Curare and Its Mechanism of Action
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Questions and Answers

Curare was originally used in South America for hunting purposes.

True

Curare has no effect on skeletal muscles.

False

Curare can be used in combination with anesthetics during surgical procedures.

True

The use of curare leads to increased muscle activity.

<p>False</p> Signup and view all the answers

Curare is a stimulant that enhances muscle contractions.

<p>False</p> Signup and view all the answers

Physostigmine is an irreversible cholinesterase inhibitor.

<p>False</p> Signup and view all the answers

Physostigmine can cross the blood-brain barrier.

<p>True</p> Signup and view all the answers

Curare's action can be countered by increasing the concentration of acetylcholine.

<p>True</p> Signup and view all the answers

Physostigmine decreases the concentration of acetylcholine in the body.

<p>False</p> Signup and view all the answers

Curare is classified as either isoquinoline or indole alkaloid.

<p>True</p> Signup and view all the answers

Kewar is used solely as a local anesthetic during surgeries.

<p>False</p> Signup and view all the answers

Curare can easily cross the blood-brain barrier due to being a non-polar molecule.

<p>False</p> Signup and view all the answers

The active ingredient in crude curare is D-tubocurarine.

<p>True</p> Signup and view all the answers

Curare acts as a non-depolarizing inhibitor of acetylcholine at the neuromuscular junctions.

<p>True</p> Signup and view all the answers

D-tubocurarine promotes the binding of acetylcholine to nicotinic receptors.

<p>False</p> Signup and view all the answers

Physostigmine can reverse the effects of curare by competing with it for receptors.

<p>True</p> Signup and view all the answers

Curare is a substance that increases muscle tone and strength.

<p>False</p> Signup and view all the answers

Cholinergic disorders can be treated using physostigmine.

<p>True</p> Signup and view all the answers

Myasthenia gravis is a condition that worsens with increased levels of acetylcholine.

<p>False</p> Signup and view all the answers

Acetylcholine accumulation can lead to decreased muscle power.

<p>False</p> Signup and view all the answers

Physostigmine is ineffective in improving the memory of Alzheimer's patients.

<p>False</p> Signup and view all the answers

The experiment described involves testing the effects of curare on rabbits.

<p>True</p> Signup and view all the answers

Curare has been used solely for recreational purposes and is not used in scientific experiments.

<p>False</p> Signup and view all the answers

The anticholinesterase activity of physostigmine makes it useful for treating myasthenic disorders.

<p>True</p> Signup and view all the answers

The experiment mentioned evaluates the antagonistic effects of morphine solely.

<p>False</p> Signup and view all the answers

Study Notes

 Curare

  • Curare is an organic compound classified as either isoquinoline or indole alkaloid.
  • Curare is an aromatic, nitrogen-containing structure.
  • Curare does not cross the blood-brain barrier (BBB) because of the two quaternary nitrogens, making it a polar molecule.
  • The active ingredient in crude curare is D-tubocurarine.

Mechanism of Action

  • Curare acts as a non-depolarizing and competitive inhibitor of acetylcholine (ACh) at neuromuscular junctions.
  • Curare prevents ACh from binding to the nicotinic ACh receptors.
  • The binding of curare prevents an action potential from occurring on the postsynaptic membrane.
  • This results in paralysis of voluntary muscles.

Uses of Curare

  • Curare was discovered in South America and was used as a poison in arrows for hunting.
  • Curare has been used in conjunction with general anesthetics, as a paralyzing agent to relax skeletal muscles during surgical procedures.

Physostigmine

  • Physostigmine is a parasympathomimetic alkaloid, meaning it mimics the effects of the parasympathetic nervous system.
  • Physostigmine can cross the blood-brain barrier.
  • Physostigmine is a reversible cholinesterase inhibitor, which means it inhibits the enzyme that breaks down acetylcholine.
  • The inhibition of cholinesterase increases the concentration of ACh.

Physostigmine and Curare

  • Physostigmine can counteract and reverse the action of curare.
  • Since Physostigmine increases ACh, this accumulated ACh can compete with curare for receptors, restoring muscle tone.

Uses of Physostigmine

  • Physostigmine is used to treat cholinergic disorders (disorders of the parasympathetic nervous system) and myasthenia gravis (a neuromuscular disease causing weakness of voluntary muscles).
  • Physostigmine has also been used to improve memory in Alzheimer's patients due to its potent anticholinesterase activity.

Morphine Experiment

  • This experiment was designed to biologically assay curare and evaluate the antagonism effect.
  • The experiment uses a rabbit as the animal.
  • The drugs used in the experiment are curare and physostigmine, both administered intravenously.

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Description

Explore the fascinating properties of curare, an organic compound used historically as a poison and in medicine. This quiz covers its structure, mechanism of action at neuromuscular junctions, and its applications in modern medicine, including surgical use. Test your knowledge on this unique alkaloid and its interactions with acetylcholine.

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