Digestive system

• Digestive Tract/Food tube/Gastrointestinal tract

  • Mouth Buccal Cavity
  • Esophagus
  • Stomach
  • Small Intestine
  • Large Intestine
  • Rectum
• Digestive Tract


  • Direct path between organs
• Mouth Buccal Cavity


  Mechanically break down food
• Teeth


  • Incisors
  • Canine
  • Premolars
  • Molars
• Incisors


  Front teeth with sharp edges, bite food
• Canine


  Sharp fangs, tearing food
• Tongue


  Mixes food with saliva
• Amylase/Ptyalin


  Saliva contains it
• Epiglottis


  Flap-like structure at the back of throat, closes to prevent food entering trachea
• Esophagus


  20cm long tube from pharynx to stomach, moves food via peristalsis, can cause heartburn if acid from stomach enters
• Cardiac Sphincter


  Relaxes to allow food into stomach
• Stomach


  Stores food and breaks it down with digestive juices
• Digestive Juices in Stomach

  • Hydrochloric Acid
  • Pepsinogen (converted to Pepsin)
• Chyme


  Food in the stomach
• Small Intestine


  6 meters long, final digestion and absorption of nutrients
• Divisions of Small Intestine

  • Duodenum
  • Jejunum
  • Ileum
• Villi


  Lining of intestine walls, covered in microvilli to increase surface area for absorption
• Large Intestine


  1.5 meters long, accepts undigested material from small intestine, absorbs water, stores feces
• Parts of Large Intestine

  • Ascending Colon
  • Transverse Colon
  • Descending Colon
  • Rectum
• Accessory Digestive Glands


  • Liver
  • Gall Bladder
  • Pancreas
  • Salivary Glands
• Liver


  Largest accessory gland, produces bile to help digest fat, filters toxins
• Gall Bladder


  Stores and releases bile into small intestine, can cause gallstones
• Pancreas


  Produces digestive enzymes, regulates blood sugar by producing insulin
• Salivary Glands


  Produce saliva for mastication, swallowing, speech, taste, and digestion (amylase and ptyalin)
• Enzymes


  Proteins that speed up chemical reactions without being consumed or permanently altered, affected by temperature, require activation energy
• Substrate


  The enzyme's reactant
• Active Site


  The part of the enzyme that binds to the substrate
• Enzymes for Carbohydrate Digestion

  Amylase, Lactase, Sucrase
• Protein Digestion


  Mechanical digestion in mouth, chemical digestion begins in stomach and continues in small intestine, broken down into amino acids
• Fat/Lipid Digestion


  Bile from gall bladder emulsifies fats, pancreatic enzymes break down fats into fatty acids and glycerol in small intestine
• Nucleic Acid Digestion


  Begins in small intestine, broken down into nucleotides and then into pentose sugars and nitrogenous bases
• Health Problems Related to Digestion

  • Indigestion/Dyspepsia
  • Constipation
  • Diarrhea
  • Heartburn/Acid Reflux
  • Ulcers
  • Flatulence
  • Colitis
• Cell is the basic unit of structure and function of life
• Types of Cells


  • Prokaryotic
  • Eukaryotic
• All organisms are made of cells, all cells come from pre-existing cells
• Cell Division


  Production of new cells, including mitosis in somatic cells and meiosis in reproductive cells
• Phases of Cell Cycle

  • G1 Phase
  • S Phase
  • G2 Phase
  • M Phase
• Checkpoints


  Features that ensure ordered progression through the cell cycle
• Chromosomes


  Thread-like structures in the nucleus made of protein and DNA, contain genes
• DNA


  Deoxyribonucleic acid, the molecular blueprint for life, made up of 4 nitrogenous bases (A, T, G, C)