5. DIGESTION Flashcards
This module covers: • Digestion and its influences on health and other body functions. • The different areas and organs of the digestive system, including their anatomy and functions. • How food is digested and how the different macronutrients are acted on by digestive juices. • The gut-brain connection and the microflora. • How digestion can be impaired and supported. • Digestion and energetics. • Naturopathic signs of poor digestive health.
Explain the three functions of the digestive system
1. Digestion
* Mechanical digestion (i.e., chewing, peristalsis).
* Chemical digestion (gastric juices, pancreatic enzymes, bile and enterocyte enzymes).
2. Absorption
* Primarily in the small intestine.
* Absorption into the blood and lymph.
3. Excretion
Waste materials (including toxins acted on by the liver) are excreted via the intestines as faeces.
Elimination also occurs via the urine, skin and lungs.
What is digestion?
The process of breaking down food by mechanical and chemical action (in the digestive tract) into substances that can be used by the body.
View as NP: See the digestive system as the one responsible for transforming the foods ingested into the crucial nutrients, that can nourish the cells and the tissues of the body.
Give two examples of mechanical and chemical digestion
Mechanical: Chewing, peristalsis
Chemical: gastric juices, pancreatic enzymes, bile, enterocyte enzymes
Where does absorption mainly occur?
- Primarily in small intestine (90%)
- Absorption into the blood (water soluble) and lymph (fat soluble)
poor digestion leads to poor absorption!
Name four organs of elimination
- Intestines
- Bladder
- Skin
- Lungs
As a NP, optimize them!
Name four accessory organs of the digestive system
- salivary glands
- pancreas
- liver
- gall bladder
- biliary tract
Which enzyme is released by the salivary glands?
Salivary amylase
What is the optimal pH for salivary amylase and what does it break down?
It has a pH of 6.8 and breaks down polysaccharides found in starchy foods, into smaller sugar units.
3D shape is important for the function
Saliva contains also IgA for defence.
Suggest two things that help digestion in the mouth
- Chewing up to 20 times
- Avoid drinking during meals
“the stomach has no teeth”
Give 4 examples of factors that can impair the functionality of salivary amylase
and lower the pH in the mouth
- Heavy metals (dental amalgams)
- refined sugars
- meat
- dairy
- chewing gum
- processed foods
- cigarettes
- alcohol
- chronic stress
Urin and saliva are outputs of the body for excess of acidity.
What happens when food enters the stomach?
Food entering the stomach = bolus
The hormone gastrin is released and the enteric nerves are stimulated.
Both stimulate the peristalsis of the stomach (churning) –> release and formation of gastric juice with HCl (from the parietal cells) and the digestive enzymes (lipase and pepsinogen) from the chief cells.
NSAID: by inhibiting prostaglandin production, they reduce the mucus production , –> lining of stomach damaged by HCl.
Name four anatomical parts of the body that form part of the digestive tract
- mounth
- pharynx
- oesophagus
- stomach
- small and large intestine
What does gastric juice contain?
HCI and digestive enzymes (lipase and pepsinogen)
Name the two enzymes released from the stomach wall and explain their functions
(from inactive pepsinogen ) Pepsin breaks down protein and Gastric lipase breaks down lipids
HCl transforms Pepsinogen in Pepsin.
Name four substances absorbed in the stomach which go directly to the liver via the portal vein.
- Water
- alcohol
- iodine
- fluoride
What’s the pH of HCI?
2-3
Which mineral and which vitamin are required for the production of HCI? Name two food sources for each.
- Zinc (oysters / pumpkin seeds/fish, meat, eggs)
- Vitamin B6 (Walnuts / sunflower seeds/green veggies/avocado, fish)
What are the actions performed by stomach acid
- Breaks down proteins and lipids into chyme
- The acid of the chyme further triggers peptide cholecystokinin (CCK), which activates the gallbladder and the pancreas to release pancreatic juice and bile into duodenum
- eliminates micro-organisms such as bacteria, viruses and fungi, protecting against infection.
NB: Iron and Calcium need stomach acid to be ionised
Name four possible causes of low stomach acid
- Chronic stress
- chronic H. pylori
- autoimmune gastritis
- low Vit B6 and Zinc
- Ageing
- Medications such as PPI
How does low stomach acid typically present?
- Bloating, belching and flatulence within 1-2 h after eating
- abdominal pain and fullness after eating, with foul-smelling stools or floating stools
- Nails are brittle, thin, easy breaking
- Get nauseous after supplementing
Test: first thing in the morning, 1/2 teaspoon of bicarbonate soda in a glass water , swallow: - if audible belching within 2-3 minutes, ok. If early and repetitive, excess ; if no belching within 3 min, low stomach acid.
Detail three ways in which low stomach acid can impair digestion
- Poor protein digestion, leading to putrefaction and polyamines, implicated in colorectal cancer
- Undigested food allows bacteria to proliferate in the small intestine, causing SIBO
- Reduced gastric activity results in less intrinsic factor, compromising Vit B12 absorption.
Name 5 ways of increasing stomach acid
- Apple cider vinegar in a little water before meals.
- Bitter herbs and foods taken 15-20 minutes before meals stimulate stomach acid release. (Herbs: Gentian, Barberry bark, Andrographis, Dandelion, Goldenseal. Foods: rocket, chicory, artichoke and watercress).
- Zinc (meat, Fish, eggs, Rice, Pumpkin seeds) and Vit B6 (Organ meat, Poultry, Tuna, Salmon, Chickpeas)-rich foods.
- Avoid over-eating and ensure meals are relaxed (eat mindfully). Avoid processed foods.
- A diet rich in fruit & vegetables.
- Eat fermented vegetables (e.g. sauerkraut).
- Himalayan and sea salt provide the chloride for HCl (and cayenne pepper).
Bitters are colding foods. Gentian: not in ulcers; berberine in barverry dark good for SIBO; apple cider vinegar with the mother (unfiltered and unpasteurised) Warm foods acting on the gastric juices: ginger, cardamome, fennel.
What is CCK and what triggers its release?
CCK (Cholecystokinin) is a hormone released from the duodenal wall, triggering the release of pancreatic juice and bile.
Its release is triggered by the initial presence of the acidic chyme in the duodenum, meaning that low stomach acid can ultimately significantly impair digestion.
What is the pH of chyme and how is it neutralised?
Chyme has a pH of about 2. It is usually acted upon quickly by bicarbonate, which is secreted by the pancreas and liver. This neutralises chyme and creates a pH of about 6.5 in the duodenum.
Chyme is formed in the stomach
90% of nutrient absorption takes place in the small intestine.
Name the three regions of the small intestine and what characteristically happens in each.
- Duodenum (30cm) – most digestion occurs here, aided by the influx of pancreatic juices and bile. Some vitamins and minerals are absorbed, too.
- Jejunum (2.5m) – most absorption occurs here, i.e. sugars, fatty acids, amino acids, vitamins.
- Ileum (3.5m) – vitamin B12 is absorbed.
Which structures in the small intestine creates a vast surface area to aid digestion?
Villi and microvilli
‘Brush border enzymes’ are attached to the small intestinal lining and break double-chained carbohydrates and proteins, allowing them to be absorbed. Name four and state their specific functions.
- Maltase, Sucrase & Lactase: Breaks down sugars into glucose, fructose, galactose, etc.
- Dipeptidase: Breaks down proteins into amino acids.
Complete:
————- and —– —- enter the blood capillaries of the small intestine to be sent to the liver.
Carbohydrates
amino acids
Complete:
—– —– including fat-soluble vitamins are digested in the small intestine and enter ——— ———–.
Fatty acids
lymphatic capillaries
What is the key exocrine function of the pancreas?
The key exocrine function of the pancreas is to produce enzymes that digest carbohydrates, proteins and fats. These enzymes are secreted into the small intestine.
How much pancreatic juice is produced daily?
1.2-1.5L
Name three pancreatic enzymes and what they digest.
- Pancreatic Amylase: carbohydrate-digesting.
- Pancreatic Lipase: fat-digesting.
- Proteases (trypsin, chymotrypsin): protein-digesting.
Summary of digestive enzymes slide 22
What can result from poor pancreatic enzyme production?
Foods ferment in the intestines, resulting in symptoms such as bloating, flatulence and abdominal pain about 1 hour after eating. The lack of digestion can also lead to weight loss.
Same symptoms as candida overgrowth. So how to differentiate ? with a Comprehensive Digestive Stool Analysis (CDSA)
What are the consequences of over-eating?
- When eating often and too much, digestive enzymes are used up.
- Not all food can then be digested, resulting in malnutrition and bodily dysfunctions.
- Organs such as the pancreas and stomach are placed under stress.
- Energy is directed away from healing & repair, increasing the risk of disease.
Name three ways that can help to support the digestive system
– Do not eat more than 3 meals a day.
– Avoid over-eating and snacking between meals.
– Don’t drink with meals.
Nutritious diet : 10% of energy expenditure to digest it; 50% necessary when dense forms of proteins (meat, soya and junk food) are eaten.
Explain Bernard Jensen’s findings
- Bernard Jensen found that undigested materials are stored in the mucus-secreting lining of the intestines, impairing the absorption and delivery of nutrients to body tissues.
- This would create an optimal environment for parasites and candida to flourish, as well as under-nourishing body tissues and organs.
Support detox is key to aid the body’s elimination. Intermittent fasting to minimise the digestive system load is also important. Jensen recommended also vegetable broths.
What did Jensen suggest to support the digestive system?
- Detoxification
- intermittent fasting
- vegetable broths
What is the function of the gallbladder?
Storage and release of bile which is produced by the liver.
What are the main components of bile?
Bile consists mostly of water, as
well as bile salts , cholesterol and bilirubin.
Bilirubin gives the colours to the stool, it’s a waste product from haem (haemoglobin)
Describe the function of bile in relation to:
1. Fat Emulsification
2. Detoxified liver products
3. Peristalsis
4. Cholesterol
- Bile breaks lipids into smaller molecules, increasing the surface area for digestion by pancreatic lipase.
- The liver excretes detoxified harmful materials into bile to be excreted.
- Bile stimulates intestinal peristalsis.
- Bile contains excess cholesterol that the body wishes to excrete.
A poor bile flow means an impaired capacity to eliminate waste of the liver into the digestive system (bowel) and all th abilities cited above impaired…
What is carried by the pancreatic duct?
Pancreatic enzymes and bile
What is the result of poor bile flow?
Poor bile flow negatively affects fat digestion and the body’s ability to eliminate toxins via the bowel.
What can be used to stimulate the release of pancreatic juice and bile?
Bitters
(such as gentian, dandelion, milk thistle, golden seal, artichoke leaves)
What is the production and release of bile and pancreatic juice dependent on?
Sufficient water consumption
but also for the release, dependent on the acidic drive of the chyme and CCK (Choleocytokinin).
How many liters of blood does the liver filter per minute?
1.4L
What substances are stored by the liver?
Carbohydrates (in form of glycogen), fats, iron, Vit A, D, E, K and B12
Name two functions of the liver other than storage.
- Detoxification and deactivation of hormones;
- creates bile,
- produces albumin;
- produces heat for the body
TIREDNESS will be a key symptom, if the liver can not do its functions.
What can impair liver detoxification?
- Lack of nutrients,
- trans fats,
- heavy metals,
- alcohol,
- caffeine
- and pesticides
Outline Phase I Liver Detoxification
- Volatile toxins are converted into smaller substances that are water soluble (important to excrete them).
- CYP450 enzymes create an active binding site on the toxin / hormone so that it can be conjugated (in phase II).
- On completion of phase I, toxins are oxidised and free radicals are formed. These must be neutralised by anti-oxidants (Vit A, C and E) to protect against oxidative damage.
Needed in P.I: Milk thistle, glutathione, anti-ox, B vit and flavonoids.
Outline Phase II Liver Detoxification
Conjugation phase:
* Reactive toxins are made safe and excretable by conjugation with a chemical group.
* The bound toxins are then pumped into the blood or bile for excretion mostly via the kidneys or bowels, but also sweat and exhalation.
- The key antioxidant for neutralising free radicals
in the liver is glutathione, which is a tripeptide formed from cysteine, glycine and glutamine.
*Nutrients including sulphur (e.g., garlic and onions), magnesium, B vitamins are required for phase II. Whilst herbs such as dandelion, milk thistle and liquorice root support liver detoxification.
Hg (teeth?) is a pb: it deposits in the liver
Selenium (found in Brasil Nuts) crucial for prod of glutathione peroxidase.
Which nutrients are required for Phase ll liver detoxification?
- Sulphur (garlic and onions),
- magnesium
- and B vitamins
Add garlic only at the end of the cooking and gepressed for having allicin
Which herbs support liver detoxification?
- Dandelion,
- pepper
- shallots
- ginger
- milk thistle
- and liquorice root
Which tripeptide is the key antioxidant for neutralising free radicals in the liver? Which three amino acids is it formed from?
- Glutathione
- Formed from cysteine, glycine and glutamate
Where does the final stages of digestion and absorption occur?
Large intestine
Water as well as some minerals and vitamins are absorbed.
Mucus (from goblet cells) lubricates the lining of large intestine, but no digestive enzymes are released there.
Describe the four regions of the large intestine
- Caecum – attached to appendix (twisted tube about 8cm long, almost entirely formed of immune tissue in its wall (macrophages, lymphocytes) which acts as a key reservoir for beneficial gut bacteria.
- Colon – ascending, transverse, descending regions.
- Rectum – pushes stool into anal canal.
- Anal canal – contains an involuntary internal anal sphincter and voluntary external anal sphincter.
Appendix: breeding ground for the microflora, heps with development of good bacteria, a lot of GALT around, area for immune defense and regulation of microflora.
Where are nutrients absorbed?
The most absorption occurs in the small intestine , especially in the jejunum.
It is also the part affected by coeliac . Csqces : malabsorption with coeliac and if they eat gluten.
What is absorbed in the STOMACH?
- Water,
- Ethyl alcohol (only stomach)
- Copper (Stomach and Duodenum)
- Iodide (only stomach)
- Fluoride (only stomach)
- Molybdenum (stomach and jejunum)
pH 1-3
What is absorbed in the DUODENUM?
- Vit A,D,E,K
- Biotin B7
- Folate B9
- Niacin B3
- Riboflavin B2
- Thiamin B1
- Calcium
- Copper ( only stomach and duodenum)
- Iron
- Magnesium
- Phosphorus
- Selenium (only dudodenum)
pH goes from 1-3 with the chyme till 6-8 when the bicarbonate has done i
What is absorbed in the JEJUNUM?
everything, except : copper, selenium, vitamin B12 and others found exclusively in Stomach, in Ileum or large intestine.
pH: 5-7
What is absorbed in the ILEUM?
- vitamin C
- vit B9 (folate)
- vit B12 (only ileum)
- vit D
- vit K
- Magnesium
- bile salts and acids
pH 5-7
What is absorbed in the LARGE INTESTINE?
- Sodium
- chloride
- potassium
- vit K2
- Biotin B7
- Short fatty chain acids
pH 5-7
Where is GALT found and what does it contain?
Gut associated Lymphoid Tissue is found in GIT wall and houses leukocytes (macrophages and lymphocytes).
What is the function of the leukocytes in the GALT?
Identification of microbes through close interaction with bacterial surface antigens (identity markers)
Providing immune defence, what is secreted into the GIT mucosa and is reduced during periods of stress?
Secretory IgA
s. notes done page 36bis of slides.
What are the functions of the microflora?
- Final stages of nutrient extraction through microbial fermentation
- Fermentation of carbohydrates (creating methane & hydrogen), if in excess, it’s due to poor digestion
- Fermentation of amino acids (creates hydrogen sulphide). If gas in excess with strong odour, it’s a sign of poor digestion
- Synthesis of vitamins such as Biotin and K2.
- Supports intestinal barrier: Bacteria produce short-chain fatty acids from fibre they ingest, that is then used by enterocytes. Protective against leaky gut.
- Pathogen protection: Out-competes for attachment to the intestinal epithelium and nutrients (e.g. against candida).
- GALT: Crucial for effective functioning of the immune system.
- Appetite-regulating proteins are produced by bacteria (satiety) .
- Mood Regulation: The microflora can synthesise neurotransmitters (Bach Therapy by Edward Bach). Connection gut-brain through microflora.
