Chapter_15-review_sheet.docx

Chapter 16: The Digestive System Label the diagram below: What is the digestive system composed of? Consists of a tube that extends from the mouth to the anus and accessory organs What are the 4 accessory organs and what are their functions? Salivary glands – Three pairs of glands that secrete saliv...

Chapter 16: The Digestive System Label the diagram below: What is the digestive system composed of? Consists of a tube that extends from the mouth to the anus and accessory organs What are the 4 accessory organs and what are their functions? Salivary glands – Three pairs of glands that secrete saliva, moistens food, enzyme (amylase) in saliva begins starch digestion Liver – secretes bile Gallbladder – small sac that stores bile, releases bile into intestine Pancreas – gland located behind stomach Secretes enzymes that digest all major nutrients Secretes bicarbonate ions that neutralize acid from stomach Releases secretions into small intestine What is the function of the salivary glands? Three pairs of glands that secrete saliva, moistens food, enzyme (amylase) in saliva begins starch digestion Where does the chemical digestion of carbohydrates begin? Begin in the mouth Label the diagram: Discuss the 4 layers of the digestive tube. Mucosa – The lining of the tube (epithelial cells) 1 Submucosa – is a layer of connective tissue that contains blood vessels, lymph vessels, and nerves 2 Muscularis – is made up of two layers of visceral or smooth muscle 3 Serosa – outer connective tissue covering that secretes a fluid to lubricate the outside of the GI tract 4 Mouth – opening to the digestive tube Palate – roof of the mouth; it separates the oral and nasal cavities Uvula – flap that hangs from the soft palate. It moves backward during swallowing to keep food out of the nasal cavity. Tongue – moves the food around to assist in chewing. It contains taste buds that allow tasting of different types of foods. Teeth – breaks the food into smaller pieces. Different types cuspids, tear, incisors, biting, canines, tearing, premolar, crushing, molars, grinding What is the difference between mechanical digestion and chemical digestion? Mechanical digestion – chewing Chemical digestion – salivary amylase acts on carbohydrates breaking them to disaccharides What is a bolus? A soft mass of food, suitable for swallowing The tongue helps form the bolus Describe the swallowing process Swallowing pushes the bolus into the esophagus Esophagus – tube that carries food to the stomach Epiglottis – cartilage flap that closes off the airway to keep food from entering the trachea. Peristalsis – muscular contractions pushes food Lower esophageal sphincter – relaxes as food approaches Gastroesophageal Reflex Disease – GERD, Lower esophageal sphincter fails to close and allows stomach acid to enter esophagus and cause heartburn Define gastrin, gastric juice and pepsin. Stomach – storage area for food, j shaped muscular organ Muscularis – contains 3 layers of muscle Longitudinal Circular Oblique Mucosa – has folds called rugae Stomach contains gastric glands that produce gastric juice Pepsin – helps starts the chemical breakdown of proteins Gastrin – a hormone made by stomach that stimulates the gastric glands Gastric juice – contains pepsinogen and HCl (pepsin) Where does chemical digestion of proteins begin? Chemical digestion of proteins begin in the stomach Define chyme. Chyme – a soupy acidic mixture of food and gastric juice Label the diagram below: Name and describe the three phases of gastric digestion. Cephalic Phase – in the first phase, thoughts of food and the fell of food in the oral cavity stimulate increased secretion from the gastric pits. The stomach begins to churn more actively in preparation for the incoming food Gastric Phase – When the bolus reaches the stomach, the second phase of gastric digestion begins. Here the stomach produces gastrin as well as continuing the production of pepsin and HCI. Gastrin aids in stimulation of the gastric pits, providing a feedback system that speeds digestion also go back to the brain, maintaining contact with the nervous system. Intestinal Phase – In the final phase of gastric digestion, the chyme begins to leave through the pyloric sphincter. As the chyme leaves the stomach, gastrin production decreases, the impulses to the brain indicate a lessening of chyme, and the brain begins to slow the stimulation of the gastric pits. Label the diagram below: Name the three parts of the small intestines. Duodenum – upper portion, pyloric sphincter controls the food going into the duodenum. Jejunum – middle portion Ileum – last part that joins the large intestines. Small intestines – part of the digestive tube where most of the digestive process occurs. It is also where digestion is completed and absorption occurs Define villi. Finger like projections in the mucosa. Each villus contains blood vessels, lacteals, and goblet cells to secrete mucus Plicae circulares – permanent folds in the mucosa What are the functions of Villi, Lacteals and Blood vessels? Villi – absorb nutrients and secrete enzymes that complete digestion Lacteals – absorbs fats Blood vessels – absorb all other nutrients except fats Explain how digestion is completed and where absorption occurs. How is the absorption of fats different from other substances? Label the diagram below: Define bile. How is it produced and where is it stored? Bile – emulsifies fats, breaks fats into fat droplets The liver produces bile The bile is stored in the gallbladder What is pancreatic juice? What does it contain? The pancreas produces pancreatic juice Sodium bicarbonate – neutralizes stomach acid Trypsin – break down proteins Pancreatic amylase – breaks down carbohydrates Pancreatic lipase – breaks down fats Describe carbohydrate, protein and fat digestion. Chemical digestion of carbohydrates begin in the mouth with salivary amylase and ends in the small intestines by enzymes from the pancreas and enzymes produced by the villi Chemical digestion of proteins begin in the stomach with pepsin and ends in the small intestines by enzymes from the pancreas and enzymes produces by the villi Chemical digestion of fats begins and end in the small intestines Bile breaks fats into fat droplets, micelles Lipase breaks down fats into glycerol and fatty acids Fatty acids are covered with proteins called chylomicrons What are the functions of Gastrin, Secretin and CCK? Gastrin – stimulates the gastric glands to make gastric juice Secretin – made by the small intestines, stimulates the pancreas to release sodium bicarbonate and the liver to make bile Cholecystokinin – CCK, made by the small intestines, stimulates the pancreas to make digestive enzymes and stimulates the gallbladder to contract releasing bile How does the liver function in the body? Produces bile – digestion process Largest organ in the body Detoxifies the blood Composed of 100K lobules Hepatocyte – liver cell Stores iron and fat soluble vitamins A, D, E, and K Produces plasma proteins Stores glucose as glycogen Help regulates the amount of cholesterol in the blood What are the four parts of the large intestine? Abosrorbs water, salts, and vitamins form the digestive tract and return it to the body Ascending colon – runs up the right side of the abdominal cavity Transverse colon – cuts across the top of the abdominal cavity, underneath the stomach Descending colon – on the left side of the abdominal cavity, Sigmoid colon – At the lower left of the abdominal cavity, the colon turns back down makes an S turn to wind up in the center of the body This portion of the colon is where feces may sit for long periods of time before moving out the rectum Cecum- upper part of the large intestines that joins the small intestines Vermiform appendix – pouch on the cecum Colon – ascending, transverse, and descending Rectum – holds feces temporarily and opens into the anus Anus – sphincter muscles controls defecation, reflex action Feces – waste material, ¾ water and ¼ solids, usually brown in color due to bilirubin Define E.coli. Escherichia coli – E. Coli, bacteria break down waste producing gas Produce vitamin K, blood clotting What are polyps? Polyps can develop in the colon as feces rest against the mucosa Growths in the epithelial lining Enzymes – large molecule of food enters the digestive system Enzyme binds to food, substrate molecules Enzyme uses H2O to splite the substrates molecule, leaving and OH- on one product molecule and an H+ on the other