Ganglionic Stimulants and Blockers Overview

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Questions and Answers

What is the primary function of ganglionic stimulants?

To inhibit the release of neurotransmitters at ganglionic synapses.

To enhance the transmission of nerve impulses through autonomic ganglia. (correct)

To decrease the sensitivity of postsynaptic receptors to neurotransmitters.

To block the reuptake of neurotransmitters at ganglionic synapses.

Which of the following is NOT a pharmacological effect of ganglionic blockers?

Increased gastrointestinal motility. (correct)

Increased blood pressure.

Decreased salivation.

Decreased heart rate.

What is the role of predominant tone in the autonomic nervous system?

To determine the overall activity level of the sympathetic nervous system.

To establish the baseline activity of specific organs and tissues. (correct)

To control the rate of action potential propagation through autonomic ganglia.

To regulate the release of neurotransmitters from preganglionic neurons.

Which of the following is an example of a ganglionic stimulant?

Nicotine (A) Signup and view all the answers

Which of the following is a potential adverse effect of ganglionic blockers?

Hypotension (C) Signup and view all the answers

Which of the following neurotransmitters is responsible for transmission at all preganglionic autonomic fibers, all postganglionic parasympathetic fibers, and a few postganglionic sympathetic fibers?

Acetylcholine (C) Signup and view all the answers

Which division of the autonomic nervous system is responsible for the 'fight or flight' response?

Sympathetic (B) Signup and view all the answers

What is the effect of loss of predominant parasympathetic tone on the heart SA node?

Increased heart rate (C) Signup and view all the answers

Which of the following is a known side effect of ganglionic blockers?

Hypotension (C) Signup and view all the answers

What is the action of nicotinic acetylcholine receptor agonists on ganglionic neurons?

They stimulate the receptors (B) Signup and view all the answers

What is the key difference between the preganglionic fibers of the sympathetic and parasympathetic nervous systems?

Parasympathetic fibers are longer (C) Signup and view all the answers

Which of the following is an example of a ganglionic blocker?

Hexamethonium (A) Signup and view all the answers

What is the primary effect of ganglionic stimulants on the heart?

Increased heart rate (D) Signup and view all the answers

Which of these is NOT a therapeutic use of ganglionic stimulants?

Treating glaucoma (C) Signup and view all the answers

What is the effect of a large dose of nicotine on ganglionic neurons?

Blockade of the neurons (D) Signup and view all the answers

Which of the following drugs acts as a selective nicotinic agonist?

Nicotine (small dose) (B) Signup and view all the answers

What is the primary therapeutic application of ganglionic blockers?

Managing hypertension (B) Signup and view all the answers

What is the effect of ganglionic blockers on the digestive system?

Decreased peristalsis (A) Signup and view all the answers

Which of the following is an example of a non-selective muscarinic agonist?

Carbachol (A) Signup and view all the answers

Which of these is an effect of loss of predominant parasympathetic tone on the urinary bladder?

Urinary retention (B) Signup and view all the answers

Which of the following drugs can be used to treat urinary retention?

Bethanechol (B) Signup and view all the answers

What is the primary reason ganglionic stimulants have limited therapeutic use?

They lack specificity in targeting the sympathetic or parasympathetic nervous systems. (A) Signup and view all the answers

Which of the following is NOT a common example of nicotine replacement therapy?

Nicotine injections (A) Signup and view all the answers

How does varenicline, a drug used for smoking cessation, work?

It partially blocks nicotine from activating its receptors, reducing the rewarding effects of smoking. (A) Signup and view all the answers

What is the primary mechanism by which nicotine replacement therapy helps people quit smoking?

It provides a safe and controlled dose of nicotine, reducing withdrawal symptoms. (A) Signup and view all the answers

Why has the clinical use of ganglionic blockers diminished over time?

The development of more selective agents has made them less necessary. (B) Signup and view all the answers

What is the primary mechanism by which ganglionic blockers lower blood pressure?

They block the transmission of signals through sympathetic ganglia, leading to vasodilation. (B) Signup and view all the answers

Which of the following is a potential use of a ganglionic blocker in a clinical setting?

Treating severe, sudden increases in blood pressure (hypertensive emergencies). (C) Signup and view all the answers

Which of the following statements about ganglionic stimulants is FALSE?

They are primarily used in the treatment of chronic pain. (A) Signup and view all the answers

Study Notes

Ganglionic Stimulant and Blockers

Ganglionic stimulants and blockers affect the autonomic nervous system.
Learning objectives include understanding the predominant tone in the autonomic nervous system, describing the effects of ganglion stimulants and blockers, and listing therapeutic uses of ganglionic blockers.
The peripheral nervous system has sensory/afferent and motor/efferent divisions.
The efferent division has somatic and autonomic nervous systems.
The autonomic nervous system is further divided into sympathetic and parasympathetic divisions.
The somatic nervous system controls skeletal muscles (voluntary actions).
The autonomic nervous system controls smooth and cardiac muscles (involuntary actions).
The sympathetic division is associated with "fight or flight" responses - raising heart rate, constricting blood vessels, and releasing glucose.
The parasympathetic division is associated with "rest and digest" responses - digestion, waste expulsion, and general maintenance.
The sympathetic division originates from thoracic and lumbar regions of the spinal cord, with short preganglionic and long postganglionic fibers.
The parasympathetic division originates from brain and sacral regions of the spinal cord, with long preganglionic and short postganglionic fibers.
The neurotransmitter for all preganglionic autonomic fibers, parasympathetic postganglionic fibers, and some postganglionic sympathetic fibers is acetylcholine (ACh).
Most effector tissues and organs receive innervation from both sympathetic and parasympathetic systems; only one sets the predominant tone.
The heart's predominant tone is parasympathetic at rest, causing a lower heart rate.
Ganglionic blockers disrupt the parasympathetic system, allowing the sympathetic system to dominate and increase heart rate.
Different effector sites (e.g., heart, veins, iris) have predominant tone from either sympathetic or parasympathetic divisions, and various receptors (e.g., M2 cholinergic, β1 adrenergic).

Types of Ganglionic Stimulants

Stimulants can be selective (nicotinic) or non-selective (nicotinic/muscarinic). -Nicotine, in small doses, is a selective nicotinic agonist.
Other agonists include dimethyl phenyl piperazinium, and tetramethyl ammonium.
Varenicline blocks nicotine from activating receptors, reducing smoking's reinforcing effects, and used in smoking cessation.
Anticholinesterases increase ACh levels.
Acetylcholine, carbachol, and pilocarpine are muscarinic agonists.

Ganglionic Blockers

Their clinical use is less common due to more selective agents but has some applications in specific emergencies.
Examples include Trimethaphan.
Ganglionic blockers cause vasodilation by blocking sympathetic ganglia.
They inhibit reflex tachycardia by blocking sympathetic and parasympathetic input to the heart.
In emergencies, they rapidly lower blood pressure by inducing hypotension.
Also used for controlled hypotension during surgery to decrease bleeding, though less common now due to other targeted vasodilators.

Nicotine Replacement Therapy (NRT)

Using nicotine patches, gum, lozenges, or nasal spray to quit smoking.
Mimics the effects of smoking in the autonomic nervous system and central nervous system.
Reduces withdrawal symptoms and cravings by offering a controlled amount of nicotine.

Normal Physiological Function of Ganglionic Neurons

Ganglionic neurons require an optimal amount of neurotransmitter (ACh/N); too little results in no effect; too much blocks the receptor.
Nicotine (small dose) simulates the normal function, leading to depolarization via sodium ion channels..
Nicotine (large dose) and anticholinesterases (big dose) lead to chronic or continuous stimulation, thus causing continuous influx of Na+, making the neuron dormant.

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Description

This quiz tests your knowledge on ganglionic stimulants and blockers, which play a crucial role in the autonomic nervous system. Understand the effects, therapeutic uses, and the various divisions of the autonomic and somatic nervous systems. Explore the sympathetic and parasympathetic responses and their physiological implications.