- produced in the salivary glands - used in the mouth - breaks down starch - end products are disaccharides (e.g. maltose) - optimum pH 7-8

- produced in the pancreas - used in the duodenum - breaks down starch - end products are disaccharides (e.g. maltose) - optimum pH is 7-8

diet and digestion Flashcards by zara hamilton

key adaptations of the villi

large surface area (villi and microvilli)
-> increases rate of diffusion
good blood supply
-> maintain concentration gradient of blood
lacteal absorbs lipids
long
-> lots of chance for diffusion to occur
thin/near capillary
-> short diffusion distance

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what is assimition

small food molecules are used to build larger molecules (e.g. amino acids are used to synthesise proteins)

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what is absorbtion

small, soluble molecules move from the small intestine to the blood

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what is ingestion

food enters the digestive system via the mouth

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what is egestion

removal of undigested food (faeces) from the anus

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what is digestion

breakdown of large insoluble molecules into small soluble ones

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what is mechanical digestion

teeth break down food into small pieces and peristalsis helps to move food along

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what is chemical digestion

enzymes break down food to small soluble molecules

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what is the order of digestion

mouth -> oesophagus -> stomach -> duodenum -> ileum -> colon -> rectum -> anus

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function of salivary glands

produces saliva
-> helps to moisten food
-> contains enzyme salivary amylase which starts the breakdown of food

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function of the mouth

food is ingested
mechanical digestion occurs here - teeth cut and crush food into smaller pieces which increases the surface area for enzymes to work

food is mixed with saliva - contains digestive enzymes (salivary amylase) to break down starch and moisten food

form a bolus of food which is pushed to the back of the mouth using the tongue

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function of the teeth

involved in mechanical digestion (physical breakdown of food)

incisor - for cutting and biting
canine - for holding and cutting
premolar and molar - for crushing and chewing

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function of the oesophagus

food passes down oesophagus and into the stomach
food is moved through the digestive system via peristalsis
- circular and longitudinal muscles involved to produce wave-like contractions

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function of the stomach

muscular bag that stores food for several hours

secrete HCl which makes stomach very acidic - the acid kills bacteria so you don’t get food poisoning and provides optimum pH for pepsin

produces the enzyme pepsin, which breaks down proteins to dipeptides

muscles in the wall of the stomach contract and churn the food

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function of the liver

filters toxins from the blood

acts like a food processing factory and will break down some molecules and build/store others

produces bile which emulsifies lipids

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function of the gall bladder

stores bile and releases bile into bile duct to enter the duodenum
in the duodenum bile has two roles:
- neutralising acids
- emulsifying lipids

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function of the pancreas

produces trypsin, lipase, pancreatic amylase

these are released into duodenum for chemical digestion

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function of the duodenum

food is continued to be broken down here, resulting in lots of small soluble molecules that can be absorbed in the ileum

bile (neutralises HCl from stomach) creates an alkaline environment, which is ideal for the enzymes maltese and peptidase

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function of the ileum

absorption of small soluble molecules into the blood stream and lacteal (absorbs fats)

villi has key adaptations to quickly and efficiently absorb soluble products of digestion

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function of the large intestine

any excess water is absorbed in the first part of the large intestine, the colon

leaving the non soluble/indigestible food (cellulose, dead and living cells from the gut) to move through

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function of the rectum

stores the faeces

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function of the anus

expels faeces from the body (egestion - removal of indigestible material)

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salivary amylase

produced in the salivary glands
used in the mouth
breaks down starch
end products are disaccharides (e.g. maltose)
optimum pH 7-8

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pancreatic amylase

produced in the pancreas
used in the duodenum
breaks down starch
end products are disaccharides (e.g. maltose)
optimum pH is 7-8

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maltase

- produced in the duodenum - used in the duodenum - breaks down maltose - end products are glucose - optimum pH 7-8

pepsin

- produced in the stomach - used in the stomach - breaks down protein - end products are dipeptides - optimum pH 1-2

trypsin

- produced in the pancreas - used in the duodenum - breaks down protein - end products are dipeptides - optimum pH 1-2

peptidase

- produced in the duodenum - used in the duodenum - breaks down dipeptides - end products are amino acids - optimum pH 1-2

lipase

- produced in the pancreas - used in the duodenum - breaks down triglycerides - end products are glycerol and fatty acids

practical: effect of temperature on enzyme activity

- will use bacterial amylase to breakdown starch - can measure the activity of the enzyme by looking at the speed at which the starch disappears - will use iodine to work out when the reaction is finished - iodine will be blue/black independent - temp dependant - speed of colour change controls - pH level, volume of starch, volume of iodine, volume of bacterial amylase 1) place single drops of iodine into depressions on a spotting tile 2) prepare a water bath for 20, 30, 40, 50, 60, 70 degrees celsius 3) place 2cm^3 of amylase into a test tube then put one in each water bath for 5 mins 4) add 2cm^3 starch into each amylase solution 5) place one drop of mixture into each drop of iodine - wait 10 seconds in between each drop 6) stop when the solution stays orange 7) each iodine drop used equals 10 seconds of reaction time 8) repeat for all temps

what elements are found in carbohydrates

carbon, oxygen, hydrogen

what elements are found in lipids

carbon, oxygen, hydrogen

elements present in proteins

carbon, oxygen, hydrogen, nitrogen, sometimes sulphur

monosaccharide example

glucose, fructose, galactose

what is formed when two monosaccharides join together

a disaccharides

disaccharides example

maltose, lactose, sucrose

what is formed when lots of monosaccharides join together

polysaccharide

polysaccharide examples

starch, glycogen, cellulose

what are lipids made of

triglycerides

what are triglycerides made of

1x glycerol 3x fatty acids

what are triglycerides made of

1x glycerol 3x fatty acids

what is the monomer of proteins

amino acids

what are two amino acids joined together called

dipeptide

what are many amino acids joined together called

polypeptide

function of vitamin a

- helps vision - helps keep tissues healthy

vitamin a deficiency

night blindness (nyctalopia)

good food sources of vitamin a

- cod liver oil - broccoli

function of vitamin c

- tissue repair - keeping skins/gums healthy

vitamin c deficiency

scurvy

good food sources of vitamin c

- citrus fruits - kiwi - potatoes

function of vitamin d

helps absorption of calcium

vitamin d deficiency

rickets

good food sources from vitamin d

- dairy - fish oil - egg

calcium function

stronger bones and teeth

calcium deficiency

osteoporosis

good food source of calcium

dairy

iron function

in haemoglobin, helps carry oxygen to respiring cells

iron deficiency

anaemia

good food sources for iron

- red meat - liver - eggs

fibre function

helps push indigestible material through large intestine

iron deficiency

constipation

good food sources for iron

- whole mead bread/pasta/rice - all bran

water function

all metabolic reactions occur

water deficiency

dehydration

good food sources for water

- water - cucumber - pepper - celery

what is the role of bile

- neutralising stomach acids - emulsifying lipids

what is energy content of food measured in

kilojoules (kJ)

method to investigate energy content in food

1) fill a boiling tube with 20cm^3 water + measure temp 2) measure mass of chosen food 3) light food on fire 4) immediately, place food under boiling tube 5) measure temp of water once food has stopped burning 6) repeat with other foods 7) use equation: energy released per gram = [mass of water(g) x temperature rise x 4.2] / mass of food sample

diet and digestion Flashcards

(68 cards)