Vital functions, maintenance

Virchow, who was largely responsible for the acceptance of the cell theory, developed microscopy of cells from normal and diseased tissues as a major tool (histopathology) in the clinical armory. He believed the vital functions of the cell, growth, maintenance, and multiplication were discharged by its nucleus the specialised, distinguishing functions were made possible by the extranuclear constituents. In a Sunday evening lecture in Edinburgh in 1868, On the Physical Basis of Life , Thomas Huxley described cells as protoplasmic masses usually... 

The lung contains more than 40 different types of cells, amongst which epithelial cells are vital for maintenance of the pulmonary blood-gas barrier. The epithelium also provides absorptive and secretive functions. The diversity of epithelial cell types is summarized as airway epithelium and alveolar epithelium cells. 

Management of the poisoned patient consists of maintenance of vital functions, identification of the toxic substance, decontamination procedures, enhancement of elimination, and, in a few instances, the use of a specific antidote. 

Mitochondria. Cellular organelle oxidizing energy substrates in the tricarboxylic acid cycle, coupled with the respiratory chain producing the bulk of the high-energy compound ATP, indispensable for maintenance of all vital functions of each cell and the whole organism. 

Given that the effective and continuous control of boiler section corrosion is a vitally important function, the establishment and maintenance of the passivity of the boiler surface s metal at the metal-water interface is critical. 

To achieve their different effects NTs are not only released from different neurons to act on different receptors but their biochemistry is different. While the mechanism of their release may be similar (Chapter 4) their turnover varies. Most NTs are synthesised from precursors in the axon terminals, stored in vesicles and released by arriving action potentials. Some are subsequently broken down extracellularly, e.g. acetylcholine by cholinesterase, but many, like the amino acids, are taken back into the nerve where they are incorporated into biochemical pathways that may modify their structure initially but ultimately ensure a maintained NT level. Such processes are ideally suited to the fast transmission effected by the amino acids and acetylcholine in some cases (nicotinic), and complements the anatomical features of their neurons and the recepter mechanisms they activate. Further, to ensure the maintenance of function in vital pathways, glutamate and GABA are stored in very high concentrations (10 pmol/mg) just as ACh is at the neuromuscular junction. 

As its name suggests, the hypothalamus lies beneath the thalamus and above the pituitary gland. Although it is quite small, accounting for only about 4 g of the total 1400 g of the adult human brain, it plays a vital role in maintenance of homeostasis in the body. It is composed of numerous cell groups and fiber pathways, each with a specific function. 

The circulatory system carries out many important functions that contribute to homeostasis. It obtains oxygen from the lungs nutrients from the gastrointestinal tract and hormones from the endocrine glands and it delivers these substances to the tissues that need them. Furthermore, it removes metabolic waste products, such as carbon dioxide, lactic acid, and urea, from the tissues. Finally, it contributes to the actions of the immune system by transporting antibodies and leukocytes to areas of infection. Overall, the circulatory system plays a vital role in maintenance of optimal conditions for cell and tissue function. 

There are countless situations where the relative acidity or alkalinity of a substance or system is of critical importance. Agricultural conditions, water quality, food preservation, lung and kidney function—all are circumstances in which quantitative measures of acidity or basicity enable proper maintenance and regulation of vital processes. The term pH is widely used as an expression of acid/base content, but what is the origin of such nomenclature ... 

Acid-base balance involves chemical and physiological processes responsible for the maintenance of the pH of body fluids at levels that allow optimal function of the whole individual. The ability for the body to regulate pH is critically important in maintaining the operation of many cellular enzymes and the function of vital organs, such as the brain and the heart [143],... 

Ca normally circulates in the bloodstream, within a 2.25-2.50 mmol concentration range, bound to proteins (40 5%), complexed with ions (8-10%), and ionized as Ca " " (45-50%) (Weaver and Heaney, 2006a). Circulating Ca in excess of that required for maintenance of plasma levels is ideally transferred from the blood to be deposited in bone via the bone formation process. The Ca concentration outside of blood vessels in the ECF that bathes cells is tightly regulated close to 1.25 mmol (Weaver and Heaney, 2006a), almost to the point of invariance. It is this ECF Ca pool that cells are immediately reliant upon to sustain vital cellular functions that are imminently critical to the maintenance of life (e.g., cardiac muscle contraction). Circulating Ca is constantly utilized to replenish ECF pools, and when Ca derived from dietary intake is insufficient to replace the amoimt of Ca used for replenishment, Ca in bone is transferred to the blood via a bone resorption process. 

Copper is an essential component of numerous key metalloenzymes which are critical in melanin formation, myelin formation and crosslinking of collagen and elastin. Copper plays a vital role in hemopoiesis, maintenance of vascular and skeletal integrity, and structure and function of the nervous system. Thus a deficiency of copper can lead to a variety of adverse effects such as increased fragility in bones, aneurysm formation in arteries and a loss of lysyl oxidase activity in cartilage.54 57 Articles on copper also appear in Siget1, volumes 3 and 5, all of volumes 12 and 13, and volume 14,... 

Once the nutrients enter the bloodstream, they are transported to various parts of the body for vital body functions. Nutrients are used to maintain essential functions such as breathing, circulation of blood and muscle movement, replacement of worn-out cells (maintenance), growth, reproduction and egg production. 

The kidney and bladder are very important in toxicology because they are the main route of elimination of hydrophilic toxicant metabolites and because damage to them in the form of impaired kidney function or bladder cancer is one of the major adverse effects of toxicants. The kidney plays a key role in maintaining body homeostasis. The basic unit of the kidney, through which the organ performs its crucial blood filtration action, is the nephron. As the main organ through which fluid is lost from the body, it is vital in the maintenance of extracellular fluid volume. It acts to maintain... 

The composition of the lysis solution is dictated by the nature of the proteins under study and the subsequent techniques applied to the sample. One of the major choices to be made is whether or not a detergent is required at this stage. If the membrane and soluble fractions are to be separated the initial cell disruption protocol should not include a detergent, as many of the membrane proteins would be solubilized. In this case physical disruption of the cells should be used (e.g., sonication of cells or homogenization of tissues). The choice of lysis conditions is a vital consideration in this work, as proteins need to be solubilized while preservation of posttranslational modifications, inhibition of proteases, maintenance of protein-protein interactions, and, if an immunoaffinity purification step is to be performed, suitability for the antibody to function are essential. For example, SDS is very good at solubilizing membrane proteins but... 

The morphological and functional integrity of the liver is vital to the health of the human organism. This essentially depends upon constant maintenance of the numerous biochemical functions of the liver and the diverse metabolic processes occurring in the hepatocytes and sinusoidal cells. 

The studies reviewed in this chapter demonstrate that a strong and reciprocal relationship exists between the central nervous system and the immune system. Indeed, the term neuroim-mune system is clearly justified and appropriate to emphasize the fact that nervous and lymphoid tissues constitute a unified system that functions in the maintenance of homeostasis. The conventional division between the two systems has blurred, as well as the distinction between neuropeptides on the one hand, and immune cytokines on the other. Two lines of research have altered our perspective on neuroimmune interactions (a) the identification of conventional neuropeptides and then-receptors, especially those related to the HPA axis, in most lymphoid tissues, and (b) the large body of evidence that cytokines, historically associated with immune system communication, play vital roles in nervous function. 

Foods may contain precursors of vitamin D as well as vitamin D. The precursors are converted to the vitamin following their absorption from the diet. T c body is a source of one of the precursors, 7-dehydnocholesteroL Conversion of the precursor to the vitamin form occurs in the skin. The major function of vitamin D is to maintain the concentration of calcium ions in the plasma. Maintenance of these concentrations is vital for normal functioning of the nervous system and for the growth of bones and the maintenance of bone mass. Although vitamin D is closely associated with bone growth, it is thought that the relationship is only indirect. T he vitamin stimulates the absorption of dietary calcium by the gut, but it seems not to stimulate the subsequent deposit of calcium in the bone. 

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