By H. Moff. University of Saint Francis.
These CNS ef- fects are probably the result of reductions in brain cat- Pharmacological Actions echolam ine levels super avana 160mg with amex treatment for erectile dysfunction before viagra. O ther side effects purchase 160 mg super avana with amex doctor for erectile dysfunction in ahmedabad, also typical of A n acute intravenous injection of clonidine m ay pro- sym pathetic depression, are dry m outh, nasal conges- duce a transient pressor response that apparently is due tion, orthostatic hypertension, and im potence. The reduction in cardiac output is the result of both a Clonidine and Related Drugs decreased heart rate and reduced stroke work; the lat- Clonidine (Catapres) is effective orally and is used pri- ter effect is probably caused by a dim inished venous m arily for the treatm ent of m oderate hypertension. Plasm a renin activity is re- Adverse Effects duced by clonidine, presum ably as a result of a centrally It is estim ated that about 7% of patients receiving cloni- m ediated decrease in sym pathetic stim ulation of the dine discontinue the drug because of side effects. A lthough the sym ptom s are generally m ild and tend to subside if therapy is continued for several weeks, as Clinical Uses m any as 50% of the patients com plain of drowsiness The prim ary indication for clonidine use is in m ild and and dryness of m outh. O ther untoward effects include m oderate hypertension that has not responded ade- constipation, nausea or gastric upset, and im potence. Since These effects are characteristic of interference with the clonidine causes sodium and water retention and plasm a functioning of the sym pathetic nervous system. A vasodilator can be added to the sion, which follows abrupt withdrawal of clonidine ther- clonidine–diuretic regim en in the treatm ent of resistant apy. The genesis of quite effective, since the reﬂex increases in heart rate the syndrom e is not well understood. A contributing and cardiac output that result from vasodilator adm inis- factor m ay be developm ent of supersensitivity in either tration are reduced or negated by clonidine-induced de- the sym pathetic nerves or the effector organs of the car- creases in heart rate and cardiac output. Thus, when the drug is been used in com bination with a diuretic, a vasodilator, abruptly withdrawn, an exaggerated response to “nor- and a -blocker. If treatm ent with cause the coadm inistration of clonidine and a -blocker clonidine is term inated gradually, rebound hyperten- m ay cause excessive sedation. Patients should be warned of the danger useful in patients with renal failure, since its duration of of abruptly discontinuing clonidine treatm ent. In the contraindicated in a hypertensive patient with a course of history taking, she tells you that she takes pheochrom ocytom a? W hich of the following com pounds depends least (C) Captopril upon the release of ED RF (nitric oxide) from en- (D ) Nitroprusside dothelial cells to cause vasodilation? A lthough m any drugs can evoke a reaction such (D ) H ydralazine as a rash, a rash and a dry cough are well-recog- (E) A cetylcholine nized side effects of angiotensin converting enzym e 238 III DRUGS AFFECTING THE CARDIOVASCULAR SYSTEM (A CE) inhibitors, such as captopril. U p to 20% of periphery and therefore reduces the sym patheti- these patients m ay develop a cough with A CE in- cally induced stim ulation of renin release. The cause is not known for certain, but it pathetic effect on renin release is m ediated by - m ay be related to the accum ulation in the lungs of receptors, so prazosin, an -blocker would not de- bradykinin or other inﬂam m atory m ediators. Captopril is an A CE inhibitor and is Inhibiting A CE leads to an increase in bradykinin, likely to enhance renin release, although it would which is norm ally broken down by this enzym e. The prevent the effects of renin by reducing the form a- rash was originally attributed to a sulfhydryl group tion of angiotensin II. Nitroprusside and diazoxide in captopril but is known to occur with other are directly acting vasodilators and will prom ote non–sulfhydryl-containing A CE-inhibitors. The vasodilation caused by bradykinin, hista- m ine, hydralazine, and acetylcholine depends in part SUPPLEM ENTAL READING upon nitric oxide release from the endothelium. The treatm ent of adults with essential hyper- M inoxidil activates K channels, which results in tension. C a s e S tudy Hypertensive Emergency 50-year-old wom an is seen in the em ergency needs to be hospitalized and receive drug therapy A departm ent com plaining of a severe headache, to lower the blood pressure. H er vision is such as this would likely choose intravenous blurry and her blood pressure is 200/140 m m H g. A chest A lthough there are a num ber of choices, sodium radiograph reveals an enlarged cardiac silhouette. It m ay beneﬁt this patient to im prove ANSW ER: This patient appears to be have m alignant cardiac output by reducing afterload and preload. O ther antihypertensives that could be considered in The azotem ia and proteinuria are signs of renal this situation are labetalol, a com bined - and - disease and often portend deteriorating renal blocker, and nicardipine, a calcium channel function. Berndt D R U G L IS T GENERIC NAM E PAGE GENERIC NAM E PAGE Acetazolamide 244 Hydrochlorothiazide 245 Amiloride 248 Isosorbide 251 Bumetanide 249 Methazolamide 244 Chlorothiazide 245 Mannitol 250 Chlorthalidone 245 Metolazone 245 Dichlorphenamide 244 Quinethazone 245 Dorzolamide 245 Spironolactone 247 Ethacrynic acid 249 Torsemide 249 Furosemide 249 Triamterene 248 Glycerin 251 Urea 251 By selectively regulating solute or ﬂuid reabsorp- though diuretic therapy provides welcom e relief from tion, the kidneys play the m ajor role in m aintaining the pulm onary congestion, ascites, edem a, and hyperten- volum e and com position of extracellular ﬂuid. D iuretics inhibit renal sodium ﬂuid balance and renal function that are essential to un- transport and thereby interfere with the norm al regula- derstanding diuretic action, a discussion of the uses of tory activity of the kidney. In som e instances, adm inis- diuretics for treating abnorm alities of ﬂuid balance, and tration of a diuretic drug is the prim ary treatm ent indi- a detailed description of the various classes of diuretics.
The male Y chromosome is other purchase super avana 160 mg erectile dysfunction treatment with diabetes, but no two look exactly alike (unless they are iden- smaller than other chromosomes and mainly determines tical twins) generic super avana 160 mg visa erectile dysfunction diagnosis, because they receive different combinations sex. If a letter is used for the dominant gene and the recessive sperm cell with an X chromosome fertilizes an ovum, the gene is represented by the lower case of the same letter. Gametes Some human traits, including the traits involved in many genetic diseases, are determined by a single pair of genes; most, however, are the result of two or more gene pairs acting together in what is termed multifactorial in- heritance. This type of inheritance accounts for the wide range of variations within populations in such character- istics as coloration, height, and weight, all of which are F1 (offspring) determined by more than one pair of genes. For example, the Female Female Sperm genes for certain types of baldness and certain types of color blindness may be inherited by either males or fe- males, but the traits appear mostly in males under the ef- fects of male sex hormone. Mutations may occur spontaneously and if a recessive gene is located on the X chromosome in or may be induced by some agent, such as ionizing radi- a male it cannot be masked by a matching dominant gene. The vast will exhibit that characteristic, whereas a female must have majority of harmful mutations never are expressed be- two recessive genes to show the trait. Beneficial mutations, HEREDITY AND HEREDITARY DISEASES ✦ 497 Box 25-2 Clinical Perspectives Mitochondrial Disease: When the Powerhouses Shut DownMitochondrial Disease: When the Powerhouses Shut Down itochondria are the powerhouse organelles of cells, con- diseases are believed to affect several thousand children in the Mverting the energy in nutrients into the ATP needed for United States, causing serious damage to metabolically active cell activities. Because they may have evolved as separate or- cells in the brain, heart, liver, muscles, kidneys, and endocrine ganisms early in the history of life on earth, they exist almost organs. If, however, it Some mitochondrial diseases are caused by genetic mutations is carried in the mitochondrion itself, it would be passed only in mitochondrial DNA, while others are caused by mutations in from a mother to her offspring. People with ◗ Genetic Diseases these genetic defects may pass them on to their children before they are aware of them unless genetic testing re- Any disorders that involve the genes may be said to be ge- veals their presence. In the case of our earlier examples, netic, but they are not always hereditary, that is, passed the clubfoot is congenital, but not hereditary, having re- from parent to offspring in the reproductive cells. Nonin- sulted from severe distortion of the developing extremi- herited genetic disorders may begin during maturation of ties during intrauterine growth; the extra fingers are the sex cells or even during development of the embryo. To illustrate, tion that is ordinarily a mild disease, but if maternal in- let us assume that two infants are born within seconds in fection occurs during the first 3 or 4 months of preg- adjoining delivery rooms of the same hospital. It is noted nancy, the fetus has a 40% chance of developing defects that one infant has a clubfoot, a condition called talipes of the eye (cataracts), ear (deafness), brain, and heart. Congenital means present at nols and PCB), as well as some drugs, notably LSD, are the time of birth; hereditary means genetically transmit- known to disrupt genetic organization. This Male and female sex cells are present at birth but do not be- process can be studied in males with specimens obtained from come active until the reproductive years. Males be- mercury compounds have found their way into the food tween 20 and 45 years of age carry the least risk of transmit- chain, causing neural damage to the children of parents who ting a genetic error. Because new sperm cells are produced on a 64- when ingested, as from air or water pollution, has been im- day cycle, men are advised to avoid conception for a few plicated in sperm cell abnormalities and in reduced sperm months after exposure to x-rays, cancer chemotherapy, or counts. If the meninges protrude (herniate), the defect is termed a meningocele (meh-NIN- go-sele); if both the spinal cord and meninges protrude, it is a myelomeningocele (mi-eh-lo-meh-NIN-go-sele). Women of childbearing age should eat foods high in folic acid (green leafy vegetables, fruits, and legumes) and should take folic acid supplements even before pregnancy, as the nervous system develops early. Examples of Genetic Diseases C The best known example of a genetic disorder that is not hereditary is the most common form of Down syndrome, Figure 25-3 Spina bifida, incomplete closure of the spinal cord. Cystic fibro- sis is characterized by excessively thickened secretions in the bronchi, the intestine, and the pancreatic ducts, re- sulting in obstruction of these vital organs. Cystic fibrosis was once fatal by the time of adolescence, but now, with appropriate care, life expectancies are ex- Figure 25-4 Child with Down syndrome (trisomy 21). There is no cure for hood of having a baby with Down syndrome increases Tay-Sachs, but a blood test can identify genetic carriers of dramatically in women past the age of 35 years and may the disease. Atro- Most genetic diseases are familial or hereditary; that phy (AT-ro-fe) means wasting due to decrease in the size is, they are passed on from parent to child in the egg or of a normally developed part. In the case of a disorder carried by a dominant muscle movement in the infant proceeds within a few gene, only one parent needs to carry the abnormal gene to months to extreme weakness of the respiratory muscles, give rise to the disease. Note, however, that hereditary forms of cancer F 2 account for only about 1% of all cancers and that the de- Cc Cc velopment of cancer is complex, involving not only spe- cific genes but also gene interactions and environmental F3 factors. Genetic components have been suggested in some other diseases as well, including certain forms of heart disease, diabetes mellitus, types of cleft lip and cleft Normal male Normal female palate, and perhaps Parkinson and Alzheimer disease.
In Addison disease super avana 160mg amex impotence with lisinopril, in which the adrenal cor- zyme activities purchase super avana 160 mg otc erectile dysfunction patient.co.uk doctor, and it helps regulate the chemical re- tex does not produce enough aldosterone, there is a loss actions by which carbohydrate is converted to energy of sodium and water and an excess of potassium. When the blood concentration of sodium rises above ◗ Calcium is required for bone formation, muscle con- the normal range, the pituitary secretes more antidiuretic traction, nerve impulse transmission, and blood clot- hormone (ADH). Phosphates are mone increases blood calcium levels by causing the bones found in plasma membranes, nucleic acids (DNA and to release calcium and the kidneys to reabsorb calcium. Although some electrolytes are lost in Regulation of pH the feces and through the skin as sweat, the job of bal- ancing electrolytes is left mainly to the kidneys, as de- The body constantly produces acids in the course of me- scribed in Chapter 22 on the urinary system. Catabolism of fats yields fatty acids and other BODY FLUIDS ✦ 427 Box 21-2 Clinical Perspectives Sodium and Potassium: Causes and Consequences of ImbalanceSodium and Potassium: Causes and Consequences of Imbalance he concentrations of sodium and potassium in body fluids The term hyperkalemia is taken from the Latin name for Tare important measures of water and electrolyte balance. It refers to excess potassium in body flu- An excess of sodium in body fluids is termed hypernatremia, ids, which may result from kidney failure, dehydration, and taken from the Latin name for sodium, natrium. Hypona- pokalemia, or low potassium in body fluids, may result from tremia, a deficiency of sodium in body fluids, can come from taking diuretics, which cause potassium to be lost along with water intoxication, heart failure, kidney failure, cirrhosis of water. It can cause much aldosterone from the adrenal cortex, and it causes mus- muscle weakness, hypotension, confusion, shock, convul- cle fatigue, paralysis, confusion, hypoventilation, and cardiac sions, and coma. This condition depresses and, under anaerobic conditions, lactic acid; carbon diox- the nervous system, leading to mental confusion and ul- ide dissolves in the blood and yields carbonic acid (see timately coma. It may also arise from kidney failure or prolonged gether to counteract these changes and maintain acid- diarrhea, which drains the alkaline contents of the intes- base balance: tine. Buffers are substances that prevent Acidosis may also result from inadequate carbohy- sharp changes in hydrogen ion (H ) concentration and drate metabolism, as occurs in diabetes mellitus, inges- thus maintain a relatively constant pH. The main buffer systems in the body are bi- from food or body materials, leading to the production of carbonate buffers, phosphate buffers, and proteins, excess acid. When acidosis results from the accumulation such as hemoglobin in red blood cells and plasma pro- of ketone bodies, as in the case of diabetes, the condition teins. This abnormality excites the release from the lungs makes the blood more alkaline nervous system to produce tingling sensations, muscle by reducing the amount of carbonic acid formed. Table 21•1 Causes of Acidosis and Alkalosis Checkpoint 21-7 What are three mecha- ACIDOSIS ALKALOSIS nisms for maintaining the acid—base bal- ance of body fluids? Metabolic Kidney failure; anaerobic me- Overuse of antacids; prolonged tabolism; lack of carbohy- vomiting drate metabolism, as in dia- Abnormal pH betes, starvation; prolonged diarrhea If shifts in pH cannot be controlled, ei- Respiratory Respiratory obstruction, lung Hyperventilation (overbreathing ther acidosis or alkalosis results (Table disease such as asthma due to anxiety or oxygen 21-1). Metabolic acidosis or alkalosis results ◗ Increased loss of fluid through the capillaries, as caused from unregulated increases or decreases in any other acids by injury, allergic reaction, or certain infections. Tubercu- ◗ Interference with normal fluid return to the heart, as losis, cancer, and some infections may give rise to effu- caused by congestive heart failure or blockage in the ve- sion. It may occur in disor- ure of the liver to manufacture adequate amounts of the ders of the liver, kidneys, and heart, as well as in cancers, protein albumin, as frequently occurs in liver disease. In sulting from the inability of the kidneys to eliminate such cases, it may be necessary to administer intravenous adequate amounts of urine fluids to correct fluid and electrolyte imbalances. Eprofessionals to arrive at the scene of an automobile accident, At medical facilities, EMTs work closely with physicians and heart attack, or other emergency situation. EMTs must assess and nurses, reporting on histories, physical examinations, and respond rapidly to a medical crisis, taking a medical history, per- measures taken to stabilize the patient. Most EMTs receive forming a physical examination, stabilizing the patient, and, if their training from a college or technical school and must be necessary, transporting the patient to the nearest medical facility. To perform their life-saving duties, EMTs need extensive As the American population continues to age and become training, including a thorough understanding of anatomy and concentrated in urban centers, the rate of accidents and other physiology. For more information about this rewarding ca- diographs to monitor heart activity, and defibrillators to treat reer, contact the National Association of Emergency Medical cardiac arrest, and they must also be proficient at giving in- Technicians. In this formulation, the it is isotonic, this type of solution does not change the ion electrolyte concentrations are equal to normal plasma val- distribution in the body fluid compartments. This solution is hypertonic tional plasma volume with the electrolyte concentration when infused, but becomes hypotonic after the sugar is equal to that of the blood. Use of these Fluids containing varied concentrations of dextrose, hypotonic fluids is not advisable for long-term therapy sodium chloride, potassium, and other electrolytes and because of the common occurrence of water intoxication. Small amounts of potassium chloride are often taining concentrated sugar, protein, and fat are available added to replace electrolytes lost by vomiting or diarrhea. The urinary system is also called the excretory system be- ◗ The respiratory system eliminates carbon dioxide and cause one of its main functions is excretion, removal and water. It has many other functions as well, including regulation ◗ The skin, or integumentary system, excretes water, of the volume, acid–base balance (pH), and electrolyte salts, and very small quantities of nitrogenous wastes. These all appear in perspiration, although water also Although the focus of this chapter is the urinary system, evaporates continuously from the skin without our certain aspects of other systems are also discussed, because being conscious of it.
In contrast to preprocessing neurons order super avana 160 mg overnight delivery erectile dysfunction treatment rochester ny, presetting neurons discharge in a similar way after the occurrence of the response signal in both conditions of prior information order 160mg super avana overnight delivery erectile dysfunction treatment herbal remedy. The timing of the peak changes in activity is in favor of the hypothesis presented above, according to which each type of neuron may intervene at different moments during sensorimotor transformation. First, in the majority of the preprocessing neu- rons, the discharge was time-locked to the response signal in the condition of no prior information (see Figure 8. This indicates a rather early involvement in sensorimotor transformation, closely related to processing the information contained in the signal rather than to movement execution. On the contrary, most of the preset- ting neurons changed their activity time-locked to movement onset (Figure 8. Second, the number of presetting neurons whose preparatory activities were signiﬁcantly correlated with reaction time, thus clearly modulating the moment of movement initiation, was much higher than that of preprocessing neurons. When gradually manipulating movement direction, it has been shown that the selectivity of neuronal discharge is rather broad, i. As a consequence, it has been suggested that large populations of neurons should be active when any single motor act is executed. This has led to the notion of population coding, in which all activated neurons are assumed to contribute to the speciﬁcation of individual values of movement parameters. The preparatory signal (PS) provided complete prior information about the forthcoming move- ment. Trials were rank-ordered off-line according to increasing reaction time, the time between the response signal (RS) and movement onset (ﬁrst range of large dots). Information about movement direction is represented as peaks of activation localized at those sites of the ﬁeld that are mapped onto the indicated movement directions. Second, command input leads to the development of a single full-ﬂedged peak of activation representing the ﬁnal motor choice. This model predicts a large set of reaction time effects based on the fact that more highly preactivated ﬁeld sites reach thresholds faster than less highly preactivated sites. Based on the directional tuning curves of individual motor cortical neurons, determined during reaction time, distributions of the population activation were constructed, which were then extended into the preparatory period (Figure 8. The authors found that these distributions were preshaped by prior information, with a peak of activation centered over the precued movement direction. Wider ranges of precued movement directions were represented by broader distributions, and the peak shifted to the requested movement direction as soon as it was speciﬁed by the response signal. The monkey had to execute a delayed multidirec- tional pointing task in six movement directions (see Figure 8. Note that the population distribution is preshaped in response to the preparatory signal (PS). Location and width of activation reﬂect precisely prior information as early as it is provided. The activation peak is localized over the precued target during the preparatory period and the distribution increases in acti- vation and sharpens subsequent to the response signal (RS). These ﬁndings extend our knowledge about neuronal mechanisms underlying motor preparation. In particular, the concept of speciﬁc preactivation of distributions of population activation deﬁned over the relevant movement parameter space appears to be a powerful one, which accounts for how partial prior information is integrated with new sensory information during movement preparation. The preshape concept may be relevant quite generally for examining context-dependent processes underlying behavior. For instance, the method of constructing distributions of population activity with a preshaping approach might be useful for getting further insight into processes that underly decision-making — as, for instance, in Go–NoGo tasks,70,71 stimulus–response-compatibility tasks,72,73 and categorization tasks. However, it is much less clear how these networks organize dynamically in space and time to cope with momentary computational demands. The concept emerged that some computational processes in the brain could also rely on the relative timing of spike discharges among neurons within such functional groups,75–80 commonly called cell assemblies. In other words, neurons may participate in different cell assemblies at different times, depending on stimulus context and behavioral demands. To test whether such a temporal scheme is actually implemented in the central nervous system, it is necessary to observe the activities of many neurons simultaneously, and to analyze these activities for signs of temporal coordination. Indeed, it has been argued that the synaptic inﬂuence of multiple neurons converging onto others is much stronger if they ﬁre in coincidence,82,83 making synchrony of ﬁring ideally suited to raise the saliency of responses and to express relations among neurons with high temporal precision. If cell assemblies are involved in cortical information processing, they should be activated in systematic relation to the behavioral task.
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