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Ch. 18 - Nervous System Infections
Norman-McKay- Microbiology: Basic and Clinical Principles 2nd Edition
Norman-McKay2nd EditionMicrobiology: Basic and Clinical PrinciplesISBN: 9780137661619Not the one you use?Change textbook
Chapter 18, Problem 8

Tetanospasmin and botulinum toxins affect muscles by
a. blocking the action potential traveling from the CNS to the PNS.
b. allowing the bacteria to enter neurons.
c. blocking the relaxation or contraction of the muscles.
d. damaging the axon itself.

Verified step by step guidance
1
Understand the nature of tetanospasmin and botulinum toxins: both are neurotoxins produced by Clostridium species that interfere with normal muscle function by targeting neuronal communication.
Recall that tetanospasmin (from Clostridium tetani) primarily blocks the release of inhibitory neurotransmitters in the central nervous system, leading to continuous muscle contraction (spastic paralysis).
Recognize that botulinum toxin (from Clostridium botulinum) blocks the release of acetylcholine at the neuromuscular junction, preventing muscle contraction and causing flaccid paralysis.
Analyze the options: the toxins do not block the action potential traveling from CNS to PNS (option a), nor do they allow bacteria to enter neurons (option b), nor do they damage the axon itself (option d). Instead, they interfere with neurotransmitter release, affecting muscle contraction or relaxation (option c).
Conclude that the correct understanding is that these toxins block the relaxation or contraction of muscles by interfering with neurotransmitter release at the neuromuscular junction or within the CNS.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Mechanism of Action of Neurotoxins

Neurotoxins like tetanospasmin and botulinum toxins interfere with nerve signal transmission by targeting synaptic vesicle release. They inhibit neurotransmitter release, disrupting communication between neurons and muscles, which affects muscle contraction or relaxation.
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Differences Between Tetanospasmin and Botulinum Toxins

Tetanospasmin causes muscle rigidity by blocking inhibitory neurotransmitters, leading to continuous muscle contraction, while botulinum toxin causes muscle paralysis by preventing acetylcholine release, stopping muscle contraction. Both affect muscle control but in opposite ways.
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Neuromuscular Junction Function

The neuromuscular junction is where motor neurons communicate with muscle fibers using neurotransmitters like acetylcholine. Proper release and reception of these chemicals are essential for muscle contraction and relaxation, and disruption here leads to muscle dysfunction.
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Related Practice
Textbook Question

During a lumbar puncture procedure, the nurse observed that the patient’s CSF pressure was high. However, when the analysis of the CSF sample comes back, the glucose levels are normal. The nurse would most likely suspect:

a. arboviral meningitis.

b. Neisseria meningitidis.

c. Listeria monocytogenes.

d. poliovirus.

Textbook Question

A patient who has just immigrated to the United States after serving in the Iraqi army is displaying a bruiselike rash, headache, and sensitivity to light. The doctor will immediately recommend administration of

a. ceftriaxone.

b. penicillin.

c. gentamycin.

d. rifampicin.

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Textbook Question

An HIV/AIDS patient is presenting with flulike symptoms, headache, fever, and disorientation. The MOST important piece of information a nurse must obtain for the patient is his or her

a. travel history, in and outside the United States.

b. diet for the last 3 days.

c. exposure to lakes or streams.

d. exposure to bats.

Textbook Question

A vaccine against Listeria monocytogenes is a challenge to develop because

a. very few people get Listeria meningitis.

b. the antibody-mediated immune response is not effective against L. monocytogenes.

c. better prevention approaches exist, such as food preparation precautions.

d. vaccinations are not used for foodborne illness.

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Textbook Question

CSF glucose levels are often assessed to differentiate between bacterial and viral meningitis. This is because

a. bacteria cells use glucose and lower the overall concentration in the CSF.

b. viral meningitis causes inflammation that blocks glucose transport into the CSF.

c. viral infection of the meninges causes cell lysis, releasing glucose into the CSF.

d. None of the above.

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Textbook Question

The protists Trypanosoma brucei, Naegleria fowleri, and Toxoplasma gondii

a. invade host cells to cause cellular damage.

b. are only infective in the flagellated form.

c. have a nucleus and are eukaryotic.

d. have all of the above characteristics.

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