Digestive Systm Flashcards
7 classes of food
Carbohydrates
Proteins
Nucliec acids
Fats
Vitamins
Minerals
roughage (fibre) very critical for gut mobility
Why do we need carbs
Energy
Why do we need proteins
Growth and repair
What do we need nucleotides
To make dna
Why do you need fats
Energy storage
Why do we need mineral and vitamins
Essential for 100 of functions
What does GI tract do
It takes large particles of food (polymers)
Makes them smaller (digestion)
Smallest molecules (monomers) are absorbed
Waste (non absorbed) is eliminated
Types of carbs
Monosaccharides
Disaccharide
Polysaccharides (starch)
Sugar in tea
Sucrose ( plant derived) sugar cane
Is a disaccharide of glucose and fructose
Fructose - monosaccharide goes to liver to make glucose and glycogen
Lactose - monomer of glucose goes to liver
Fats (lipids)
3 fattys acids
1 glycerol
Food and water - GI Tract in mouth ————>
- Pharynx
- Oesophagus
- Stomach
- Small intestine - has accessory organs (liver and pancreas)
- Large intestine ————> out the body
Digestion two major activities
*Mechanical
Teeth (mastication)
Churning by muscles
- peristalsis-propulsion analward (longitudinal muscles)
- segmentation -mixing(circular muscles)
* chemical
Enzymes
Bile
Three sets of salivary glands
Subli
Content and function of saliva
Salivary amylase
Lubrication
Ph 6.35-7.0
Lingual Lipase
Smell of mouth
Can provide health clues
Faeculent
Ammonia - liver failure
Pear drops - diabetes (smell of acetone)
Uvula in throat
Seal of nasal cavity
Stops food going into nose
Epiglottis
Stops food from going into trachea
GI Tract layers
- Muscosa
- Sub mucosa
- Muscularis
4.Serosa
Function of stomach
Production of gastric juice
Stimulated by release if hormone - gastrin)
Components of gastric juice
- Hydrochloric acid
- Pepsinogen ( hydrochloric acid activates pepsinogen to make enzyme pepsin)
- Mucus
What is the mixture of food and gastric juice called
Chyme
Three different cells in production of gastric juice
- Hydrochloric acid - parietal cells
- Pepsinogen - Chief cells
- Mucus - mucous cells
Materials that will pass through the stomach wall
Water
Glucose
Certain salts
alcohol and lipid based drugs
What is GORD
Gastro oesophageal reflux disease
What is GORD
When gastric juice rises back up into the oesophagus through the lower oesophageal sphincter
Symptoms - burning pain, chest pain on bending or lying, heartburn
Manage with antacids
Why do ulcers form
When mucosa, lining is exposed to gastric acid and its resistance (mucus production) is undermined
How are ulcers managed
With antibiotics
PPI Drugs
Average length of adult male small intestine
6.9m
Adult female length small intestine
7.1m
Small intestine is divided into 3 structural parts
- Duodenum
- Jejunum
- Ileum
Function of small intestine
- Digestion
- Absorption
What are bile salts
Sodium glycocholate and sodium taurocholate
Bile pigments
- Biliverdin
- Bilirubin
Main role of bile
Neutralise stomach acids entering duodenum
Emulsification of fats
What are the enzymatic sources of digestion
- Walls of small intestine
- Pancreas
Enzymes in pancreas
- Pancreatic amylase
- Pancreatic lipase
- Trysinogen
- Chymotrysinogen
Hormones involved in digestion
- Gastrin
- Secretin
- CCK
What are hormonal controls
- Gherlin
- Leptin
- Cortisol
Ghrelin hormone
Hunger hormone stimulates appetite
Leptin hormone
Satiety hormone
Blocks appetite
More Leptin made by fatter people but they may build up resistance to it
Cortisol hormone
Stress hormone
Stimulates appetite and intake of palatable foods
How does absorption take place
The jejunum contains villi that increases surface area
So products of digestion are absorbed into the bloodstream here
Larger fat molecules go into central lacteals if lymphatic system
How else does absorption take place
The ileum contains villi
But it absorbs mainly b12 and bile acids as well as any remaining nutrients
The brush border of small intestine
Microvilli
Role of SI brush border
A series of digestive enzymes are found here
These include lactase, sucrase and other intestinal lipases and peptidases
These enzymes are involved in final stages of digestion of ingested proteins and carbs
Specialised for absorption
Function of large intestine
6.7cm in diameter
Harbours good bacteria eg. E. coli
Store food residues prior to elimination as faeces
Secretion of mucus
Absorption of remaining water and sodium
