Digestive System

Mouth Esophogus Liver Anus Stomach Pancreas Large intestine Small intestine Rectum

Digestion: Accessory Organs Liver Gall Bladder Pancreas

Chemical Environment of the GI Tract Neutral in mouth -(pH approx 7) Acid in stomach -(pH approx 2) Neutral in small intestine - (pH approx 7)

Digestion The process of PHYSICALLY and CHEMICALLY… Changing the composition of food in the digestive tract and the process of reducing nutrients to particles usable by cells.

Digestion: Physical Changes Grinding and mixing by teeth (MASTICATION) in the mouth and muscular actions of the stomach and small intestine and…Grinding and mixing by teeth (MASTICATION) in the mouth and muscular actions of the stomach and small intestine and… Liquefying by the addition of water and digestive juices in the mouth, stomach and small intestine (GASTROINTESTINAL TRACT/ GI TRACT)Liquefying by the addition of water and digestive juices in the mouth, stomach and small intestine (GASTROINTESTINAL TRACT/ GI TRACT)

Digestion: Chemical Changes Complex nutrients are broken down into particles usable by cells:Complex nutrients are broken down into particles usable by cells: -Starch and disaccharides to monosaccharides -Proteins to amino acids -Fats to fatty acids to glycerol Chemical changes occur because of digestive enzymesChemical changes occur because of digestive enzymes

Enzymes Big food molecules can’t pass through cell walls.Big food molecules can’t pass through cell walls. ENZYMES are used to break up big molecules into small ones (they act like chemical scissors).ENZYMES are used to break up big molecules into small ones (they act like chemical scissors). These small molecules can pass through the wall of the small intestine into the blood. They then pass into cells and are used.These small molecules can pass through the wall of the small intestine into the blood. They then pass into cells and are used.

Big food molecules can’t pass through cell walls. ENZYMES are used to break up big molecules into small ones (they act like scissors). These small molecules can pass through the wall of the small intestine into the blood.

Digestion: Mouth Physical Changes: -Teeth grind food -Salivary glands add water Chemical Changes: -Salivary amylase

Digestion: Esophagus Transport tube Muscular (muscular contractions move the food peristalsis) Enables swallowing to move bolus (food) from the mouth to the stomach No enzymes added

Digestion: Stomach pH Shift -Inflow of gastric juice containing HCL (hydrochloric acid) -pH rapidly decreases Mucus (thick fluid) helps soften and lubricate food Protein digestion starts with the enzyme pepsin starting this The mixture of food and juices is called chime

Digestion: Release from stomach to small intestine (SI) Chime released in small bolus to small intestine -fat slows the release from the stomach Hormones stimulated by the arrival of chime in SI cause contraction of gall bladder (accessory organ) and release of pancreatic juice (accessory organ) Bile, which is released by the liver, aids in fat digestion

Digestion: Large Intestine The small intestine is connected to the large intestine (3.5 feet long in the body) Water is reabsorbed with the aid of bacteria which also help make vitamins Solid wastes called feces leave through the rectum and then finally out the anus

Match the organ to its function!! Mouth 1. This is where water is absorbed. Gullet 2. Makes bile which breaks up fats and it is alkaline to give the right pH for the enzymes in the S. intestine. Stomach 3. Makes all 3 enzymes. Liver 4. Mixes the food with enzymes that digest proteins AND contains acid to kill bacteria. Pancreas 5. Produces more enzymes AND this is where the food is absorbed through the gut wall into the blood. Small intestine 6. Chew and mix the food with saliva (contains enzymes). Large intestine 7. Links the mouth to the stomach. Rectum 8. Here food that can’t be digested is stored as faeces and then leaves through the anus.

Well Done!!