stress and the digestive system

​I have exposed in part 1, how stress affects digestion. By switching off all secondary systems, the body can therefore preserve energy, and prepare vital organs for an increase demand on their functions: heart beats faster, pupils dilate, blood vessels dilate, Cortisol release glucose into the blood so that the body can rely on instant fuel to run away from danger. 
   The body cannot differentiate between actual physical danger, emotional or psychological distress. Stress is stress, and the response is always the same; however, the body learns to operate, make do, in chronic stress state, as survival is the key. 
   The immune system switches off, the body cannot spare energy to fight off pathogens, and certainly not for digestive functions. This is why during acute and chronic stress states, your mouth may be dry, and you find it hard to swallow saliva. Stomach juices are reduced, leading to fermentation, and undigested food to enter the intestine. Production of pancreatic enzymes — vital for the digestion of protein and carbohydrates —, are also affected. Contractions of the body, which also include contractions of the intestine (also called ‘guarding’ or ‘rigidity of the abdomen') prevent the absorption of food. The presence of undigested food, fermentation, and possibly bacteria, funguses and viruses that survived the low stomach acid, create inflammation in the small intestine, which also leads to Dysbiosis (imbalance in symbiotic microflora), further inflammation (due to the activation of the immune response) and subsequently to leaky gut. Compromised gut wall permeability means that some larger protein molecules can then enter the blood stream, as can viruses and bacteria, leading to systemic inflammation, and many more serious symptoms, including skin conditions (e.g. eczema), asthma, and autoimmune disorders. (see next article)
   "There is growing evidence that dysbiosis of the gut microbiota is associated with the pathogenesis of both intestinal and extra-intestinal disorders. Intestinal disorders include inflammatory bowel disease, irritable bowel syndrome (IBS), and coeliac disease, while extra-intestinal disorders include allergy, asthma, metabolic syndrome, cardiovascular disease, and obesity,” write Simon Carding and his colleagues, in the Microbial Ecology in Health and Disease Journal (2015).
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Research focused on the human microbiome suggests an important role for the gut microbiota in influencing brain development, behaviour and mood in humans

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   The digestive tract is also the first barrier against foreign “bodies”, and rely on special cells that act as police officers/law enforcers and keep harmful substances at bay. IgA (antibodies) present in the mucous membrane, which lines the wall of the digestive tract, prevent invading pathogens to attach and penetrate epithelial surfaces. During chronic Stress state, IgA numbers are known to be reduced. The gut therefore is loosing its function as a barrier against pathogens. Because the digestion process is mostly incomplete, the liver is missing key nutrients in order to detoxify the body of harmful compounds, including viruses, bacteria, fungus, and their toxins, bringing an overload of harmful compounds into the gut, which can also a the source of recurring colds and flu, and overall low immunity. 
   The colon is where most water reabsorption occurs, and to maintain an elevated blood pressure, most water is reabsorbed, leading to acute-to-chronic constipation, with hard to pass pellet-like stools. 
There is much to suggest that at least certain types of stress (e.g., emotional stimuli) can increase the production of antidiuretic hormoneChronic constipation can lead to some manageable symptoms (e.g. haemorrhoids), but also to quite concerning conditions, such as autointoxication (toxins can re-enter circulation, due to an increased holding of waste within the bowel), recycling of hormones (especially oestrogen), and Diverticulitis. Once an ulcerated diverticulum (pl. diverticulae) bursts it can lead to septicaemia, kidney failure, and death.
   Simon Carding writes further: "This review outlines the current evidence showing the extent to which the gut microbiota contributes to the development of disease,” adding: "Coupled with evidence that probiotic interventions may alter psychological endpoints in both humans and in rodent models, these data suggest that CNS-related co-morbidities frequently associated with GI disease may originate in the intestine as a result of microbial dysbiosis.” To explain further, CNS stands for Central Nervous System (or the brain), and a link between the Gut and CNS has now been identified, and this leads to understand why accumulation of waste in the bowel and altered peristalsis (contractions of the digestive system to get stools moving) can lead to autointoxication, including of the brain. Symptoms usually are: foggy brain, confusion, judgement affected by emotions, reduced concentration/memory, ADHD, dementia, anxiety and depression… 
   "Although in its early stages, the emerging field of research focused on the human microbiome suggests an important role for the gut microbiota in influencing brain development, behaviour and mood in humans. The recognition that the gut microbiota interacts bidirectionally with other environmental risk factors, such as diet and stress, suggests promise in the development of interventions targeting the gut microbiota for the prevention and treatment of common mental health disorders.” writes Sarah Dash, et al, in the Current Opinion in Psychiatry Journal (2015), in an article entitled: "The Gut Microbiome and Diet in Psychiatry: Focus on Depression”  

Dendritic Cells are cells that form parts the immune system. During chronic stress state, the digestive system is altered, leading to Dysbiosis, low-grade-to-systemic inflammation, which in turn adds fuel to the fire, and induces further stress to the body. 
   Dendritic cells expand their arm into the lumen of the digestive tract and respond to the microflora present in the area. Symbiotic microflora (the good gut bacteria) generates an non-inflammatory response from the Dendritic cells, while Dysbiosis (bad bacteria have taken over, displacing the good gut bacteria) generates an inflammatory response as shown in the illustration above. 
   Increased permeability, causing leaky gut syndrome, is due to the cells contracting and pulling on the protein hiding them tight together, until those proteins give way. The cells of the gut wall may separate, and larger particles enter the blood stream. 
 
   Illustrations below from Doctor Axe are pretty self explanatory, and thought they were important to visualise the process. 
Source: https://draxe.com/4-steps-to-heal-leaky-gut-and-autoimmune-disease/