gut and brain

enteric nervous system

• controlling motility: the stretching and contractions of the muscles of the GI tract that enable food to move through the digestive tract

• detecting nutrients for the body to use

• regulating fluids and blood flow within the enteric system

• immune and defence response (against toxic foods and bacteria)

• maintaining the chemistry of the gut (hormones, digestive acids and neurotransmitters)

• communicating with the CNS

gut-brain axis

• the gut-brain axis (GBA) is the network of bidirectional (two-way) neural pathways that enable communication between bacteria in the gastrointestinal (GI) tract and the brain

• includes the CNS, sympathetic and parasympathetic branches of the autonomic NS, enteric NS, vagus nerve and the gut microbiota

• linked to the immune and endocrine (hormonal) systems

how communication occurs between the gut and brain

Communication between the gut and brain happens primarily through the vagus nerve

→ vagus nerve: longest running nerve in the human body running from the brain stem to the intestines.

• the vagus nerve connects the gut and brain through the gut-brain axis

• it communicates information from the gut to the brain using neurotransmitters (serotonin and glutamate) and gut hormones, all of which play a vital role in sleep, mood, pain, stress and hunger

• vagus is comprised of neurons

• afferent pathways send information from the gut to the brain

• efferent pathways send information from the brain to the gut

• the gut communicates with the brain about many processes related to digestion

gut microbiota/micrbiome

• is highly diverse and dynamic system of almost 100 trillion bacteria and other microorganisms that live in the human gastrointestinal (GI) tract

• “the gut microbiota affects your gut, which affects your brain”

• “the brain affects you gut, which affects your micrbiome”

• disruptions to the gut can trigger reactions in the body that mat affect physiological and psychological health