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