Digestion And Absorbtion Flashcards by Eva Beauvoisin

What does the mouth do?

Where digestion begins
• Dentition
• Tongue

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What is the function of the salivary glands?

➢Amylase and lipase
➢Acts as a buffer
➢Antimicrobial compounds

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What is the function of the stomach?

Stores food
•Mechanical and
chemical digestion
•Parietal cells produce gastric acid
•Chemical digestion – pepsin and lipase

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What is the structure of the small intestine?

• Main organ involved
•Over 6m long
• Chemical digestion
• Nutrients absorption ➢ Huge surface area

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Where is the duodenum?

• First section of small intestine
• Food mixes with enzymes and digestive juices

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What are the accessory organs?

liver and gall bladder
pancreas

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What is the function of the liver and gall bladder?

• Produces bile which is
stored in gall bladder until required
• Breaks down fat molecules

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What is the function of the pancreas?

Secretes digestive enzymes:
➢Lipase
➢Amylase
➢Protease
• Bicarbonate rich pancreatic juices

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What does the colon do(large intestine)?

• Reabsorb water
• More than 90% reabsorbed
➢If too little absorbed: diarrhoea
➢If too much absorbed: constipation

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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

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What is the function of the rectum( large intestine) ?

• Last section of the digestive system
• Eliminates faeces:
➢ Undigested materials
➢ Salts
➢ Bacteria

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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

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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

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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

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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

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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?

1. Stomach: pepsin 2. Small intestine: protease 3. Broken down into amino acids 4. 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