Cyanide combines with iron in the mitochondrial cytochrome oxidase system, blocking the ability of cells to use oxygen for cellular respiration, as a result of which tissues become anoxic. The brain, as the organ is the first tissue to show signs of anoxia, followed by the heart. The victim loses consciousness, convulses and goes into cardiac arrest.
In a nutshell, cyanide prevents cells from using oxygen to make energy molecules. ... It acts as an irreversible enzyme inhibitor, preventing cytochrome C oxidase from doing its job, which is to transport electrons to oxygen in the electron transport chain of aerobic cellular respiration.
Apple seeds, and many other fruit seeds or pits, have a strong outer layer resistant to digestive juices. But if you chew the seeds, amygdalin could be released in the body and produce cyanide. Small amounts can be detoxified by enzymes in your body. However, large amounts can be dangerous.
Cyanide is one of the fastest acting poisons known, and if a significant amount is ingested, it can lead rapidly to death. Upon ingestion, it binds to haemoglobin, the molecule in red blood cells responsible for carrying oxygen to the cells in our body. Haemoglobin then ferries it to the body’s tissues, where it can bind to an enzyme called cytochrome oxidase. This enzyme is a vital tool cells require to make use of oxygen, and with cyanide bound to it, they are unable to do so.
In summary, cyanide kills quickly because it disrupts cellular respiration by inhibiting cytochrome c oxidase, leading to a rapid shutdown of energy production in cells throughout the body. This biochemical disruption causes systemic failure, resulting in swift and severe toxicity.