Australasian Science: Australia's authority on science since 1938

Guardians of the Gut

Credit: freshidea/adobe

Credit: freshidea/adobe

By Lucille Rankin & Gabrielle Belz

The appendix has long been considered an evolutionary relic but new evidence indicates it has an important role in our immune system.

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The immune system is a complex network of white blood cells comprising two units. The first encompasses the adaptive immune cells that specifically recognise and respond to foreign bodies, while the second unit comprises innate immune cells that react in a more generic way, utilising alert signals such as the chemical factors that signal inflammation to kickstart their response.

Our body’s largest physical barrier is its epithelial surface. It forms a protective “glove” separating our internal machinery from the outside world. This barrier is formed by the skin on the surface; internally, epithelial cells line the lungs and gut to provide a protective layer.

Lying immediately beneath these barriers is a very intricate network of innate immune cells known as innate lymphoid cells. This family of cells is thought to play important roles in protection of the gut, lungs and skin. Due to the strategic location of these innate lymphoid cells at the body’s protective barriers, they are ideally situated to sense signs of danger or infection.

Bacteria and Immune Cells in the Gut

The intestine performs the important function of digesting the food we eat and converting it to energy. The gut also contains more than 100 trillion bacteria from an estimated 500–1000 species that together weigh1.3 kg. Although we often think of microorganisms as harmful,...

The full text of this article can be purchased from Informit.