Search Results

An unusual atypical pneumonia emerged in the autumn of 2002 and winter of 2003, which was recognized as a new disease and designated Severe Acute Respiratory Syndrome (SARS). A novel coronavirus (SARS CoV) was identified as the cause of SARS. This chapter describes the initial recognition of the new disease and the concerted international effort that allowed the rapid identification of SARS CoV as its aetiological agent. The tissue distribution of virus in infected patients is described with reference to the implications for onward human-to-human transmission. In contrast to other respiratory viral infections, the viral load of SARS CoV in the upper respiratory tract and faeces is low in the first few days of illness, and peaks around day 10 of illness. The chapter concludes with a discussion of the implications of this pattern of viral excretion.

Excretory systems remove excretions from the body and serve as organs of osmoregulation. Active transport and ultrafiltration are the two basic principles of excretion. The structure of filtration organs corresponds with the type of body cavity being present. Both types of organs — protonephridia and metanephridial systems — filter body fluids, either into a canal system (protonephridia) or into the coelom (metanephridial systems), and remove the excretes in a canal system, where modification takes place. Protonephridia and metanephridial systems differ in the location and structure of these two components. There are different models of excretory organ evolution, but the model considered most likely in this chapter is one which describes unique evolution and subsequent differentiation of protonephridia, and multiple evolution of metanephridial systems.

This chapter explores Lu Xun and Xu Guangping's own bodies and bodily activities and functions. When they first started to write to each other, the two rarely discussed bodies, bodily functions or activities, or personal hygiene, apart from his drinking and smoking. In 1926, by contrast, they exchanged much detailed information about a wide range of bodily activities, while in 1929 they confined their remarks mainly to getting adequate rest and good diets. Xu Guangping tended to be more frank about her body than he is about his, but her references were more likely deleted than his were. His smoking was not a personal matter, but her lectures about his habit and his response were too personal for publication. Remarks about their respective drinking habits were retained except where it may indicate serious alcoholism on his part, and his claims to sobriety were invariably retained or added.

This chapter delineates the specialized physiological characteristics of amphibians, including anatomy and physiology of physiological processes of amphibians that have served as unique and powerful model systems for other vertebrates. It first describes how the skin and urinary bladder have been models for water and solute transport, in both water and air, followed by an analysis of the physiological mechanisms involved in the remarkable capacity of amphibians to withstand dehydration. The biology and physiology of thermoregulation is then explored, followed by an analysis of the range and limitations of temperature to activity metabolism, both aerobic and anaerobic. The diverse range of nitrogen excretory products of amphibians, along with their varied kidney physiology, is then described. Finally, the benefits of developmental plasticity are explored as a model.

Migraine is a vascular headache but its pathophysiology is complex and multifactorial. Of the many pathophysiological factors that are implicated in migraine, changes in the metabolism of 5-hydroxytryptamine (5-HT) are the best documented. During the headache phase of migraine, urinary excretion of 5-hydroxyindoleacetic acid increases, whereas the blood 5-HT concentration decreases. Furthermore, in migraine patients reserpine precipitates a headache that can be alleviated by 5-HT. In the light of recent developments in the characterization and classification of the receptors for 5-HT, this article aims to discuss the relationship between the neural and cephalovascular 5-HT receptors and the antimigraine action of drugs.

This chapter provides an overview of the beaver's form, weight, and special adaptations. An adult North American beaver has an average body weight of 40–50 pounds (about 18–23 kilograms). The body including the tail measures about 48 inches in length. Most distinctive for the beaver, the tail is flat and scaly and performs a variety of functions. For example, the tail serves in heat exchange through a countercurrent arrangement of blood vessels, allowing the beaver to reduce the 25 percent heat loss in the summer to 2 percent in the winter. This chapter also discusses the beaver's other organs including the nostrils, ears, eyes, brain, skull, teeth, feet, fur, and digestive tract. It also considers the beaver's excretion, reproductive organs, and senses.

This chapter looks at basic crab anatomy. It examines the biological aspects common to many crabs, such as their digestive processes, respiration, metabolic rates, biological rhythms, excretion, osmoregulation, their five senses, their nervous system, and even their pigmentation. A crab’s major anatomical features are the boundary between the head and thorax, as well as the segments of the thorax and the attachment of the legs to the thorax. Furthermore, the chapter notes that while many aspects of crab anatomy and physiology are similar to those of other animals, some may come as a surprise, such as their blue blood, the taste buds on their toes, or even the kidneys in their head.

This chapter makes use of the same connectedness description as the previous chapter – the Central Plains Experimental Range (CPER) soil food web – as a starting point for constructing an ‘energy flux’ description. This is for the purpose of creating an energy flux food web description. If the connectedness food web description is a simple depiction of who-eats-who within the community, the energy flux food web, in turn, provides an accounting ledger of the distribution and transfer of matter and energy within the community. In addition, the description and model are also applicable in estimating the rates of mineralization for the individual functional groups and the web as a whole, and are capable of arriving at estimates of inorganic carbon respiration and nitrogen excretion, for example. The chapter, then, uses the CPER and other soil food webs to illustrate how these descriptions are constructed, and to explore patterns in the distribution of biomass and flow of matter.

This chapter describes the basic principles of toxicology and their application to occupational and environmental health. Topics covered include pathways that toxic substances may take from sources in the environment to molecular targets in the cells of the body where toxic effects occur. These pathways include routes of exposure, absorption into the body, distribution to organs and tissues, metabolism, storage, and excretion. The various types of toxicological endpoints are discussed, along with the concepts of dose-response relationships, threshold doses, and the basis of interindividual differences and interspecies differences in response to exposure to toxic substances. The diversity of cellular and molecular mechanisms of toxicity, including enzyme induction and inhibition, oxidative stress, mutagenesis, carcinogenesis, and teratogenesis, are discussed and the chapter concludes with examples of practical applications in clinical evaluation and in toxicity testing.

This chapter discusses challenging habitats, examples of the populations of fish present, and the physiological adaptations shown by the fish. The topics selected are life in hypoxic environments, air-breathing strategies, life in the coldest and warmest environments, stress, life in acid and alkaline environments and nitrogenous excretion, extremes of salinity, and the depths. Fish show an amazing range of adaptations to extreme environments, such as modifications of the respiratory and circulatory systems for air breathing; in waters of sub-zero temperatures the body is protected from freezing by seasonal production of antifreeze substances. Nitrogen is normally excreted through the release of ammonia into the water, but in pre-hatched larvae and in environments where ammonia release is unfavourable, urea is produced by an operational ornithine-urea cycle. Adaptations to deep water are characterised by responses to decreasing illumination, food availability, low population density, and increased hydrostatic pressure.

This chapter discusses how insects are affected by temperature variations and extremes, and the different adaptations that allow some independence of ambient temperatures (behavioural and physiological thermoregulation) and that facilitate survival in extreme heat or cold. Stresses from water loss are discussed in the context of water balance (excretion and osmoregulation), and focus broadly on the mechanisms that allow survival in environments where water loss may be very high, such as saline lakes and marine habitats. The final section considers some extreme examples of aquatic life stages that can survive almost total dehydration, a form of cryptobiosis. These discussions provide a general description of the stresses and survival strategies, and avoid detailed descriptions of the underlying physiology and biochemistry.

Excretion is the removal of metabolic wastes such as ammonia, carbon dioxide, ions and water as well as toxic xenobiotics and metals. The process involves the gills, kidney, liver and rectal gland (elasmobranchs and coelacanth). In the liver, amino acids, haemoglobin, steroids and molecules resulting from human activities are transformed to excretable products. The rectal gland excretes ions, notably Na⁺ and Cl⁻. The kidney in teleosts has a distinction between an anterior head-kidney containing haematopoietic tissue and endocrine tissue and the posterior region with nephrons (kidney tubules). Fish nephrons generally have a Malphigian corpuscle with a glomerulus but the structure varies between fish taxa and some marine teleosts lack a glomerulus. Control systems for fish excretion are unclear but it is expected that various hormones influence excretory homeostasis.

The extant Latin novels address disgust more than earlier Latin genres did. Petronius and Apuleius enlist psychological mechanisms and sociocultural norms of disgust to satirize characters and practices of various groups. Internal and external audiences react with shock, fear, or dismay to creatures and practices deemed disgusting or threatening to our vulnerable human bodies, such as ingestion of unusual food substances (including cannibalism), open defecation and release of other bodily substances, deviant sex, mutilation of bodies, repellent diseased or deformed bodies, and unwanted contact with repulsive creatures (animals, insects, and plants) and substances such as offal and sewage. The chapter analyzes these two authors’ representations of gender and class differences, their methods and purposes for arousing disgust, and differences between their narrators’ reactions to disgusting phenomena.

Pharmacology is defined as the study of the effects of drugs on the function of a living organism. It is an inte­grative discipline that tackles drug/ compound behaviours in varied physiological systems and links these to cellular and molecular mechanisms of action. As a scientific endeavour, pharmacology evolved from the early identification of therapeutic properties of nat­ural compounds, with herbal medicines and relatively complex pharmacopoeias widely used in early cultures. Despite this, lack of understanding of the physio­logical, pathological, and chemical processes governing the human body prevented the early establishment of pharmacology as a scientific discipline. Since then, pharmacology has progressed to be considered a fully developed integrative science that employs techniques and theories from various disciplines, such as chemistry, biochemistry, genomics, medicinal chemistry, physi­ology, and cellular and molecular biology. Collectively, these are applied to study disease causality and the rele­vant mechanistic action of compounds, to establish new treatments. In the last 100 years, the importance of clinical pharmacology has increased in line with the scientific and technological advances in biomedical research. Benefits gained from molecular and cellular approaches have enabled a more comprehensive analysis of drugs and their actions in functional context. Now, clinical pharmacology and therapeutics encompass the dis­covery, development, regulation, and application of drugs in a process that integrates scientific research with clinical practice to better treat illness and preserve health. Within this textbook the principles of pharmacology are discussed by therapeutic area so that the reader can link disease pathophysiology, drug mechanism, and modern prescribing behaviours for conditions commonly seen in clinical practice. There are, however, fundamental concepts that are universal in understanding the interaction between drugs and their ‘targets’, including receptor pharmacology, genomic pharmacology, and pharmacokinetics. The pharmacological receptor models preceded by many years the knowledge of the receptor as an entity. It was not until the last 150 years that a series of contributions from many notable biologists and chemists established the principles that founded modern day pharmacology. They produced a significant paradigm shift in therapeutics, where empirical descriptors of the activities observed (heating, cooling, moistening, emetic, etc.) were replaced by the concept of a ‘target’. After more than a century, the basic receptor concept is still the foundation of biomed­ical research and drug discovery.

Important considerations concerning nitrogen in plants include the amount of nitrogen required, the forms of nitrogen (inorganic and organic) present in plant tissue, the ways that nitrogen is used in plants and affected by fertilization, and symptoms plants show when nitrogen is deficient. After the nonmineral elements, N is found in the next largest amount. More N is needed by plants than all the other nonmineral elements combined, except for K. The range of N concentrations in plants is from 0.5 to 6.0%, with most plants having 1.5 to 3.0%. Inorganic forms of N in plants are NO3- (nitrate) and NH4+ (ammonium). These forms are usually present in relatively small amounts. Other inorganic forms of N do not accumulate without injury to the plants. Organic forms of N predominate in plants, mainly as amino acids and proteins. During and after absorption, N often follows this pathway: Proteins consist of a number of amino acids linked together into a large molecular structure. Once the proteins are formed in plants, N moves to other parts of the plant only if the proteins are split apart by hydrolysis into amino acids. The amino acids then flow freely to other parts of the plant where they can recombine into proteins again. Proteins consist of 12 to 19% nitrogen. Other complex proteins formed from amino acids are enzymes that act as catalysts in biochemical reactions. Proteins also act as reserve food in the seeds that is released during germination for early seedling growth. Another type of N-containing material is chlorophyll (the green coloring matter in leaves necessary for photosynthesis). In the center of a chlorophyll molecule is a Mg atom surrounded by four N atoms. Therefore, N is a part of the chlorophyll molecule and if N is deficient, then plants become yellow since there is insufficient chlorophyll produced. Other important N-complexes are purine and pyrimidine bases that can form adenosine triphosphate (ATP) during the respiration process as an energy carrier.