Digestion

• GALL BLADDER

  STORES BILE TO RELEASE INTO DUODENUM AS REQUIRED
• LIVER

  PRODUCES BILE TO EMULSIFY FATS (BREAK LARGE DROPLETS NTO SMALLER DROPLETS) - AN EXAMPLE OF MECHANICAL DIGESTION

  AMINO ACIDS NOT USED TO MAKE PROTEINS BROKEN DOWN HERE (DEAMINATION) WHICH PRODUCES UREA
• PANCREAS

  PRODUCES ALL THREE TYPES OF DIGESTIVE ENZYME: AMYLASE, PROTEASE AND LIPASE

  SECRETES ENZYMES IN AN ALKALINE FLUID INTO THE DUODENUM FOR DIGESTION
• LARGE INTESTINE

  WATER IS ABSORBED FROM REMAINING MATERIAL IN THE COLON TO PRODUCE FAECES

  FAECES IS STORED IN THE RECTUM AND REMOVED THROUGH THE ANUS
• SMALL INTESTINE

  FIRST SECTION IS CALLED THE DUODENUM AND IS WHERE THE FOOD COMING OUT OF THE STOMACH FINISHES BEING DIGESTED BY ENZYMES PRODUCED HERE AND ALSO SECRETED FROM THE PANCREAS

  PH OF THE SMALL INTESTINE IS SLIGHTLY ALKALINE - AROUND

  PH8 - 9

  SECOND SECTION IS CALLED THE ILEUM AND IS WHERE ABSORPTION OF DIGESTED FOOD MOLECULES TAKES PLACE THE ILEUM IS LONG AND LINED WITH VILLI TO INCREASE THE

  SURFACE AREA OVER WHICH ABSORPTION CAN TAKE PLACE
• STOMACH

  FOOD IS MECHANICALLY DIGESTED BY CHURNING ACTIONS WHILE PROTEASE ENZYMES START TO CHEMICALLY DIGEST PROTEINS.

  HYDROCHLORIC ACID IS PRESENT TO KILL BACTERIA IN FOOD AND PROVIDE THE OPTIMUM PH FOR PROTEASE ENZYMES TO WORK
• OESOPHAGUS

  TUBE THAT CONNECTS THE MOUTH TO THE STOMACH WHERE THE FOOD BOLUS GOES AFTER BEING SWALLOWED WAVE - LIKE CONTRACTIONS WILL TAKE PLACE TO PUSH THE FOOD BOLUS DOWN WITHOUT RELYING ON GRAVITY
• MOUTH /SALIVARY GLANDS

  THE MOUTH IS WHERE MECHANICAL DIGESTION TAKES PLACE

  • TEETH CHEW FOOD TO BREAK IT INTO SMALLER PIECES AND INCREASE IT'S SURFACE AREA TO VOLUME RATIO
  • AMYLASE ENZYMES IN SALIVA START DIGESTING STARCH INTO MALTOSE
  • THE FOOD IS SHAPED INTO A BOLUS (BALL) BY THE TONGUE AND LUBRICATED IN SALIVA SO IT CAN BE SWALLOWED EASILY
• Digestion - a process in which relatively large, insoluble molecules in food (such as starch, proteins) are broken down into smaller, soluble molecules that can be absorbed into the bloodstream and delivered to cells in the body.
• The alimentary canal - the channel or passage through which food flows through the body, starting at the mouth and ending at the anus. Digestion occurs within the alimentary canal.
• Bacteria's role in the human body:

  • Breaking down substances we can’t digest (like cellulose)
  • Supplying essential nutrients
  • Synthesising vitamin K
  • Providing competition with any harmful bacteria to restrict their growth.
• • Organisms need energy for:
  • Chemical reactions to build larger molecules from smaller molecules
  • Muscle contraction to allow movement
  • Keeping warm (to maintain a constant temperature suitable for enzyme activity)
• Aerobic respiration - respiration using oxygen.
• Glucose + Oxygen -> Carbon dioxide + Water