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THE DIGESTIVE SYSTEM LG: I can explain each phase of digestion and explain the role of each organ in the process
4 main parts to digestion 1) INGESTION • Food is taken into the body. 2) DIGESTION- • Food is broken down • physically (chewing, grinding) • chemically (reactions using enzymes) 3) ABSORPTION- • Nutrients diffuse or are moved into the blood and made available to cells 4) ELIMINATION- • Solid wastes pass from the digestive system out of the body. Entire process from INGESTION to ELIMINATION takes about 20-30 hours.
Step 1 Ingestion takes place as food enters the mouth. Digestion begins with chewing, as the tongue, teeth and saliva break down the food (physical and chemical digestion)
Step 2 Esophagus pushes the food into the stomach using wave-like muscular contractions. No digestion takes place here.
Step 3 Stomach muscles contract to mix the food. Stomach releases chemicals and acids to help break down the food. Physical and chemical digestion.
Step 4 Digestion continues in the small intestine. Nutrients from the food are absorbed into the bloodstream here.
Step 5 Undigested food passes into the large intestine where water and some nutrients are reabsorbed.
Step 6 Any undigested materials are called feces. Feces are stored in the rectum and eliminated through the anus.
Health Check! The colour and texture (consistency) of poop can can tell you a lot about your health A quick scan of the toilettells you which materials your digestive system can break down and which it can’t Check before you flush!
Colour Scale • Brown/Green – normal • contains bile pigments • green can mean food is moving too quickly • Yellow – contains fat (usually strong odor) • bile duct blockage prevents fat from being digested • White – contains no pigment • can be a sign of gall stones or pancreatic cancer • Red – contains fresh blood • Hemorrhoids • bleeding in lower digestive tract (no time to clot) • Black – Contains clotted blood (melena) • bleeding in upper digestive tract/ulcers • Iron supplements or high meat diet
Consistency Types 1–2 indicate constipation Types 3-4 ideal Types 5-7 indicate diarrhea
Practice questions 1. Identify four phases of digestion. 2. Show the path that a hamburger follows from the time you eat it, identify each stage digestion and the organs involved. 3. If a person needs to have part of his or her small intestine removed, how might this affect digestion?