Digestion

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  • Created by: Hindleyc
  • Created on: 18-06-18 15:48
What is digestion?
Where large insoluble molecules are hydrolysed/broken down into small soluble ones that can be absorbed across cell membranes
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What is the physical breakdown?
Large food into small pieces by teeth- making food possible to ingest and give larger SA for chemical digestion
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Where else is food physically broken down?
Stomach and SI- churned by muscles in S walls to physically breakup food and in SI
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What does Chemical digestion do?
Large insoluble molecules into small soluble ones
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What is it carried out by and what is the process?
Enzymes and hydrolysis
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What is hydrolysis?
Splitting molecules by adding water to chemical bonds that hold them together
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What are enzymes?
Specific
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How are they used in a large molecule?
More than one needed to break down large molecule
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How?
1 enzyme breaks large molecule into sections then 1 or more break sections down
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How are they made?
In diff parts of digestive system in correct sequence and nearly all finish in Small intestine so products only have to move into blood
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What do carbohydrates do?
Break down Carbohydrates ultimately into monosaccharides
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Where is Amylase produced? What does it hydrolyse and how? why?
Mouth and pancreas. H starch- every other glycosidic bond so only disaccharide maltose due to shape of active site
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EQN?
Amylase+starch=maltose
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2 types of Amylase?
Salivary amylase and pancreatic amylase
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What does salivary amylase do? what help maintain PH around neutral? what does it do little of and why? adv?
Starts digestion of starch- starts to create maltose and lubricates food. Mineral salts. Little digestion as quickly denatured in stomach and helps to clean mouth and reduce bacterial infection
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What does pancreatic juice contain?
Lipase, protease, hydrogen carbonate ions (alkaline) and PANCREATIC AMYLASE
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What does it do? how?
Digests all remaining starch in small intestine. Digests starch molecules from ends of chain into 2 glucose units- di (maltose)
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What keeps PH around 7/8 and what does this allow?
Alkaline salts in pancreatic juice and from intestine wall so amylase can function
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How does it get into upper parts of SI?
Duct squirts down in upper part
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Where is starch digested?
Mouth and upper part of SI-( not through pancreas)
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What are disaccharidases?
Bound to membrane of ileum epithelial cell and complete digestion
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What do Carbs make up ?
plant fibres can't be digested so move through
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2nd enzyme for Carbohydrate digestion ?
Maltase
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What is Maltase?
Membrane bound disaccharidase the breaks down disaccharides
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Where is it produced? where is it sat?
In lining of intestine . Sat in membrane in cells lining intestine
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What is exposed?
Active site
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Adv of them?
Products ready for absorption as released right next to where absorbed (epithelial cells of villus)
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EQN?
Maltose+Maltase=A glucose
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Overall carb digestion
Starch+Amylase=Maltose+Maltase=A glucose
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What digest lipids (fats and oils) ?
Lipases
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EQN?
Lipid+lipase= glycerol + fatty acids
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Where lipase normally made? where are they secreted into? what do they break?
In pancreas, into Small intestine and ester bonds
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Where are bile salts made and stored, ph? what do they do and what do they have?
Liver, gall bladder. Alkaline- neutralise acid (ph2) and emulsify lipids. Have hydrophilic and hydrophobic parts
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What do they do?
Interact with lipid and water breaking large lipids up into smaller droplets which mix with water- micelles increasing SA for lipase digestion
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What is there a joint effort by for lipid digestion ?
Lipases and bile
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2 Functions of bile?
Neutralise acid and emulsify fats into smaller droplets for lipid digestion
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How are proteins digested?
Proteases break down proteins ultimately into AA
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What are the 3 enzymes?
endopeptidase and exopeptidase and membrane bound Dipeptidase
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Where is Pepsin produced?/found and whats its optimum PH?
Stomach and 1/2
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Where are Endo and exo peptidases produced and secreted?
Synthesised in pancreas and secreted in SI
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Where does P digestion begin?
Stomach in acidic conditions- p long molecule
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What do exopeptidase do?
Hydrolyse peptide bonds at end of peptide molecule- break end AA off chain
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What do endopeptidases do?
Hydrolyse peptide bonds within a protein - internal peptide bonds creating dipeptides
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Eg of exopeptidase?
Dipeptidase which separates dipeptides gives individual AA often membrane bound to epithelial cells in SI
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protein digestion ?
Stomach with endopeptidases eg pepsin later in SI when mixed with exopeptidase (dipeptidases)
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Other cards in this set

Card 2

Front

What is the physical breakdown?

Back

Large food into small pieces by teeth- making food possible to ingest and give larger SA for chemical digestion

Card 3

Front

Where else is food physically broken down?

Back

Preview of the front of card 3

Card 4

Front

What does Chemical digestion do?

Back

Preview of the front of card 4

Card 5

Front

What is it carried out by and what is the process?

Back

Preview of the front of card 5
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