Aspiration pneumonia 5mg accutane visa, an inflammation of the lung, may result from the inhalation Cardiovascular Complications of foreign substances or chemical irritants. Aspiration of gastric contents is also a Other than direct effects on the heart common cause of aspiration pneumonia. Rather than being a direct can lead to potentially serious conse- result of drug use, tuberculosis is more quences (see Chapter 11). In some instances, inflam- poor hygiene, and overcrowding all con- mation of the veins with clot formation tribute to development of the disease. In (thrombophlebitis) may occur because of addition, because some drugs have an im- the toxic effects of the drug. An Respiratory Complications overdose of narcotics or sedative/hypno- tics can severely depress the respiratory The intravenous injection of drugs to center, causing cessation of breathing and which adulterants such as talc, starch, or consequent death. Overdoses of narcotics baking soda have been added may result have also been associated with develop- in pulmonary complications. Because ment of severe pulmonary edema (collec- these substances do not dissolve, they cir- tion of fluid in the lungs), which, without culate in the blood and may become treatment, can also result in death. Diagnostic Procedures 221 Gastrointestinal Complications Other Complications Because the liver acts as the detoxifica- The chronic use of some drugs may tion center for the body, individuals who result in nystagmus (involuntary eye chronically abuse drugs may damage movement). Chronic, excessive abuse of sol- renal failure, which can progress to per- vents, for example, can cause liver necro- manent kidney damage (see Chapter 13). Other substances may Individuals who abuse drugs also have a cause liver abnormalities such as inflam- higher incidence of venereal disease, such mation or fibrosis. Hepatitis A may be related to of the most serious and hazardous com- poor hygiene habits and poor envi- plications of drug use in the past few ronmental conditions. More commonly, years has been infection with HIV (see hepatitis B (serum hepatitis) occurs as the Chapter 8), which is related to both in- result of nonsterile or contaminated intra- travenous drug use and unsafe sexual venous injections. HCV causes what was pre- fetal hazards are related to the lifestyle of viously called non-A, non-B hepatitis and the mother, which results in poor prena- is transmitted through infected blood. The direct toxic effects travenous drugs and share needles are at of drugs on the developing fetus (tetrato- high risk for developing the disease.
Each cell produces waste products that must be removed from its environment and taken to the lungs accutane 10 mg without a prescription, kidneys, or ONCE AROUND THE CIRCULATION other organs for metabolism and/or excretion. Cells in en- docrine glands communicate with cells in other tissues by An understanding of the circulation depends on knowl- releasing hormones that are carried throughout the body edge of the physical principles governing blood flow. Heat produced by the work of the body first, we will briefly describe the cardiovascular system is brought to the surface of the body where it can be lost to (Fig. Contractions of the left ventricle propel blood the external environment by way of the circulation. Because of their elasticity, the aorta and large arter- tions in the face of a variety of challenges, such as exercise, ies are distended by each injection of blood from the heart. Unfortunately, failure of the cardiovascular system to per- Several regulatory mechanisms normally keep aortic form normally occurs all too often. In developed countries, pressure within a narrow range, providing a pulsatile but 210 CHAPTER 12 An Overview of the Circulation and Hemodynamics 211 Blood flows from capillaries into venules and small veins. These vessels have larger diameters and thinner walls than the companion arterioles and small arteries. When the smooth muscle in their walls contracts, the vol- ume of blood they contain is reduced. These vessels, along with larger veins, are referred to as capacitance vessels. The pressure generated by the contractions of the left ven- tricle is largely dissipated by this point; blood flows through the veins to the right atrium at much lower pres- sures than are found on the arterial side of the circulation. The right atrium receives blood from the largest veins, the superior and inferior vena cavae, which drain the entire body except the heart and lungs.
The activation of Factor XI Plasma thromboplastin factor XII requires several cofactors generic 5mg accutane amex, including kallikrein antecedent and high-molecular-weight kininogen. In this pathway, Factor XII Hageman factor Contact factor factor X is activated by a complex consisting of factor VIII, Factor XIII Fibrin stabilizing factor 2 factor IXa, platelet factor 3, and Ca. While the blood clot resolves, multiple factors partici- There are many points of interaction between the two pate in wound healing. Optimal wound healing requires the pathways, and no one pathway will account for hemosta- recruitment or generation of new tissue cells as well as new sis. For example, thrombin generated during activation of blood vessels to nourish the repairing tissue. Thus, secreted the extrinsic pathway is an essential cofactor for factor VIII proteins and lipids that attract cells (chemoattractants), in- of the intrinsic pathway. Factor VIIa of the extrinsic path- duce cells to proliferate (mitogens), and induce primitive way directly activates factor IX of the intrinsic system. The many additional points of interaction are tissue and repair the injured area. The healing area is vas- beyond the scope of this discussion, but the concept of in- cularized by a process known as angiogenesis, the forma- dependently acting intrinsic versus extrinsic coagulation tion of new blood vessels from preexisting ones. However, the activity of activated during clotting, play an important role in the an- the intrinsic system and the extrinsic system are monitored giogenic response because they secrete factors that induce individually in clinical coagulation tests for diagnostic pur- proliferation, migration, and differentiation of two of the poses. The test used to monitor activity of the intrinsic sys- major components of blood vessels, endothelial cells, and tem is the partial thromboplastin time (PTT). While plasma can eventually clot in the absence of conjunction with protein growth factors, this lipid induces surface contact, localization and assembly of coagulation the proliferation of new tissue cells to replace damaged factors on cell surfaces amplifies reaction rates by several ones and drives the formation of new blood vessels until the orders of magnitude. It does so by inducing the mi- Clot retraction is a phenomenon that usually occurs gration, proliferation, and differentiation of fibroblasts, within minutes or hours after clot formation. The clot draws smooth muscle cells, and endothelial cells at the site of tis- together, extruding a very large fraction of the serum. Sphingosine 1-phosphate exerts its effects opti- retraction requires platelets.
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