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Gut health and diet - Coggle Diagram

- - - - Chewing, lubricating, sensing and amylase addition
    - - Comprises the fundus, corpus and antrum, secreates protease, lipase and acid, smooth muscular contractions produce chyme
    - - 3-5m, digestion and absorption of food
        
        Duodenum (20-25cm)
        
        Brunner's glands secrete alkaline bicarbonate to increase pH
        
        Selective nutrient uptake: glucose amino acid and fatty acid
        
        Mixes chyme (from stomach) with bile (from gall bladder) and pancreatic enzymes, which digest food
        
        Bile helps transport fatty acids to the gut wall
        
        Active absorption of sugars, amino acids, fatty acids , electrolytes (e.g. Fe2+ & Ca2+) occurs through the apical membrane of the enterocyte
        
        Contains villi made of lamina propria, finger like protusiosn which increase the SA:V ration to increase absorption of nutrients
        
        Lamina propria contains fibroblasts, macrophages, lymphocytes, neutrophils, mast cells, vascular endothelial cells
        
        Relatively free from bacteria due to acid, bile and antibacterial substances produced by Paneth cells
        
        Jejunum (2.5m)
        
        Contains circular skin folds called plicae circulares which are covered in villi
        
        Main absorptive surface of the GI tract
        
        Brush border disaccharides and peptidases complete the digestive process initiated in the lumen
        
        Ileum (3m)
        
        Covered in villi
        
        Terminal ileum
        
        Digestion of vit B12
        
        Bile salts are reabsorbed by apical sodium -bile acid transported (ASBT) then recycled by the liver
        
        More lymphoid tissue due to greater number of bacteria
    - - 1.5m fermentation of dietary fibre and absorption of water
        
        Cecum
        
        Separated from the ileum by ileocecal valve (ICV) or Bauhin's valve
        
        Seperated from the colon by the cecocolic valve
        
        No longer has a role in humans
        
        Colon
        
        Ascending
        
        Transverse
        
        Descending
        
        Sigmoid
        
        Muscular s-shaped section which contracts to move stool into the rectum
        
        Main role is to absorb water and remaining key nutrients from waste material and recycle them back around the body
        
        Converts faecal stream into semi-solid mass
        
        Bacteria in the colon
        
        10^12 bacteria/ gram of contents
        
        Bacteria break down fibre and produce SFAs as waste products which are used by the cell lining of the colon
        
        Lactobacilli, Bifidobacteriae, Bacteriodes as well as potential pathogens e.g. E. Coli and Clostridial species
        
        Rectum
  - - - Synthesises and secretes digestive enzymes and stores as proenzymes to prevent autolysis (self digestion)
        
        Trypsin, carboxypeptide, elastase, lipase, amylase, phospholipase A2, lysophospholipase and cholesterol esterase
      - Produces insulin and glucagon to control blood sugar levels
    - - Stores bile produced by the liver
    - - Regulator of protein, fat and CHO metabolism and detoxifies
      - produces bile salts, plasma proteins and enzymes
      - Stores nutrients and vitamins: glycogen, fats, vits B12 A and K
      - Detoxifies, clears toxins and infective agents from the blood and excretes waste products
      - Can regenerate due to hepatocytes ability to proliferate
- - - - Diarrhoea causes malnutrition and weightloss
      - Steatorrhea - lipids in stool
      - Iron deficiency anaemia
      - Malabsorption of calcium and vit D causing osteoporosis
      - Abdominal pain and tiredness
      - Mild peripheral neuropathy to severe central nervous system disturbance
      - Increased risk of intestinal cell growth and intestinal lymphoma
    - - Responsible for coeliac disease
      - Member of the prolamin family
      - Globular and monomeric (can form polymers)
      - Hydrophobic amino acids
      - 20ppm = gluten free
      - 200ppm = low in gluten
  - - - Abdominal pain
      - Impaired gastrointestinal transit
        
        Constipation and/or diarrhoea
    - - IBS-C
        
        Bristol score 1-2 (constipation)
      - IBS-D
        
        Bristol score 7-8 (diarrhoea)
      - IBS-M
        
        Bristol score 1-2 and 7-8 (mixed diarrhoea and constipation)
      - IBS-U
        
        Insufficient stool abnormalities to be IBS-C,-D or -M
    - - Risk increase x6 after acute gastrointestinal infection
        
        further risk factors
        
        young age
        
        prolonged fever
        
        anxiety
        
        depression
      - Small intestinal bacterial overgrowth
        
        abnormalities in the gut flora of individuals with IBS
  - - - Due to insufficient insulin production from beta cells in the setting of insulin resistance
      - Primarily a result of obesity and insufficient exercise
      - Some are more genetically at risk
    - - Polyuria
      - Polydipsia
      - Polyphagia
      - Weight loss
      - Blurred vision
      - Itchiness
      - Peripheral neuropathy
      - Recurrent thrush
      - fatigue
    - - Obesity
      - Age
      - Low dietary fibre intake
      - Sedentary lifestyle
      - Smoking
      - Western diet
    - - Dietary intervention
      - In extreme cases insulin is prescribed
- - - - Increased transit time through GI tract
- - - - Mean diameter = ~100nm
    - - Food polymers block the holes of the mucus barrier and decrease permeability after consumption
  - - - These recognise pathogen associated patterns (PAMPs) such as lipopolysaccharides (LPS) from bacteria
        
        LPS on the outer membrane of gram negative bacteria is recognised and extracted by serum protein LBP
        
        LBP-LPS complex is recognised and bound to leukocyte extrinsic membrane protein CD14 and LPS is delivered to TLR4-MD-2 Complex
        
        MyD88/TIRAP pathway
        
        NF-k8
        
        Pro-inflammatory cytokine, chemokine, iNOS production, these are strong inflammatory signals which lead to the clearance of bacterial pathogens
        
        TRAM/ TRIF pathway
        
        IRF3 and IRF7
  - - - Fewer mucus producing goblet cells
      - More microfold "M-Cells"
      - Peyer's patches
        
        Contain b-lymphocytes which produces IgA
        
        Specialised lymphatic follicles
        
        Monitor intestinal bacteria and limit the growth of pathogenic bacteria in the ileum
        
        Antigens from microbes are absorbed via endocytosis by cells lining the patch, then they are delivered to lymphoid tissue where they are absorbed by macrophages and presented to T- and B-lymphocytes
        
        Lymphocytes then trigger the immune system and produce pathogen-specific antibodies. cytotoxic T lymphocytes the migrate to other lymphatic vessels to the lymph nodes and trigger a whole body immune system response
      - Intraepithelial T lymphocytes
      - Macropahges
      - Neutrophils
      - Dendritic cell recognition (bacteria, parasites and toxins)
      - Coordination of pro- and anti-inflammatory responses
  - - - Primarily in GI tract and on skin and surface epithelia
    - - Firmicutes
        
        Bascillius
        
        Listeria
        
        Staphylococcus
        
        Streptococcus
        
        Lactobaccilus
        
        Lactococcus
        
        Enterococcus
        
        Leuconostoc
      - Bacteroidetes
        
        Bacteroids
      - Proteobacteria
        
        E. Coli
        
        Salmonella
        
        Helicobacter
      - Actinobacteria
        
        Soil bacteria
      - Fusobacteria
      - Gut bacteria are mainly anaerobes
      - Probiotics
        
        Lactibaccilus
        
        Bifidobacterium
    - - Nutrient digestion and synthesis
      - Energy Metabolism
        
        Breakdown of cell wall polysaccharides
        
        Formation of SCFAs
        
        Around 2 kcal fibre per gram
        
        Germ Free Mice model
        
        Mice born via caesarian and kept sterile had no microbiota
        
        Required 30% more energy
        
        Less body fat than control mice
        
        Less able to store fat/ lipogenesis impaired
      - Epithelial development
      - Immune Response
        
        Response against pathogens
        
        Innate immunity and autoimmunity
      - Deglyclosylation of compounds
        
        Isoflavonols
        
        Bile salts