Mechanical Digestion (breaking food into smaller pieces) Teeth: breaks down food Tongue: moves food around mouth Chemical Digestion (bonds are broken) Saliva contains three things… Water Mucus Salivary amylase = starch digesting enzyme
Pharynx Pharynx (throat): chewed food is pushed by the tongue to the back of the throat which starts the swallowing reflex. Epiglottis: a flap of tissue that prevents food and liquids from entering the trachea during swallowing.
Esophagus Esophagus: the tube through which food passes from the pharynx to the stomach. Peristalsis: the movement of food is aided by alternate waves of relaxation and contraction of muscles lining the esophagus.
Stomach: protein digestion starts here Chemical digestion: the stomach contains two types of glands… Pyloric glands: secrete mucus which protects the stomach from acid and enzymes Gastric glands: secrete hydrochloric acid and the protein digesting enzyme pepsin. Mechanical digestion: food is broken down by contractions of the stomach muscle
Sphincter: Cardiac sphincter: a valve between the esophagus and stomach. Keeps food and acid in stomach. Pyloric sphincter: a valve between the stomach and small intestines.
The small intestines have a great amount of surface area for maximum absorption. This surface area is due to… 1. The small intestines are very long… 6.5 meters or ___ feet. The small intestines have villi which are finger like projections.
Absorption of nutrients occurs by diffusion and active transport through the walls of the cells lining the small intestine. Simple sugars, amino acids, vitamins and minerals are absorbed into the capillaries. Fatty acids and glycerol are absorbed into the lacteals
Large intestines: NO digestion occurs here The large intestine has three functions: 1. Reabsorbs water 2. Absorbs vitamins that are produced by bacteria Eliminates undigested and indigestible materials.
Pancreatic Juice: Secreted by the pancreas Passes through the pancreatic duct into the small intestines Pancreatic juice contains Sodium bicarbonate: helps neutralize stomach acid Enzymes: to digest carbs, fats, and proteins
Bile Secreted by the liver Stored in the gall bladder Passes through the bile duct into the small intestines. Bile mechanically breaks down (emulsifies) fats and oils.
Intestinal Juice Secreted by the small intestines Intestinal juice contains: Enzymes: which digest carbs, proteins, fats, and nucleic acids.