Digestion And Absorbtion Flashcards
What does the mouth do?
Where digestion begins
• Dentition
• Tongue
What is the function of the salivary glands?
➢Amylase and lipase
➢Acts as a buffer
➢Antimicrobial compounds
What is the function of the stomach?
Stores food
•Mechanical and
chemical digestion
•Parietal cells produce gastric acid
•Chemical digestion – pepsin and lipase
What is the structure of the small intestine?
• Main organ involved
•Over 6m long
• Chemical digestion
• Nutrients absorption ➢ Huge surface area
Where is the duodenum?
• First section of small intestine
• Food mixes with enzymes and digestive juices
What are the accessory organs?
- liver and gall bladder
- pancreas
What is the function of the liver and gall bladder?
• Produces bile which is
stored in gall bladder until required
• Breaks down fat molecules
What is the function of the pancreas?
Secretes digestive enzymes:
➢Lipase
➢Amylase
➢Protease
• Bicarbonate rich pancreatic juices
What does the colon do(large intestine)?
• Reabsorb water
• More than 90% reabsorbed
➢If too little absorbed: diarrhoea
➢If too much absorbed: constipation
What is the function of the flora( large intestine)?
• Contains bacteria which produce vitamins (K, biotin, folic acid)
• Generate gases as a by-product
•e.g. Escherichia coli
What is the function of the rectum( large intestine) ?
• Last section of the digestive system
• Eliminates faeces:
➢ Undigested materials
➢ Salts
➢ Bacteria
What is the hind- gut fermenters?
• Cecum
• First part of the large
intestine
• Enlarged in herbivores
•Digestion of cellulose/fibre
• Bacteria produce enzymes - help fermentation
How has the koala adapted it’s digestive system?
• Survive on diet of eucalyptus (200-500g a day)
• Very large cecum (200cm)
• Bacteria and microbes break down the fibre making it easy to digest
• Only 25% of fibre eaten can be absorbed
What is the structure of the mucosa? ( intestinal wall structures)
•Inner most layer
•Mucosal ducts and
glands:
➢Generate mucous
➢Moves digested material
•Highly folded
•Villi
What is the structure of the villi? (Intestinal wall structures)
• 1 cell thick
• Increase surface area
• Contain lacteal and blood
vessels
• Lacteal:
➢ Absorb fat and fat-soluble vitamins to lymph
➢ Helps fight infections
What does the circular muscle do?
➢Forms ring around intestine
What does the longitudinal muscle do?
➢Runs lengthwise along intestine
• Moves food along via peristalsis
What if the structure of the serosa?
•Smooth membrane
•Thin layer of connective tissue
•Serous fluid
What is the process of movement & control?
• Peristalsis:
➢Rhythmic waves
➢2 sets of muscle are involved
• Sphincters
What is Anabolism?
Set of metabolic pathways that synthesise large molecules from smaller ones
What is catabolism?
Set of metabolic pathways that breakdown larger molecules to smaller ones
- catabolism supplies the energy for anabolism
What are the 4 stages of digestion?
- Ingestion
- Digestion:
➢ Mechanical
➢Chemical/biological
➢3. Absorption: via diffusion and active transport - Elimination
What are the steps in carbohydrate digestion?
- Mouth: salivary amylase
- Duodenum: Pancreatic amylase
- Small intestine: lactase, sucrase and maltase
- Carbohydrates broken down into their monosaccharides
- Absorbed across intestinal wall
- Processed by liver and stored as glycogen
What are the steps in lipid digestion?
- Mouth: lipase
- Stomach: enzymes and stomach
acid - Duodenum: bile from gall bladder turns fat into droplets
- Pancreas: produces lipase
- Absorption across intestinal
membrane - Into lymph vessels
- Lymph deposits back into bloodstream
What are the steps in protein digestion?
- Stomach: pepsin
- Small intestine: protease
- Broken down into amino acids
- Absorbed through small intestine into blood
What is ruminant digestion?
• Cattle, sheep, deer, goat, camels
• Adapted digestion
• Multi-chambered stomach: rumen, reticulum, omasum and abomasum
What is the difference between ruminant & monogastric digestion?
Ruminant:
Mouth,oesophagus, stomach(reticulum, rumen, omasum, abomasum), small intestines(liver, pancreas), large intestine.
Monogastric:
Mouth, oesophagus, stomach, small intestines( pancreas, liver), large intestines
What is the structure of the mouth( ruminant digestion) ?
• Large muscular tongue
• Chew briefly in 2 stages:
1. Lower incisors against hard dental pad
2. Molars to grind down further
• Saliva does not contain enzymes
What is the structure of the rumen stomach( ruminant digestion) ?
➢First and largest
➢Food is stored
➢Lack enzymes
➢Bacteria and protozoa produce enzymes
➢Produce Volatile Fatty Acids (VFA)
➢VFAs are absorbed through rumen wall- primary source of energy ➢Internal surface covered in papillae
What is the structure of the reticulum stomach( ruminant digestion) ?
➢Separated from rumen by muscle fold
➢“Honeycomb filter”
➢Acts as screening device
➢ Larger particles sent back to rumen or oesophagus
➢ Common health issue is hardware disease ➢ Smaller particles filter straight into omasu
What is the function of the omasum(ruminant digestion)?
➢Lots of folds of tissue
➢ Absorbs excess water and
nutrients
➢ Filtration: only allows small particles into abomasum
What does the abomasum do(ruminant digestion)?
➢“True stomach”
➢Final breakdown
➢Produces HCl and digestive enzymes for further breakdown
What if the difference between small intestine & large intestine function?
• Small intestine = digestion and absorption
• Villi
• Receive secretions from gall bladder, pancreas and liver
• Large intestine (cecum, colon, rectum, anus) absorbs water and excretion
What are the 2 stages in partrition of protein(ruminant digestion)?
- rumen degradable protein
- Direct digestion of undegradable dietary protein
What are the the steps in rumen degradable protein?
➢ Digested by rumen microbes into amino acids, ammonia and nitrogen
➢ Nitrogen provides growth for microbes
➢ Some microbes pass through digestive system
What are the steps in direct digestion of undegradable dietary protein?
➢Occurs in abomasum
➢Protein microbes cannot break down
➢ Similar to breakdown of protein in monogastric stomach
