Science first quiz

• Digestive System


  Main groups: Alimentary Canal, Accessory Organs
• Alimentary Canal


  • Mouth Cavity
  • Pharynx
  • Esophagus
  • Stomach
  • Small Intestine
  • Large Intestine
• Accessory Organs


  • Salivary Glands
  • Liver
  • Gall Bladder
  • Pancreas
  • Tongue
  • Teeth
• Accessory Organs


  They are called accessory organs because even though they are not part of the digestive system, they also play an important role
• Digestive System


  Breaks complex molecules down into smaller, simple molecules that can be absorbed by the bloodstream
• Digestive Processes


  • Mechanical Phase - Breaking up of food into smaller pieces, pushing down food into the food tube
  • Chemical Phase - Breaking of larger molecules to simpler molecules by the action of digestive enzymes
• Mechanical Digestion


  The physical breaking down of food
• Crushing the candy to smaller pieces affects its dissolution
• Crushing the candy represents the process of digestion
• Man's Food Tube


  • Mouth Cavity
  • Pharynx
  • Esophagus
  • Stomach
  • Small Intestine
  • Large Intestine
• Main Digestive Processes


  • Ingestion - Intake of food
  • Digestion - Breaking down of food so it can be absorbed
  • Absorption - Process of absorbing food in the form of nutrients into the bloodstream
  • Assimilation - Process of nutrients being absorbed by each cell of the body in the form of energy
  • Excretion - Secretion of waste, unwanted and excess substances from the body after food has been digested
• 4 kinds of Teeth: • Incisor- cutting food • Canine- tearing meat • Molar and Premolar - crushing food
• Parotid gland is located on both sides of the face behind the ears.
• Sublingual gland is located under the tongue.
• Submandibular gland is located below the mandible (lower jaw).
• Alimentary Canal is also called Man's Food Tube
• The pharynx is the passageway between the back of the nose and throat to the esophagus and larynx.
• Esophagus is a muscular tube that carries food from the pharynx to the stomach.
• Pharynx • Common organ between the digestive and respiratory organ.

  • Epiglottis- flap-like structure that closes when we swallow food.
• Esophagus

  Peristalsis- wave-like contraction of the food tube

  • Bolus- soft mass of chewed food

  • Anti-peristalsis- reverse movement of the esophagus
• MAIN PROCESSES: • Digestion –Breaking down of food sot that it can be absorbed by the body.
• Stomach • Rugae- allow the stomach to expand; increases the capacity to store food.. • Cardiac Sphincter • Pyloric Sphincter
• Stomach: • CS- controls passage of chewed food • PS- temporarily store food mass in the stomach • Chyme- semi-fluid which leaves the stomach in squirts
• Small Intestine • The secretions of liver, gall bladder, and pancreas are poured into duodenum, jejunum and some parts in the ileum • Bile- bitter substance produced by the liver; “emulsify fats
• Large Intestine • Reabsorbs water from the indigestible materials. • Cecum- junction of the small intestine and colon. • Rectum- is the terminal portion, where feces are stored until they can be eliminated through the anus.
• Humans need to have a balanced diet which contains a variety of different types of food
• Main nutrients the body needs

  • Carbohydrates for energy
  • Proteins for growth and repair
  • Fats to store energy
  • Vitamins and minerals to keep the body healthy
• The amount of each food type needed is related to the proportions in the food pyramid
• Carbohydrates


  Long chains of identical, small sugar molecules that the body breaks down to release energy and make the body work
• Proteins


  Made up of chains of small molecules called amino acids, used by the body for growth and repair
• Fats


  Made up of fat molecules containing fatty acids and glycerol, used by the body for energy storage and to keep heat in and make cell membranes
• Large food molecules cannot pass through the walls of the small intestine, but small food molecules can when dissolved in the bloodstream
• The body carries out digestion of food to convert large insoluble food molecules into smaller soluble ones
• The process of digestion

  1. Food enters the stomach

  2. Chemical breakdown of food begins, microbes are destroyed

  3. Food enters the small intestine where digestion is completed and small digested food molecules are absorbed into the bloodstream

  4. Undigested waste travels to the large intestine where water is absorbed, then to the rectum and out of the body
• Digestive enzymes


  Chemicals that break large insoluble food molecules into smaller soluble molecules
• Main types of digestive enzymes

  • Carbohydrase - breaks carbohydrates into smaller sugars
  • Protease - breaks proteins into amino acids
  • Lipase - breaks fats into fatty acids and glycerol
• How carbohydrase enzymes work


  Break the chemical bonds between the individual sugar molecules in each carbohydrate chain
• How protease enzymes work

  Break proteins into smaller amino acids in an acidic environment
• How lipase enzymes work


  Break fat molecules into smaller glycerol and fatty acid molecules, after bile emulsifies the fat
• Liver: • Produce bile (bitter) • Store glycogen • Regulate blood sugar level • Remove toxic substances from the bloodstream