Digestion

• Digestion in the mouth involves both mechanical and chemical processes.
• The chemical within saliva is amylase which breaks down starch, starting the digestive process in the mouth.
• The esophagus is not a hollow but muscular tube through which the bolus of food moves down by peristalsis into the stomach.
• The stomach is the site of mechanical and chemical digestion, after which mechanical digestion stops and chemical digestion continues.
• The chemicals within the stomach are stomach acid and pepsin, with pepsin being able to handle high pH in stomach, optimum pH 1 or 2.
• The lower functioning of health treatment in a disaster zone can lead to a higher risk of cholera infection.
• Treatment for cholera includes rehydration, antibiotics, and access to basic sanitary conditions.
• Cholera is spread when contaminated faeces are put in a disaster zone, making it easy for contaminated diarrhoea to spread.
• Symptoms of cholera include vomiting, acute diarrhoea, and losing 12-20 l of water a day.
• Cholera is found in aquatic environments and lives in water.
• Bile, made in the liver from broken down fat, is emptied into the duodenum to neutralise stomach acid and emulsify fats.
• Fat is not mixed with water, a lot of food is water based, hence unable to break down with normal enzymes and many enzymes are polar.
• Lipases from the pancreas break down fats.
• Pancreatic amylase and lipase digest fats and carbohydrates.
• Trypsin digests polypeptides to amino acids.
• Enzymes are further released into the jejunum.
• The illeum is the lower part of the intestine where digestion is finished and focuses on absorption.
• The jejunum and illeum have villi/membrane folds on the surface which increase surface area for absorption and have a rich blood supply.
• Peristalsis is the process where food is moved through the alimentary canal, with food still moving through peristalsis through the whole of the digestive system.
• Peristalsis involves the contraction of longitudinal muscles lengthways and circular muscles contract inwards.
• The contraction along the sides of the intestine elongates the bolus of food.
• The food is moved very slowly to allow time for digestion and is unconscious and controlled by the enteric nervous system.
• Larger food molecules need to be digested before the nutrients can be absorbed.
• Digesting polymers into monomers is a process of breaking down larger molecules into smaller ones.
• Two glucose joined together form a disaccharide called maltose, through a glycosidic bond.
• To break apart two glucose, add water back in, a process called hydrolysis.
• If no enzymes, reactions would happen naturally but would take months to digest food.
• Dead cells from the intestine break off as they pass through.
• Cholera produces enterotoxin, which causes watery, painless diarrhoea and can lead to severe dehydration, potentially resulting in death within 1-2 weeks if a child, elderly person or pregnant woman contracts it.
• Bacteria not stay in stomach, need to get rid of.
• Epithelial cells need a lot of energy to make protein, hence they have a lot of mitochondria.
• Increasing the bulk (physical and mass) of material passing through the intestine by dietary fibre can lead to increased water absorption through osmosis.
• Dietary fibre is not a nutrient, but essential for digestion and if not in diet, transit through digestive system is slow.
• Cholera is essential to detect and treat as a communicable problem if it appears.
• Stomach ulcers are caused by bacteria and can be treated with antibiotics to reduce damage and kill the infection, allowing the stomach to recover and the ulcer to go away.
• Cholera spreads easily in crowded conditions, especially if there is a high proportion of children.
• Epithelial cells cover villi, stick to epithelium.
• Each villus has extensions called microvilli, termed brush border.
• Dietary fibre is also linked to a reduction in risk of diseases in the large intestine.
• Cholera is common in disaster zones due to inadequate sanitation and poor access to clean cooking water/utensils.