food and digestion

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  • Created by: sophie_kk
  • Created on: 27-12-19 20:59
what are carbohydrates?
body's main 'fuel' for supplying cells with energy
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types of sugar
fructose - fruit sugar, lactose - milk sugar, sucrose - main sugar that is transported through plant stems (used in coffee and tea)
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what is starch?
large insoluble molecule, and is found as a storage carbohydrate in many plants eg potato, rice and wheat , starch is also a polymer of glucose
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what is glycogen?
polymer of glucose, and is found in tissues such as liver and muscle - where it acts as a store of energy for these organs
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cellulose
our body cannot digest it, as we do not have the right enzymes - but it forms 'dietary fibre' which give the muscles of the gut something to push against as food is moved through the intestine.
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what does dietary fibre prevent?
avoids constipation, keeps gut contents moving and helps to prevent serious diseases of the intestine such as colits and bowel cancer
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what are lipids?
contain the three same elements as carbohydrates (carbon, hydrogen and oxygen) - but the proportion of oxygen in a lipid is much lower than a carbohydrate
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what do lipids do?
make up about 10% of our body mass, and form an essential part in the structure of all cells - with fat being deposited in certain parts of the body as a long-term store of energy eg the fat layer under skin acts as insulation (heart, kidney)
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what is the structure of a lipid?
molecule of glycerol joined to three fatty acids
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what is cholesterol?
substance the body gets from food such as eggs and meat, and we also make it from our liver ( too much causes heart disease)
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what is the difference in saturated and unsaturated fats?
saturated means that the fatty acids of the lipids contain no double bonds, and are unhealthier than unsaturated fats
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what are proteins?
make up 18% of our body mass - all cells contain protein, so we need it for growth and repair of tissues (meat, cheese , fish)
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disease caused by lack much protein
kwashiorkor - lack of protein causes a swollen belly due to fluid collecting in the stomach + weight loss, poor muscle growth , general weakness and flaky skin
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how many amino acids are there?
20
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calcium
making teeth and bones , dairy products
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phosphorus
making teeth and bones, part of many chemicals , most foods
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sodium
in body fluids eg blood, common salts
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chlorine
in body fluids eg blood, common salts
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magnesium
making bones; found inside cells , green vegetables
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iron
part of haemoglobin in red blood cells, red meat
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rickets
deformed bones caused by a lack of calcium or vitamin D
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anaemia
lack of iron means they can't make enough haemoglobin for the red blood cells
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scurvy
vitamin C deficiency, where wounds Fail to heal and bleeding occurs in various places in the body
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beri beri
lac of vitamin B1 results In the weakening of the muscles and paralysis
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vitamin A
makes a chemical in the retina + protects surface of eye, lack - night blinds + damaged cornea of eyes, fish liver oils
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vitamin C
sticks together cells lining surfaces such as the mouth, lack - scurvy , fresh fruit and vegetables
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Vitamin D
helps bones absorb calcium and phosphate, lack - rickets + poor teeth , fish liver oils
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testing for starch
iodine - placed on spotting tile and if starch is present, will go from orange to blue-black
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testing for glucose
Benedicts solution - add Benedict's to solution to sample, then heat in boiling water. will go from blue to browny orange
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testing for protein
biurets solution - break down the food sample and then add the blurted solution. add a little water if needed. will go from clear to purple
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testing for lipids
ethanol - if add to sample (in tube) and then shake vigorously, then add distilled water. if present, will go from colourless to cloudy
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measuring the energy content of foods
1. mass of food sample is found by weighing on a balance 2. known volume of water is placed in a boiling tube and supported in a clamp on a stand. 3. temp of water is recorded 4. food is speared on a mounted needle and head in a Bunsen burner until
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cont
it catches fire 5. this is done underneath the water , so the flame heats it up. 6. final temp of water is measured , using thermometer to stir it gently, so that all the heat is evenly distributed.
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energy content equation
energy content = (final temp - initial temp) x volume of water x 4.2 / mass of food
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digestion
the chemical and mechanical breakdown of food
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peristalsis
muscular contraction of circular muscles behind the food narrows the gut, passing the food along. when the circular muscles are contracted, the longitudinal muscles relax, and the vice versa
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who breaks down food using enzymes?
the mouth, stomach and duodenum (first part of small intestine) , either made in the gut wall itself or by glands such as the pancreas
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what happens in the last part of digestion?
digested food is absorbed in the second part of the small intestine (ileum) , and the large intestine absorbs water out of the remains , and stores faeces before they are removed from the body
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name the three different enzymes used
carbohydrase, proteases, lipase, amylase - starch
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what does amylase digest?
digests starch into maltose
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amylase
carbohydrase , starch -> maltose, salivary glands, mouth OR pancreas, small intestine
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maltase
(carbohydrase) maltose -> glucose , walls of small intestine, small intestine
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pepsin
(protease) protein -> peptide , stomach wall, stomach
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trypsin
(protease) protein -> peptide , pancreas, small intestine
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peptidases
(protease) peptide -> amino acid , walls of small intestine, small intestine
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lipase
(lipase) lipids -> glycerol and fatty acids, pancreas, small intestine
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what does the stomach secrete?
hydrochloric acid is secreted, and kills any bacteria taken into the gut along with the food, helping to protect from food poisoning
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pH of pepsin
2 - as it has to be able to work in acidic conditions
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how does the food get released?
held back in the stomach by a ring of muscle - sphincter muscle , when this relaxes , it releases food into the first part of the small intestine
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what does the liver produce?
makes bile, stored in the gall bladder and passes down the bile duct on to the food
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function of bile
turns any large lipid globules in the food into an emulsion of tiny droplets. this increases the SA of the lipid so that lipase can break it down more easily
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what is the purpose of pancreatic juice and bile?
both alkaline - so neutralises the mixture of semi-digested food and enzymes coming from the stomach before it continues through the gut
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how is the ileum adapted for digestion
1 length 2. folds in the lining 3. projections from the lining (villi) 4. villi contain microvilli for further SA 5. surface of a villus is made of a single layer of cells (epithelium) 6. (villus) contain muscle fibres which contract to move the
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villi, keeping them in contact with the contents of the ileum, and maintaining a steep concentration gradient
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assimilation
when soluble food molecules are absorbed from the blood into cells of tissues, and are used to build new parts of cells
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what takes place during absorption?
the blood vessels from the ileum join up to form the haptic portal vein, which leads to the liver. the liver then breaks down some molecules, whilst building up and storing others. the digested food molecules are then distributed around the body
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process of digestion
indigestible remains ; water, dead and living bacteria, cells lost from lining of gut. large intestine absorbs remaining water, and then leaves faeces stored in the rectum, until they are expelled through the anus
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elements in protein
C,H,O,N
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Other cards in this set

Card 2

Front

types of sugar

Back

fructose - fruit sugar, lactose - milk sugar, sucrose - main sugar that is transported through plant stems (used in coffee and tea)

Card 3

Front

what is starch?

Back

Preview of the front of card 3

Card 4

Front

what is glycogen?

Back

Preview of the front of card 4

Card 5

Front

cellulose

Back

Preview of the front of card 5
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