Curare and Physostigmine Overview

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Questions and Answers

What is the primary use of physostigmine in Alzheimer patients?

To induce sedation

To cause muscle paralysis

To enhance vision

To improve memory (correct)

Which animal is mentioned as used in the experiment for biological assay of curare?

Dog

Mouse

Rabbit (correct)

Guinea pig

What is the primary effect of curare on the postsynaptic membrane?

It promotes neurotransmitter release.

It prevents action potentials from occurring. (correct)

It increases muscle contraction.

It enhances action potentials.

What type of activity does physostigmine exhibit to be beneficial for Alzheimer's patients?

Anticholinesterase activity Signup and view all the answers

How does curare lead to paralysis of voluntary muscles?

By blocking neurotransmitter receptors. Signup and view all the answers

In the described experiment, which drug is used alongside curare?

Physostigmine Signup and view all the answers

What role does the postsynaptic membrane play in muscle contraction?

It generates action potentials. Signup and view all the answers

Which neurotransmitter is primarily involved in muscle contraction at the neuromuscular junction?

Acetylcholine Signup and view all the answers

What is the purpose of using the experiment described in the context?

To assess antagonism effects Signup and view all the answers

What happens to the muscles when action potentials are blocked by curare?

They remain relaxed and do not contract. Signup and view all the answers

What is the role of accumulated acetylcholine (Ach) in relation to curare?

It competes with curare for the receptors. Signup and view all the answers

Which substance is mentioned as inhibiting the metabolism of acetylcholine?

Physostigmine Signup and view all the answers

In what condition has physostigmine recently been found useful?

Cholinergic disorders Signup and view all the answers

How does physostigmine affect muscle tone in the context of curare?

It restores muscle tone by competing with curare. Signup and view all the answers

What does curare primarily do in relation to muscle receptors?

Acts as an antagonist at muscle receptors Signup and view all the answers

What is the primary effect of an excess of curare injected into the body?

Complete paralysis of muscles Signup and view all the answers

What can result from the paralysis of intercostal muscles due to curare injection?

Respiratory failure Signup and view all the answers

Which of the following outcomes can occur if curare is injected excessively?

Respiratory failure and asphyxia Signup and view all the answers

What condition may result from the paralysis of respiratory muscles due to curare?

Asphyxia and death Signup and view all the answers

Why does curare lead to death when injected in excess?

It paralyzes all muscles, including those essential for breathing Signup and view all the answers

What is the primary reason for the rabbit's head dropping after the injection of curare?

Paralysis of the neck muscles Signup and view all the answers

Where is curare administered to the rabbit?

In the marginal vein of the ear Signup and view all the answers

What type of effect does curare have when injected into the rabbit?

Neuromuscular blocking causing paralysis Signup and view all the answers

What is observed first after the administration of curare in the rabbit?

Dropping of the head Signup and view all the answers

Which physiological aspect is primarily affected by curare in the rabbit during the experiment?

Neuromuscular transmission is inhibited Signup and view all the answers

Study Notes

Curare and Muscle Paralysis

Curare binds to acetylcholine receptors at the postsynaptic membrane, preventing action potential generation and causing muscle paralysis.
Acetylcholine accumulation can compete with curare for the receptors, restoring muscle tone.
Physostigmine, an anticholinesterase, inhibits acetylcholine breakdown, increasing its concentration and helping to reverse curare's effects.

Physostigmine - Clinical Uses

Physostigmine is used to treat cholinergic disorders and myasthenia gravis.
Physostigmine improves memory in Alzheimer's patients due to its potent anticholinesterase activity.

Curare Biological Assay

The experiment uses rabbits to assess the effects of curare and evaluate its antagonism.
Curare is injected slowly into the marginal ear vein of the rabbit until the head falls, indicating paralysis of neck muscles.
Increasing curare dosage leads to paralysis of intercostal muscles, respiratory failure, asphyxia, and death.

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Description

Explore the mechanisms of curare and its effects on muscle paralysis, as well as the clinical applications of physostigmine in treating various disorders. Understand how acetylcholine's role can affect muscle tone and cognitive function. This quiz provides insights into the biological assays and implications of these substances.