Organisation

• Cells


  Basic building blocks of all living organisms
• Tissue


  group of cells with similar structure and function
• Organs


  Aggregations of tissues performing specific functions
• salivary glands


  Produce amylase in the saliva
• Stomach


  - pummels the food with its muscular walls

  - produces protease enzyme, pepsin

  - produces hydrochloride acid
• Why does the stomach produce hydrochloric acid?


  - kill bacteria

  - give the right pH for the protease enzyme to work
• liver


  - where bile is produced

  - bile neutralises stomach acid

  - emulsifies fat
• Pancreas

  - produces protease, amylase and lipase enzymes

  - release them into small intestine
• Gall bladder


  - where bile is stored

  - before its released into the small intestine
• large intestine


  - excess water is absorbed from food
• small intestine

  - produces protease, amylase and lipase enzymes to complete digestion

  - also where the digested food is absorbed out of the digestive system into the blood
• Rectum

  - faces are stored before leaving through anus
• Enzymes

  biological catalysts that speed up the rate of chemical reactions in biological processes
• Cataylyst


  a substance that changes the rate of a chemical reaction without being used up or changed in the reaction
• Lock and Key Method of Enzymes

  - enzymes are specific so the shape of the active site is complementary to the shape of the substrate

  - once 2 are bound, reaction takes place
• Enzymes need the right...

  Temp and pH
• If temp is too hot the enzyme can...

  - denature

  -so active site is changed not fitting the substrate any more
• If the pH is too high or low the enzyme can...

  - denature

  - all enzymes have an optimum pH
• Digestive enzymes covert food into...

  Small soluble molecules that can be absorbed into the bloodstream
• Carbohydrases break down...


  - carbohydrates to simple sugars

  - amylase is a carbohydrate which breaks down starch
• Protease break down...


  Proteins into amino acids
• Lipases break down...


  Lipids into glycerol and fatty acids
• Bile


  - made in liver and stored in gall bladder

  - alkaline to neutralise hydrochloride acid in stomach

  - emulsifiers fat to form small droplets which increase the surface area

  - alkaline conditions an large surface area increase the rate of far breakdown
• The effect of pH on the rate of reaction of amylase


  1- drop of done solution unto every well of a spotting tile

  2- place bunsen burner on heat proof mat and a tripod and gauze over the Bunsen burner. Put beaker on top of tripod and heat the water until 34 degrees

  3- use a syringe to add 1cm^3 of a buffer solution with a pH of 5 to a boiling tube , put test tube into beaker of water for 5 mins

  4- then add 5cm^3 of a starch solution to the boiling tube

  5-mix components and start a stop clock

  6-continuously sample , using a dropping Pipette to take a fresh sample from the boiling tube every 30s and drop into a well

  7- when I done solution remains brown/orange starch is no longer present

  8- repeat with diff pH values
• Preparing food sample


  -piece of food and break it up with pestle and mortar

  -transfer ground food to a beaker and add distilled water

  -mix with rod to dissolve the food

  -filter to get rid of solid bits
• Testing for sugars


  Benedict's solution

  -prepare food sample 5cm^3 in test tube

  -prepare water bath at 75 degrees

  -add Benedict's solution to the test tube using Pipette

  -place test tube in bath water

  -leave for 5 mins

  -if sample contains sugar it will go from least conc to high conc of blue -> green -> yellow -> brick red
• Testing for starch


  Iodine solution

  -food sample 5cm^3 in test tube

  -few drops off iodine solution

  -gently shake

  -will turn browny-orange to black/blue
• test for proteins


  Biuret solution

  -prepare food sample 2cm^3 in test tube

  -add 2cm^3 of biuret solution

  -gently shake to mix

  -if sample contains protein solution will change from blue to purple

  -if no protein it will stay blue
• Test for lipids


  Sudan III stain solution

  -food sample 5cm^3 in test tube

  -Pipette 3 drops of Sudan III to test tube

  -gently shake

  -sudan solution stains lipids

  -if sample contains lipids mixture will separate out into 2 layers

  -top layer will be bright red

  -if no lipids no red layer will form
• Heart


  An organ that pumps blood around the body in a double circulatory system
• Right ventricle pumps...


  Deoxygenated blood to lungs
• Where does gas exchange take place?

  alveoli
• Left ventricle pumps...


  Oxygenated blood around the rest of the body
• Trachea splits into ...

  Bronchi -> bronchioles -> aveoli
• Gas exchange


  -blood capillary contains lots of co2 and v little oxygen ( returned from rest of body )

  -oxygen diffuses out of alveoli into the blood

  -co2 diffuses out into alveolus to be breathed out

  -when blood reaches body cells oxygen is released from red blood cells and diffuses into body cells

  -at same time co2 diffuses put of body cells into blood carried back to lungs
• Heart pumps blood by...

  Contracting

  -mostly muscle tissue
• Journey of pumped blood in heart

  -blood flows into atria into vena cava and pulmonary vein

  -atria contract pushing blood into ventricles

  -ventricles contract forcing blood into pulmonary artery and aorta out of the heart

  -blood floes to organs trough armierst then back through veins
• vavles


  prevent back flow of blood
• Arteries function


  carry blood away from the heart
• Capillaries function


  Exchange of materials in tissues