By B. Daryl. Chicago-Kent College of Law.
They supply energy at the time of On Thermogenesis emergency and prepare the individual for either Fight or Epinephrine is more potent than norepinephrine in most flight responses order generic micardis from india. Therefore 20mg micardis otc, epinephrine plays an Effects on Intermediary Metabolism important role in body adjustment mechanisms in res- On Carbohydrate Metabolism ponse to cold buy line micardis. Catecholamines act on liver to increase glucose produc- During Hypoglycemia tion by following mechanisms: 1. Catecholamines stimulate hepatic glycogenolysis by Secretion of catecholamines increases in profound hypo- activating the key enzyme glycogen phosphorylase, glycemia, as occurs during strenuous exercise or fasting. Catecholamines induce glycogenolysis and gluconeo- activate glycogenolysis in the skeletal muscle. In such situation, catecholamines also stimulate secre- cogen synthase enzyme complex. Epinephrine inhibits insulin mediated glucose uptake Various metabolic effects of catecholamines mediated by the skeletal muscle and adipose tissue. Catecholamines also stimulate glucagon and inhibit insulin secretion from pancreas. Fight or Flight Response All these effects are primarily aimed to increase plasma Norepinephrine and epinephrine have widespread effects glucose concentration. It causes selective arteriolar constriction in renal, splanchnic and cutaneous vascular bed. However, epi- nephrine produces vasodilation in the skeletal and hepatic circulation via b2 receptors. The vasodilation effect of epinephrine overrides the vasoconstriction effect and therefore, total peripheral resistance falls. This occurs especially during sympathetic stimulation that takes place during exercise. The primary aim of all these changes is to divert blood from splanchnic and cutaneous circulation to the exer- cising (active) muscles, while maintaining the cerebral and coronary blood flow. These changes ensure delivery of substrate for energy production to the vital organs during Fight or flight situations (Application Box 58. Norepinephrine produces vasoconstriction in most of the organs via a1 receptors that increases peripheral resistance and therefore, diastolic blood pressure rises. Norepinephrine also produces some degree of tachy- cardia and increases myocardial contractility; there- fore, systolic blood pressure also increases. However, hypertension produced by norepinephrine stimulates baroreceptors in the carotid sinus and aor- tic arch (activates baroreceptor reflex) that causes reflex bradycardia, and overrides cardioacceleratory Fig. This is called Fight or flight response, which is exclu- prolonged, then the effect on the body is deleterious, because renal sively mediated by sympathetic stimulation and vasoconstriction decreases kidney blood flow and compromises catecholamines released from adrenal medulla (for kidney function. Chronic sympathetic stimulation may even result in intestinal details, refer Chapter “Sympathetic System”). Catecholamines also increase cardiac excitabil- Catecholamines inhibit gastric secretion and motility. Respiratory System Effects of Epinephrine Catecholamines cause bronchial dilation (prevent expira- 1. Epinephrine increases heart rate and force of myo- tory airway obstruction) so that gas exchange improves. Most of pheochromocytomas produce On Endocrine Glands both epinephrine and norepinephrine. The disease is associated with increased metabolic + Catecholamines increases Na reabsorption from kid- rate, profuse sweating, extreme tachycardia and high ney. In this disease, though there is continuously high + increases Na and water retention. The burst of catecholamine secretion usually occurs + following rapid change in posture or the regular physi- Catecholamines stimulate the entry of K into the muscle + ological events that stimulate sympathetic system. It has positive inotropic effects (via b1 receptors), tration of catecholamines in blood when the patient is in increases cardiac output. The system- As dopamine increases systolic pressure and at the atic improvement occurs with administration of a block- same time maintains kidney functions, it is very useful for ers. The antagonists (both a and b receptor antagonists) olysis and cortisol promotes gluconeogenesis. The antagonists (b receptor blockers) are also used for sues to the neural tissue. Dopamine is used for treatment of traumatic and car- During acute stress, a general state of arousal and vig- diogenic shock. In chronic stress, Chapter 58: Adrenal Gland: the Adrenal Medulla 505 reproductive functions, sexual activity, and feeding are 3. It, along with proadrenomedullin decreases peripheral suppressed that are also mediated by catecholamines. The hypo- thalamic-pituitary-adrenal axis works in adaptation to Chromogranin stress. This is a granular protein present in the secretory gran- ules of chromaffin cells. Chromogranins are secreted along with catechola- Adrenomedullin is a polypeptide hormone. Adrenal medulla is a neuroendocrine gland, a modified sympathetic postganglionic tissue. Therefore, sympathetic stimulation results in instantaneous increase in catecholamines level in plasma. Though, epinephrine and norepinephrine act on both a and b receptors, in general, epinephrine acts more on b receptors and norepinephrine on a receptors. Though sympathetic activation is essential in stressful situations to maintain energy metabolism and cardiovascular parameters, chronic stress (sustained sympathetic stimulation) is not good for body as it leads to depletion and degeneration. In examination, “Describe the synthesis, metabolism and physiological effects of adrenaline and noradrenaline” may come as a Long Question. In examination, Fight or flight response, Pheochromocytoma, Difference in the effects of adrenaline and noradrenaline on cardiovascular system, Effects of catecholamines on intermediary metabolism can be asked as Short Questions.
It is recommended that empirical therapy in these patents should cover these organisms buy micardis 40 mg fast delivery. However purchase micardis 20 mg without prescription, this benefit is apparent only in children who are not receiving trimethoprim-sulfamethoxazole as prophylaxis micardis 20mg amex. In extensive disease, the bacteriological confirmation rates are likely to be greater. Stabilization or resolution of disease is reported in some patients, but in others there is progressive decline in pulmonary function and development of honeycomb lung. Chest radiographs show a variable picture and patterns include upper-lobe cavitary disease (sometimes mistaken for tuberculosis), nodules, pleural-based lesions, and diffuse infiltrates, usually of the lower lobe. Transbronchial biopsies are usually negative, but positive cultures can be obtained from bronchoalveolar-lavage fluid or percutaneous aspirates. Compensatory hypertrophy also occurs but is inadequate to maintain peak systolic wall stress within the normal range. These changes result in depressed ventricular performance, but intrinsic ventricular contractility remains normal. Intervention is required if effusion leads to tamponade and hemodynamic compromise. The most common organisms recovered in these patients were: Nontyphoidal Salmonella, Streptococcus pneumoniae and Staphylococcus epidermidis were the major pathogens in these patients. The mean timeto development of renal failure or frank nephrotic syndrome after diagnosis of early disease is about 20 months. Podocyte damage with resulting loss of function seems to have a significant role in the loss of renal function. They often develop late in the course of the disease when there is marked immunosup- pression. The initial symptoms may include headache, malaise and fever without any significant neurological dysfunction. Cerebral toxoplasmosis evolves most rapidly, the time from onset to presentation being only a few days, it is also more often accompanied by altered sensorium, along with fever, headache, or constitutional symptoms. Sometimes this encephalitic picture occurs in isolation and characteristic focal findings may be absent. On neuroimaging, both toxoplasmosis and primary lymphoma usually show a mass effect and surrounding edema. However, toxoplasmosis typically involves the cortical gray matter, while lymphoma has a striking predilection for deep white matter. Contrast enhancement, is usually distinct and ring-like in toxoplasmosis and more diffuse in lymphoma. Current evidence shows that symptoms improve with institution of antiretroviral therapy. Drug delivery may pose a challenge in critically sick pediatric patients as almost all antiretrovirals are available in oral formulation only. Moreover, these drugs have complex interactions with other drugs which might be essentially required in critically sick children. Abacavir is known to cause a fatal hypersensitivity reaction characterized by fever, skin rash, fatigue, nausea, vomiting, diarrhea and abdominal pain. These symptoms develop in approximately 8% of patients taking abacavir and usually develop within 6 wks of the start of therapy. Abacavir should immediately be discontinued if these symptoms develop and rechallenge with this drug is absolutely contraindicated. Since the initial discovery of x-ray by Wilhelm Conrad Roentgen on November 8, 1895, the field of radiology has experienced two major breakthroughs that have revolutionized how we look into the patient’s body. As the x-ray tube travels around the patient, x-rays are emitted toward the patient. As these x-rays interact with the various tissues in the patient’s body, some of the x-rays are attenuated by the tissues while others are transmitted through the tissues and interact with a very sensitive electronic detector. The purpose of these detectors is to measure the amount of radiation that has been transmitted through the patient. After the amount of radiation has been measured, the detector converts the amount of radiation received into an electronic signal that is sent to a computer. The computer then performs mathematical calculations on the information received and reconstructs the desired image. This information is assigned a numerical value that represents the average density of the tissue in that respective pixel/voxel of tissue. The gradients are assigned to the tasks of slice selection, phase encoding, and frequency encoding or readout gradient. In the magnet, the patient’s hydrogen protons align either parallel (with) or antiparallel (against) the magnetic field. During the relaxation time, a signal from the patient is being received by the coils and sent to the computer for image reconstruction. These can be grouped into proton (spin) density, and T1-weighted and T2-weighted pulse sequences. These pulse sequences demonstrate the anatomy differently and help differentiate between normal and abnormal structures. Structures such as cerebrospinal fluid and simple cysts may appear with a low or dark signal. In many cases, the pathologic process will appear with low signal in T1-weighted images. Many pathologic conditions present with high signal on T2- weighted pulse sequences. Before entrance into the strong magnetic field can be obtained, everyone including patients, family members, health care professionals, and maintenance workers must be screened for any contraindications that may result in injury to themselves or others. These may include any biomedical implant or device that is electrically, magnetically, or mechanically activated such as pacemakers, cochlear implants, and certain types of intracranial aneurysm clips and orbital metallic foreign bodies. The contraindications focus on devices that may move or undergo a torque-effect in the magnetic field, overheat, produce an artifact on the image, or become damaged or functionally altered. It is very important, therefore, that the technologist has a working knowledge of how to perform venipuncture and how to safely administer the specific contrast agent required. Upon the completion of the examination, all pertinent details of the venipuncture and administration of the contrast agent should be documented in the patient chart by the technologist, along with the overall patient outcome.
The practice of removing brain tissue for the alleviation last 20 years has been the identifcation of surgically remediable of seizures would wait for the late 19th century with the advent of syndromes of epilepsy purchase micardis 40 mg line, the chief one being mesial temporal lobe efective anaesthesia techniques cheap micardis 20 mg visa. The The original temporal lobe resections for non-lesional epilepsy frst series of cases involving resective brain surgery for seizures originating in this area were quite extensive buy micardis 20mg amex. All of these early moval extended back from the anterior temporal pole for 7–8 cm surgeries, and those in successive years, were based on pathological (almost the entire length), included the medial temporal lobe struc- substrates with clear physical markers, such as post-traumatic le- tures of the hippocampus and amygdala and would sometimes be sions and infections. The surgical technique consisted of removing extended across the Sylvian fssure into the frontal lobe based on the lesion (lesionectomy) and sometimes removing the abnormal or electrocorticography . Early epilepsy surgery programmes were associated with on abnormal electroencephalography tracings. This approach fun- extensive research endeavours, including neuropathology research, damentally changed the nature of the operation, from a procedure that were trying to better elucidate the mechanisms underlying the focused on a structural abnormality to one targeted by electrical unique temporal lobe epilepsy phenomenon. Grossly visible pathologies remained the target these ‘non-lesional’ temporal lobe epilepsies commonly had abnor- of many of the surgeries, but intraoperative electrocorticography malities of the hippocampus with profound loss of neurons within (EcoG) was used to determine how far to extend the resection into the subfelds. Pathological examination of surgical specimens from the cortex surrounding a lesion. Also, for the frst time, surgery temporal lobectomy patients having electrophysiologically demon- for seizures with a cortical focus that was not grossly apparent on strated medial temporal seizures made possible the determination inspection was possible by directing the cortical resection to the that these pathological changes within the hippocampus were caus- electrophysiologically abnormal region. Since the time of Penfeld, sev- seizure-free outcome, the sclerotic hippocampus became a lesion eral new modalities for localizing and delimiting the cortical focus to be targeted in mesial temporal lobe epilepsy surgery. Early ex- of seizure activity for resection have been developed; however, the periences made it clear that bilateral hippocampal pathology could fundamental principle of using electrocorticography to delineate not be addressed by resective surgery. In this approach, only the anterior lateral temporal lobe contrast, surgical approaches to extratemporal lobar resections rely is resected, followed by entry into the temporal horn of the lateral more on a process of delineation of the epileptogenic network, or ventricle, where the hippocampus is then identifed and resected. This approach allows extensive resection of the then a surgical approach is developed, ofen aimed at removal of hippocampus back to the tectal plate, an important detail given the the lesion and, when appropriate, additional afected brain tissue fndings of several studies that indicate there is a greater chance presumed to be involved in the generation of seizures. Such le- of seizure control as more hippocampus is removed but not with sions may be neoplastic, vascular, traumatic, infectious or related greater neocortical tissue resection in mesial temporal lobe epilep- to developmental anomalies. The frst of these was developed by Ojemann and colleagues range from strict lesionectomy to large-scale resection and even [9,10] and included awake craniotomies with extensive intraop- hemispherectomy or hemispherotomy for particular syndromes. Greater knowledge of the neocortical localization tools are employed in the process of delineating the epileptogenic of language during surgery enabled more extensive resections network responsible for such epilepsies. The selective transcortical, trans- and may help only in focusing the work-up process on regions that ventricular amygdalohippocampectomy procedure was developed will need further study using invasive recordings with subdural by Niemeyer  and further refned with an approach through electrodes and/or parenchymal depth electrodes directed to specif- the Sylvian fssure by Yasargil . Intracranial electrodes are discussed in the section tical incision is made through the superior temporal gyrus or by on intracranial studies. Once in the ventricle, the localized to a particular lobe, and the surgical work-up and surgical hippocampus and part of the amygdala are removed, similar to approach then become more focused. In each lobe the existence of the other temporal lobectomy procedures, but the temporal neo- an epileptogenic network or focus may warrant special considera- cortex is lef almost entirely intact, especially when the approach tion regarding clinical semiology, the details of the work-up, and the is transsylvian, although this approach does involve resection in surgical approach, taking into account both epileptogenic and func- the temporal stem. Epileptogenic considerations may be based ed similar seizure-free outcome rates as the other types of tem- on seizure spread patterns that may vary according to location. For poral lobe surgeries  with some claims of less impairment on instance, epilepsy of parietal and occipital origin may spread quite some neurocognitive measures, especially in the dominant tem- fast to the medial temporal lobe and have a clinical and electroen- poral lobe [14,15]. However, the technique can be more techni- cephalographic profle similar to that of mesial temporal lobe ep- cally challenging and has greater potential for disruption of the ilepsy. Functional considerations are of particular importance; for middle cerebral artery branches in the Sylvian fssure, possibly example, resection in the occipital lobe may entail very diferent resulting in hemiparesis. Medial temporal lobe resections are also neurological sequelae than resection in the posterior frontal cortex. A variety of neoplastic, vas- cular and other lesions can involve the medial temporal lobe, and Frontal lobe surgery their resection involves complex considerations regarding the risk The frontal lobe is the largest lobe of the brain, the majority of inherent in the lesional pathology as well as the epileptogenicity of which is the association cortex or cortex involved in executive the lesion. Tese issues are discussed in a separate chapter devoted functions with signifcant bilateral representation; therefore, uni- to lesional epilepsy. Epilepsy surgery in the frontal lobe in the parietal lobe epilepsy have no symptoms referable to the lobe of sei- absence of a structural lesion (non- lesional frontal lobe epilepsy) zure origin. For this reason it is not uncommon that seizures of the seizures and the complex and critical spectrum of functions with parietal lobe onset are thought to come from the frontal or embedded in these regions. Proportionate to the size of the frontal temporal lobes based on semiology with the symptomatogenic zone lobe, many of the frontal epileptic foci are difuse and widespread, being diferent from the seizure onset zone . Most com- the primary motor cortex and Broca’s area on the dominant side are monly, the patients will have sensory loss, especially loss of pro- in the frontal lobe, making surgical resection unfeasible if these re- prioception. Frontal lobe seizure activity is known to spread proprioception can lead to a lack of coordination that may hinder ipsilaterally and to the contralateral side rapidly, making identifca- higher-level motor activities, including driving a vehicle. Frontal lobe seizures have tion, resection within the dominant parietal lobe can lead to Gerst- several characteristic semiologies that may help localize the region mann syndrome, characterized by agraphia, acalculia, an inability of seizure onset [17,18]. Seizures originating in the primary motor to distinguish right from lef and fnger agnosia. Resections in the cortex typically present with focal motor activity and may produce non-dominant parietal lobe may lead to signifcant defcits, such the Jacksonian march as they progress, with ipsilateral clonic activ- as contralateral neglect and impairment in spatial orientation and ity spreading anatomically from the region of onset to involve the skills . Supplementary motor seizures are charac- disabling to a person with certain cognitively demanding careers terized by more complex motor activity, including the stereotypical and may lead to job loss. The other characteristic frontal lobe semiology is a complex par- Insular epilepsy has received increasing attention in recent years. Mesial frontal lobe epilepsy originating in the anterior regions of the frontal, temporal and parietal lobes, and is covered cingulate gyrus and the supplementary sensorimotor area may be by arterial branches, making it a difcult target for surgical inves- difcult to diagnose and localize because of atypical semiologies tigation and intervention. Yet, resection in the insular region of including ictal fear, laughter, palilalia, singing, paroxysmal arousal, tumours or other lesions, including epileptogenic lesions, have be- piloerection and negative motor symptoms . Although primary come more common with the advent of advanced functional map- motor cortex is not a region in which resection of the seizure focus ping and monitoring techniques. Early observations by Penfeld can occur without signifcant motor defcits, supplementary motor reported gustatory and abdominal sensations with electrical stimu- cortex can be the target of efective and safe resection. Distinct semiology features of insular epilepsy supplementary motor cortex may lead to a postoperative dense con- include laryngeal discomfort, dyspnoea unpleasant perioral dysar- tralateral defcit, but this resolves within days or weeks, returning thric speech and various viscera–somatic sensations . Insular the patient to full motor strength in the afected limb, with little or epilepsy may also involve alterations in consciousness, but many of no residual defcit . A good Occipital lobe surgery portion of epilepsy surgery in the insula has been carried out for Occipital lobe epilepsy is typically characterized by visual or oc- lesions, mostly neoplastic or dysplastic lesions, but also for vascu- ulomotor signs and symptoms, including visual auras that can be lar lesions such as cavernomas [28,29,30]. Tese have been carried complex in nature, transient visual loss, blinking and eye move- out with increasing success and decreasing morbidity.
But it can occur due to motor problems − It is seen in nervous individuals who have decreased in pharynx discount micardis 20 mg visa, upper esophagus or foreign body discount micardis 20 mg with visa, acute tone of the upper oesophageal sphincter cheap micardis online american express. Laryngeal opening closes during deglutition, preventing entry of food into respiratory passage. Speaking or coughing during eating allows food to enter into trachea and may cause choking in severe cases. Mastication increases salivary secretion and facilitated swallowing and digestion in the stomach. In Viva, examiner may ask… Functions of mastication, phases of deglutition, afferent and efferent pathways and mechanism of deglutition in each phase, Problems of deglutition. Understand the physiological abnormalities in reflux esophagitis and achalasia cardia. Once food enters the esophagus, reflex contraction of esophagus is initiated that transports food into the stomach. In the upper part of esophagus, the muscles are stri- ated (like skeletal muscles) muscles, in the lower part the muscles are smooth muscles and in the middle part, there is mixture of smooth and skeletal muscles (Fig. A transitional zone of striated and smooth muscles exists between Special Features them. Muscles in the body of the esophagus are relaxed always, except during deglutition. Activation of deglutition reflex initiates peristaltic con Upper esophageal sphincter is mainly a physiological traction by neural mechanism (primary peristalsis) or sphincter. Fundoplication may also be tried in this condition, constricts to prevent regurgitation of food back into in which a portion of the fundus of the stomach is the pharynx. Lower Esophageal Sphincter Lower esophageal sphincter remains tonically contracted. Barrett’s Esophagus It relaxes only when food from the esophagus enters the In few cases of chronic reflux esophagitis, the normal stomach. Therefore, it always prevents reflux of food back squamous epithelium of esophagus is replaced by colum into the esophagus from the stomach. However, vagal fibers inhibit circular muscles of Achalasia Cardia the sphincter in response to primary peristalsis that ‘Achalasia’ means failure to relax. Normally, when food relaxes the sphincter and allows food to enter the enters esophagus, esophageal peristalsis pushes food into stomach. Primary Peristalsis Causes Primary peristalsis is initiated by deglutition reflex. Diagnosis Secondary Peristalsis Diagnosis is made by demonstrating rat tail in barium meal Xray (body of esophagus is dilated and lower part When primary peristalsis fails to push the bolus from the is narrowed giving appearance of a rat) (Fig. Secon demonstrating retained food and fluid in esophagoscopy dary peristalsis is initiated by activation of mechano (Fig. Experimentally, it can be induced by inflating a balloon in Treatment the body of the esophagus. In severe cases, surgical weakening of the sphincter by Reflux Esophagitis and Barrett’s Esophagus myotomy (incision of the esophageal muscle) is per formed. Also, administration of drugs that decrease tone of the contracted except during swallowing when food in the sphincter has been successfully tried. In the long of the swallowed air is removed by belching (regurgitation run, it can cause stricture or ulceration of esophagus. These individuals develop about 200 mL as a large volume of produced and swal abdominal discomfort and borborygmi (rumbling lowed air is removed regularly as flatus. Esophagus is a unique structure having both striated and smooth muscle, and both the muscle are innervated by vagus nerve. Esophageal peristalsis is initiated by swallowing, which may be air, or saliva, and need not be food. In Viva, examiner may ask…… Special features of esophageal muscles, Esophageal sphincters, Types and mechanism of esophageal peristalsis, Causes and treatment of achalasia cardia and reflux esophagitis. Correlate the electrophysiology of gastric contractions with gastric motor dysfunctions. The proximal stomach, for its property of receptive systematically study the digestive processes in relaxation, receives and stores food, and for its tonic human beings. He was first physiologist to study gastric motility in a patient with a gastric fistula. The distal stomach for its property of phasic contrac- psychophysiology: a reappraisal. Canadian Journal (1785–1853) tions, mixes, grinds, and breaks down food into smaller of Psychiatry 1988;33(7):650–3. To allow the stomach to act as a reservoir for storage Parts of Stomach of large amount of food of a single meal. To cut foodstuff into smaller particles and mix the food stomach is divided into two parts: the proximal stomach with gastric juice, the process in which food is con- and distal stomach (Fig. To allow gastric contents to enter the duodenum at a Proximal Stomach slow but controlled rate, so that duodenum and jeju the proximal part of stomach accommodates large volume num being narrower tubes, handle the chyme appro of food (as large as 2 to 4 liters) without much increase in priately. Chapter 48: Gastric Motility 405 Gastroduodenal Junction the junction between the stomach and duodenum is called gastroduodenal junction. There is a sphincter in the pylorus consisting of a ring like thickening of circular muscle fibers, known as pyloric sphincter. To allow gastric contents to enter the duodenum at a slow and controlled rate (the rate at which duodenum is capable of possessing the chyme). Gastroduodenal Mucosa the duodenal mucosa is relatively resistant to bile acids but Fig. The proximal stomach is formed sensitive to gastric acid, whereas gastric mucosa is appar by fundus and major portion of the body. The distal stomach is ently resistant to gastric acid but sensitive to bile acids. Therefore, in case of incompetent pyloric sphincter, regurgitation of duodenal content (containing bile acids) into the stomach usually results in gastric ulcer.