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By N. Amul. University of Colorado at Boulder. 2019.

Though buy cialis extra dosage with mastercard erectile dysfunction doctors in st louis mo, traditionally homeostasis (constancy of internal Blood pressure regulation: the normal systolic pres- environment) refers to the stability of extracellular fluid sure in adult is kept constant between 100 and 140 mm Hg volume and composition cheap 100 mg cialis extra dosage mastercard impotence what does it mean, it is also applicable to intracel- and diastolic pressure between 60 and 85 mm Hg order 40mg cialis extra dosage overnight delivery erectile dysfunction commercials. Rather, the pri- tained rise in pressure is called hypertension, and fall in mary objective of homeostasis is to maintain intracellular pressure is called hypotension that initiates many neural homeostasis that promotes cell or tissue (organ) functions. For example, pH homeostasis, temperature homeostasis, Regulation of hormone secretion: Secretion of many + + Na homeostasis, K homeostasis, etc. Hence, homeostasis is and decrease in concentration facilitates their production mainly by altering the secretion of their regulating trophic mostly achieved by the coordinated and balanced interac- hormones. This forms the basis of diagnosis of these hor- tion between intracellular and extracellular environments monal disorders. Homeostatic regulation is achieved by two feedback mechanisms: the negative feedback and the positive feedback. Negative Feedback the negative feedback mechanism is the general mechanism of regulations in which if the variable is raised above the set point, the feedback mechanism triggers processes that inhibit the formation of the variable and if the variable is lowered below the set point, the feedback system withdraws the inhibition to allow production of the variable. Positive Feedback In a positive feedback system, increase in the variable triggers the processes that further increase the variable. This process triggers a vicious cycle that terminates only when the stimulus applied to trigger is withdrawn or the process itself is self­terminated. Homeostasis, Feedback mechanisms, Negative feedback system, may be the Short Questions. In Viva, examiner may ask… Define homeostasis, Give examples of homeostasis, and What are the feedback mechanisms and give their examples. Give the structure and list the functions of cell membrane, organelles and nucleus. Give the details of composition of cell membrane and function of each constituent. Describe the details of the structure, functions and dysfunctions of each organelle of the cell. Explain the detailed structure, functions and dysfunctions of microfilaments, cellular motors and cell adhesion molecules. A cell consists of three fundamental structures: cell mem­ brane, cytoplasm and nucleus (Fig. The cell membrane or the plasma membrane is the boundary in all animal cells that surrounds the cyto- plasm, the fluid medium containing a variety of orga­ nelles. In cytoplasm, organelles are bound by membranes simi­ lar to the structure of cell membrane. The organelles usually present in animal cells are mitochondria, ribo­ some, peroxisome, lysosomes, centrioles, endoplasmic reticulum and Golgi apparatus. Cytoplasm also contains filamentous cytoskeletal structures such as microfila­ ments, intermediate filaments and microtubules. Cell Membrane Structure of Cell Membrane Cell membrane is the protective sheath of the cell. It the cell membrane is basically a double layer of lipid mole­ exchanges materials between the cytoplasm and the cules having thickness of 7–10 nm, into which are inserted 14 Section 1: General Physiology Fig. The major lipids in the cell membrane are phospholipids, glycolipids and cholesterol. The phospholipids are phosphatidylcholine, sphingo­ Though, many models for cell membrane have been myelin, phosphatidylserine and phosphatidyl ethano­ described in the past, the widely accepted one is Fluid- lamine. Special features of this model are: Lipids are amphipathic (“amphi” means both) mole­ 1. Cell membrane consists of a double­layer of phospho­ cules as their head or polar region is hydrophilic lipid that contains protein molecules. The model is called fluid mosaic model as the mem­ the globular or the head end contains phosphate or brane lipids are present in the fluid form that allows hydroxyl moieties that are positively charged and solu­ the flexibility of the membrane without disturbing the ble in water. The membrane proteins are loosely attached and float in is such that the hydrophobic tail ends are directed the fluid phospholipid bilayer. Rapid and random redistri­ toward the center and the hydrophilic head is located bution of integral proteins occurs in the membrane. Also, phospholipids undergo rapid redistribution in the to periphery of the membrane (as depicted in Figure plane of the membrane. This type of diffusion within the plane of the mem­ the aqueous phase from both inside and outside the brane is called translational diffusion. A similar bilayer arrangement is found in bile salts rapidly for phospholipids, which can move several where they form spherical micelles. The fluidity of the membrane is mainly dependent on regions of the membrane, and serves to reinforce the the lipid composition of the membrane. Effect of temperature: In a lipid bilayer, the hydropho­ bic chains of fatty acids are highly aligned or arranged Application Box 4. When tempe­ Determinant of the fluidity of membrane: the fluidity of a membrane rature increases, the hydrophobic side chains undergo a depends on the composition of lipids and the degree of unsaturation. Higher cholesterol content reduces order or melting occurs is called transition temperature the fluidity of the membrane. Chapter 4: Cellular Organization and Intercellular Connections 15 of the membrane (intracellular fluid). Serve as channel proteins: Channels or pores are inte­ gral proteins through which water­soluble substances like glucose and electrolytes can diffuse across the cell membrane. Act as carriers: Carrier proteins transport substances through cell membrane by facilitated diffusion; for exam­ ple transport of glucose through glucose transporter. Serve as receptor and enzyme proteins: Integral pro­ (outer membrane and inner membrane) proteins. A membrane teins that are present toward the outer half of the channel is formed by a transmembrane protein. Antigenic functions: Complex membrane proteins within the specific layer (but not from one layer to another). Functions of the Lipid Bilayer Peripheral Proteins the main function of the lipid bilayer of a cell membrane Some protein molecules are inserted lightly in the outer is to create a permeability barrier between the interstitial or inner border of the membrane or are just bound to the fluid and the cytoplasm. Such proteins are called peri­ depends on whether it is lipid­soluble or water­soluble. Lipid soluble substances like oxygen and alcohol can pass They are of two types: Intrinsic and extrinsic proteins. Intrinsic proteins: They are present on the inner sur­ easily through the cell membrane, whereas water soluble face of the membrane. They usually serve as enzymes or substances like urea and glucose cannot pass easily. Thus, anchor proteins for cytoskeleton and other microfilaments lipid bilayer makes the membrane semipermeable. Membrane Proteins Extrinsic proteins: They are present on the outer sur­ face of the membrane.

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The femoral component of the hip arthroplasty is seen with posterior acoustic reverberation (arrowheads) 200mg cialis extra dosage otc erectile dysfunction drugs free sample. The echogenicity of the fluid does not indicate the cause of the effusion as both septic and aseptic effusions can appear identical on ultrasound buy discount cialis extra dosage 60 mg online erectile dysfunction doctors in connecticut. Reproducibility and inter-reader agreement of a scoring system for ultrasound evaluation of hip osteoarthritis purchase cialis extra dosage 100 mg with amex erectile dysfunction doctor near me. Longitudinal ultrasound image of the hip demonstrating tearing of the anterior labrum. Longitudinal ultrasound image of the hip demonstrating a large tear of the anterior labrum. The echogenic acetabular labrum (asterisk) is separated from the acetabular labrum, due to a displaced labral tear. Longitudinal ultrasound image demonstrating crystal deposition disease of the hip. Longitudinal ultrasound image of the hip demonstrating avascular necrosis of the femoral head. Longitudinal sonogram image shows needle tip (arrowhead) in anechoic effusion (asterisk) along anterior aspect of femur (F). Ultrasound has special utility in the evaluation of patients who have undergone total hip arthroplasty (Figs. This modality has clinical utility at the bedside in the evaluation of heterotopic ossification of the hip joint and surrounding tissues in spinal cord-injured patients (Fig. Sonogram of the anterior hip longitudinal to the femoral neck shows the hyperechoic surface of the total hip arthroplasty (arrowheads) with posterior reverberation artifact. The native acetabulum (A) and proximal femur (F) show posterior acoustic shadowing. Sonogram of the anterior hip longitudinal to the femoral neck shows abnormal anechoic fluid (curved arrow), which distends the pseudocapsule. A: Longitudinal ultrasound images of the hip in a patient with heterotopic ossification. The zone phenomenon or “cloudy appearance” (arrowheads) is detected within the muscle compartment overlying the proximal portion of femur (Fe). Arrows indicate the secondary acoustic shadowing that interrupts the white cortical lining of the femur. Platelet-released growth factors enhance the secretion of hyaluronic acid and induce hepatocyte growth factor production by synovial fibroblasts from arthritic patients. Anatomy, special imaging considerations of pelvis, hip, and lower extremity pain syndromes. Correlation of power Doppler sonography with vascularity of the synovial tissue of the knee joint in patients with osteoarthritis and rheumatoid arthritis. The nerve fibers enter the psoas muscle where they fuse together within the muscle body and then descend laterally between the psoas and iliacus muscles. The femoral nerve provides motor innervation to the iliacus muscle as it descends toward the iliac fossa. The nerve then passes just lateral to the femoral artery, lying on top of the iliacus muscle and beneath the fascia iliaca as it travels beneath the inguinal ligament with the artery, vein, and nerve enclosed in the femoral sheath (Fig. It is at this point that the nerve can be consistently identified with ultrasound scanning and is amenable to ultrasound-guided nerve block. The femoral nerve provides motor innervation to the sartorius, quadriceps femoris, and pectineus muscles and also provides sensory fibers to the knee joint as well as the skin overlying the anterior thigh (Fig. The femoral nerve is subject to the development of neuropathy from a variety of causes including compression, iatrogenic trauma, and metabolic abnormalities, vasculitis, ischemia, and most notably diabetes mellitus. The clinical findings of femoral neuropathy include weakness of the quadriceps femoris and occasionally the iliacus muscle, diminished or absent knee jerk, and sensory loss over the anteromedial aspect of the thigh and medial aspect of lower leg. Spontaneous retroperitoneal hematomas within the psoas-iliacus groove in anticoagulated patients can severely compress the femoral nerve (Fig. The femoral nerve, artery, and vein can also be compressed by tumor, lymphadenopathy, and abscess. The neurovascular bundle is subject to traumatic injury from penetrating injuries, hip fracture, iatrogenic injuries during abdominal, pelvic, groin, and hip surgery as well as during needle-induced trauma during femoral arterial cannulation (Fig. Hematoma in the left iliacus muscle (thin arrows), left psoas muscle was displaced to anteriorly and medially due to hematoma (thick arrows). Conservative treatment of femoral neuropathy following retroperitoneal hemorrhage: a case report and review of literature. Plain radiograph demonstrating a transcervical fracture of the femoral neck resulting in varus deformity and external rotation. Plain radiographs of the hip and pelvis are indicated in all patients who present with femoral neuralgia to rule out occult bony pathology. Based on the patient’s clinical presentation, additional testing may be warranted including a complete blood count, uric acid level, erythrocyte sedimentation rate, and antinuclear antibody testing. Magnetic resonance imaging of the lumbar spine and lumbar plexus and retroperitoneum is indicated if herniated disc, tumor, or hematoma is suspected. Ultrasonography and Doppler evaluation of the femoral artery and nerve can help identify thrombus, embolus, occlusion by hematoma, tumor, abscess, foreign bodies, for example, bullet fragments, clot, and arteriosclerotic plaque (Fig. A: Long-axis image demonstrating obstruction to flow at the bifurcation of the right common femoral artery. B: 732 Reconstructed three-dimensional computed tomography angiogram confirming the findings of the ultrasound examination. Clinical sonopathology for the regional anesthesiologist: part 1: vascular and neural. The inguinal crease on the affected side is identified and a linear high-frequency ultrasound transducer is placed in an oblique plane perpendicular with the inguinal ligament. The iliacus muscle is identified with the femoral nerve lying between the muscle and the pulsatile femoral artery (Fig. The femoral vein lies medial to the femoral artery and is easily compressible by pressure from the ultrasound transducer (Fig. Color Doppler can be used to aid in the identification of the femoral artery and vein (Fig. When these anatomic structures are clearly identified on oblique ultrasound scan, each structure is evaluated for abnormality (Fig. Femoral neuropathy can be identified by abnormal echogenicity of the neurofibular pattern and enlargement of the nerve (Fig. The nerve, artery, and vein are then evaluated for the compression by abnormal mass or tumor, and the vasculature is evaluated using both ultrasound and color Doppler for the presence of thrombus, embolus, and plaque (Figs. Oblique placement of the ultrasound transducer placed in a plane perpendicular with the inguinal ligament with the inferior aspect of the transducer lying over the anterior-superior iliac spine and the superior aspect of the transducer pointed directly at the umbilicus. Oblique ultrasound image demonstrating the iliacus muscle, the fascia iliacus, the femoral nerve, artery, and vein. Oblique ultrasound image demonstrating the compressibility of the femoral vein which lies medial to 733 the pulsatile femoral artery.

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As adjacent entorhinal and temporal neocortex are Tese slow waves are not necessarily indicative of ictal propagation recruited buy cialis extra dosage visa erectile dysfunction pills natural, a synchronous and regular 5–9 Hz ictal rhythm evolves but may refect ‘surround inhibition’ [90] buy discount cialis extra dosage 50mg line erectile dysfunction age onset. About 25–30% of hippocampal-onset seizures will Termination Tere are three typical patterns of termination: (i) sud- spread frst to the contralateral hippocampus and the remaining den cessation of difuse of focal seizure activity; (ii) gradual decrease 10% of seizures involve the contralateral hippocampus and ipsi- in frequency and increase in amplitude order generic cialis extra dosage from india johns hopkins erectile dysfunction treatment, usually focally; and (iii) lateral temporal neocortex simultaneously [87]. Long propagation decreased frequency of a burst-suppression-like pattern, usually dif- time from one hippocampus to the other (>8–50 s) correlates with fusely. Low frequency flter was set at 1 Hz, high frequency flter was turned of and notch flter was of. Tose with seizures termi- Studies of correlation between ictal patterns and surgical out- nating in the onset location fared signifcantly better. The ictal-onset rhythm consisting of gamma or beta fre- terms of morphology, discharge frequency, focality, spread pattern quencies was more prevalent in the group with favourable outcome. The most common ictal It is conceivable that ictal patterns are related to underlying pathol- onset is characterized by a low-voltage high-frequency discharge ogies, explaining conficting results in diferent settings [97,98]. In a more recent series with more regional, repetitive and sometimes periodic sharp waves by Noe et al. A more focal, low-voltage, high-frequency discharge may were found to be associated with excellent surgical outcome. Apart from the obvious occurrence of ictal dis- focal pattern (initial changes involving fewer than fve to six con- charges from the lateral temporal neocortex, simultaneous involve- tacts); (ii) to a regional pattern (initial changes involving more than ment of lateral and mesial structures can also be found [6,12,95], and six contacts, usually > 20); (iii) or an extremely difuse pattern (in- can occur independently at times. The phenomenon of secondary itial changes involving essentially the entire grid simultaneously); epileptogenesis is ofen cited as an explanation for these observations. Although the regional pattern Propagation Seizures arising from this region propagate initially to is the most commonly found, there is usually some degree of initial ipsilateral mesiolimbic structures. Tere is some evidence suggest- focal preponderance usually in terms of amplitude of the initial dis- ing early involvement of contralateral mesiolimbic structures and charge or small time diferences. However, spread patterns in neocorti- to be a characteristic of an intracranial ictal onset close to a true cal seizures are not as well established. Tere is signifcantly more ictal onset zone, whereas regional onset may imply volume conduc- rapid seizure spread from mesiotemporal structures ipsilateral to tion or propagation from a distant generator [3]. This is tentatively explained by the strong inhibitory action lepsy, several studies have found no statistically signifcant difer- of the dentate gyrus confning the ictal activity to the hippocampal ence between the size of epileptogenic zone and surgical outcome structure itself. This was observed regardless of the underlying pathology, suggesting that Onset Several patterns of neocortical seizure onset can be observed seizure characteristics are also dependent on anatomical location [97,98,99]. For example, medial occipital electric activity arising above 4 semirhythmic slow waves <5 Hz; the calcarine fssure usually propagates to the frontal lobe, while 5 high-amplitude beta spike activity. Lateral occipital Low-voltage fast activity appears to be the most common pattern seizures usually spread to the parietal and lateral temporal lobes (Figure 58. Propagation may be further subdivided into rapid (usually or an electrodecremental response [97,100]. Seizure onset was identifed at G 25, G 17 and G 33 (located on the grid, and marked by yellow circle) as prominent low voltage fast activity, this progressed to repetitive spikes in the same region with spread to surrounding contacts. Low frequency flter was set at 1 Hz, high frequency flter was turned of and notch flter was of. Stimulation at each site usually consists of with non-contiguous spread (0% seizure free). Neocortical seizures 100–300 µs monophasic square-wave pulses delivered at 50 Hz and ofen spread to medial temporal regions. A low-intensity current were involved early (within 1–2 s) or late (usually 10–40 s) had no (around 0. For the same reason, when possible, stimu- functions cannot be surgically removed [107]. Functional corti- lation is ofen begun at sites distant from or surrounding the epilep- cal mapping allows identifcation of these regions that need to be togenic zone to avoid the occurrence of a seizure until the majority preserved during resective epilepsy surgery to avoid postoperative of contact pairs have been assessed. Hamberger ard for this purpose, there is exciting evidence demonstrating the et al. Be- available studies already show good concordance [108,109,110,11 cause of time restraints, the intensity of stimulation is usually deter- 1,112,113,114,115]. Intraoperative stimulation electrodes can be positioned using chronically implanted electrodes and is the gold standard precisely where one wishes. Because the electrodes are small in di- technique for mapping functionally important areas. Stimulation parameters Minimum settings to classify a site as negative mA Hertz Stimulation duration (s) Pulse width (ms) mA Hertz Language Mean 11. Once language mapping temporal horn afer partial resection to sample the hippocampal is completed, resection can be done while the patient is awake, al- surface [119]. Extraoperative cortical stimulation is preferred if long-term ably using a large number of channels for simultaneously record- monitoring is necessary to delineate the epileptogenic area, if the ing from as many contacts as possible (or else adequate sampling patient will not tolerate an awake craniotomy and if more time-con- requires montage adjustments with prolongation of the recording suming mapping of language is required, as is ofen the case with time). Reasonable pre- and postexcision sampling requires up to infants or young children. If the epileptogenic zone has already 20 min each, depending on the spike frequency. General anaesthesia using drugs such as barbiturates, Gamma oscillations are spatially located over specifc areas of the benzodiazepines and inhalational agents (halothane, high-dose cortex, directly related to the individual’s environment and behav- isofuorane and nitrous oxide) can suppress epileptiform activity. A majority beit with small sample sizes, have shown that with movement or of epilepsy centres employ low-dose isofuorane for its lack of pro- language-related tasks, amplitudes typically decrease in the mu convulsant activity and absence of deleterious efect on interictal (8–12 Hz) and beta (18–25 Hz) bands, while they increase in the activity at very low concentrations Local anaesthesia avoids these gamma (>40 Hz) and high gamma (>70 Hz) bands. Corticocortical evoked potentials However, spikes might be rare or absent, widespread and multifo- Matsumoto et al. In theory, by means of intrac- surgical manipulation or postexcisional activation spikes. It is theoretically assumed that the ir- cal potentials are recorded from remote cortical regions. This does ritative zone delineated by interictal activity from all recorded sites not require any direct patient participation. The irritative opportunity for tracking functional connectivity across diferent zone, while probably (but not always) containing the epileptogen- brain regions with superior spatiotemporal resolution. The debate continues even can be performed in many diferent ways using commercial or with the advent of advanced electrophysiological techniques, as de- custom-made electrodes arranged in various montages. At Yale, we employ an L-shaped 37-contact Silastic grid and two High-frequency oscillations 1 × 8 contact subdural strips. The frst strip is positioned all activities >40 Hz including gamma (30–80 Hz), high gamma over the middle temporal gyrus and is wrapped around the tem- (60–120 Hz), ripples (80–250 Hz) and fast ripples (250–500 Hz). The second strip is placed over the posterior inferior In the past, most intracranial studies used a 200-Hz sampling rate temporal region [118]. Others include acute depth electrodes to sample the to the fact that oscillations with frequencies above ∼30 Hz are of amygdala and hippocampus. Recent studies using feld at onset and may help identify seizure onset accurately. Adding or repositioning intracranial electrodes a possible surrogate marker of the epileptogenic zone. Fast ripples during presurgical assessment of neocortical epilepsy: electrographic seizure pat- tern and surgical outcome. The role of intracranial electrode interictal epileptiform discharges, that is spikes, which tend to more reevaluation in epilepsy patients afer failed initial invasive monitoring.

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