Digestive System Study Guide (Answers)

Study guide for the Digestive System 1. What membranes cover the digestive organs? What are the tunics or layers of the tissue in digestive organs walls? Visceral Peritoneum is the membrane that covers digestive organs. The four tunics, or layers, of tissue in digestive organ walls are Serosa, Muscularis, Submucosa, and Mucosa. 2.Know the function of the mouth, tissue type. Know how many baby teeth, permanent teeth. Mouth Function: Ingestion Mouth Tissue Type: Stratified Squamous Epithelium # of Baby Teeth: 20 # of Permanent Teeth: 32 3.Know about the tongue muscles (intrinsic, extrinsic), papillae. Tongue Function: Speech, food position, taste Muscles that help move the tongue: Intrinsic muscles: Change shape of the tongue Extrinsic muscles: Change tongue position Papillae - Peg like projection, bumps on tongue, some have taste buds in them Filiform - most numerous, don’t have taste buds in them, roughen the tongue some Fungiform - large, reddish, dots on tongue, contain taste buds, scattered all over Circumvallate (vallate) - V shaped row of large papillae on the back of the tongue, contain taste buds 4.Salivary glands - function, composition of saliva. What division of ANS increases salivation, decreases? Functions of Saliva: Contains enzymes, Amylase - breaks down starch, Lipase - breaks down lipids. Enzymes and antibodies to kill pathogens, Helps to remove food particles from our mouth and teeth, Helps make bolus - compact mass of food we swallow Parasympathetic division of ANS increases saliva. Sympathetic division of ANS decreases saliva. 5.What is the pharynx? What is the name for swallowing? What is the term for chewing? The pharynx is the throat, a common passageway for air, food, and liquids. The term for swallowing is deglutition. The term for chewing is mastication. 6.What is the function of the esophagus? What is the outer layer around the esophagus, serosa or adventitia? Does the esophagus absorb nutrients? What is the difference between digestion and absorption? Function: Passageway for food. Outer layer around the esophagus is the adventitia. The esophagus does not absorb nutrients. Digestion is when the ingested food is broken down into smaller building blocks. Absorption is when the digested building blocks are then absorbed into the bloodstream or lymphatic system through the intestines and then transported to various cells, tissues, organs in the body. 7. What is the difference between physical (mechanical) and chemical digestion? Mechanical digestion involves physically breaking the food into smaller pieces. Mechanical digestion begins in the mouth as the food is chewed. Chemical digestion involves breaking down the food into simpler nutrients that can be used by the cells. Chemical digestion begins in the mouth when food mixes with saliva. In the stomach, chemical and mechanical digestion occur forming chyme (liquefied food) - which is formed from bolus. In the small intestine, mostly chemical digestion occurs. Some mechanical digestion called segmentation (back and forth movement). Peristalsis (slow movement) moves it forward. 8.What is chyme? What is a bolus? Chyme is liquefied food which is formed in the stomach from the bolus and proceeds into the small intestine. A bolus is a compact mass of food we swallow. 9. What do goblet cells secrete? Goblet cells secrete mucus, look like little bubbles and are found throughout the body. 10. Know the function of gastrin, cholecystokinin (CCK), secretin, and VIP. Gastrin is a hormone secreted by enteroendocrine cells, which increases stomach activity. Cholecystokinin (CCK) - slows stomach, inhibits stomach secretions. Secretin - inhibits stomach secretions. Vasoactive intestinal peptide (VIP) - inhibits stomach secretions. 11.What are the regions of the stomach? What is a hiatal hernia? cardiac (cardia) - closest to esophagus fundus - top curve of stomach body - middle part pyloric region - part that connects to intestines A hiatal hernia is a condition in which part of the stomach pushes up through the diaphragm muscle. 12.What are the secreting cells in the stomach, what do they secrete? Gastric pits contain four major secretory cells: a. Chief cells Secrete pepsinogen, inactive form of the enzyme Pepsin (active) When secreted into gastric pit and stomach, it is activated by HCl to breakdown proteins to amino acids b. Parietal cells Make HCl (hydrochloric acid) for Pepsin, and Intrinsic factor - which is needed later to absorb B12 in small intestine Low B12 causes Pernicious anemia, which is usually caused by not enough Intrinsic factor c. Enteroendocrine cells Secrete hormone (absorbed into blood) called Gastrin, which increases stomach activity (from the outside) d. Mucus Neck cells Found near top of gastric pit, secretes small amount of mucus 13. What protects the stomach from being damaged from the low pH? The inner lining of the stomach is protected from its own acid by a thick layer of mucous and epithelial cells that produce a bicarbonate solution. 14.What modification does the muscularis layer of the stomach have? (extra layer?) Besides the usual circular and longitudinal layers of smooth muscle, it also an innermost layer of smooth muscle that runs obliquely. 15.What is the function of the small intestine? What are the parts of the small intestine? Major site of chemical digestion and absorption - where we absorb most nutrients - moves through by segmentation and peristalsis. Three major segments: a. Duodenum = about 10 inches, main function: receives chyme from stomach and neutralizes acidic chyme b. Jejunum = about 8 ft. - where most chemical digestion and nutrient absorption happens c. Ileum = about 12 ft. - controls material flow into cecum of large intestine 16. What are plicae circulares? Where are they found? Mucosa in small intestine have circular folds (plicae circulares),big ridges, (villi, and microvilli) for increased surface area for greater nutrient absorption. 17.What is the digestive role of the liver? 1. Receives nutrient rich blood from small intestine via the hepatic portal vein 2. Removes toxins from the blood, stores glucose as glycogen 3. Regulates carb and lipid metabolism 4. Makes bile The main function within the digestive system is to process the nutrients absorbed from the small intestine. Bile from the liver secreted into the small intestine also plays an important role in digesting fat. 18.What do hepatocytes do? Cells that make Bile are called hepatocytes 19.What is the function of the gallbladder? How can gallstones affect the pancreas? The Gallbladder stores bile, which is made in the liver. Gallstones in the bile duct can block pancreatic duct - pancreatitis. 20.What does bile do? Where is bile made? Bile emulsifies fat, which means it chemically breaks it down. Bile is made in the liver. 21.What is the digestive role of the pancreas? Know that pancreatic juice is high in bicarbonate ions that help to increase the pH in the small intestine. Know what acinar cells are. The digestive role of the pancreas is to produce insulin and glucagon. Pancreatic juice is high in bicarbonate ions that help to increase the pH in the small intestine. Acini (acinar cells) - exocrine cells - secretory cells that make digestive enzymes are called acinar cells. Many different components in pancreatic secretions, acinar cells secrete these. a. (HCO3- = bicarbonate ion) - buffers pH of chyme coming from stomach (pH2 to pH7) b. Pancreatic amylase - breaks down carbohydrates c. Trypsinogen - inactive form of protein digesting enzyme, active form is trypsin Brush boarder secretes proteolytic enzymes to activate trypsinogen to trypsin d. Lipase - breaks down lipids e. Ribonuclease - breaks down nucleic acids (DNA, RNA) CCK and parasympathetic increase pancreatic secretions 22.What type of digestion takes place in the small intestine? Mechanical, chemical, or both? Major site of chemical digestion and absorption - where we absorb most nutrients - moves through by segmentation and peristalsis. Mostly chemical digestion in small intestine, some mechanical digestion called segmentation (back and forth movement). Peristalsis (slow movement) moves it forward. 23.What are the subdivisions of the large intestine? What is the major function of the large intestine? Be familiar with the anatomy of the large intestine - how does it differ from the small intestine (the wall any differences)? What are epiploic appendages? Teniae coli? haustra? Our large intestine consists of 4 major regions: the cecum, colon, rectum, and anal canal. Major function to absorb water and eliminate indigestible matter. The large intestine lacks villi and plicae circularis that the small intestine has. The large intestine also has small collections of fat in the serosa on its outer surface. Major structures a. Cecum with vermiform appendix - contains tissue to help control bacterial growth b. Ascending, transverse, descending and sigmoid colon c. Rectum - where fecal matter collects d. Haustra are pouches in wall of large intestine, Haustral churning - slow movement from Haustram to Haustram Mass movements - slow powerful muscular wave that passes over large intestine when stomach is stretched, usually after a meal e. Teniae coli - strips of muscle, reduced muscularis Epiploic appendages - fat that sticks off the sides f. Anal canal - internal and external sphincters - internal involuntary smooth muscle - external is voluntary, skeletal muscle 24.How is chemical digestion accomplished? Chemical digestion is accomplished by enzyme action that begins in the mouth and ends in the small intestine. 25. Where is the brush border found? The brush border is found in the small intestine. 26.Where does most nutrient absorption take place? Small intestine 27.What are some of the problems with the digestive system? What is diverticulitis and what organ in the digestive system does diverticulitis affect? Hemorrhoids - superficial veins in anal canal become inflamed - caused by strain Diverticulitis - protrusion in large intestine wall, food matter irritates it Diarrhea - when material moves through the large intestine too rapidly