10_Digestive System_Accessory Organs and Clinical Anatomy.pptx

Digestive System – Part 2 Chapter 21, Human Anatomy (LibreTexts) “Digestive System Diagram” by Mariana Ruiz is in the Public D omain CC0. Accessory Organs • Outside of GI tract • They help with chemical digestion in small intestine • 3 organs • Liver: produces bile (which helps digesting lipids);...

Digestive System – Part 2 Chapter 21, Human Anatomy (LibreTexts) “Digestive System Diagram” by Mariana Ruiz is in the Public D omain CC0. Accessory Organs • Outside of GI tract • They help with chemical digestion in small intestine • 3 organs • Liver: produces bile (which helps digesting lipids); detoxifies blood; stores excess nutrients absorbed by GI tract. • Gallbladder: stores, concentrates, and releases bile. • Pancreas: produces digestive enzymes and bicarbonate that are released in duodenum; produces hormones. Accessory Organs “Accessory Organs” by OpenStax is licensed under CC BY 3.0 Bile • Made by hepatocytes in the liver: 1 liter/day • Mixture of water, bile salts, bile pigments (including bilirubin), phospholipids (such as lecithin), electrolytes, cholesterol, and triglycerides • Stored and secreted by gallbladder into small intestine. • Helps with emulsification of lipids in the small intestine. Liver • Function: produces bile (which helps digesting lipids); detoxifies blood; stores excess nutrients absorbed by GI tract. • Made by 4 incompletely separated lobes: • 2 primary lobes anteriorly: right lobe (biggest) and left lobe • 2 smaller lobes posteriorly: caudate lobe (next to inferior vena cava) and quadrate lobe (next to gallbladder) • Supported by 5 ligaments (peritoneal folds) • Falciform ligament separates right and left lobes • Round ligament of the liver (AKA Ligamentum teres hepatis): remnant of umbilical vein • Coronary ligament • 2 Lateral ligaments • Porta hepatis is where arteries, veins and lymph vessels enter and leave the liver Liver Anterior View "Liver Diagram" by T Sheasby is licensed under CC BY-SA 3.0 Liver Posteroinferior View "Hilum of the Liver" by Henry Vandyke Carter / Labeled added by Mikael Häggström is in the Liver Histology • Divided into hexagonal hepatic lobules made by hepatocytes • In the middle of each hepatic lobule a central vein takes deoxygenated blood away from liver • At the 6 corners of each hepatic lobule, a portal triad contains 3 structures: • bile duct carries bile made by hepatocytes • branch of hepatic vein (portal venule) carries deoxygenated blood rich in nutrients from digestive tract • branch of hepatic artery (portal arteriole) carries oxygenated blood to the liver Blood and Bile Flow through the Liver • Blood and bile flow in opposite direction Direction of blood flow: • From portal venule and portal arteriole blood mixes and goes through hepatic sinusoids that pass next to hepatocytes. Then blood is drained by central vein into hepatic veins and inferior vena cava. Direction of bile flow: • From hepatocytes to bile canaliculi, to bile duct of portal triad, eventually getting into gallbladder. Microscopic Anatomy of Liver Hepatic sinusoids “Microscopic Anatomy of Liver” by OpenStax is licensed under CC BY 3.0 Gallbladder • Function: Stores, concentrates, and, when stimulated, propels the bile into the duodenum • Muscular sac with 3 regions: fundus, body, and neck • Bile flows out of liver through left and right hepatic ducts, then enters the common hepatic duct. • Bile flows into and out of gallbladder through cystic duct then into common bile duct to duodenum at major duodenal papilla Gallbladder “Gallbladder” by OpenStax is licensed under CC BY 3.0 Pancreas • Functions: endocrine to make hormones and exocrine to make digestive enzymes • Retroperitoneal organ • Regions: • head adjacent to duodenum • body • tail adjacent to spleen • Pancreatic duct runs the length of pancreas. It receives products from cells of pancreas and drains them into duodenum at major duodenal papilla. A secondary duct called accessory pancreatic duct also drains into duodenum at minor duodenal papilla. Exocrine and Endocrine Pancreas “Exocrine and Endocrine Pancreas” by OpenStax is licensed under CC BY 3.0 Clinical Anatomy: Tooth Decay • Tooth decay is damage to the enamel of the tooth. It happens when bacteria in your mouth make acids that attack the enamel. • Tooth decay can lead to cavities, pulpitis, and abscess. Depending on the degree of decay, it can be treated with fluoride treatments, filling, crown, root canal or tooth extraction. • Root canal is a procedure in which the nerves and pulp are removed, the tooth is sealed with a filling and an artificial crown replaces the old crown. Clinical Anatomy: Acid Reflux • Acid reflux happens when acid comes back up from the stomach. This is usually caused by the opening of the lower esophageal sphincter which can happen if the sphincter is not mature yet (such as in babies having spit ups) or if the sphincter is damaged. It can cause reflux esophagitis which is a painful inflammation of esophagus. It is more common in smokers, overweight people, overeaters. • Gastroesophageal reflux disease (GERD) is the chronic, more severe form of acid reflux that causes erosion and scarring of esophageal tissue. More advanced cases become Barrett esophagus which increases chance of cancer. GERD Image "GERD" by BruceBlaus is licensed under CC BY-SA 4.0 Clinical Anatomy: Ulcers and Appendicitis • Ulcers are thinnings or openings in the lining of the GI tract. Most often they happen in the stomach. The most common cause is an infections of a bacterium called Helicobacter pylori which causes inflammation of the lining of the stomach and decreased secretion of mucin from gastric cells. Consequently, the layer of mucus is reduced and the acid is able to degrade the gastric cells. • Appendicitis is the inflammation of the appendix, usually because fecal matter obstructs the appendix. If appendix bursts, the leaked contents can cause the inflammation of the peritoneum, called peritonitis. The spasms of smooth muscle in the appendix cause pain around umbilicus, often referred to T10 dermatome. More advanced appendicitis can be felt in lower right quadrant of torso. Gastric Ulcer Image "Gastric Ulcer" is licensed under CC BY-SA 4.0 Clinical Anatomy: Diverticulosis and Diverticulitis • Diverticula are out-pockets of intestinal wall and are most common in sigmoid colon. Diverticula are likely caused by low-fiber diet causing strain on the colon. The presence of diverticula is called diverticulosis and while it is not harmful per se, it can lead to the inflammation of diverticula which is called diverticulitis. • Symptoms of diverticulitis include abdominal pain, fever, nausea, and a change in bowel habits. Treatment can include rest, a liquid or low-fiber diet, and antibiotics. Severe cases may need hospital care and surgery. Doctors may recommend a high fiber diet after recovery to prevent future episodes. Diverticulitis Image "Ds00070 an01934 im00887 divert s gif" by Lfreeman04 is licensed under CC BY-SA 4.0 Clinical Anatomy: Colorectal Cancer • Colorectal cancer is most common in descending colon. It arises from polyps, which are outgrowths of the colon mucosa towards the lumen (the mirror image of diverticula). The formation of polyps is linked to lowfiber diets. • Most polyps never become cancerous but some can become dysplastic and cause colorectal cancer. Colorectal cancer can form metastasis and proliferate in other organs. Colorectal cancer is often without symptoms, and sometimes causes rectal bleeding, constipation, abdominal pain, unexplained weight loss. Colorectal Cancer Image "Blausen 0246 ColorectalCancer" by Blausen Medical Communications, Inc. is in the Public Domain Clinical Anatomy: Liver Pathology • Hepatitis, obesity, high blood cholesterol, diabetes, or genetic inheritance can cause pathology to the liver. • The first stage of pathology is called "fatty liver" because the liver accumulates lipids (non-alcoholic fatty liver disease, NAFLD). • This causes hepatitis which is the inflammation of the liver. If the liver disease is diagnosed and treated successfully at this stage, the inflammation may go away. • If left untreated, the liver will start scarring (depositing fibers) which can lead to fibrosis or cirrhosis (a late stage fibrosis) with deposit of fibers in place of healthy hepatocytes. Scar tissue cannot do the work that healthy liver tissue can. Moreover, scar tissue can keep blood from flowing through your liver. At this point, the damage is irreversible and treatment will focus on stopping the progression from getting worse. • Cirrhosis can lead to a number of complications, including liver cancer. Cirrhosis and hepatitis B are leading risk factors for primary liver cancer. Liver Pathology Progression "NAFLD liver progression" by Signimu is licensed under CC BY-SA 3.0 Clinical Anatomy: Gallstones • Gallstones are caused by high concentrations of certain materials inside the gallbladder. They are more common in women, Caucasian people, and in developed countries. • Risk factors for gallstones are obesity, age, female sex hormones, lack of physical activity. • The treatment is the removal of gallbladder (cholecystectomy). The liver will continue to produce bile and it will release the bile directly into the small intestine. The bile will then be less concentrated and less effective towards a fatty meal. A low-fat diet is usually recommended after a cholecystectomy. Gallstones Image "Gallstones” by BruceBlaus is licensed under CC BY-SA 4.0