SCIENCE 4

• Mouth


  Breaks up food particles
• Pharynx


  Swallows food and liquid
• Liver


  • Breaks down and builds up many biological molecules
  • Stores vitamins and iron
  • Destroys old blood cells
  • Destroys poisons
• Bile


  Aids in digestion
• Gallbladder


  Stores and concentrates bile
• Small Intestine


  Completes digestion
• Mucus


  Protects gut wall, absorbs nutrients, most water
• Peptidase


  Digests proteins
• Sucrases


  Digest sugars
• Amylase


  Digests polysaccharides
• Anus


  Opening for elimination of faeces
• The digestive system processes important materials needed for the function of the body. Its main purpose is to grind and juice out our food and get its nutrients.
• Mechanical digestion


  Food is broken down by means of chewing, biting, and grinding to make it into smaller particles
• Chemical digestion


  Digesting food with the use of enzymes to make food soluble for it to be absorbed by the body and be transferred through the circulatory system
• Ingestion


  Taking in food that starts in the mouth
• Digestion


  Breaking down of food into smaller particles in order to use its nutrients
• Absorption


  Taking in the nutrients from the digested food to be used by the body for different life processes
• Egestion


  Removing any leftover wastes after the digestion process
• Parts of the mouth

  • Incisors
  • Canine
  • Premolars
  • Uvula
  • Throat
  • Molars
  • Tongue
• Mechanical digestion in the mouth


  Use of canines and incisors for cutting and tearing of food
• Saliva

  Contains ptyalin, also known as salivary amylase, which softens the food and converts the starch in the food we eat into a simple sugar called maltose while chewing
• Pharynx

  Muscular hollow tube found at the region of the neck, a passageway of the ball of food mixed with saliva, known as the bolus, to the esophagus
• Divisions of the pharynx

  • Nasopharynx
  • Oropharynx
  • Hypopharynx
• Esophagus


  Passageway of food from the pharynx to the stomach with the use of peristalsis
• Peristalsis

  A wave of muscular contractions that push the masticated food (bolus) down towards the stomach
• Stomach


  Food goes to be chemically digested
• Cardiac sphincter


  An opening in the stomach that allows food to get inside the esophagus and closes to prevent backflow of food and digestive enzymes
• Stomach digestion

  Churns, squeezes, and mixes food which contributes to the mechanical digestion and uses enzymes to chemically digest it
• Gastric glands


  Found in the lining of the stomach, produce gastric juices
• Pepsinogen


  Produced by chief cells in the stomach, transformed into pepsin, an enzyme that breaks down proteins into peptides in an acidic environment
• Hydrochloric acid (HCl)


  Activates pepsinogen and is important for the destruction of microorganisms left in the food
• Rennin


  Also called as chymosin, curdles milk in the stomach
• Mucin

  Also called as mucus, protects the lining of the stomach from its own acid, also present in the esophagus as a lubricant
• Stomach digestion


  Food stays in the stomach for six hours where it is being thoroughly digested until it becomes chyme, a semisolid form of digested food, then goes to the pyloric sphincter and the duodenum
• Jejunum


  The longest part of the small intestine, where nutrients are mainly absorbed with the tiny hair-like projections in the intestinal wall called villi
• Large Intestine

  Undigested food is deposited here for water reabsorption and some vitamins and electrolytes
• Pancreas

  Secretes pancreatic juice that enables the acidic content of the chyme to be neutralized before they go into the rest of the small intestine
• Bile


  An enzyme that breaks downs fats into tiny droplets so that it can be absorbed easily
• Parts of the large intestine

  • Cecum
  • Ascending colon
  • Transverse colon
  • Descending colon
  • Sigmoid colon
• Mucus


  Present in the large intestine to lubricate the food as it goes to the rectum and to the anus