2The Start of Digestion The Mouth Food enters here The Teeth mechanically breaks down foodThe Tongue Chemically recognizes food. Moves food around the mouth. Assists in swallowingSalivary Glands Releases Saliva into the mouth. Saliva starts chemical breakdown and moistens food for swallowing.
3The Pharynx The area in the very back of the mouth that receives air from the nasal cavities (air from the nose) and food from the mouth.Esophagus The food tube. The tube that goes from the mouth to the stomach. Many muscles surround this tube to help swallow. When muscles work to swallow its called PeristalsisTrachea Tube that goes down to the lungs to breath. This has cartridge rings so it is always open.Epiglottis covers the Trachea when swallowing so food does not go down into the lungs.
5During swallowing the Trachea moves up and forces the Epiglottis to close over the trachea’s opening
6SwallowingStep 1: food is chewed in the mouth. Saliva is added for lubrication. Saliva also contains the digestive enzyme Salivary amylase. This enzyme breaks down starches into disaccharides like maltoseStep 2: Food is turned into a Bolus ( a ball of food) and pushed back of mouth by tongue.Step 3: Muscles move the bolus down the esophagus. This is called peristalsis. The trachea moves up and the epiglottis closes access to the trachea. A muscle in the pharynx closes access to the nasal cavity
9Into the StomachThe bolus moves down the esophagus and into the stomach.The cardiac sphincter prevents the food from going from the stomach back up the esophagus.A sphincter is a muscle that goes around a tube to act as a valve.The cardiac sphincter is located at the joining of the stomach and the esophagus
10Gastric Juice Contains: The stomach has many gastric glands the release gastric juices into the stomachGastric Juice Contains:Pepsin enzyme breaks proteins to peptidesHCl acid the acid kills some bacteria, activates pepsin, and breaks up food (but does not digest)Mucus slime that covers your stomach wall to protect it against the acidMuscles around the stomach help mix the food with the gastric juices
12Into the Small Intestine After the stomach the pyloric sphincter opens and lets Chyme pass on into the small intestineThe first part of the small intestine is called the duodenumThe duodenum has ducts that enter the duodenum that release many different chemicals
13Duodenum releasesBile comes from liver. Bile is often stored in the Gall Bladder Emulsifies fat.Pancreatic JuicesJuices from the organ called the pancreasSodium bicarbonate NaHCO3 turns the acidic chyme basicPancreatic amylase breaks down starch into disaccharides. Enzyme.Trypsin breaks down protein into peptides. EnzymeLipase breaks down fat. EnzymeNuclease breaks down nucleic acid into nucleotides
15The small intestine is designed to absorb nutrients. It has a huge surface area. This is because the inside of the small intestine has finger-like projections called villi. Each villi has finger-like projections called microvilliThe small intestine has a thin layer of mucus over it. Under the mucus are the villi and microvilli. Sugars and amino acids pass through the mucus and get moved into the blood vessels.
16Enzymes of the Small Intestine The small intestine has many enzymes that work there to help let materials pass through the wall of the small intestineMaltase digests maltose into glucosePeptidase digests peptides into amino acidsNucleosidases digests nucleotides into bases, sugar, and phosphate
17Amino acids, sugars, and components of nucleotides, move into the blood by going through the microvilliThe parts of Fat (glycerol and fatty acids ) get moved into the Lacteal.The lacteal is part of the lymphatic system.
20Moving into the Large Intestine The Large Intestine is shorter in length but wider in diameterMade up of several partsAscending colon – part of colon that goes upTransverse colon – part of colon that goes along sideDescending colon – part of colon that goes downCecum – attached to ascending colon. Goes nowhereAppendix – attached to cecum. Can get infected.Rectum – where all the feces is stored. End of colon.Anus – the muscular opening to expel feces.
22What happens in the Large Intestine The large intestine is full of bacteria. A lot the bacteria are anaerobic bacteria.Anaerobic bacteria bacteria that do not use oxygen. Bacteria that will die in the presence of oxygen.These bacteria break down indigestible materials. They also produce some vitamins that are then absorbed by the large intestine wall.The large intestine absorbs water out of the waste
24Review Salivary Glands Stomach Pancreas Salivary amylase, moistens foodStomachGastric Juices: Pepsin, HCl, MucusPancreasPancreatic Juices: NaHCO3, Trypsin, LipaseInsulin hormone is secreted into the bloodThis hormone tells cells in the body to take up glucoseThis hormone is released after eating when there is high glucose levels in the blood
25Pancreas Blood glucose levels are high releases Insulin Insulin causes cells to take up glucoseBlood glucose levels are low releases GlucagonTells body to break down glycogen into glucose. Glycogen is found in the liverTells body to break down fat into glycerol and fatty acids.
26Liver Makes Bile Removes any poisons from the blood Stores Iron and many vitaminsStores glycogen. This can be made into glucoseRegulates blood cholesterol levelsProduces Urea:2NH3 + CO2 H2N-C-NH2 + H2O=O
27Optimal pH for the Enzyme LocationpHSalivary AmylaseMouth. Salivary GlandNeutralPancreatic AmylaseDuodenum. PancreasBasicPepsinStomachAcidicTrypsinPancreas. DuodenumPeptidaseSmall IntestineNucleaseNucleosidaseLipasePancreas, Duodenum