System circulatory

The heart, consequently, is the beginning of life the sun of the microcosm, even as the sun in his turn might be designated the heart of the world for it is the heart by whose virtue and pulse the blood is moved, perfected, made apt to nourish, and is perceived from corruption and coagulation it is the household divinity which, discharging its function, nourishes, cherishes, quickens the whole body, and is indeed the foundation of life, the source of all action. 

The circulatory systems in plants and animals conform to physical principles. Each system has a means to propel the fluid, because, from Newton s laws of motion, fluid will not move by itself. Power is required to move the fluid. In plants, this power is supplied by a combination of water evaporation in the leaves, an osmotic gradient from root to leaf, and capillary action. In animals, this power is usually supplied by one or more hearts through which the blood flows. 

The power expended by the heart has no particular advantage for an organism this power does not directly aid reproduction, nor does it directly improve survival. As long as there is adequate blood flow, the organism can both survive and reproduce. Any extra power expended by the heart actually reduces the capacity of an individual to survive a physical challenge, so there is both a survival and reproduction advantage to reduce expended power as much as possible and still provide adequate circulation. 

The main objective of circulating blood is to provide oxygen and essential nutrients while removing metabolic wastes. In order to perform this function adequately, blood vessels must be in intimate contact with tissue cells. If these vessels were large and still in intimate contact with tissue cells, there would be little room for the cells themselves, and the body would consist mainly of blood vessels and blood. All the functions of the body, including muscular movement, digestion, chemical functions, etc., would be crowded out by the blood circulation. Thus, the vessels that serve the immediate needs of the tissues must be small. 

Fluid that moves faster requires more power to propel it. Thus, there is a penalty to be paid for the small vessels in the circulatory system. 

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The disease takes two different forms depending apparently on whether ergotoxia, the alkaloid ia ergot, attacks predomiaantiy the aervous or the circulatory system. The former coaditioa is characterized by severe coavulsive seizures the latter produces an iatense burning and itching of the skin called St. Anthony s Fire. 

Lead enters the body through inhalation and ingestion, is absorbed into the circulatory system from the lungs and digestive tract, and excreted via the urine and feces. Normally, intake of lead approximately equals output. However, excessive exposure and intake can cause tissue concentrations to increase to the point where illness can result. 

Strong acids and strong alkaUes can severely bum the skin, chromium compounds can produce skin rashes, and repeated exposure to solvents causes removal of natural oils from the skin. Infection is always a concern for damaged skin. Absorption through the skin is possible for materials that are appreciably soluble iu both water and oil, eg, nitrobenzene, aniline, and tetraethyllead. Other materials can be absorbed if first dissolved iu extremely good solvents, eg, dimethyl sulfoxide. Subcutaneous iujection can occur accidentally by direct exposure of the circulatory system to a chemical by means of a cut or scratch or iuadvertent penetration of the skin with a hypodermic needle. 

Ca.rdia.c-AssistDevices. The principal cardiac-assist device, the intra-aortic balloon pump (lABP), is used primarily to support patients before or after open-heart surgery, or patients who go into cardiogenic shock. As of the mid-1990s, the lABP was being used more often to stabilize heart attack victims, especially in community hospitals which do not provide open-heart surgery. The procedure consists of a balloon catheter inserted into the aorta which expands and contracts to assist blood flow into the circulatory system and to reduce the heart s workload by about 20%. The disposable balloon is powered by an external pump console. 

The biodistribution of the ideal radiopharmaceutical would show extremely rapid distribution via the circulatory system to the organs of interest and htfle distribution to others. It would be rapidly extracted by the organ or tissue of interest differentially in a way that reflects the disease process of interest. Ideally, abnormahties should be defined by substantial increases in the concentration of the agent because lesions defined by a decrease from surrounding concentrations, ie, cold-spot imaging, are more difficult to image. 

The filariform larva found in moist soils may be either ingested or penetrate the skin of its host. It is then carried through the circulatory system to the lungs and migrates up the respiratory tree into the digestive tract. The worms feed on intestinal tissue and blood. Some worms may persist in humans as long as nine years. Infestations cause cutaneous reactions, pulmonary lesions, intestinal ulcerations, and anemia. 

The second example of an air pollutant that affects the total body burden is carbon monoxide (CO). In addihon to CO in ambient air, there are other sources for inhalation. People who smoke have an elevated CO body burden compared to nonsmokers. Individuals indoors may be exposed to elevated levels of CO from incomplete combustion in heating or cooking stoves. CO gas enters the human body by inhalation and is absorbed directly into the bloodstream the total body burden resides in the circulatory system. The human body also produces CO by breakdown of hemoglobin. Hemoglobin breakdown gives every individual a baseline level of CO in the circulatory system. As the result of these factors, the body burden can fluctuate over a time scale of hours. 

CO Reduction in the ability of the circulatory system to transport O Impairment of performance on tasks requiring vigilance Aggravation of cardiovascular disease. 

Arsenic none 0.05 Skin damage circulatory system problems increased risk of cancer ceramics electronics solder Erosion of natural deposits runoff from glass electronics production wastes... 

When cells lie adjacent to each other in animal tissues, they are often connected by gap junction structures, which permit the passive flow of small molecules from one cell to the other. Such junctions essentially connect the cells metabolically, providing a means of chemical transfer and communication. In certain tissues, such as heart muscle that is not innervated, gap junctions permit very large numbers of cells to act synchronously. Gap junctions also provide a means for transport of nutrients to cells disconnected from the circulatory system, such as the lens cells of the eye. 

Acetoacetate and /3-hydroxybutyrate are transported through the blood from liver to target organs and tissues, where they are converted to acetyl-CoA (Figure 24.29). Ketone bodies are easily transportable forms of fatty acids that move through the circulatory system without the need for eomplexation with serum albumin and other fatty acid—binding proteins. 

FIGURE 25.38 Lipoprotein components are synthesized predominantly in the ER of liver cells. Following assembly of lipoprotein particles red dots) in the ER and processing in the Golgi, lipoproteins are packaged in secretory vesicles for export from the cell (via exocy-tosis) and released into the circulatory system. 

Thromboxane A-2 has been implicated in a number of disorders of the circulatory system including coronary artery spasms, unstable angina pectoris, traumatic and endotoxic shock, and heart attacks. It is formed normally very near its receptors and is rapidly deactivated by metabolizing enzymes so circulating levels are quite low. Furthermore, it is opposed in its actions by the prostacyclins. When these controls are defective, pathology results and drugs can be the resort in attempts to restore the normal healthy balance. For one example, furegrelate (6) is a throm-... 

Linear polarization instruments provide an instantaneous corrosion-rate data, by utilizing polarization phenomena. These instruments are commercially available as two-electrode Corrater and three electrode Pairmeter (Figure 4-472). The instruments are portable, with probes that can be utilized at several locations in the drilling fluid circulatory systems. In both Corrater and Pairmeter, the technique involves monitoring electrical potential of one of the electrodes with respect to one of the other electrodes as a small electrical current is applied. The amount of applied current necessary to change potential (no more than 10 to 20 mV) is proportional to corrosion intensity. The electronic meter converts the amount of current to read out a number that represents the corrosion rate in mpy. Before recording the data, sufficient time should be allowed for the electrodes to reach equilibrium with the environment. The corrosion-rate reading obtained by these instruments is due to corrosion of the probe element at that instant [184]. 

Use only chemical additives that are compatible with drilling fluids in circulatory systems. 

Machine-tool gears can be lubricated by oil-spray, mist, splash or cascade. Sealed oil baths are commonly used, or the gears may be lubricated by part of a larger circulatory system. 

The circulatory systems used in association with machine tools are generally conventional in nature, although occasionally their exceptional size creates special problems. The normal installation comprises a storage tank or reservoir, a pump and filter, suitable sprays, jets or other distribution devices, and return piping. The most recent designs tend to eliminate wick feeds and siphon lubrication. 

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