Autonomic Nervous System Quiz

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Questions and Answers

Which neurotransmitter is released by all pre-ganglionic fibers?

Acetylcholine (correct)

Serotonin

Dopamine

Norepinephrine

What is the role of hexamethonium as a ganglion blocking drug?

It has clinical uses in pain management.

It stimulates sympathetic ganglia.

It acts as a depolarizing agonist.

It is a non-depolarizing nicotinic antagonist. (correct)

Which of the following is synthesized from the amino acid L-tyrosine?

Norepinephrine (correct)

GABA

Serotonin

Acetylcholine

Which neurotransmitter is primarily released by most postsynaptic sympathetic fibers?

Norepinephrine Signup and view all the answers

What is the function of local anesthetics like lidocaine in the autonomic nervous system?

To block sympathetically-mediated pain pathways. Signup and view all the answers

What is the historical clinical use of hexamethonium?

As an antihypertensive agent. Signup and view all the answers

Which component acts as an analog to a postsynaptic nerve in terms of releasing adrenaline?

Adrenal medulla Signup and view all the answers

Which substance primarily regulates the synthesis of norepinephrine through a feedback mechanism?

Norepinephrine itself Signup and view all the answers

Which neurotransmitter is primarily used at the autonomic ganglions in both sympathetic and parasympathetic branches?

Acetylcholine Signup and view all the answers

What type of receptors do autonomic ganglions primarily utilize to generate fast excitatory post-synaptic potentials?

Nicotinic ACh receptors Signup and view all the answers

Which organs are regulated solely by sympathetic stimulation?

Blood vessels Signup and view all the answers

What is the typical innervation pattern of blood vessels by the parasympathetic nervous system?

No innervation occurs Signup and view all the answers

Which physiological aspect does the autonomic nervous system NOT directly influence?

Oxygen transport in blood Signup and view all the answers

What effect does sympathetic stimulation have on the heart's function?

Increases heart rate Signup and view all the answers

How does the autonomic nervous system primarily influence smooth muscle in organs?

Through alternating contraction and relaxation Signup and view all the answers

Which of the following is primarily regulated by the autonomic nervous system in terms of glandular secretion?

Temperature regulation through sweat glands Signup and view all the answers

Which of the following best describes the main role of the autonomic nervous system?

Regulation of subconscious body functions Signup and view all the answers

What neurotransmitter is primarily associated with the sympathetic nervous system?

Noradrenaline Signup and view all the answers

Which of the following is NOT a main subsystem of the autonomic nervous system?

Somatic Signup and view all the answers

What is a key characteristic of preganglionic neurons in the autonomic nervous system?

Myelinated with small diameter Signup and view all the answers

Which type of receptors does acetylcholine (ACh) act upon in post-synaptic neurons?

Nicotinic receptors Signup and view all the answers

Which statement accurately describes the main differences between the sympathetic and parasympathetic systems?

Sympathetic system is active during stressful situations, while parasympathetic system promotes relaxation. Signup and view all the answers

Where is the cell body located for post-ganglionic neurons in the autonomic nervous system?

In an autonomic ganglion Signup and view all the answers

The two neuron system in the sympathetic and parasympathetic systems typically includes which types of neurons?

Pre and post-ganglionic neurons Signup and view all the answers

What enzyme catalyzes the conversion of L-tyrosine to DOPA?

Tyrosine hydroxylase Signup and view all the answers

Where is dopamine beta-hydroxylase located?

Membrane of synaptic vesicles Signup and view all the answers

Which stage of noradrenaline synthesis is affected by carbidopa?

Second stage (DOPA to dopamine) Signup and view all the answers

What characterizes pheochromocytoma?

A rare tumor in the adrenal glands Signup and view all the answers

Which of the following symptoms is NOT commonly associated with pheochromocytoma?

Weight loss Signup and view all the answers

What is the clinical use of alpha-methyl-p-tyrosine?

To manage pheochromocytoma Signup and view all the answers

What effect does carbidopa have on levodopa in relation to norepinephrine synthesis?

It reduces norepinephrine synthesis effects in the periphery Signup and view all the answers

Which enzyme is specifically responsible for the conversion of noradrenaline to adrenaline?

Phenylethanolamine N-methyltransferase Signup and view all the answers

What is the result of calcium channel opening in the depolarization of nerve endings?

Release of norepinephrine (NA) Signup and view all the answers

Which transporter is responsible for the rapid removal of norepinephrine from the synaptic cleft?

Neuronal Epinephrine Transporter (NET) Signup and view all the answers

What is the primary function of vesicular monoamine transporter (VMAT)?

Store norepinephrine and ATP in vesicles Signup and view all the answers

Which enzyme is primarily responsible for the metabolism of norepinephrine within neurons?

Monoamine oxidase (MAO) Signup and view all the answers

What role does ATP play when co-released with norepinephrine?

It prevents excessive leakage from vesicles Signup and view all the answers

What are the two primary mechanisms for the termination of noradrenergic transmission?

Reuptake by NET and metabolism by MAO Signup and view all the answers

Which combination of drugs is known to inhibit norepinephrine release?

Guanethidine, Reserpine, and Methyldopa Signup and view all the answers

What is the function of Catechol-o-Methyl Transferase (COMT) in noradrenergic transmission?

Metabolizes catecholamines in both neuronal and non-neuronal tissues Signup and view all the answers

What is the primary mechanism of action of methyldopa?

Acts as an alpha-2 adrenergic agonist Signup and view all the answers

Which of the following statements about guanethidine is true?

It accumulates in vesicles and stabilizes them. Signup and view all the answers

What is a significant side effect of reserpine?

Depression Signup and view all the answers

Which of the following is NOT a common unwanted effect of inhibiting norepinephrine release?

Increased heart rate Signup and view all the answers

Methyldopa is preferred for treating high blood pressure in which situation?

During pregnancy Signup and view all the answers

What is a primary effect of high doses of guanethidine?

Destruction of adrenergic neurons Signup and view all the answers

Which medication also inhibits DOPA decarboxylase like carbidopa?

Methyldopa Signup and view all the answers

What mechanism does reserpine use to lower blood pressure?

Inhibiting vesicular monoamine transporters (VMAT) Signup and view all the answers

Study Notes

Autonomic Nervous System (ANS)

The ANS controls subconscious functions, maintaining homeostasis and regulating involuntary bodily processes.
It's comprised of two main subsystems: sympathetic and parasympathetic.
The sympathetic system is involved in "fight or flight" responses.
The parasympathetic system is associated with "rest and digest" activities.

Peripheral Nervous System Subsystems

The peripheral nervous system (PNS) has two main subsystems: autonomic and somatic.
The autonomic system regulates involuntary functions (e.g., heart rate, digestion).
The somatic system controls voluntary functions (e.g., movement).

Peripheral Nervous System Roles

The PNS carries information to and from the CNS (central nervous system).
It conveys signals between the central nervous system (CNS) and body tissues.
It relays sensory and motor impulses between the CNS and the body.
It serves as a communication channel between the brain, spinal cord, and the rest of the body.

Autonomic Nervous System Roles

This system controls all involuntary actions originating from the CNS except skeletal muscle movement.
It's involved in maintaining homeostasis, regulating various organs and functions.

Autonomic Nervous System Subsystems

Sympathetic: preps the body for action ("fight or flight").
Parasympathetic: calms the body down ("rest and digest").

Neurotransmitters

Sympathetic: Noradrenaline (NA) is the primary neurotransmitter.
Parasympathetic: Acetylcholine (ACh) is the main neurotransmitter.

Two Neuron System (Sympathetic)

Generally, the sympathetic system uses a two-neuron pathway.
Pre-ganglionic neurons synapse with post-ganglionic neurons.
The adrenal medulla is an exception, functioning as a specialized ganglion with chromaffin cells acting as post-synaptic neurons.

Ganglia

Autonomic ganglia act as junctions between pre and post-ganglionic neurons.
These ganglia are crucial for signal transmission between different parts of the autonomic nervous system.
They contain specific neurotransmitter receptors.

Ganglion Blocking Drugs

Hexamethonium is a non-depolarizing nicotinic antagonist.
Local anesthetics can act as ganglion-blocking drugs by blocking sympathetically-mediated pain pathways.

Neurotransmitter Effects

Nicotinic receptors in post-synaptic neurons respond to ACh.
Ganglionic stimulation involves ACh as the primary neurotransmitter, causing depolarization and generating fast excitatory postsynaptic potentials.

Organ Regulation (Sympathetic vs. Parasympathetic)

Heart rate: sympathetic increases heart rate, parasympathetic decreases it.
Blood vessels: sympathetic constricts, parasympathetic has negligible effect.
Sweat glands: predominantly controlled by sympathetic stimulation.
Eyes (ciliary muscles): parasympathetic controls constriction of pupils and accommodation of focus.

Autonomic Nervous System and Glandular Secretion

Generally, the ANS regulates both exocrine and some endocrine glands.

General Function of ANS

Regulates body functions like cardiovascular activity, metabolism, and glandular secretion.

Synthesis of Noradrenaline

A multi-enzyme pathway synthesizes noradrenaline (NA).
Key enzymes like tyrosine hydroxylase and dopamine beta-hydroxylase are involved.

Drugs Affecting Noradrenaline Synthesis

Various drugs influence noradrenaline production and release at different stages (e.g., alpha-methyl-p-tyrosine (Metirosine) inhibiting initial synthesis of dopamine from tyrosine).
Drugs like carbidopa are used to prevent peripheral side effects of levodopa.

Termination of Noradrenergic Transmission

Noradrenaline is removed from the synaptic cleft via neuronal uptake and metabolism.
Monoamine oxidase (MAO) and catechol-o-methyltransferase (COMT) play roles in this process.

Drugs Affecting Noradrenaline Release

Drugs affecting NA release work by influencing calcium channels regulating vesicle release or acting on presynaptic receptors.
Methyldopa, guanethidine, and reserpine affect NA release.

Additional Considerations

Phaeochromocytoma: A rare tumor affecting chromaffin cells and producing hormones involved in the "fight or flight" response.
Drugs to remember: Certain drugs frequently discussed in relation to noradrenaline synthesis and release, including carbidopa, a-methyl-p-tyrosine, methyldopa, reserpine, and guanethidine.

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Description

Test your knowledge on the autonomic nervous system with this comprehensive quiz. Explore neurotransmitters, their roles, and the effects of ganglion blocking drugs. Challenge yourself with questions covering key concepts and historical applications in the field.