Exam 3 (PDF)

7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology Important 1/17/2023 First Layer The inner mucosal (first) layer is made up of a lining epi...

7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology Important 1/17/2023 First Layer The inner mucosal (first) layer is made up of a lining epithelium, an underlying connective tissue called the lamina propria, and the muscularis mucosae, composed of smooth muscle cells that can contract and change the shape and surface area of the mucosal layer.4 The mucosal layer performs numerous functions in its role as an interface between the body and environment, including Production of the mucus that lubricates and protects the inner surface of the alimentary canal Secretion of the digestive enzymes and substances that break down food Absorption of the breakdown products of digestion Maintenance of a barrier to prevent the entry of noxious substances and pathogenic organisms (This barrier includes lymphatics within the mucosa, which serve as the body’s first line of immune defense.) The epithelial cells in the mucosal layer are constantly turning over and move from the outside of the wall structure to the luminal face every 5 days.5 Because of the regenerative capabilities of the mucosal layer, injury to this layer heals rapidly without leaving scar tissue. Exam content Important 1/19/2023 Intestinal Flora The gut is the natural habitat of a large and diverse bacterial community. The major functions of the gut microflora include metabolic activities that salvage energy and absorbable nutrients, trophic effects on intestinal epithelial cells, and protection of the colonized host against invasion by pathogenic organisms. Exam three content, roles of local flora, essential vitamins involved in clotting. PRINTED BY: [email protected]. Printing of Notes and Highlights is for personal, private use only. Notes created by user are not part of publisher content. No part of this book may be reproduced or transmitted without publisher's prior permission. Violators will be prosecuted. about:blank 205/288 7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology Important 8/16/2022 he major metabolic function of colonic microflora is the fermentation of undigestible dietary residue and endogenous mucus produced by the epithelial cells. The genetic diversity of the microorganisms in the gut provides various enzymes and biochemical pathways that are distinct from those of the host. Fermentation of nondigestible carbohydrates, including resistant starches, cellulose, pectins, and unabsorbed sugars, is a major source of energy in the colon. Colonic microorganisms also play a role in vitamin synthesis and in absorption of calcium, magnesium, and iron. The colonic flora, for example, synthesizes vitamin K. The newborn infant does not synthesize an adequate amount of vitamin K for the first week or so of life until the normal colonic bacterial flora becomes established. The resident gut flora also provides a crucial line of resistance to colonization by exogenous microbes. Therefore, it is highly protective against invasion of tissues by pathogens. Colonization resistance also applies to opportunistic bacteria that are present in the gut but whose growth is restricted. The administration of broad-spectrum antibiotics can disrupt the microbial balance and allow overgrowth of species with potential pathogenicity, such as Clostridium difficile.18 The role of probiotics as a supplement to the normal diet and as a treatment for several disease states has become increasingly recognized. Probiotics are live microorganisms that, when ingested, can modify the composition of enteric microflora. Commonly used probiotics are lactobacilli, bifidobacteria, and nonpathogenic Escherichia coli.19 Probiotics have shown value in several diseases, such as maintaining remission in ulcerative colitis.20 Important 8/16/2022 Gastric Mucosal Barrier Effect of medications on the mucosal layer and risk for GI bleeding. Important 1/19/2023 Gastritis Exam three content. What medications affect the mucosal lining in the stomach? Risk for GI bleeding? PRINTED BY: [email protected]. Printing of Notes and Highlights is for personal, private use only. Notes created by user are not part of publisher content. No part of this book may be reproduced or transmitted without publisher's prior permission. Violators will be prosecuted. about:blank 206/288 7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology Important 8/16/2022 Acute Gastritis Acute gastritis is characterized by an acute mucosal inflammatory process, usually transient in nature. The inflammation may be accompanied by emesis, pain, and, in severe cases, hemorrhage and ulceration.33 This erosive form is an important cause of acute GI bleeding. The condition is most commonly associated with local irritants such aspirin or other NSAIDs, alcohol, or bacterial toxins. Oral administration of corticosteroids may also be complicated by acute hemorrhagic gastritis. Any serious illness or trauma that is accompanied by profound physiologic stress that requires substantial medical or surgical treatment renders the gastric mucosa more vulnerable to acute hemorrhagic gastritis because of mucosal injury (discussed under stress ulcers).13 Uremia, treatment with cancer chemotherapy drugs, and gastric radiation are other causes of acute gastritis. The complaints of people with acute gastritis vary. People with aspirin-related gastritis can be totally unaware of the condition or may complain only of heartburn or sour stomach. Gastritis associated with excessive alcohol consumption is often a different situation; it often causes transient gastric distress, which may lead to vomiting and, in more severe situations, to bleeding and hematemesis. Gastritis caused by the toxins of infectious organisms, such as the staphylococcal enterotoxins, usually has an abrupt and violent onset, with gastric distress and vomiting ensuing approximately 5 hours after the ingestion of a contaminated food source. Acute gastritis usually is a self-limiting disorder, with complete regeneration and healing occurring within several days of removal of the inciting agent. Important 1/17/2023 Inflammatory Bowel Disease The term inflammatory bowel disease is used to designate two related inflammatory intestinal disorders: Crohn disease and ulcerative colitis. Over 1 million residents in the United States and 2.5 million in Europe are estimated to have IBD. Currently, the prevalence of IBD in the Western world is up to 0.5% of the general population.64 Although the two diseases differ sufficiently to be distinguishable, they have many features in common. Both diseases produce inflammation of the bowel, both lack confirming evidence of a proven causative agent, both have a pattern of familial occurrence, and both can be accompanied by systemic manifestations. Crohn disease most commonly affects the distal small intestine and proximal colon, Important 10/26/2022 Alterations in Intestinal Motility PRINTED BY: [email protected]. Printing of Notes and Highlights is for personal, private use only. Notes created by user are not part of publisher content. No part of this book may be reproduced or transmitted without publisher's prior permission. Violators will be prosecuted. about:blank 207/288 7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology Important 10/26/2022 Normally, approximately 400 mL of water, 55 mEq of sodium, 30 mEq of chloride, and 15 mL of bicarbonate are absorbed each day in the colon. Important 10/26/2022 t the same time, approximately 5 mEq of potassium is secreted into the lumen of the colon. Important 10/26/2022 Acute diarrheas that last less than 4 days are predominantly caused by infectious agents and follow a self-limited course.113 Important 10/26/2022 Diarrhea that is acute in onset and persists for less than 2 weeks is commonly caused by infectious agents Important 10/26/2022 Noninflammatory diarrhea is associated with large-volume watery and nonbloody stools, periumbilical cramps, bloating, and nausea or vomiting. It is commonly caused by toxin-producing bacteria Important 10/26/2022 Inflammatory diarrhea is usually characterized by the presence of fever and bloody diarrhea (dysentery). Important 10/26/2022 Diarrhea is considered to be chronic when the symptoms persist for 4 weeks or greater.1 PRINTED BY: [email protected]. Printing of Notes and Highlights is for personal, private use only. Notes created by user are not part of publisher content. No part of this book may be reproduced or transmitted without publisher's prior permission. Violators will be prosecuted. about:blank 208/288 7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology Important 10/26/2022 In osmotic diarrhea, water is pulled into the bowel by the hyperosmotic nature of its contents to such a quantity that the colon is unable to reabsorb the excess fluid. Important 10/26/2022 Nondigested lactose can cause osmotic diarrhea Important 10/26/2022 Magnesium salts, which are contained in milk of magnesia and many antacids, are poorly absorbed and cause diarrhea when taken in sufficient quantities. Another cause of osmotic diarrhea is decreased transit time, which interferes with absorption. Important 10/26/2022 Secretory diarrhea occurs when the secretory processes of the bowel are increased. Important 10/26/2022 Inflammatory diarrhea commonly is associated with acute or chronic inflammation or intrinsic disease of the colon, such as ulcerative colitis or Crohn disease. Important 10/26/2022 tenesmus Important 10/26/2022 fecal soiling of clothing, and awakening during the night with the urge to defecate. PRINTED BY: [email protected]. Printing of Notes and Highlights is for personal, private use only. Notes created by user are not part of publisher content. No part of this book may be reproduced or transmitted without publisher's prior permission. Violators will be prosecuted. about:blank 209/288 7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology Important 10/26/2022 diarrhea can be particularly serious in infants and small children, people with other illnesses, elderly people, and even previously healthy people if it continues for any length of time. Thus, the replacement of fluids and electrolytes is considered to be a primary therapeutic goal in the treatment of diarrhea. Important 10/26/2022 Antibiotics should be reserved for use in people with identified enteric pathogens. Important 10/26/2022 nfants in particular are more susceptible to dehydration because of their greater surface area, higher metabolic rate, and inability effectively to concentrate their urine. Oral replacement therapy (ORT) is usually the method of choice for infants and children with uncomplicated diarrhea that can be treated at home. Important 10/26/2022 Evidence suggests that feeding should be continued during diarrheal illness, particularly in children. Important 10/26/2022 Fecal Impaction Fecal impaction is the retention of hardened or putty- like stool in the rectum and colon, which interferes with normal passage of feces Important 10/26/2022 Intestinal Obstruction Important 10/26/2022 PRINTED BY: [email protected]. Printing of Notes and Strangulation with necrosis of the bowel may occur and lead to Highlights is for personal, private use only. Notes created by user are not part of publisher content. No part of this perforation, peritonitis, and sepsis. book may be reproduced or transmitted without publisher's prior permission. Violators will be prosecuted. about:blank 210/288 7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology Important 10/26/2022 Intussusception involves the telescoping of bowel into the adjacent segment (Fig. 37.14). It is the most common cause of intestinal obstruction in children younger than 2 years of age.1 Important 10/26/2022 Peritonitis Peritonitis is an inflammatory response of the serous membrane that lines the abdominal cavity and covers the visceral organs. It can be caused by bacterial invasion or chemical irritation. Most commonly, enteric bacteria enter the peritoneum because of a defect in the wall of one of the abdominal organs. Causes of peritonitis include perforated peptic ulcer, ruptured appendix, perforated diverticulum, gangrenous bowel, pelvic inflammatory disease, and gangrenous gallbladder. Other environmental causes are abdominal trauma, foreign body ingestion, and infected peritoneal dialysis catheters. Generalized peritonitis, although no longer the overwhelming problem it once was, is still a leading cause of death after abdominal surgery. Important 1/19/2023 Celiac Disease Celiac disease, also known as Celiac sprue and Gluten-sensitive enteropathy, is an immune-mediated disorder triggered by ingestion of gluten-containing grains (including wheat, barley, and rye).135,136 Until recently, celiac disease was considered to be a rare malabsorption syndrome that manifested during early childhood, but today it is known to be one of the most common genetic diseases, with a mean prevalence of 1% to 6% in the general population.137–139 Exam three content PRINTED BY: [email protected]. Printing of Notes and Highlights is for personal, private use only. Notes created by user are not part of publisher content. No part of this book may be reproduced or transmitted without publisher's prior permission. Violators will be prosecuted. about:blank 211/288 7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology Important 8/16/2022 The diagnosis of celiac disease is based on clinical manifestations, supported by serologic tests and confirmed by intestinal biopsy.135,141 Based on very high sensitivities, the best available tests are the Ig A antihuman tissue transglutaminase (TTG) and IgA endomysial antibody immunofluorescence (EMA) tests.135 Biopsies of the proximal small bowel are indicated in people with a positive celiac disease antibody test.141 Usually, additional laboratory tests are done to determine if the disorder has resulted in nutritional disorders such as iron deficiency anemia. The primary treatment of celiac disease consists of removal of gluten and related proteins from the diet. Gluten is the primary protein in wheat, barley, and rye. Oat products, which are nontoxic, may be contaminated with wheat during processing. Many gluten-free types of bread, cereals, cookies, and other products are available.136 Meats, vegetables, fruits, and dairy products are free of gluten as long as they are not contaminated during processing. Complete exclusion of dietary gluten generally results in rapid and complete healing of the intestinal mucosa. Important 1/19/2023 Bile Production and Cholestasis Exam three content. Dietary fat absorption. Bile production and cholestasis. Function/role of bile. PRINTED BY: [email protected]. Printing of Notes and Highlights is for personal, private use only. Notes created by user are not part of publisher content. No part of this book may be reproduced or transmitted without publisher's prior permission. Violators will be prosecuted. about:blank 212/288 7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology Important 1/19/2023 The secretion of bile is essential for digestion of dietary fats and absorption of fats and fat-soluble vitamins from the intestine. The liver produces approximately 500 to 600 mL of yellow-green bile daily.4 Bile contains water, bile salts, bilirubin, cholesterol, and certain by-products of metabolism. Of these, only bile salts, which are formed from cholesterol, are important in digestion. The other components of bile depend on the secretion of sodium, chloride, bicarbonate, and potassium by the bile ducts. Bile salts serve an important function in digestion; they aid in emulsifying dietary fats, and they are necessary for the formation of the micelles that transport fatty acids and fat- soluble vitamins to the surface of the intestinal mucosa for absorption. The system for the recirculation of bile, the enterohepatic circulation, involves multiple components. The liver, biliary tract, gallbladder, portal venous circulation, small intestine, colon, and kidneys, all play a role to varying degrees. Greater than 90% of bile salts that enter the intestine are reabsorbed into the portal circulation by an active transport process that takes place in the distal ileum.4 From the portal circulation, the bile salts move into the liver cells and are recycled. Normally, bile salts travel this entire circuit approximately 17 times before being expelled in the feces.3 Exam three content. Role of bile. Important 8/16/2022 Cholestasis Cholestasis represents a decrease in bile flow through the intrahepatic canaliculi and a reduction in secretion of water, bilirubin, and bile acids by the hepatocytes. Important 8/16/2022 Bilirubin Elimination and Jaundice Bilirubin elimination and jaundice. How do we get rid of bilirubin? PRINTED BY: [email protected]. Printing of Notes and Highlights is for personal, private use only. Notes created by user are not part of publisher content. No part of this book may be reproduced or transmitted without publisher's prior permission. Violators will be prosecuted. about:blank 213/288 7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology Important 8/25/2022 Bilirubin is the final product of the breakdown of heme contained in aged red blood cells. Bilirubin is the substance that gives bile its color. In the process of degradation, the hemoglobin from the red blood cell is broken down to form biliverdin, which is rapidly converted to free bilirubin (Fig. 38.7). Free bilirubin, which is insoluble in plasma, is transported in the blood attached to plasma albumin. Even when it is bound to albumin, this bilirubin is still called free bilirubin, to distinguish it from conjugated bilirubin. As it passes through the liver, free bilirubin is absorbed through the hepatocytes’ cell membrane and released from its albumin carrier molecule. Inside the hepatocytes, free bilirubin is converted to conjugated bilirubin, making it soluble in bile. Conjugated bilirubin is secreted as a constituent of bile, and in this form it passes through the bile ducts into the small intestine. In the intestine, approximately one half of the bilirubin is converted into a highly soluble substance called urobilinogen by the intestinal flora. Approximately one fifth of the urobilinogen produced is either absorbed into the portal circulation and the remaining is excreted in the feces.10 Most of the urobilinogen that is absorbed is returned to the liver to be reexcreted into the bile. Figure 38.7 The process of bilirubin formation, circulation, and elimination. Usually, only a small amount of bilirubin is found in the blood; the normal level of total serum bilirubin is less than 1.5 mg/dL (17 to 20.5 μmol).11 Laboratory measurements of bilirubin usually measure the free and the conjugated bilirubin as well as the total bilirubin. These are reported as the direct (conjugated) bilirubin and the indirect (unconjugated or free) bilirubin. Final exam content Important 8/16/2022 The five major causes of jaundice are excessive destruction of red blood cells, impaired uptake of bilirubin by the liver cells, decreased conjugation of bilirubin, obstruction of bile flow in the canaliculi of the hepatic lobules or in the intrahepatic or extrahepatic bile ducts, and excessive extrahepatic production of bilirubin.12 Important 8/16/2022 From an anatomic standpoint, jaundice can be categorized as prehepatic, intrahepatic, and posthepatic. Chart 38.1 lists the common causes of prehepatic, hepatic, and posthepatic jaundice. PRINTED BY: [email protected]. Printing of Notes and Highlights is for personal, private use only. Notes created by user are not part of publisher content. No part of this book may be reproduced or transmitted without publisher's prior permission. Violators will be prosecuted. about:blank 214/288 7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology Important 8/25/2022 Tests of Hepatobiliary Function Good review of hepatobiliary function with implications for NP practice PRINTED BY: [email protected]. Printing of Notes and Highlights is for personal, private use only. Notes created by user are not part of publisher content. No part of this book may be reproduced or transmitted without publisher's prior permission. Violators will be prosecuted. about:blank 215/288 7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology Important 8/25/2022 Diagnostic tests help to evaluate liver function and the extent of liver damage. Laboratory tests commonly are used to assess liver function and confirm the diagnosis of liver disease. Liver function tests, including serum levels of liver enzymes, are used to aid in the diagnosis of disease, differentiate between different disorders, determine the severity of present disease, and monitor responses to established treatment.13 Elevated serum enzyme test results usually indicate liver injury earlier than other indicators of liver function. The key enzymes are alanine aminotransferase (ALT) and aspartate aminotransferase (AST), which are present in liver cells. These two enzymes were previously known as the SGPT (serum glutamic-pyruvic transaminase) and the SGOT (serum glutamic-oxaloacetic transaminase). ALT is found predominately in the liver, with lesser quantities found in the kidneys, heart, and skeletal muscle. As a result, ALT is a more specific indicator of liver inflammation than AST, as AST may also be elevated in diseases affecting other organs, such as the heart or muscles. AST is also elevated after a myocardial infarction. In most types of liver disease, ALT activity is higher than that of AST; exceptions include alcoholic hepatitis, hepatic cirrhosis, and hepatocellular carcinoma.14 The reasons for the higher AST activity in alcoholic hepatitis appear to be multiple. Alcohol increases mitochondrial damage leading to increased release of mitochondrial AST in serum, whereas other causes of hepatitis typically do not.15 The most dramatic rise is seen in cases of acute hepatocellular injury, as occurs with viral hepatitis, hypoxic or ischemic injury, acute toxic injury, or Reye syndrome. The liver’s synthetic capacity is reflected in measures of serum protein levels and prothrombin time (i.e., synthesis of coagulation factors). Hypoalbuminemia because of depressed synthesis may complicate severe liver disease. Deficiencies of coagulation factor V and vitamin K–dependent factors (II, VII, IX, and X) may occur. Serum bilirubin, γ-glutamyltransferase (GGT), 5′-nucleotidase, and alkaline phosphatase measure hepatic excretory function. Alkaline phosphatase and 5′-nucleotidase are present in the membranes between liver cells and the bile duct and are released by disorders affecting the bile duct.13 GGT is located in the endoplasmic reticulum of the hepatocytes and in the bile duct epithelial cells. It is thought to function in the transport of amino acids and peptides into liver cells. Measurement of GGT may be helpful in diagnosing alcohol abuse and is an indicator of hepatobiliary disease.16 Ultrasonography provides information about the size, composition, and blood flow of the liver. It has largely replaced cholangiography in detecting stones in the gallbladder or biliary tree. Computed tomography (CT) scanning provides information similar to that obtained by ultrasonography. Magnetic resonance imaging (MRI) has proved to be useful in some disorders. Selective angiography of the celiac, superior mesenteric, or hepatic artery may be used to visualize the hepatic or portal circulation. A liver biopsy affords a means of examining liver tissue without surgery. There are several methods for obtaining liver tissue: percutaneous liver biopsy, which uses a suction, cutting, or spring-loaded cutting needle11; laparoscopic liver biopsy; and fine-needle biopsy, which is performed under endoscopic ultrasound guidance.17 The type of PRINTED BY: [email protected]. Printing of Notes and Highlights is for personal, private use only. Notes created method used is based on the number of specimens needed and the by user are not part of publisher content. No part of this book may be reproduced or transmitted without publisher's amount of tissue required for evaluation. Laparoscopic liver biopsy prior permission. Violators will be prosecuted. about:blank 216/288 7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology provides the means for examining abdominal masses, evaluating ascites of unknown cause, and staging liver cancers. Important 1/19/2023 The known hepatotropic viruses include hepatitis A virus (HAV), hepatitis B virus (HBV), the hepatitis B–associated delta virus (HDV), hepatitis C virus (HCV), and hepatitis E virus (HEV). Although all of these viruses cause acute hepatitis, they differ in the mode of transmission and incubation period; mechanism, degree, and chronicity of liver damage; and ability to evolve to a carrier state. The presence of viral antigens and their antibodies can be determined through laboratory tests. Epidemiologic studies have indicated that some cases of infectious hepatitis are due to other agents. A viral agent similar to HCV has been cloned and was identified as hepatitis G virus (HGV), also referred to as GBV-C.25 Evidence of HGV has been found in 2% of blood donors in the United States.26 However, HGV is not linked to liver disease or exacerbations of liver disease.25 Exam three content. see the following highlights on pages 1127-31 Important 1/3/2023 Etiology and Pathogenesis. Hepatitis A is contracted primarily by the fecal–oral route.31 It has a brief incubation period of 14 to 28 days.32 The virus replicates in the liver, is excreted in the bile, and is shed in the stool. The fecal shedding of HAV occurs during the first 2 weeks of the illness.31 The disease often occurs sporadically or in epidemics. Drinking contaminated milk or water and eating shellfish from infected waters are fairly common routes of transmission. At special risk are people traveling abroad who have not previously been exposed to the virus. Because young children are asymptomatic, they play an important role in the spread of the disease. Institutions housing large numbers of people (usually children) sometimes are stricken with an epidemic of hepatitis A. Oral behavior and lack of toilet training promote viral infection among children attending preschool day care centers, who then carry the virus home to older siblings and parents. Hepatitis A usually is not transmitted by transfusion of blood or plasma derivatives, presumably because its short period of viremia usually coincides with clinical illness, so that the disease is apparent and blood donations are not accepted. PRINTED BY: [email protected]. Printing of Notes and Highlights is for personal, private use only. Notes created by user are not part of publisher content. No part of this book may be reproduced or transmitted without publisher's prior permission. Violators will be prosecuted. about:blank 217/288 7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology Important 1/3/2023 Hepatitis B has a longer incubation period and represents a more serious health problem than hepatitis A. The virus usually is transmitted through inoculation with infected blood or serum. However, the viral antigen can be found in most body secretions and can be spread by oral or sexual contact. In the United States, most people with hepatitis B acquire the infection as adults or adolescents. The disease is highly prevalent among injecting drug users, heterosexuals with multiple sex partners, and men who have sex with men.43,44 Health care workers are at risk owing to blood exposure and accidental needle injuries. Although the virus can be spread through transfusion or administration of blood products, routine screening methods have appreciably reduced transmission through this route. The risk of hepatitis B in infants born to HBV-infected mothers ranges from 10% to 85%, depending on the mother’s HBV status. Infants who become infected have a 90% risk of becoming chronic carriers, and up to 25% will die of chronic liver disease as adults.44,45 Important 1/3/2023 In the United States, about 2% of people have chronic hepatitis C.50 In 2014, an estimated 30,500 new acute hepatitis C cases occurred. After many years of decrease, the incidence of HCV infection doubled between 2010 and 2014. Before 1990, the main route of transmission of HCV was through contaminated blood transfusions or blood products. With implementation of HCV testing in blood banks, the risk of HCV infection from blood transfusion is almost nonexistent in the United States and other developed countries.51,52 However, unsafe medical procedures and unscreened blood transfusions may be the most important sources of HCV infections in less developed countries of the world. Currently, recreational injecting drug use is the most common mode of HCV transmission in the United States and Canada.51,52 High-risk sexual behavior, defined as having sex with multiple sexual partners or sex with an HCV-infected partner, is currently the second most common risk factor in the United States. The rate of transmission to infants born to HCV RNA–positive mothers ranges from 4.6% to 10%.51 HCV also can be spread through exposure in the health care setting, primarily through needle-stick injuries. There also is concern that transmission of small amounts of blood during tattooing, acupuncture, and body piercing may facilitate the transmission of HCV. Hepatitis C is the leading reason for liver transplantation, though the virus usually recurs after transplantation.53 PRINTED BY: [email protected]. Printing of Notes and Highlights is for personal, private use only. Notes created by user are not part of publisher content. No part of this book may be reproduced or transmitted without publisher's prior permission. Violators will be prosecuted. about:blank 218/288 7/19/24, 6:06 PM Highlights & Notes: Lippincott CoursePoint for Norris: Porth's Pathophysiology Important 8/16/2022 Adipose Tissue as an Endocrine Organ Energy storage. Adipose tissue as an endocrine organ and control of appetite. PRINTED BY: [email protected]. Printing of Notes and Highlights is for personal, private use only. Notes created by user are not part of publisher content. No part of this book may be reproduced or transmitted without publisher's prior permission. Violators will be prosecuted. about:blank 219/288