A Nervous System Is Found in Simpler Animals Like Jellyfish
Cephalization
The Chest Radiograph in Cardiovascular Affliction
Douglas P. Zipes Doctor , in Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine , 2022
Congestive Heart Failure
In congestive heart failure, both the left ventricle and the left atrium become enlarged considering of the elevated LV cease-diastolic volume (encounterChapters 21and23). This enlargement may exist exaggerated if the mitral annulus dilates and mitral regurgitation develops. As LA pressures increase, pulmonary venous hypertension (PVH) develops. Based on its severity, PVH can be divided into three grades: I or mild, Ii or moderate, and 3 or severe (seeClassic References,Sharma). Each class of PVH is associated with specific imaging findings (Table fifteen.1).
The initial finding of PVH is redistribution of menstruation to the upper lung zones, resulting in equalization of the sizes of the vascular markings on an upright CXR. Over time the findings progress, with the upper lobe vessels larger than the lower lobe vessels. This miracle is known ascephalization, or pulmonary vascular redistribution (Fig. 15.5A).
As the mean LA pressure increases, interstitial pulmonary edema develops from extravasation of fluid into the lung interstitium surrounding the bronchovascular bundles and into the inter- and intralobular septa.thirteen Such edema is manifest on a CXR with enlarged, poorly defined hilar vessels; thickening of the bronchial walls (peribronchial cuffing when viewed on finish); fine central linear interstitial markings (Kerley A-lines), or peripherally appearing as parallel horizontal lines abutting the pleura (Kerley B-lines); and thickening of the fissural stripes, representing subpleural edema along the inner margin of the visceral pleura (Fig. 15.5B).
In astringent pulmonary edema the fluid extends from the interstitium into the alveolar spaces, creating alveolar consolidations (or air space opacities), which tend to brainstorm around the hila and progress in the center and lower lung zones. Pleural effusions often develop in severe pulmonary edema (Fig. fifteen.5C). The distribution of findings is typically symmetric, creating a "bat wing" or "butterfly" appearance of the alveolar consolidations. If the patient has been lying on one side, the pulmonary edema tends to exist more severe on that side because of the effect of gravity. Unilateral or focal pulmonary edema tin can result from central obstruction of a vein past a mass or surrounding mediastinal fibrosis or from a venous stricture, which can exist a complication of LA ablation14 (seeAffiliate 38).
It is important to distinguish cardiogenic from noncardiogenic pulmonary edema. Noncardiogenic pulmonary edema has many causes beyond heart failure, such every bit asphyxiation, drowning, intracranial hypertension, smoke and baneful smoke inhalation, adult respiratory distress syndrome, and agin reaction to sure drugs (e.m., diazepam, cocaine). In such patients the LA and pulmonary venous pressures are not significantly elevated, and heart size tends to be normal with no pleural effusions. The principal cause of noncardiogenic pulmonary edema is diffuse alveolar impairment with interruption of the alveolar-capillary membranes, leading to leakage of fluid into the alveolar spacesfifteen (eFig. 15.6).
Mitral valve stenosis unremarkably is caused and is caused by rheumatic fever. It is the salient lesion of rheumatic heart illness. Other rare causes are built valvular, subvalvular (parachute mitral valve), or supravalvular stenosis; LA myxoma; and astringent mitral annular calcification. Mitral stenosis often is accompanied by a variable degree of mitral regurgitation (MR).
Mitral stenosis causes elevated LA force per unit area throughout diastole, and PVH produces pulmonary arterial hypertension. In long-standing mitral stenosis, pulmonary arterial hypertension may be severe, and pulmonary regurgitation eventually ensues across a dilated pulmonary annulus. The RV somewhen dilates, causing tricuspid regurgitation from a dilated annulus.
Breast Radiography
Chest radiography provides good insight into the severity of mitral stenosis by showing the relative severity of PVH.
In mild disease, there may exist only equalization or reversal of the bore of upper and lower lobe pulmonary vessels (cephalization). In more severe disease or with an imposed hypervolemic land, interstitial pulmonary edema or alveolar pulmonary edema becomes axiomatic. In compensated mitral stenosis, merely mild cardiomegaly or a normal middle size is seen. The LA and LAA invariably are enlarged.
Note: Enlargement of the pulmonary arterial segment and correct heart indicates pulmonary arterial hypertension. Enlargement of the right heart in the absence of pulmonary arterial enlargement ordinarily indicates concomitant tricuspid regurgitation.
The ascending aorta and aortic curvation are characteristically small in isolated mitral valve disease. Even slight prominence of the thoracic aorta should raise suspicion of associated aortic valve illness2 (Box 6.one).
Lee Goldman Doc , in Goldman-Cecil Medicine , 2022
Vascular Patterns
Arterial patterns reflect changes in pulmonary perfusion. The termcaudalization reflects the normal blood flow distribution pattern in an upright person in which the basal pulmonary vessels are two to iii times wider than the upper lobe vasculature.Cephalization, in which the ratios of diameters of vessels are reversed, is frequently seen in recumbent persons, in whom it may be considered normal; all the same, when it is present in individuals imaged in the upright position, information technology indicates left ventricular failure, mitral valve disease, or basal emphysema (Fig. 78-7). Equalization, or counterbalanced menstruation with well-demonstrated vessels to upper and lower lung zones, is found in hyperkinetic circulation due to anemia, obesity, pregnancy, hyperthyroidism, or left-to-right shunts. Equalization or balanced flow with oligemia tin can be seen in hypovolemia, diffuse emphysema, or correct-to-left shunts. Centralization reflects dilationof fundamental pulmonary arteries, with accompanying normal or diminished peripheral circulation. Typically, it is seen in pulmonary arterial hypertension (Fig. 78-8). Lateralization of flow, favoring one lung over the other, also chosenasymmetrical perfusion, is visible with unilateral emphysema, unilateral bronchiolitis obliterans (Swyer-James-McLeod syndrome), or unilateral obstacle of the pulmonary artery. Locally dilated pulmonary vessels occur next to affected oligemic lung regions in patchy emphysema, multiple pulmonary emboli, arteriovenous malformations, and nonuniform bronchiolitis obliterans. This pattern produces mosaic attenuation on high-resolution CT scanning. Focal oligemia with vascular deficiency is characteristically seen in emphysema but also can occur after pulmonary embolism (Westermark sign). Centrilobular emphysema, paraseptal emphysema, and bullous lung affliction have a predilection for the upper lung regions, whereas panlobular emphysema induces basal oligemia with vascular deficiency.
14 What laboratory studies are useful in evaluating the patient with middle failure?
The posteroanterior and lateral chest radiograph may detect cardiomegaly or bear witness of pulmonary vascular congestion, including perihilar engorgement of the pulmonary veins, cephalization of the pulmonary vascular markings, or pleural effusions.
The electrocardiogram is often nonspecific, simply ventricular or supraventricular dysrhythmias; conduction abnormalities; and signs of myocardial hypertrophy, ischemia, or infarction are present frequently.
Echocardiography characterizes sleeping accommodation size, wall motion, valvular function, and LV wall thickness. Stroke volume tin can exist measured using Doppler methods. EF tin can be calculated past measuring the finish-diastolic and cease-systolic volumes. Diastolic function can be evaluated past studying the flow pattern through the mitral valve and the left upper pulmonary vein using Doppler technique. Radionuclide angiography provides a fairly reproducible and accurate cess of left and right ventricular ejection fraction.
Serum electrolytes, arterial blood gases, liver-role tests (LFTs), and blood cell counts are oftentimes evaluated. Many patients with heart failure are hyponatremic from activation of the vasopressin organization or from the treatment with ACEI. Treatment with diuretics may lead to hypokalemia and hypomagnesemia. Some degree of prerenal azotemia, hypocalcemia, and hypophosphatemia is oftentimes present. Hepatic congestion may issue in elevated bilirubin levels and elevated LFTs. Elevated encephalon natriuretic peptide levels may aid in suspected diagnosis of HF or trigger consideration of HF when the diagnosis is unknown but should not be used in isolation to confirm or exclude the presence of HF.
Fred F. Ferri MD, FACP , in Ferri's Clinical Advisor 2022 , 2022
Noninvasive Imaging
•
ECG: May elucidate the etiology of pulmonary edema. Causes may include ischemia/infarct, arrhythmias, LV hypertrophy, and atrial enlargement.
•
Breast x-ray (Fig. 2):
1.
Bilateral interstitial and alveolar infiltrates
2.
Cephalization of the pulmonary vessels
3.
Kerley B lines; fluffy perihilar infiltrates
iv.
Pleural effusions
v.
Enlarged cardiac silhouette
•
Echocardiogram:
1.
Assess left and correct ventricular systolic/diastolic function.
two.
Structural abnormalities (VSD, LV rupture).
three.
Evaluate valvular abnormalities including endocarditis.
4.
Engorged inferior vena cava (IVC) and IVC plethora, based on bedside ultrasound, suggests elevated filling pressures.
•
Computed tomography of the chest; may differentiate betwixt cardiogenic and noncardiogenic pulmonary edema.
•
Lung ultrasound has emerged equally a tool to diagnose pulmonary edema. It is easy to apply, accessible, and noninvasive, and has a high accurateness. Kerley B lines and pleural effusions are suggestive of pulmonary edema.
Evolution of the head and neck begins early on in embryonic life and continues until the cessation of postnatal growth in the late teens. Cephalization begins with the rapid expansion of the rostral end of the neural plate. Very early, the hereafter brain is the dominant component of the craniofacial region. Beneath the brain, the face, which does not have shape until later in embryogenesis, is represented past the stomodeum (Figure 2). In the early embryo, the stomodeum is sealed off from the primitive gut past the oropharyngeal membrane, which breaks down by the end of the first embryonic calendar month. Surrounding the stomodeum are several tissue prominences that plant the building blocks of the face (Figure 3). In the rostral midline is the frontonasal prominence, which is populated by mesenchymal cells derived from the forebrain and some midbrain neural crest. On either side of the frontonasal prominence, ectodermal nasal placodes, which arose from the anterior neural ridge, develop into horseshoe-shaped structures, each consisting of a nasomedial procedure, also derived from the forebrain neural crest, and a nasolateral process, derived from the midbrain neural crest. Further caudally, the stomodeum is bounded by maxillary and mandibular processes, which are also filled with neural crest-derived mesenchyme.
Figure 2. Basic organization of the pharyngeal region of the man embryo at the stop of the outset calendar month.
Figure iii. Frontal and lateral views of heads of homo embryos 4–8 weeks of age.
Scanning electron micrographs from Steding, Grand. (2009). The anatomy of the human embryo. Basel: Karger; courtesy of Dr. J. Männer.
The futurity cervical region is dominated by the pharyngeal apparatus, consisting of a series of pharyngeal pouches, arches, and clefts. Many components of the face, ears, and glands of the head and cervix arise from the pharyngeal region.
Identification and quantification of sleep-wake states in invertebrate species
As described above, sleep is present in virtually all animals. Chiefly, contempo enquiry has shown that even animals with a simple nervous system that lacks encephalon cephalization such as cnidarias accept a sleep-like country. In jellyfish, there is a quiescent state during the night revealed by the reduction in its bell pulsation, a behavior used to generate currents of fluid for feeding and expulsion of byproducts (Nath et al., 2017; Jha and Jha, 2022). Similarly, prolonged periods of behavioral quiescence take too been shown in nematodes (Iwanir et al., 2013) and annelids (Morrison, 2013). In beast species that lack a thalamocortical organisation do non have any of the EEG features that define sleep in birds or mammals. However, in some of them, changes in the neuronal action have been demonstrated betwixt wakefulness and sleep-like states. In Drosophila (the fruit fly), studies using recordings of local field potentials (LFPs) from the medial function of the brain take shown that, relative to wakefulness, at that place is a significant reduction in spike-like potentials during the quiescent land (Nitz et al., 2002; Cirelli and Bushey, 2008). Moreover, electrophysiological recordings from the protocerebrum of crayfish revealed high-amplitude and slow-frequency waves (8 Hz) during a sleep-like state (Ramón et al., 2004). Collectively, ample show demonstrates that sleep is universally present in beast organisms and has a common behavioral signature (quiescence) and species-specific electrographic characteristics.
The Central Nervous System, When Present, Organizes Behavior
The complexity and size of the central nervous system varies from elementary nervus nets in organisms like jellyfish (Cnidaria) to highly centralized systems (see Figure 2.4). Cephalization is the concentration of elements of the nervous system, particularly those involved in sensory activities and coordination of responses, into an anterior caput. Cephalization is strongly linked to behavior, because information technology is usually found in mobile animals, and characterizes the part of the animal (anterior) that encounters the environment beginning. Sessile (nonmoving) animals are less cephalized; they run across the surround from all directions, which favors a distributed nervous system.
Figure 2.four. Mussels, a common intertidal mollusc. Their sessile, filter-feeding lifestyle is associated with a nervous system that lacks any cephalization.
Photo: Michael Breed.
Key Term
A nervus net is a elementary, decentralized, multipolar multipolar nervous system found in animals like jellyfish.
Cephalized animals have brains of varying complication. Complex brains are typically compartmentalized, with split up but interconnected structures for functions such every bit olfaction, vision, and integration. The structures of highly sophisticated brains that evolved independently, such equally those found in octopi, insects, and mammals, share this compartmentalization.
Does brain size matter? This is an intriguing but surprisingly complex question. In humans, people over a broad range of brain sizes seem to take roughly equal intelligence and cognitive abilities, a signal that was vigorously argued by Stephen Jay Gould, i of the deepest evolutionary thinkers of the past century. Gould, in his brilliant book, The Mismeasure of Homo, argued that the temptation to appraise people'due south intelligence by looking at brain size was based in racism and securely held assumptions most the superiorities of some human cultures over others.1 Gould's argument is reasonable, nevertheless within a larger (multispecies) taxonomic group such every bit birds or mammals, it does appear that cerebral abilities correlate with encephalon size across a broad range of species; in mammals, cognition and cognitive cortex volume have a particularly strong human relationship. (Note that such broad interspecific comparisons differ from intraspecific comparisons.)
The highly intelligent representatives of the molluscan phylum, squid and octopi, have very big brains relative to their more sedentary cousins, such equally clams, oysters, and scallops. Simply the "smartest" insects, at least as measured past navigational and communication abilities, like the honeybees, take tiny brains compared to any squid, octopus, bird, or mammal. Adult homo brains weigh 1300–1400 grams and have over 100 billion neurons. Octopus brains have about 300 million neurons and counterbalance upward to a gram. Honeybees have slightly less than a million neurons packed into less than a cubic millimeter (about 1 milligram in weight). Some insects are so tiny every bit to be barely visible to the naked eye, however they deport on all the basics of insect life—feeding, flight, mating—with a brain that is g-fold miniaturized when compared to a honeybee's brain. How basic functions are maintained in miniscule brains is a fascinating unanswered question.
Discussion Point: Intelligence
The idea of honeybees being the "smartest" insects, based on navigation and communication abilities, raises a question that has challenged biologists and psychologists for decades: How do we measure intelligence? We will return to this question in later chapters, but now would be a good time to begin thinking over this puzzle. What is intelligence? Is it the aforementioned for all animals—is dog intelligence the same as human intelligence? What aspects of intelligence are favored by natural pick in different habitats or lifestyles? Afterwards pondering this question (for which at that place is probably no single right reply), call up nearly how intelligence can be measured and whether it tin be defined and measured in a way that would allow comparison among species. How does umwelt affect "intelligence"?
The encephalon receives information about the animal's physiological state and serves as a command centre for translating physiological needs into behavioral responses. Cnidarians and echinoderms accept neurons but no centralized brain. They still manage to organize fairly complex behaviors, as practice protists. The echinoderms' lack of cephalization is taken to reflect sessile ancestry—will mobile echinoderms be cephalized millions of years from at present? Cnidarians are anatomically different from most other animals, and their nervous organization is no exception. Showtime of all, while some cnidarians do movement (e.grand., jellyfish), that movement is largely at the mercy of currents; they are not powerful swimmers. In addition, many other cnidarians are mostly sessile (east.k., corals, anemones). In cnidarians a cyberspace of neurons lies between the inner and outer body walls. Unlike fretfulness in most other animals, these nerves can transmit impulses in whatsoever direction. Sensory nerves projection to the surfaces of the animate being, and nerves also attach to contractile cells, which function similarly (if weakly) to muscles in other animals. This nerve net allows manual of information from one part of the brute to another and coordination of uncomplicated movements. The stinging organs of cnidarians, nematocysts, discharge without nervous command. Well-fed cnidarians are less probable to discharge their nematocysts. Nervous connections to the nematocysts may bear on the likelihood of belch, depending on the need for nutrient (come across Effigy 2.five).
Figure ii.5. The anemones in the two upper photos are underwater, with their tentacles and mouths exposed. Below, the mass of anemones sits above the tideline, exposed to the sun and air. They have retracted their tentacles, thus minimizing their surface area and reducing hazard of dessication and other threats.
Photos: Michael Breed and Tricia Soares (tiptop left).
Cardiomegaly—defined on chest 10‐ray every bit a "cardiothoracic ratio" (horizontal width of the eye divided by the widest internal diameter of the thorax) in a higher place 0.v
b
Large hila with indistinct vessel margins
c
Cephalization of flow—present when upper lobe vessels in an upright patient are larger than the lower lobe vessels at approximately the aforementioned distance from the hilum (normally, the upper lobe vessels are smaller than the lower lobe vessels because gravity directs nigh blood catamenia to the lung bases). Cephalization of catamenia implies elevated left heart pressures.
d
Pleural effusions
e
Kerley B lines—imply interstitial edema and occur when fluid thickens the interlobular septa, causing short lines to appear perpendicular to the pleural surface
f
Alveolar edema
k
Peribronchial cuffing—develops when fluid extravasates from peri‐bronchial vessels and outlines the bronchi. The bronchi announced equally dark circles surrounded by a water‐dense ring.
h
Fluid in the interlobar fissures
Many of these findings may be obscured or distorted if at that place is underlying lung affliction. Findings may exist absent in patients with chronic HF who have longstanding elevations in pulmonary capillary wedge force per unit area
A chest radiograph is the minimum imaging modality for the evaluation of CHF exacerbation. This is valuable for the evaluation of pulmonary edema and infiltration and for the approximation of the heart size. Echocardiography (transthoracic or transesophageal) is also useful for the evaluation of ventricular and valvular office and determination of the ejection fraction. The earliest finding of left-sided heart failure on the chest radiograph is cephalization of the pulmonary vessels. Normally, the vessels in the lung bases are larger and more numerous than those in the lung apices. This is secondary to the effects of gravity and the anatomically larger book of the lungs at the base. With the progression of heart failure, the increased pressure is transmitted "backward" to the pulmonary veins and capillaries (hence the term "backward failure"). The lung bases are affected first; therefore, blood is preferentially "shunted" to the upper, or more cephalad, lobes, giving the radiographic advent of cephalization. If the force per unit area in the vessels continues to rising, the fluid in the interstitium becomes radiographically evident as interstitial edema, bronchial wall thickening, and interlobular septa. The most noticeable are the Kerley B lines. These are brusk, thin, perpendicular lines extending to the pleura at the lung bases on a chest radiograph. The following imaging findings were noted for the electric current patient.
Chest radiograph. Bilateral blunting of the costophrenic angles with pronounced infiltrates in the lower lobes (consistent with bilateral pleural effusions and pulmonary edema).
Cephalization of the pulmonary vessels bilaterally. Increased cardiac silhouette (an increased cardiac silhouette, spanning more one third of the thoracic cavity on an anteroposterior motion picture, is indicative of an enlarged centre or dilated cardiomyopathy).
Transthoracic echocardiography. Dilated left ventricle consistent with dilated cardiomyopathy with decreased wall move (systolic dysfunction) and mild mitral regurgitation. The pulmonic, aortic, and tricuspid valves were without stenosis or regurgitation. The ejection fraction was estimated at 25% (compromised ventricular role). No pericardial fluid and normal wall thickness were seen in all four chambers. Moderate elevation of the pulmonary artery pressure level was noted.
CT (maxillofacial). Mildly displaced fracture at the Le Fort I level. (A CT scan of the chest can also be used to further evaluate the pulmonary parenchyma and cardiac structures.)
