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Digestive System
Bio 12, Digestive system.
| Term | Definition |
|---|---|
| Digestive system | Contributes to homeostasis by ingesting food, separating it into nutrients, absorbing nutrients, and eliminating indigestible remains |
| Mechanical digestion | Chewing food, churning and mixing of food in the stomach |
| Chemical digestion | Many different enzymes break down macro molecules to small organic molecules that can be absorbed |
| Roof of the mouth | Separates the nasal cavity from the mouth |
| Salivary glands | Produce saliva, keep the mouth moist, contains salivary amylase to begin the process of digesting starch |
| Mumps | Swelling of the salivary glands, caused by viral infection |
| Pharynx | Receives both air and food passes bolus from moth to esophagus |
| Esophagus | Passageway from the pharynx to the stomach, muscular tube that is normally collapsed. |
| Swallowing | The soft palate closes off the nasopharynx and the epiglottis covers the glottis, forcing the bolus to enter the esophagus |
| Peristalis | Rhythmic muscular contractions that push food along the digestive tract |
| Sphincters | Muscles that encircle tubes in the body |
| Cardiac sphincter | entrance of the esophagus to the stomach, prevents acidic contents of the stomach to rise into the esophagus |
| Heartburn | Acid reflux, when acid from the stomach rises up into the esophagus |
| Stomach | Thick walled organ on the left side of the abdominal cavity. Receives food from the esophagus, starts digestion of proteins, moves food to the small intestine |
| Capacity of the stomach | 4 Liters |
| Rugae | Deep folds in the stomach's wall that disappear to allow the stomach to expand |
| Gastric | Term referring to the stomach |
| Columnar epithelium | line the stomach, has millions of gastric pits, which lead to gastric glands |
| Gastric juice | Contain pepsinogen, hydrochloric acid, and mucus |
| Pepsinogen | Becomes the enzyme pepsin when exposed to HCl |
| How long it takes for the stomach to empty | 2 to 6 hours |
| Chyme | Thick, soupy liquid that leaves the stomach |
| Pyloric sphincter | Acts like a valve to the small intestine, repeatedly opens and closes |
| Small intestine | 6 m in length, made of the duodenum, jejunum, and ileum. Secretes enzymes that complete food digestion |
| Duodenum | Receives bile from the liver and pancreatic juice from the pancreas. Has a slightly basic pH to neutralize acid from the stomach |
| Villi | Finger like projections that give the small intestine a larger surface area. Has an outer layer of columnar epithelial cells, each cell has microvilli that absorb nutrients |
| Lacteal | Small lymphatic capillary in the villi that absorb lipoprotein droplets |
| Hormone | Substance produced by cells that affects a different set of cells, usually transported by the blood stream |
| Gastrin | Stimulated by eating meat high in protein, produced by the stomach, acts on the stomach via secretion of gastric acid. Allows stomach to break down proteins, stimulates growth of stomach lining |
| CCK | Stimulated by partially digested protein and fat, produced by the duodenum, acts on the duodenum, small intestine, pancreas, and gall bladder. Pancreas increases output of pancreatic juice, liver increases output of bile, and gall bladder releases bile |
| Secretin | Stimulated by acid in the small intestine, produced by the duodenum, acts on the duodenum via secretions in the stomach, pancreas, liver. Stimulates production of bicarbonate to regulate pH of chyme |
| Large intestine | Cecum, colon, and rectum. Absorbs water, salts, and vitamins. Stores indigestible materials until it can be released as feces |
| Appendix | Small pouch at the beginning of the small intestine, fights infections, contains healthy bacteria |
| Peritonitis | Inflammation of the lining of the abdominal cavity, can lead to death |
| Sections of the colon | Ascending colon (up the right side of body), transverse colon (crosses abdominal cavity), descending colon (passes down the left side of the body), sigmoid colon (last 20 cm) |
| Rectum | Opens at the anus where defecation occurs |
| Defecation reflex | Stretching of the rectal wall caused by feces being forced intot he rectum by peristalis |
| Feces | 3/4 water, 1/4 solids. Bacterial action causes odor and gas. |
| Accessory organs | Pancreas, liver, gall bladder, salivary glands |
| Pancreas | Exocrine function, producing pancreatic juice (containing bicarbonate that neutralizes chyme). Endocrine function, creates insulin and glucagon to keep blood glucose at normal limits. |
| Pancreatic islets | Clusters of alpha cells (produce glucagon), beta cells (produce insulin), delta cells (produce somatostatin) |
| Insulin | Stimulated by high blood glucose levels, produced by the pancreas, acts on liver cells, muscle cells and adipose tissue. Increases glucose absorption rate, lowers blood glucose level |
| Glucagon | Stimulated by lower blood glucose levels, produced by the pancreas, acts on the liver and adipose tissue. Stimulates liver to break down glycogen to glucose. Raises blood glucose level. |
| Somatostatin | Stimulated by high blood glucose, amino acid levels, produced by the pancreas, cells in the stomach, small intestine. Acts on digestive tract to reduce absorption of nutrients. Suppresses the release of insulin and glucagen. Inhibits growth hormones |
| Liver | Largest gland in the body (100,000 lobules), detoxes blood, stores iron and vitamins, makes plasma proteins from amino acids, stores glucose and glycogen, produces urea, excretes bile, regulates blood cholesterol, creates bile salts |
| Average blood glucose level | 50 to 80 mg per 100 mL |
| Hepatic portal system | Hepatic portal vein takes the products of digestion from the digestive system to the liver, where they are processed before entering a hepatic vein. |
| Bile | Stored in the gall bladder, yellow-green colour. Derived from the breakdown of hemoglobin. Contains bile salts derived from cholesterol. Emulsify fats, breaks it into droplets providing a larger surface area. |
| Gall bladder | Muscular sac attached to the surface of the liver. Stores excess bile. Reabsorbs water. Bile leaves the gall bladder by the common bile duct. |
| Digestive enzymes | proteins that speed specific chemical reactions. |
| Formula for salivary amylase | starch + H20 -> maltose |
| Formula for pepsin | protein + H2O -> peptides |
| Formula for bile salts | fat -> fat droplets |
| Formula for lipase | fat droplets + H2O -> glycerol + 3 fatty acids |
| Formula for peptidase | Peptides + H2O -> amino acids |
| Formula for maltase | Maltose +H2O -> glucose + glucose |
| Pancreatic amylase | Produced by the pancreas, acts in the small intestine, optimum pH is neutral, turns starch to maltose |
| Maltase | Produced by the small intestine, acts in the small intestine, optimum pH is basic, turns maltose to glucose |
| Pepsin | Produced by the gastric glands, acts in the stomach, optimum pH is acidic, turns proteins to peptides |
| Trypsin | Produced by the pancreas, acts in the small intestine optimum pH is basic, turns proteins to peptides |
| Peptidases | Produced by the small intestine, acts in the small intestine, optimum pH is basic, turns peptides to amino acids |
| Nuclease | Produced in the pancreas, acts in the small intestine, optimum pH is basic, turns RNA and DNA to nucleotides |
| Nucleosidasis | Produced in the small intestine, acts in the small intestine, optimum pH is basic, turns nucleotide to bases, sugar and phosphate |
| Lipase | Produced in the pancreas, acts in the small intestine, optimum pH is basic, turns fat droplets to glycerol and fatty acids |
| Digestive system optimum temperature | 37 degrees Celsius |
| pH of the stomach | 1 to 2 |
| pH of the small intestine | 7.4-7.8 |
| Stomach ulcers | When the thick mucus layer of the stomach is broken down, and the stomach wall is damaged by stomach acid. An open sore in the wall. Usually initiated by infections that affect the ability of mucus cells. Treatment is antibiotics |
| Diarrhea | Loose, watery feces. Acute is normally caused by infection (food poisoning). In all cases, the intestinal walls are irritated, less water is absorbed, and diarrhea helps rid of infectious organisms. Can lead to dehydration and salt imbalance. |
| Crohn's disease | Chronic diarrhea. Persistent inflammation of the intestine, resulting in abdominal cramping. Caused by misdirected immune response against one's own intestinal tissues |
| Constipation | Dry and hard feces. May be because the person inhibits the defecation reflex. Can lead to development of hemorrhoids. Can be reversed by increasing intake of water and fiber |
| Hemmoroids | Enlarged and inflamed blood vessels of the anus |
| Polyps | Small growths in the epithelial lining. Detected during a colonoscopy. May be cancerous |
| Colon cancer | May be caused by increased consumption of dietary fat. Certain bacteria may convert bile salts into substances that promote development of cancer |
| Pancreatitis | Inflammation of pancreas. May be caused by alcohol, gallstones that block the pancreatic duct. In chronic cases, digestive enzymes secreted by the pancreas damage pancreas and surrounding tissues. May cause diabetes by inhibiting insulin secretion. |
| Pancreatic cancer | Almost always fatal because of the essential functions of the pancreas. Pancreas is resistant to disease treatment and allows spread to other organs. |
| Diabetes mellitus | Condition affecting ability to regulate glucose metabolism. Type 1 cannot produce insulin, type 2 cannot properly use insulin. Excess glucose is secreted through urine, causing an increased volume of urine. Can lead to acidosis. |
| Jaundice | Yellowing in the whites of the eyes, and skin. Can be caused be large amount of bilirubin the the blood (pigment from bile) |
| Hepatitus | Inflammation of the liver caused by viruses (Hep A, B, C) |
| Cirrhosis | Chronic disease of the liver, often seen in alcoholics as alcohol is a toxin to the liver. Liver is infiltrated with fat and liver tissue is replaced by scar tissue. Treatment is liver transplant |
| Gallstones | Cholesterol in the bile come out of the solution and form crystals, the crystals grow and form gallstones. Block the common bile duct. If they cannot be removed, gallbladder must be removed. Common for people who have recently lost significant weight |
Created by:
WeijinRoss
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