Biology SL chapter 6.1 (Digestion)

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Role of digestion
Most food is solid and in large, complex molecules which are insoluble and chemically inert. Large molecules need to be broken down for absorption and small molecules can be rebuilt (amino acids-> proteins)
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Need for enzymes in digestion
Enzymes speed a chemical reaction(digestion)by lowering the activation energy.Allows digestive processes to occur at body temperature and fast enough to ensure survival of organism.
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Three enzymes in human digestive system
Salivary amylase,Pepsin (a protease enzyme),Pancreatic lipase lipase
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Source, substrate, product and optimum pH of salivary amylase
Source: salivary glands, Substrates: starch (sugars), Product: maltose, Optimum pH: 7 (neutral)
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Source, substrate, product and optimum pH of pepsin
Source: Gastric juices in stomach, Substrate: Protein, Product: Short polypeptides, Optimum pH: 2 (highly acidic)
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Source, substrate, product and optimum pH of pancreatic lipase
Source. Pancreas, Substrate:lipids (triglycerides), Product: glycerol, fatty acids, Optimum pH: 8 (slightly alkaline)
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Alimentary canal
Contains organs through which the food actually passes (esophagus, stomach, small intestine, large intestine, etc.)
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Accessory canal
Organs that assist in digestion but no food passes through them (liver, pancreas, gall bladder, salivary glands, etc.)
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Function of stomach
Temporary storage tank where protein digestion begins. Acid creates environment which denatures proteins while pepsin hydrolyses proteins. The mechanical action of the stomach (churning) also promotes digestion by mixing the food
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Function of small intestine (SI)
This is where most of the nutrients are absorbed into the blood stream. The pancreas and gall bladder secrete substances into SI to aid in digestion. Food is moved by peristalsis. Contains villi to aid absorbtion
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Function of large intestine
The large intestine absorbs water and dissolved minerals from the indigestible food residues, and by doing so converts what remains from a fluid state into a semi-solid faeces The faeces is stored in the rectum and eliminated out the ****
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Distinguish between absorption and assimilation
Absorption is when a fluid or dissolved substance moves across a membrane. Assimilation is the conversion of nutrients into solid or fluid parts of an organism
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Explain the role of microvilli, rich capillary networks (RCN) and single epithelial layer (SEL)
Microvilli: increases surface area of villus for better absorption. RCN: maintain absorption gradient by quickly transporting absorbed products away. SEL: ensures minimal distance for diffusion between lumen and capillary network
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Explain role of lacteals, intestinal crypts and membrane proteins
Lacteals: absorb lipids from intestine into lymph system. Intestinal crypts: between villi and release juices which acts as carrier fluids for nutrients. membrane proteins: allow active transport into cells
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Card 2

Front

Need for enzymes in digestion

Back

Enzymes speed a chemical reaction(digestion)by lowering the activation energy.Allows digestive processes to occur at body temperature and fast enough to ensure survival of organism.

Card 3

Front

Three enzymes in human digestive system

Back

Preview of the front of card 3

Card 4

Front

Source, substrate, product and optimum pH of salivary amylase

Back

Preview of the front of card 4

Card 5

Front

Source, substrate, product and optimum pH of pepsin

Back

Preview of the front of card 5
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