Atoms (may not be in test, but it’s in my notes):
All substances are made of particles called atoms
Elements: composed of one type of atom
Compound: when 2 or more different elements are chemically bonded
Molecule: separate units of 2 or more molecules (eg. Water molecules)
Mixture: 2 or more elements are found together but not chemically bonded
We eat for:
-energy
-health
-nutrients: vitamins, minerals, fats, fibre/roughage, protein, carbs, water
-life
-growth and recovery
-to function properly
-warmth
-fun
All living organisms require energy; in animals cellular respiration supplies this
Oxygen + glucose = carbon dioxide + water + energy
Digestion:
a: salivary glands – Makes saliva containing enzymes which break down starch
b: liver – makes bile which breaks down fats, controls blood sugar, destroys poisons and stores vitamin A, D and iron
c: gall bladder – bile is stored here, which breaks down fats into small droplets so that lipases can access them
d: bile duct – tube that carries bile from gall bladder to duodenum
e: duodenum – site of digestion for carbs, fats and proteins, short part of small intestine connecting to stomach
f: appendix: kind of useless, may help fight some diseases
g: anus: faeces passes through
h: rectum: final part of large intestine, faeces storage
i: large intestine: absorbs water, vitamins and minerals from undigested material which passes through
j: small intestine: digestion of fats carbs and proteins; foods and liquids are broken down into nutrients which are absorbed into bloodstream
k: pancreas – makes alkaline pancreatic juice to neutralise stomach acids and enzymes
l: stomach – hydrochloric acid and muscle movement mixes food with gastric juice to break down protein.
m: diaphragm*
n: oesophagus – carries food from mouth to stomach using peristalsis (involuntary muscle contractions)
o: trachea*
p: mouth - food and saliva mixed, teeth for mechanical digestion
q: nasal passage*
r: pyloric sphincter – band of muscle that regulates movement of food out of the stomach
caecum: in plant-eating mammals it breaks down cellulose which is found in plant cell walls
ileum: last section of small intestine, absorbs nutrients
*m, o, and q are probably not needed
Process of digestion:
-food enters the mouth where it is chewed with teeth and mixed with saliva to break down starch
-travels down the oesophagus to the stomach
-stomach churns food, hydrochloric acid kills germs and allows enzymes to work
-food travels to the first part of the small intestine, the duodenum. Food mixes with bile from the gall bladder and pancreatic juices with enzymes from the pancreas. Carbs fats and proteins are digested. Minerals are absorbed
-food goes through small intestine; nutrients absorbed into bloodstream
-indigestible food continues to large intestine; water, vitamins and minerals are absorbed. Faeces is formed
-Faeces stored in rectum
-Passes through anus
Mechanical and Chemical digestion:
Mechanical: physically breaks down food into smaller pieces. (chewing with your teeth, stomach churning)
-3 types of teeth; incisors for biting and cutting, canines for tearing and grasping, molars/premolars for grinding and crushing
Chemical: where chemicals in your body react with the food which change the substances in food into simpler chemicals that can be absorbed into you blood (amylase in saliva, protease, lipase)
Enzymes:
-Assist chemical digestion by increasing rate of reactions
-The smaller an object is, the higher its volume to surface area ration becomes
-In digestion, this means smaller food particles are more exposed to digestive chemicals and enzymes
-Made of protein
-If enzymes become overheated they become denatured so they can’t work
-Substance being broken down is the substrate
-Resulting substance is the product
-Are specific for jobs they do
-Amylases: break down carbs (eg starch) into glucose
Produced by pancreas and small intestine
-Lipases: break down fats/oils into fatty acids and glycerol
Salivary glands, pancreas, small intestine
-Proteases (such as pepsin): break down protein into amino acids
Stomach, pancreas and small intestine
-Hydrochloric acid: kill bacteria and help produce acidic conditions for enzymes to work
Produced in stomach
Carbohydrates:
-rice, pasta, bread, cereal, oats, potato
-energy source
-extra energy stored as starch in plants, glycogen in animals
-cellulose in plant walls=fibre/roughage to maintain cholesterol and glucose levels and keeps food moving along the digestive system
-building blocks are glucose
-in fruit = fructose
-in milk = lactose
-normal sugar = sucrose
-starch, occurs in plant cells as grains. Each grain is surrounded by a membrane which comes apart when cooked
Proteins:
-meat, poultry, fish, eggs, dairy, nuts, lentils, beans soy, wheat
-molecules are enzymes, antibodies (defending the body), structural such as keratin and hormones
-major function – growth and repair
-made of chains of amino acids
-some amino acids must be eaten, others produced by the body
Fats:
-butter, lard, dripping, oil, margarine, nuts, fried food
-Animal fats become liquid when heated, plant fats usually liquid at room temperature
-energy
-in mammals, stored under skin for warmth and organ protection
-building blocks are fatty acids and glycerol
-saturated fats: maximum amount of hydrogen possible, they increase cholesterol and risk of heart disease. Animal fats are saturated.
-polyunsaturated fats: contain considerably less hydrogen than maximum amount. Plant oils contain high proportion of polyunsaturated fats which reduce cholesterol.
Nutrient tests:
Reagent Nutrient
Sugar Diastix
Starch Iodine
Protein Sodium hydroxide + copper sulphate
Fat Brown paper
Water None, this was used as a control for comparison
Some definitions:
Ulcer: a break in the mucus lining of the stomach
Quantitative: Deals with numbers and measurable information such as lengths, weights, ages time
Qualitative: Deals with descriptions and can be observed but not measured, such as colours, tastes or opinions
Emulsify: separate (mechanical digestion); bile emulsifies lipids like fats so that it has a larger surface area
Denatured: cannot go back to original state so cannot function
Carnivores: eat meat
Herbivores: eat plant material (will have a larger caecum)
Omnivores: eat plants and meat (may have larger caecum)
Insectivores: feed on insects
Insulin: turns excess glucose to glycogen for storage
I will update tomorrow night, tell me if i missed anything, you've probably been in more lessons than I have :)
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