The Simplified Guide to the Gut-Brain Axis – How the Gut and The Brain Talk to Each Other
Time to read: 10–12 minutes
The gut-brain axis (GBA) is a bidirectional link between the central nervous system (CNS) and the enteric nervous system (ENS) of the body. It involves direct and indirect pathways between cognitive and emotional centres in the brain with peripheral intestinal functions. The GBA involves complex crosstalk between the endocrine (hypothalamic-pituitary-adrenal axis), immune (cytokine and chemokines) and the autonomic nervous system (ANS).
The GBA primarily combines the sympathetic and parasympathetic arms of the autonomic nervous system (ANS), which drives both afferent and efferent neural signals between the gut and the brain, respectively. The HPA axis meanwhile coordinates adaptive responses against stress including activation of memory and emotional centres in the limbic system of the brain.
The neuro-immuno-endocrine mediators of the GBA allow the brain to influence intestinal function (immune cells, epithelial cells, enteric neurons, and smooth muscle cells). Moreover, the cells of the gastrointestinal (GI) tract are also under the influence of the gut microbiota and recent evidence suggests that there is an emerging concept whereby the microbiome plays an important role in the GBA structure. 
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