Organisation

• organelles → cells → tissues → organs → organ systems → organisms
• enzymes: large proteins, biological catalysts

  reactant(substrate)→w/ enzyme→product

  lock and key theory: enzyme has active site (area complementary to substrate), enzyme changes shape slightly to bind

  
• FACTORS AFFECTING ENZYMES

  Temperature: rate increases, then decreases

  • bonds break, enzyme denatures (active site changes shape until substrate can’t fit)

  pH: too acidic/alkaline decreases rate of reaction

  • denatures
• Carbohydrates / starch (starchy foods - spaghetti)

  • main energy source for chemical reactions

  Lipids / fats & oils (olive oil)

  • long term store of energy (keeps us warm and protects organs)

  Proteins (meat, etc)

  • used to grow and heal, last option for energy
• VITAMINS: organic molecules

  • A: good vision, skin, hair
  • C: prevents * scurvy * disease
  • D: made using sunlight, helps absorb calcium, prevents * rickets * disease *

  MINERALS: inorganic molecules

  • Calcium: strong bones
  • Iron: important part of haemoglobin, prevents * anemia * disease

  FIBRE: carbohydrates that aren’t absorbed into body

  • helps food move through intestines properly, prevents constipation
• DIGESTIVE ENZYMES:

  Amylase: breaks STARCH into MALTOSE, then with maltase into glucose

  • found in pancreas, small intestine, salivary glands

  Protease: breaks PROTEINS into AMINO ACIDS

  • found in pancreas, small intestine, stomach

  Lipases: breaks LIPIDS into GLYCEROL & FATTY ACIDS

  • found in pancreas, small intestine
• PRACTICAL 4: Food tests (part 1)

  Preperation:

  • break up food using water and pestle
  • put crushed food in beaker with distilled water
  • stir with glass rod until it dissolves
  • use funnel lined with filter paper to get rid of solids, solution is made
• PRACTICAL 4: Food tests (part 2)

  Benedict’s test for reducing sugars:

  • 5cm^3 solution, 10 drops of benedicts
  • waterbath 75 C, put in test tube for 5 minutes with test tube holder for safety
  • [BLUE to GREEN (low conc) / YELLOW / BRICK RED (high conc)]

  Iodine test for starch:

  • 5cm^3 solution, few drops of iodine solution
  • [BROWN/ORANGE to BLUE/BLACK]

  Biuret test for proteins:

  • 2cm^3 solution, 2cm^3 of biuret
  • [BLUE to PURPLE/PINK]

  Sudan III test for lipids:

  • 5cm^3 * non filtered * solution, 3 drops of Sudan III , shake
  • [BRIGHT RED LAYER ON TOP]
• Circulatory system function: to transport oxygen and nutrients to body tissues
• Blood carries oxygen, blood vessels hold blood & heart pumps blood via vessels
• circulatory system: oxygenated blood comes from lungs, deoxygenated blood comes from body

  TRUE OR FALSE?

  TRUE

  
• circulatory system: oxygenated blood comes from body, deoxygenated blood comes from lungs TRUE OR FALSE?

  FALSE

  
• The heart:

  A: Left atrium

  B: Pulmonary vein

  C: Left ventricle

  D: Right ventricle

  E: Vena cava

  F: Right atrium

  G: pulmonary artery

  H: aorta

  
• Blood movement in heart:

  On the left half:

  • oxygenated blood comes from lungs to pulmonary vein and enters left atrium
  • atrium contracts to push blood into left ventricle
  • left ventricle contracts to push blood out the aorta to the body

  On the right half:

  • deoxygenated blood comes from body to vena cava and enters right atrium
  • atrium contracts to push blood into right ventricle
  • right ventricle contracts to push blood out the pulmonary artery to the lungs
• Coronary arteries branch from aorta (gives muscle tissue oxygen + nutrients)
• Valves in the heart prevent blood flowing backwards
• In right atrium: pacemaker cells make small electric impulses and spread through muscular cells in heart for continuous contraction

  Artificial pacemaker does this when cells fail
• Arteries: carry blood AWAY from heart

  Veins: carry blood TO heart
• The left ventricle has thicker walls because it pumps blood all the way around the body
• Valves are used in veins to prevent backflow
• Blood vessels:

  A: Capillary

  B: Artery

  C: Vein

  
• Blood movement in blood vessels:

  • heart
  • arteries
  • capillaries
  • veins
  • heart
• Arteries, veins and capillaries are all blood vessels

  Capillary function: exchange nutrients & oxygen with tissues, take away waste products
• Arteries adaptations

  Blood is at high pressures as its been pumped out of ventricles

  • thick layer of muscle tissue strengthens it, elastic tissue stretches it
• Capillaries adaptations

  Really small, but lots of them

  • total area larger than arteries

  Exchange substances with cells

  • single cell thick reduces distance, permeable allows diffusion
• Veins adaptations

  Thin wall

  • low blood pressure means it doesn’t need to be strong
• DIGESTIVE SYSTEM FUNCTION

  Digestion: break down large molecules into small ones

  Absorption: provide big surface area for maximum food absorption
• Digestive system:

  Mouth (1)

  • chews, physical breakdown
  • saliva has amylase to break carbohydrates

  Oesophagus (2)

  • muscular walls contract to move and mix food

  Stomach (3)

  • hydrochloric acid kills bacteria and is good environment for enzymes

  Small intestine (4)

  • digested food absorbed into bloodstream
  • LINING AS AN EXCHANGE SURFACE: [villi increases surface area] [single layer of surface cells=short distances] [good blood supply = good concentration gradient]

  Large intestine (5)

  • absorbs excess water, waste is faeces
• Assisting digestive system:

  Pancreas: has lots of digestive enzymes, pushed to small intestine

  Gall bladder: stores bile which is produced in the liver, bile:

  • neutralises stomach acid
  • emulsifies fats, creating a bigger surface area for digestive enzymes
• WHAT’S IN BLOOD?

  Red blood cells (most abundant)

  • carries oxygen from lungs to body tissue for cellular respiration, haemoglobin carries oxygen

  White blood cells (fight against pathogens)

  • phagocytosis: engulfs pathogen to destroy it
  • antibody production: binds onto pathogen to destroy it
  • antitoxin production: neutralise toxins let off by pathogen

  Platelets (small cell fragments)

  • float around blood until cut in skin
  • CLOTTING: rushes to wound and patches it up like glue

  Plasma (makes blood watery in order to flow)

  • carries: RBCS, WBCS, platelets, glucose, amino acids
• Cardiovascular disease: general term for heart and blood diseases
• Coronary heart disease: when coronary arteries get blocked by fatty material (narrow lumen means less oxygen to the heart)


  STENT: expands lumen

  ✅ quick surgery

  ❌ surgery has risk of infection


  STATIN: medication altering balance of testosterone

  • reduces LDL (fatty) and increases HDL (fatty killer)

  ✅ reduces fat to expand lumen

  ❌ taken regularly, side effects like headaches
• Faulty valves: result in little blood flow or back flow of blood


  • Biological or mechanical valves can be used as replacements

  ❌ require surgery, risk of blood clots
• Heart failure: requires new heart


  • artificial heart is a temporary fix

  Biological:

  ❌ hard to find a donor, might be rejected as foreign
• Risk factor: factor increasing risk of a disease
• Lifestyle:

  EG: Obesity leads to diabetes and heart attacks

  Environment:

  EG: air pollution leads to lung cancer
• Radiation can lead to cancer

  Smoking can lead to lung cancer, cardiovascular disease

  Alcohol can lead to liver cancer
• Viruses living in cells can trigger cancer
• Carcinogens cause cancer by damaging DNA. Carcinogens cause mutations to occur. A single mutation will not cause cancer – several are required. For this reason, we are more likely to develop cancer as we get older.
• Being ill leads to no work = poor family, family must support you, more national spending on health