**Tetrodotoxin (TTX) and its Effects on the Nervous System**Tetrodotoxin (TTX) is a toxin extracted from pufferfish that completely inhibits (blocks) voltage-gated sodium channels. This effect on the body depends on the dose consumed. In low doses, TTX can cause slight numbness, which is often reported by individuals who consume contaminated pufferfish. However, in high doses, TTX is lethal. Below are the reasons for its lethal nature:- **a.** It prevents glutamate uptake and reuptake, causing seizures in the brain.- **b.** It causes excess neuronal activity, leading to excitotoxicity and cell death.- **c.** It destroys myelin around axons, slowing action potential propagation.- **d.** It prevents action potentials from being initiated, stopping all synaptic transmission.**Correct Explanation:**- **d.** Tetrodotoxin prevents action potentials from being initiated by blocking voltage-gated sodium channels. This blockage stops all synaptic transmission, leading to paralysis and potentially fatal respiratory failure. Understanding TTX's mechanism is crucial since it underscores the importance of sodium channels in the normal functioning of nerve cells and the potential consequences of their inhibition.

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Human Anatomy & Physiology (11th Edition)

11th Edition

ISBN:9780134580999

Author:Elaine N. Marieb, Katja N. Hoehn

Publisher:Elaine N. Marieb, Katja N. Hoehn

Chapter1: The Human Body: An Orientation

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**Tetrodotoxin (TTX) and its Effects on the Nervous System**

Tetrodotoxin (TTX) is a toxin extracted from pufferfish that completely inhibits (blocks) voltage-gated sodium channels. This effect on the body depends on the dose consumed. In low doses, TTX can cause slight numbness, which is often reported by individuals who consume contaminated pufferfish. However, in high doses, TTX is lethal. Below are the reasons for its lethal nature:

- **a.** It prevents glutamate uptake and reuptake, causing seizures in the brain.
- **b.** It causes excess neuronal activity, leading to excitotoxicity and cell death.
- **c.** It destroys myelin around axons, slowing action potential propagation.
- **d.** It prevents action potentials from being initiated, stopping all synaptic transmission.

**Correct Explanation:**

- **d.** Tetrodotoxin prevents action potentials from being initiated by blocking voltage-gated sodium channels. This blockage stops all synaptic transmission, leading to paralysis and potentially fatal respiratory failure.

Understanding TTX's mechanism is crucial since it underscores the importance of sodium channels in the normal functioning of nerve cells and the potential consequences of their inhibition.

Expert Solution

Step 1

Tetrodotoxin (TTX) is a potent neurotoxin that is responsible for many bouts and deaths each year. The origin of TTX is unknown, but in pufferfish, it appears to be produced by endosymbiotic bacteria that appear to be transmitted to a food chain. The inclusion of dirty pufferfish, considered to be the most delicious fish in Japan, is a common form of poisoning. The neurotoxin, reported as a threat to human health in Asian countries, has spread to the Pacific and the Mediterranean, thanks to global warming. TTX, which is not its antidote, inhibits the sodium channel that produces heart failure in most cases and in death.