Geneeskunde H5
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Questions and Answers

What is the term for the phenomenon where multiple neurotransmitters are found within some neurons in the autonomic nervous system?

  • Neuroplasticity
  • Cotransmission
  • Colocalization (correct)
  • Synaptic transmission

Which neurotransmitters are traditionally recognized as the main transmitters in the autonomic nervous system?

  • Dopamine and serotonin
  • Glutamate and endorphins
  • GABA and glycine
  • Norepinephrine and ACh (correct)

What does the term NANC stand for in relation to neurotransmitters?

  • Nonactive, neurally controlled
  • Neurotransmitters affecting natural cells
  • Nonadrenergic, noncholinergic (correct)
  • Neurologically active, noncholinergic

What is one potential role of nonclassical transmitters in the autonomic nervous system?

<p>They may modulate responses to other inputs. (C)</p> Signup and view all the answers

What was the focus of research regarding neurotransmitters in the ANS for many years?

<p>The roles of cholinergic and adrenergic neurotransmitters (D)</p> Signup and view all the answers

What is the primary neurotransmitter released at low firing rates by medullary raphé neurons?

<p>Serotonin (B)</p> Signup and view all the answers

What controls the proportion of neurotransmitters released from neurons?

<p>Neuronal firing frequency (B)</p> Signup and view all the answers

Which of the following is NOT a neurotransmitter identified in the autonomic nervous system?

<p>Acetylcholine (D)</p> Signup and view all the answers

What class of receptors does ATP activate in vascular smooth muscle?

<p>P2 purinoceptors (B)</p> Signup and view all the answers

What was first proposed by Geoffrey Burnstock and colleagues in the 1970s?

<p>The existence of nonadrenergic, noncholinergic neurons (D)</p> Signup and view all the answers

Which two nonclassic neurotransmitters were first identified in the ANS?

<p>ATP and Nitric Oxide (C)</p> Signup and view all the answers

At intermediate neuronal firing rates, which neurotransmitter is also released along with serotonin?

<p>Thyrotropin-releasing hormone (D)</p> Signup and view all the answers

What effect does ATP have when applied directly to vascular smooth muscle?

<p>Vascular constriction (A)</p> Signup and view all the answers

What is the role of P2X receptors in smooth muscle cells?

<p>They bind ATP and induce depolarization. (B)</p> Signup and view all the answers

What is the primary effect of norepinephrine on smooth muscle contraction?

<p>It releases Ca^2+ from intracellular stores. (C)</p> Signup and view all the answers

Which phase of contraction is induced by ATP in vascular smooth muscle?

<p>The rapid phase of contraction. (A)</p> Signup and view all the answers

How does neuropeptide Y contribute to muscle contraction?

<p>Through its action on Y1 receptors to increase Ca^2+ levels. (B)</p> Signup and view all the answers

What channel property is associated with P2X receptors?

<p>High Ca^2+ permeability. (C)</p> Signup and view all the answers

Which signaling pathway is involved in the action of norepinephrine?

<p>Gq/PLC/IP3 pathway. (C)</p> Signup and view all the answers

What is one of the key components of contraction induced by ATP in smooth muscle?

<p>Activation of voltage-gated channels. (A)</p> Signup and view all the answers

What effect does nitric oxide have on vascular smooth muscle?

<p>It causes relaxation. (C)</p> Signup and view all the answers

What is the primary way nitric oxide (NO) exerts its effects in neighboring cells?

<p>By activating guanylyl cyclase (A)</p> Signup and view all the answers

Which enzyme is responsible for the production of nitric oxide (NO) from l-arginine?

<p>Nitric oxide synthase (D)</p> Signup and view all the answers

In the context of vascular smooth muscle relaxation, what role does acetylcholine (ACh) have?

<p>It activates muscarinic receptors leading to NO production (B)</p> Signup and view all the answers

Which neurotransmitter is involved in the second phase of relaxation of vascular smooth muscle cells?

<p>Vasoactive intestinal peptide (VIP) (C)</p> Signup and view all the answers

From where is nitric oxide (NO) NOT derived as per the description?

<p>Gastrointestinal epithelial cells (D)</p> Signup and view all the answers

What physiological process do NO and ACh collectively mediate in vascular smooth muscle cells?

<p>Relaxation of vascular smooth muscle (B)</p> Signup and view all the answers

What type of molecule is nitric oxide (NO) classified as?

<p>Gas (C)</p> Signup and view all the answers

Which statement correctly describes the nature of nitric oxide (NO)?

<p>It is a short-lived gas used for intercellular communication. (C)</p> Signup and view all the answers

Which neurotransmitter is NOT found in postganglionic autonomic neurons?

<p>Glutamate (A)</p> Signup and view all the answers

Which of the following neurotransmitter categories includes norepinephrine?

<p>Monoamines (C)</p> Signup and view all the answers

Which neurotransmitter is primarily associated with visceral afferent neurons?

<p>Substance P (C)</p> Signup and view all the answers

Which amino acid is indicated as present within the CNS neurons?

<p>Glutamate (A)</p> Signup and view all the answers

Which of the following is classified as a neuropeptide?

<p>Oxytocin (B)</p> Signup and view all the answers

Which neurotransmitter is associated with ganglion interneurons?

<p>Endogenous opioids (D)</p> Signup and view all the answers

Which neuropeptide is indicated to be present in both preganglionic and postganglionic autonomic neurons?

<p>Substance P (D)</p> Signup and view all the answers

Which nonclassical neurotransmitter is specifically listed in the table?

<p>Nitric Oxide (C)</p> Signup and view all the answers

Which neurotransmitter would NOT typically be found in enteric neurons?

<p>Adenosine (B)</p> Signup and view all the answers

Which type of neuron predominantly uses acetylcholine?

<p>CNS neurons (C)</p> Signup and view all the answers

Which neurotransmitter is primarily associated with the regulation of smooth muscle?

<p>Norepinephrine (D)</p> Signup and view all the answers

Which of the following neurotransmitters is not classified as an amino acid?

<p>Serotonin (B)</p> Signup and view all the answers

What role does dopamine have among the listed neuron types?

<p>In enteric neurons and ganglion interneurons (C)</p> Signup and view all the answers

Which neurotransmitter is specifically associated with the action of gastrointestinal motility?

<p>5-hydroxytryptamine (C)</p> Signup and view all the answers

Flashcards

Cotransmission

The release of multiple neurotransmitters from a single neuron, contributing to a complex and varied response.

Colocalization

The presence of multiple neurotransmitters within the same neuron, enabling a wider range of potential responses.

Nonadrenergic, Noncholinergic (NANC) Transmitters

Neurotransmitters that are not acetylcholine (ACh) or norepinephrine (NE).

Effects of NANC Transmitters

These transmitters can cause slow, gradual changes in the postsynaptic neuron, or they may modulate the effects of other neurotransmitters.

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Location of NANC Transmitters

NANC transmitters are found at all levels of the autonomic nervous system, contributing to a range of physiological functions.

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ATP as a Neurotransmitter

ATP is a co-transmitter with norepinephrine in sympathetic neurons, released from synaptic vesicles on electrical stimulation.

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ATP's Effect on Vasoconstriction

ATP induces vascular constriction by activating purinoceptors (P2X and P2Y) on smooth muscle.

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Purinoceptors (P2X and P2Y)

P2X and P2Y are receptors for ATP, mediating its effects on smooth muscle.

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CNS Neurons

A class of nerve cells responsible for transmitting information within the central nervous system.

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Preganglionic Autonomic Neuron

A type of autonomic neuron that transmits signals from the central nervous system to autonomic ganglia.

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Postganglionic Autonomic Neuron

A type of autonomic neuron that transmits signals from autonomic ganglia to target organs.

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Visceral Afferent Neuron

A type of sensory neuron that transmits information from internal organs to the central nervous system.

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Ganglion Interneuron

A neuron located within an autonomic ganglion, connecting preganglionic and postganglionic neurons.

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Enteric Neuron

A type of neuron found within the walls of the digestive tract, responsible for regulating digestive functions.

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Acetylcholine (ACh)

A neurotransmitter used by both preganglionic and postganglionic neurons in the parasympathetic nervous system.

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Monoamines

A group of neurotransmitters that include norepinephrine, epinephrine, dopamine, and serotonin.

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Norepinephrine

A neurotransmitter involved in the sympathetic nervous system, responsible for 'fight-or-flight' responses.

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Epinephrine

A neurotransmitter involved in heart rate, blood pressure, and the sympathetic nervous system.

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5-Hydroxytryptamine (Serotonin)

A neurotransmitter involved in mood, sleep, appetite, and many other functions.

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Dopamine

A neurotransmitter involved in movement, learning, and reward pathways.

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Glutamate

An excitatory neurotransmitter involved in learning and memory.

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Gamma-Aminobutyric Acid (GABA)

An inhibitory neurotransmitter involved in muscle relaxation and inhibition.

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Substance P

A peptide neurotransmitter involved in pain transmission, mood, and other functions.

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P2X Receptor

A type of receptor found on autonomic neurons and smooth muscle cells, allowing calcium ions to pass through when ATP binds to it.

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Fast Contraction Phase

A rapid phase of contraction in smooth muscle, triggered by ATP binding to P2X receptors and the subsequent increase in intracellular calcium.

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Slow Contraction Phase

A process where norepinephrine activates α1 adrenergic receptor and Gq protein, leading to calcium release from internal stores in smooth muscle cells.

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Neuropeptide Y

A neurotransmitter involved in smooth muscle contraction, acting through Y1 receptors to increase intracellular calcium levels.

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Nitric Oxide (NO) and Relaxation

The release of nitric oxide by the vascular endothelium, leading to relaxation of vascular smooth muscle.

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Endothelial Relaxing Factor

The production of a substance that induces relaxation of vascular smooth muscle, discovered in the 1970s. This substance is now understood to be nitric oxide.

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Nitric Oxide (NO)

A short-lived gas that mediates intercellular communication by diffusing to neighboring cells, where it primarily activates guanylyl cyclase.

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Nitric Oxide Synthase (NOS)

An enzyme responsible for producing NO from l-arginine, found in both pre- and postganglionic neurons of the sympathetic and parasympathetic divisions and in vascular endothelial cells.

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Guanylyl Cyclase

A protein targeted by NO, which, upon activation, produces a rise in cyclic GMP (cGMP) within the receiving cell.

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NO and ACh - Joint Action

The action of NO in the autonomic nervous system is often mediated by both NO and ACh, working together to achieve a coordinated effect.

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Neuropeptide VIP's Role

In some cases, prolonged or intense stimulation of a parasympathetic neuron can activate neuropeptides, especially VIP, leading to delayed relaxation through increased cAMP or decreased Ca2+ inside the target cell.

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Combined Action of NO, ACh, and VIP

The release of NO, ACh, and VIP from the postganglionic parasympathetic neuron contributes to the relaxation of vascular smooth muscle cells.

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Relaxation of Vascular Smooth Muscle

A combination of NO and ACh can cause the smooth muscle around blood vessels to relax, helping to lower blood pressure.

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Study Notes

Nonclassic Transmitters in the Autonomic Nervous System (ANS)

  • Nonclassic Transmitters: Neurotransmitters involved in the ANS that aren't solely adrenergic or cholinergic. They mediate a range of postsynaptic responses, including slow potentials and modulating other inputs.

  • Colocalization: The presence of multiple neurotransmitters within a single neuron. As many as eight different neurotransmitters can colocalize.

Distribution and Types of Nonclassic Transmitters

  • Diverse Distribution: Found at all levels of autonomic control.

  • Non-Specific Roles: Their roles aren't fully understood, but they can cause varied responses and modulate other inputs rather than acting directly.

Examples of Nonclassic Transmitters

  • ATP: Colocalizes with norepinephrine in postganglionic sympathetic neurons. Releases on electrical stimulation, leading to vascular constriction by activating P2 purinoceptors (P2X and P2Y).
  • Nitric Oxide (NO): Produced by endothelial cells and neurons. Relaxes vascular smooth muscle through guanylyl cyclase activation. NO, acetylcholine, and vasoactive intestinal peptide (VIP) are often released together in parasympathetic neurons.

Action of NO in the ANS

  • Multiple phases of relaxation: Stimulation of parasympathetic fibers can initiate multiple phases of smooth muscle relaxation (e.g., through acetylcholine and nitric oxide).

  • Delayed Relaxation: Neuropeptide VIP can cause delayed relaxation by increasing cAMP or decreasing Ca2+.

  • Co-release: Different neurotransmitters often act together in parallel to yield a diverse response, for example, acetylcholine and nitric oxide in conjunction to achieve a relaxed response.

Table of Neurotransmitters by Location

  • The provided tables detail which neurotransmitters are found in various locations within the peripheral and central nervous systems, such as CNS, preganglionic, postganglionic, visceral ganglia, and enteric neurons.

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Description

Explore the intriguing roles of nonclassic transmitters in the autonomic nervous system. This quiz covers their distribution, colocalization, and examples like ATP and Nitric Oxide. Understand how these neurotransmitters contribute to diverse physiological responses and interactions.

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