Digestive System

• Digestive system


  Involved in the breakdown of food into simpler substance to be absorbed by the body
• Organs of the digestive system

  • Mouth
  • Pharynx
  • Esophagus
  • Stomach
  • Small intestine
  • Large intestine
  • Anus
• Mouth


  • Upper and lower jaws which contains your teeth
  • Upper jaw is fixed
  • Lower jaw is movable, helps in chewing food
  • Saliva is secreted as we chew our food
• Boli (Bolus)


  The slippery mask produced on the partially digested food
• Pharynx


  • Common passage for food and air
  • Part of our respiratory system
  • Leads the food from the mouth to the esophagus or trachea
• Epiglottis


  Structure that prevents food from entering the trachea
• Esophagus


  • A narrow, muscular tube that carries food you have swallowed to the stomach
  • Peristalsis: Wavelike contractions that happen on the esophagus to help food go down to the stomach
• Stomach


  • A J-shaped organ
  • Where the partially digested food enters
  • Food in the stomach stimulates the gastric glands to secrete gastric juice into the stomach cavity
  • Once the stomach detects food, they secrete juices to help break down the food
• Gastric juices


  • Hydrochloric acid
  • Pepsin
• Chyme


  The form the food is converted into after being broken down in the stomach
• Gastrointestinal tract


  Another term for the digestive tract
• Small intestine


  • Longest tube in the gastrointestinal tract, 6 to 7.6 meters in total length
  • Connects the stomach to the large intestine
  • Its main function is to digest food further and absorb its nutrients
• Parts of the small intestine

  • Duodenum
  • Jejunum
  • Ileum
• Large intestine


  • Main function is to absorb water and mineral salts from the undigested food material
• Parts of the large intestine

  • Cecum
  • Appendix
  • Colon (ascending, transverse, descending)
• Rectum


  • Storage of remnants of food materials
  • Contains bacteria, which is why it smells bad
• Anus


  The end of the gastrointestinal tract where waste is eliminated
• Accessory organs and glands

  • Tongue
  • Salivary glands
  • Pancreas
  • Liver
  • Gallbladder
• Tongue


  • Has special sense cells called taste buds
• Salivary glands


  • Releases saliva
  • Saliva contains the enzymes mucin (softens food) and ptyalin (breaks down starches)
• Starches


  Long chains of complex sugar
• Liver


  • Largest gland in our body
  • Produces bile
• Bile


  • Breaks down fatty acids from the food we eat
  • Temporarily stored in the gallbladder
• Gallbladder


  • A small organ located beneath the liver where bile is temporarily stored
• Pancreas


  • Produces pancreatic juices, a mixture of digestive enzymes that help break down proteins, starches, and fats
  • Produces insulin (lowers sugar) and glucagon (increases sugar)
  • Part of both the endocrine and digestive systems
• Stages of food processing

  • Ingestion
  • Digestion
  • Absorption
  • Elimination
• Ingestion


  Food intake
• Digestion


  Process of mechanical and chemical breakdown of food to get necessary nutrients
• Distinct processes of digestion

  • Physical digestion (chewing, stomach)
  • Chemical digestion (breaking down proteins, starches, fats)
• Absorption


  Where nutrients from food are absorbed into the bloodstream
• Elimination


  Releasing of materials that will not be used by the body
• Feces


  The materials that are not absorbed by the large intestine, composed of dead bacteria, some fat and protein
• Defecation


  The process of eliminating waste materials
• Time food stays in digestive structures

  • Mouth: 5-30 seconds
  • Esophagus: 7-10 seconds
  • Stomach: 2-24 hours
  • Small intestine: 3-5 hours
  • Large intestine: 18 hours-2 days
• Unhealthy diet and improper eating habits may lead to digestive disorders, which is caused by our modern lifestyle
• Gastrointestinal diseases


  Diseases of the digestive system
• Symptoms of gastrointestinal diseases

  • Change in bowel habits
  • Sudden weight loss
  • Severe abdominal pain
  • Blood in the stool
  • Heartburn and release of gas
• Diarrhea


  • Occurs when the lining of the large intestine cannot maintain the usual level of water absorption
  • Caused by bacteria salmonella and amoeba
  • Results in dehydration
  • Can be prevented by proper handwashing
• Salmonella and amoeba


  Invade the lining of the large intestine and destroy the cells that absorb water
• Constipation


  • Happens when the stool moves too slowly in the colon
  • Can be relieved by drinking water and eating foods high in fiber