chloride channels) and GABA B (metabotropic potassium channels).

Acetylcholine

Found in: Neurons producing and releasing acetylcholine (cholinergic neurons) in the neuromuscular junction, autonomic nervous system (preganglionic synapses and postganglionic synapses), and within the central nervous system (brain).

Neuropeptides

Produced in the cell body and transported to the axon terminal to be released.
Often coexist in the same neuron with a small molecule neurotransmitter and act to modify its effect.
A single neuron may contain and release several different neuropeptides.
Action at synapse is prolonged.
Contains: Endogenous Opiates (endorphins), Substance P, Cholosectokin, Insulin, Vasopressin, Oxytocin (Cuddle Hormones), and Endorphins.

Gaseous Neurotransmitters

May diffuse through membranes and interact with internal receptors to transmit information.
Nitric oxide (NO) is involved in neural communication, maintenance of blood pressure, penile erection, and is the target of the drug Viagra to produce smooth muscle relaxation.

Agonist

Boosts the activity of a neurotransmitter.

Drugs

Most drugs act at the synapse.
2 types of drugs: Agonist and Antagonist.

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Description

Learn about the production, function, and characteristics of neuropeptides, including their coexistence with neurotransmitters and prolonged action at synapses. Also, explore endogenous opiates like endorphins.