Balanced diet and nutrition/Digestion Flashcards
Carbs - made of C, H, O
- body’s main energy source
- simple, small and soluble
MONOSACHARIDES - 1 ring sugars e.g glucose or fructose
DISACCHERIDES - 2 ring sugars e.g maltose = glucose + sucrose/ sucrose = glucose + fructose/ lactose = glucose + galactose
POLLYSACCERIDES - large molecules with many joint rings. E.g. Starch/gelucose/glycogen
PROTEIN:
-made up H,O,C,N,S
-composed of amino acids (20 kinds - order + number determines which one)
- Thousands of proteins made by cell:
- soluble - enzymes/hormones/anti bodies
- muscle - keratin/collagen/myosin
Found in meat/fish/eggs/nuts
Uses - growth + repair/ anti bodies/ hormones and enzymes
8 amino acids essential - to be obtained via diet
FATS + LIPIDS
Make up- C/H/O Sterol fat - made of 3 fatty acids and glycerol = triglyceride
Found in - saturated: butter + lard
- unsaturated: oils at room temp
Uses - energy store
Other - contain twice the energy gram for gram as protein or carb
- saturated implicated in heart and circulatory disease
Vitamins.
A- makes rhodopsin (cells in retina)/ found in carrots/spinach/cabbage/fish liver oil. Lack of = night blindness
C- needed in enzyme reaction/connective tissue. Found in fresh fruit/veg. Lack of = scurvey + loose teeth + wound heal failure
D - calcerita made in skin using UV rays - Absorbs calcium in gut. Found in fish oils aswell. Lack of = rickets in chidren
Energy requirements:
- chemical energy measured in kilojoules(kJ) 4.2 joules per calorie
- energy input = metabolism + energy of activity
Man doing light work = 11,500 KJ per day
Teenager = 12500 KJ per day
Woman = 11000 KJ per day
Bomb calorimeter: food mass ignited in brass container in pure oxygen. Water around container is heated
Energy (J) = mass of water x 4.2 x temp rise
Food tests:
Benedicts - for sugar (maltose/glucose/fructose)
1) crush food + distilled water. 2) add reagent
3) stir, boil in water bath. Neg = blue/ Pos = green-yellow-orange - brick red
Starch test: 1) add iodine. Neg = yellow/brown
Positive = blue/black
Fat test: Put on filter paper. Pos = turns translucent/ shake with ethanol, pour into water. White emulsion forms.
Biuret: add 2cm3 of solution with protein. Vio = positive, blue = neg
Digestion:
- breaking down of food from large/insoluble molecules to small and soluble to be absorbed into blood stream
System: mouth/oesophagus/stomach/small/ large intestine/rectum/anus
Mouth: mechanical- cutting with teeth = inc s.a
- saliva secreted (amylase - starch to moltose) for lubrication
Oesophagus- forced with persistalsis= muscular contractions that push food along
Stomach - muscular bag that churns. Lining secretes: HCl (pH1) kill bacteria /pepsin - protease enzyme for proteins/mucus- protection from attack
Small intestine - place of chemical absorbtion/digestion. Wall glands secrete: protease/lipase/maltase/sucrase/lactase
Large intestine - colon/rectum/anus. Absorbs water and minerals from faeces/anus egests faeces = fibre/bacteria/bile salts/pigment.
Pancreas - produces alkaline (juice) for HCl
Bile - liver + gall bladder. Emulsifies fats. pH>7
Small intestine further.
- has villi( contain blood caps for inc S.A for blood absorption
- epithelial cells have microvilli for inc S.A
- Glycerol + fatty acids absorbed into lacteal system
Digestive Enzymes in small intestine:
- protease: protein to amino acid
- lipase: fat to fatty acids + glycerol
- maltase: maltose to glucose + sucrose
- sucrase: sucrose to glucose + fructose
- lactase: lactose to glucose and galactose
Enzymes:
- Bio catalysts which speed up reactions
-Enzyme has active site which must bind with substrate (reactant)
Effect of pH on enzyme activity: enzyme operate at optimum pH - outside = amino acid breakdown/distorted active site/enzymes denature
Effect of Temp:works at optimum 37*C. Above =denature and active distort.IRREVERSIBLE. Opt temp = faster movement/ increase collision rate/ increased reaction chance
