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By O. Hanson. Westwood College California.

Laws were eventually passed that enabled students to dissect the corpses of criminals and those who donated their bodies for research buy plaquenil 200mg mastercard. Still purchase plaquenil 200mg line, it was not until the late nineteenth century that medical researchers discovered non-surgical methods to look inside the living body buy plaquenil 200 mg without prescription. X-Rays German physicist Wilhelm Röntgen (1845–1923) was experimenting with electrical current when he discovered that a mysterious and invisible “ray” would pass through his flesh but leave an outline of his bones on a screen coated with a metal compound 200 mg plaquenil overnight delivery. In 1895, Röntgen made the first durable record of the internal parts of a living human: an “X-ray” image (as it came to be called) of his wife’s hand. Scientists around the world quickly began their own experiments with X-rays, and by 1900, X-rays were widely used to detect a variety of injuries and diseases. The X-ray is a form of high energy electromagnetic radiation with a short wavelength capable of penetrating solids and ionizing gases. As they are used in medicine, X-rays are emitted from an X-ray machine and directed toward a specially treated metallic plate placed behind the patient’s body. X-rays are slightly impeded by soft tissues, which show up as gray on the X-ray plate, whereas hard tissues, such as bone, largely block the rays, producing a light-toned “shadow. Like many forms of high energy radiation, however, X-rays are capable of damaging cells and initiating changes that can lead to cancer. This danger of excessive exposure to X-rays was not fully appreciated for many years after their widespread use. Although often supplanted by more sophisticated imaging techniques, the X-ray remains a “workhorse” in medical imaging, especially for viewing fractures and for dentistry. The disadvantage of irradiation to the patient and the operator is now attenuated by proper shielding and by limiting exposure. Modern Medical Imaging X-rays can depict a two-dimensional image of a body region, and only from a single angle. In contrast, more recent medical imaging technologies produce data that is integrated and analyzed by computers to produce three-dimensional images or images that reveal aspects of body functioning. The technique was invented in the 1970s and is based on the principle that, as X-rays pass through the body, they are absorbed or reflected at different levels. It is especially useful for soft tissue scanning, such as of the brain and the thoracic and abdominal viscera. Its level of detail is so precise that it can allow physicians to measure the size of a mass down to a millimeter. In 1970, a physician and researcher named Raymond Damadian noticed that malignant (cancerous) tissue gave off different signals than normal body tissue. This has helped scientists learn more about the locations of different brain functions and more about brain abnormalities and diseases. Ultrasonography Ultrasonography is an imaging technique that uses the transmission of high-frequency sound waves into the body to generate an echo signal that is converted by a computer into a real-time image of anatomy and physiology (see Figure 1. Ultrasonography is the least invasive of all imaging techniques, and it is therefore used more freely in sensitive situations such as pregnancy. Ultrasonography is used to study heart function, blood flow in the neck or extremities, certain conditions such as gallbladder disease, and fetal growth and development. The main disadvantages of ultrasonography are that the image quality is heavily operator-dependent and that it is unable to penetrate bone and gas. In the past, anatomy has primarily been studied via observing injuries, and later by the dissection of anatomical structures of cadavers, but in the past century, computer-assisted imaging techniques have allowed clinicians to look inside the living body. The two disciplines are typically studied together because form and function are closely related in all living things. Therefore, molecules combine to form cells, cells combine to form tissues, tissues combine to form organs, organs combine to form organ systems, and organ systems combine to form organisms. These processes include: organization, in terms of the maintenance of essential body boundaries; metabolism, including energy transfer via anabolic and catabolic reactions; responsiveness; movement; and growth, differentiation, reproduction, and renewal. Although the body can respond to high temperatures by sweating and to low temperatures by shivering and increased fuel consumption, long-term exposure to extreme heat and cold is not compatible with survival. The body requires a precise atmospheric pressure to maintain its gases in solution and to facilitate respiration—the intake of oxygen and the release of carbon dioxide. Homeostasis is regulated by negative feedback loops and, much less frequently, by positive feedback loops. Both have the same components of a stimulus, sensor, control center, and effector; however, negative feedback loops work to prevent an excessive response to the stimulus, whereas positive feedback loops intensify the response until an end point is reached. Regions of the body are identified using terms such as “occipital” that are more precise than common words and phrases such as “the back of the head. Images of the body’s interior commonly align along one of three planes: the sagittal, frontal, or transverse. The body’s organs are organized in one of two main cavities—dorsal (also referred to posterior) and ventral (also referred to anterior)—which are further sub-divided according to the structures present in each area. Serous membranes cover the lungs (pleural serosa), heart (pericardial serosa), and some abdominopelvic organs (peritoneal serosa). A scientist wants to study how the body uses foods and studying all of the structures of the ankle and foot? Which of the following is an example of a normal changes physiologic process that uses a positive feedback loop? The person is standing facing the observer, with upper limbs extended out at a ninety-degree angle 13. Cancer cells can be characterized as “generic” cells that from the torso and lower limbs in a wide stance perform no specialized body function. Humans have the most urgent need for a continuous long, thin, right and left sides along the ________. Which of the following imaging techniques would be best to use to study the uptake of nutrients by rapidly a. Identify the four components of a negative feedback characteristics of the human heart come more easily: an loop and explain what would happen if secretion of a body alien who lands on Earth, abducts a human, and dissects his chemical controlled by a negative feedback system became heart, or an anatomy and physiology student performing a too great. Explain why the smell of smoke when you are sitting produce sequential images of the body in the sagittal plane? If a bullet were to penetrate a lung, which three anterior thoracic body cavities would it enter, and which layer of the 33. Introduction Chapter Objectives After studying this chapter, you will be able to: • Describe the fundamental composition of matter • Identify the three subatomic particles • Identify the four most abundant elements in the body • Explain the relationship between an atom’s number of electrons and its relative stability • Distinguish between ionic bonds, covalent bonds, and hydrogen bonds • Explain how energy is invested, stored, and released via chemical reactions, particularly those reactions that are critical to life • Explain the importance of the inorganic compounds that contribute to life, such as water, salts, acids, and 42 Chapter 2 | The Chemical Level of Organization bases • Compare and contrast the four important classes of organic (carbon-based) compounds—proteins, carbohydrates, lipids and nucleic acids—according to their composition and functional importance to human life The smallest, most fundamental material components of the human body are basic chemical elements. In fact, chemicals called nucleotide bases are the foundation of the genetic code with the instructions on how to build and maintain the human body from conception through old age. Human chemistry includes organic molecules (carbon-based) and biochemicals (those produced by the body). All of the elements that contribute to chemical reactions, to the transformation of energy, and to electrical activity and muscle contraction—elements that include phosphorus, carbon, sodium, and calcium, to name a few—originated in stars. These elements, in turn, can form both the inorganic and organic chemical compounds important to life, including, for example, water, glucose, and proteins. This chapter begins by examining elements and how the structures of atoms, the basic units of matter, determine the characteristics of elements by the number of protons, neutrons, and electrons in the atoms.

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The liver lies inferior to the diaphragm in the right upper quadrant of the abdominal cavity and receives protection from the surrounding ribs cheap plaquenil 200 mg without a prescription. In the right lobe generic plaquenil 200 mg overnight delivery, some anatomists also identify an inferior quadrate lobe and a posterior caudate lobe order plaquenil 200mg with visa, which are defined by internal features purchase plaquenil 200mg without prescription. The liver is connected to the abdominal wall and diaphragm by five peritoneal folds referred to as ligaments. These are the falciform ligament, the coronary ligament, two lateral ligaments, and the ligamentum teres hepatis. The falciform ligament and ligamentum teres hepatis are actually remnants of the umbilical vein, and separate the right and left lobes anteriorly. The porta hepatis (“gate to the liver”) is where the hepatic artery and hepatic portal vein enter the liver. These two vessels, along with the common hepatic duct, run behind the lateral border of the lesser omentum on the way to their destinations. The hepatic portal vein delivers partially deoxygenated blood containing nutrients absorbed from the small intestine and actually supplies more oxygen to the liver than do the much smaller hepatic arteries. After processing the bloodborne nutrients and toxins, the liver releases nutrients needed by other cells back into the blood, which drains into the central vein and then through the hepatic vein to the inferior vena cava. This largely explains why the liver is the most common site for the metastasis of cancers that originate in the alimentary canal. Plates of hepatocytes called hepatic laminae radiate outward from the portal vein in each hepatic lobule. Between adjacent hepatocytes, grooves in the cell membranes provide room for each bile canaliculus (plural = canaliculi). The bile ducts unite to form the larger right and left hepatic ducts, which themselves merge and exit the liver as the common hepatic duct. This duct then joins with the cystic duct from the gallbladder, forming the common bile duct through which bile flows into the small intestine. A hepatic sinusoid is an open, porous blood space formed by fenestrated capillaries from nutrient-rich hepatic portal veins and oxygen-rich hepatic arteries. Hepatocytes are tightly packed around the fenestrated endothelium of these spaces, giving them easy access to the blood. From their central position, hepatocytes process the nutrients, toxins, and waste materials carried by the blood. Other materials including proteins, lipids, and carbohydrates are processed and secreted into the sinusoids or just stored in the cells until called upon. The hepatic sinusoids also contain star-shaped reticuloendothelial cells (Kupffer cells), phagocytes that remove dead red and white blood cells, bacteria, and other foreign material that enter the sinusoids. The portal triad is a distinctive arrangement around the perimeter of hepatic lobules, consisting of three basic structures: a bile duct, a hepatic artery branch, and a hepatic portal vein branch. Thus, before they can be digested in the watery environment of the small intestine, large lipid globules must be broken down into smaller lipid globules, a process called emulsification. Bile is a mixture secreted by the liver to accomplish the emulsification of lipids in the small intestine. The components most critical to emulsification are bile salts and phospholipids, which have a nonpolar (hydrophobic) region as well as a polar (hydrophilic) region. The hydrophobic region interacts with the large lipid molecules, whereas the hydrophilic region interacts with the watery chyme in the intestine. This results in the large lipid globules being pulled apart into many tiny lipid fragments of about 1 µm in diameter. Bile salts act as emulsifying agents, so they are also important for the absorption of digested lipids. While most constituents of bile are eliminated in feces, bile salts are reclaimed by the enterohepatic circulation. Once bile salts reach the ileum, they are absorbed and returned to the liver in the hepatic portal blood. Bilirubin, the main bile pigment, is a waste product produced when the spleen removes old or damaged red blood cells from the circulation. These breakdown products, including proteins, iron, and toxic bilirubin, are transported to the liver via the splenic vein of the hepatic portal system. Bilirubin is eventually transformed by intestinal bacteria into stercobilin, a brown pigment that gives your stool its characteristic color! In some disease states, bile does not enter the intestine, resulting in white (‘acholic’) stool with a high fat content, since virtually no fats are broken down or absorbed. Hepatocytes work non-stop, but bile production increases when fatty chyme enters the duodenum and stimulates the secretion of the gut hormone secretin. The valve-like hepatopancreatic ampulla closes, allowing bile to divert to the gallbladder, where it is concentrated and stored until the next meal. The Pancreas The soft, oblong, glandular pancreas lies transversely in the retroperitoneum behind the stomach. Its head is nestled into the “c-shaped” curvature of the duodenum with the body extending to the left about 15. It is a curious mix of exocrine (secreting digestive enzymes) and endocrine (releasing hormones into the blood) functions (Figure 23. The exocrine part of the pancreas arises as little grape-like cell clusters, each called an acinus (plural = acini), located at the terminal ends of pancreatic ducts. These acinar cells secrete enzyme-rich pancreatic juice into tiny merging ducts that form two dominant ducts. The larger duct fuses with the common bile duct (carrying bile from the liver and gallbladder) just before entering the duodenum via a common opening (the hepatopancreatic ampulla). The smooth muscle sphincter of the hepatopancreatic ampulla controls the release of pancreatic juice and bile into the small intestine. The second and smaller pancreatic duct, the accessory duct (duct of Santorini), runs from the pancreas directly into the duodenum, approximately 1 inch above the hepatopancreatic ampulla. Scattered through the sea of exocrine acini are small islands of endocrine cells, the islets of Langerhans. Unlike bile, it is clear and composed mostly of water along with some salts, sodium bicarbonate, and several digestive enzymes. If produced in an active form, they would digest the pancreas (which is exactly what occurs in the disease, pancreatitis). The intestinal brush border enzyme enteropeptidase stimulates the activation of trypsin from trypsinogen of the pancreas, which in turn changes the pancreatic enzymes procarboxypeptidase and chymotrypsinogen into their active forms, carboxypeptidase and chymotrypsin. The enzymes that digest starch (amylase), fat (lipase), and nucleic acids (nuclease) are secreted in their active forms, since they do not attack the pancreas as do the protein-digesting enzymes. The entry of acidic chyme into the duodenum stimulates the release of secretin, which in turn causes the duct cells to release bicarbonate- rich pancreatic juice. Parasympathetic regulation occurs mainly during the cephalic and gastric phases of gastric secretion, when vagal stimulation prompts the secretion of pancreatic juice.

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A break in the endothelial continuity of a heart valve would expose subendothelial structures (vimentin discount plaquenil 200mg with mastercard, laminin and valvu- lar interstitial cells) and lead to a “chain reaction” of valvular destruc- tion plaquenil 200mg. Once valve leaflets are inflamed through the valvular surface endothelium and new vascularization occurs generic 200 mg plaquenil free shipping, the newly formed mi- crovasculature allows T-cells to infiltrate and perpetuate the cycle of valvular damage discount plaquenil 200mg fast delivery. The presence of T-cell infiltration, even in old min- eralized lesions, is indicative of persistent and progressive disease in the valves. Valvular interstitial cells and other valvular constituents under the influence of inflammatory cytokines perpetuate aberrant repair. Although the foregoing offers a very feasible explanation of the ex- perimental data, questions remain that have significant implications for choosing streptococcal vaccines (22–24). For example, there is no direct and conclusive evidence for a pathogenetic role of cross-reac- tive antibodies in vivo and there is no exact animal model of rheu- matic fever for study. The need for a better understanding of the epidemiology of streptococci is underscored by a report that one group A streptococcal serotype can be rapidly and completely re- placed by another serotype in a stable population with adequate access to health care (25). This serotype change still has not been adequately explained and it raises questions about the efficacy of any type-specific streptococcal vaccine that is synthesized by combining M-protein sequences from virulent streptococcal serotypes. Identification and characterization of novel superantigens from Streptococcus pyogenes. European Journal of Clinical Microbiology and Infectious Diseases, 1991, 10:55–57. VirR and Mry are homologous trans-acting regulators of M protein and C5a peptidase expression in group A streptococci. Interactions of fibronectin with streptococci: the role of fibronectin as a receptor for Streptococcus pyogenes. Genetic variability of the emm-related gene of the large vir regulon of group A streptococci: potential intra- and intergenomic recombination events. Protection against a heterologous M serotype with shared C repeat region epitopes. Treatment of streptococcal pharyngotonsillitis: reports of penicillin’s demise are premature. Antibody-mediated autoimmune myocarditis depends on genetically determined target organ sensitivity. Dynamic epidemiology of group A streptococcal serotypes associated with pharyngitis. Major manifestations were least likely to lead to an improper diagno- sis and included carditis, joint symptoms, subcutaneous nodules, and chorea. Modified in part from reference (45) 20 two minor, manifestations offered reasonable clinical evidence of rheumatic activity. Although the Jones criteria have been revised repeatedly, the modi- fications were often made without prospective studies and were based on the perceived effects of previous revision(s). The prophylactic and prognostic stakes clearly underscore the importance of correctly identifying carditis. A diagnosis of recurring carditis requires the demonstration of valvular damage or involvement, with or without pericardial or myocardial involvement (11). Such clinical findings include a documented change in a previous murmur to a new murmur or pericardial rub, or an obvious radiographic increase in cardiac size, respectively. Further, recurrences of the disease are common in developing coun- tries, owing to gaps in the detection and secondary prevention of disease caused by a lack of health-care facilities. It is prudent to consider them as cases of “probable rheumatic fever” (once other diagnoses are excluded) and advise regular secondary prophylaxis. This cautious approach is particularly suitable for patients in vulnerable age groups in high incidence settings. However, an echo-Doppler examination should be per- formed if the facilities are available. Subcutaneous nodules are almost always associated with cardiac involvement and are found more commonly in patients with severe carditis. The major noncarditic manifestations occur in varying combinations, with or without carditis, during the evolution of the disease. The presence of noncarditic manifestations facilitates the detec- tion of rheumatic carditis and their identification is particularly important in recurrences of disease, when the diagnosis of carditis is difficult. Diagnosis of rheumatic carditis Although the endocardium, myocardium and pericardium are all affected to varying degrees, rheumatic carditis is almost always asso- ciated with a murmur of valvulitis (Table 4. Accordingly, myocardi- tis and pericarditis, by themselves, should not be labeled rheumatic in origin, when not associated with a murmur and other etiologies must be considered. Simultaneous demonstration of valvular involvement generally considered essential. The strict application of diagnostic criteria is mandatory to demonstrate pathological valvular regurgitation. Currently, data do not allow subclinical valvular regurgitation detected by echocardiography to be included in the Jones criteria, as evidence of a major manifestation of carditis. Myocarditis Myocarditis (alone) in the absence of valvulitis is unlikely to be of rheumatic origin and by itself should not be used as a basis for such a diagnosis. If previous clinical findings are known, they can be compared with current data — myocardial involvement is likely to result in a sudden cardiac enlargement that will be detectable radiographically. At times, however, the friction rub can mask the mitral regurgitation murmur, which becomes evident only after the pericarditis subsides. Since isolated pericarditis is not good evidence of rheumatic carditis without supporting evidence of a valvular regurgitant murmur, it may be helpful to have Doppler echocardiography available in such circumstances to look for signs of mitral regurgitation. Echocardiography could also corroborate the mild-to-moderate pericardial effusion likely to be associated with pericarditis; large effusions and tamponade are rare (18). Patients with this form of pericarditis are usually treated as cases of severe carditis. Noncardiac manifes- tations may be the best guide for a diagnosis of rheumatic carditis. Arthritis is often the only major manifestation in adolescents, as well as in adults, where carditis and chorea become less common in older age groups. Joint pain without objective findings does not qualify as a major disease manifestation because of its nonspecificity. Inflamed joints are characteristically warm, red and swollen, and an aspirated sample of synovial fluid may reveal a high -3 -3 average leukocyte count (29000mm , range 2000–96000mm ) (21). Tenderness in rheumatic arthritis may be out of proportion to the objective findings and severe enough to result in excruciating pain on touch. The term “migratory” reflects the sequential involvement of joints, with each completing a cycle of inflammation and resolution, so that some joint inflammation may be resolving while others are beginning. Frequently, several joints may be affected simulta- neously, or the arthritis may be additive rather than migratory. In- flammation in a particular joint usually resolves within two weeks and the entire bout of polyarthritis in about a month if untreated.

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