1. DIGESTIVE SYSTEM

2. DIGESTIVE SYSTEM 4 Stages of Food Processing INGESTIONAct of eating and drinking DIGESTION (2 Types) Process of breaking down food into smaller molecules for the body to absorb Example: Polysaccharides  monosaccharides Example: Proteins  Amino acids 1.Mechanical Digestion: Chewing to increase surface area 2.Chemical Digestion: Breaks chemical bonds to make smaller molecules Enzyme- amylase (saliva - mouth)

3. 4 Stages of Food Processing ABSORPTIONWhen cells take up small molecules  Circulatory system sends these molecules around the body ELIMINATIONUndigested materials are passed out of the body

4. The Role of Each Organ in Digestion MOUTH 1 st stage of digestion (Ingestion) Both types of digestion (Chemical & Mechanical) Saliva- Contains enzymes (Amylase) Enzymes (Amylase) breaks down starch (carbohydrates) into smaller units PHARYNX Upper part of the throat Junction area for food and air Junction of alimentary canal & airway (trachea) Epiglottis seals off the airway & prevents food from entering ESOPHAGUSConnecting tube to stomach Muscle contraction called peristalsis moves food Voluntary muscle movement at top Involuntary muscle movement toward bottom Moves bolus toward stomach

5. The Role of Each Organ in Digestion STOMACH Elastic, muscular sac (Can hold up to 2 L of food) Gastric juice bathes the bolus Gastric juice – Mixture of enzymes, mucus, and hydrochloric acid  Cells are broken apart; pepsin hydrolyzes large protein molecules into smaller polypeptides Mechanical Digestion- Stomach contraction  Bolus is turned into an acidic liquid = Chyme

6. The Role of Each Organ in Digestion SMALL INTESTINE Long and narrow tube where digestion is completed and absorption of most nutrients occurs Peristalsis – moves chyme along the small intestine Digestion occurs in the 1 st section; absorption occurs throughout Chyme mixes with bile in the duodenum – 1 st part of the small intestine End result of digestion  Carbohydrates broken down into monosaccharides (Providing cells with energy; Source of carbon skeletons for constructing other organic molecules Complete digestion of proteins  Amino acids  Cells then use these amino acids to build their own proteins Hydrolysis of fats by the enzyme – lipase  Fatty acids and glycerol  Cells use these raw materials to build their own lipids

7. The Role of Each Organ in Digestion SMALL INTESTINE Highly specialized for absorbing nutrients into the circulatory and lymphatic systems for transport Wall of the small intestine – villi  microvilli  increases the total surface area of the small intestine to the size of a tennis court Each villus has a small lymph vessel and a network of capillaries Lymph vessel transports fat Sugars and amino acids are absorbed into the bloodstream through the capillaries in each villus

8. The Role of Each Organ in Digestion LARGE INTESTINE Also called the colon  Wide, short tube Contains bacteria that produce vitamin K & several B vitamins Reabsorbs water… Saliva, gastric juices, etc  All contain large amounts of water (7L of fluid is secreted into the alimentary canal each day)  Much of the water and nutrients are reabsorbed in the small intestine  Large intestine finishes the job 90% of the water that enters the alimentary canal is reclaimed by the small and large intestine Feces – undigested food material and other wastes are produced here Peristalsis moves the material along

9. The Role of Each Organ in Digestion LIVER Body’s largest INTERNAL organ (Skin = largest organ overall) Produces bile * Bile contains no enzymes  it simply helps prepare fats for digestion  prevents the formation of large clumps which enables digestive enzymes to break the fats down more efficiently Filters toxins out of the blood Stores excess glucose as glycogen

10. The Role of Each Organ in Digestion PANCREAS Produces and secretes pancreatic juice into the duodenum  Neutralizes the acid chyme and contains enzymes that break down carbohydrates, proteins and lipids Produces insulin * Diabetes GALLBLADDER Bile is stored in this sac like structure