Tissues artery

As indicated in Table 2.1, drugs may be injected into veins, muscles, subcutaneous tissue, arteries, or into the subarachnoid space of the spinal canal (intrathecal). For obvious reasons, intraarterial and intrathecal injections are reserved for specialized drug administration requirements, such as regional perfusion of a tumor with a toxic drug or induction of spinal anesthesia, respectively. Therefore, the more routine injection routes are intravenous (IV), intramuscular (IM), and subcutaneous (SC). Because these three modalities involve skin puncture, they carry the risks of infection, pain, and local irritation. 

Parenchyma setting When incisions are made in the parenchyma, all structures within the tissue (arteries, portal veins, hepatic veins, bile ducts) must remain intact. Apart from the well-established method called finger fracture (W. Anschutz, 1903), ultrasonic cutters, water beam dissectors or laser scalpels are used... 

The method has been applied to many biological systems perfused heart, lung and vascular tissue, arterial and venous blood, culture fluids from various cells (from endothelium, blood, bone, thymus) and blood platelets. The influence of diet (different poly-unsaturated fatty acids, e.g. n-6 versus n-3), medicines (aspirin) and drugs (nicotine) was studied. We could not detect any prostacyclin (< 20 pg/ml) in whole human blood obtained during diagnostic catherization of the arteries and... 

An organ like the stomach or the brain contains structures within it such as arteries, nerves and other specialised components. These components, which contain cells of a similar kind, are referred to as tissues. So we have nervous tissue, arterial tissue, muscular tissue and so on making up specialised organs which have a specific function. (The stomach, for example, is concerned with the first stage in the digestive process.)... 

The value of the continuum models is that they do not require a separate solution for the blood subvolume. In each continuum formulation, the behavior of the blood vessels is modeled by introducing assumptions that allow solution of only a single differential equation. But by solving only one equation, all detailed information on the temperature of the blood in individual blood vessels is lost. Several investigators have introduced multiequation models that typically model the tissue, arteries, and veins as three separate. 

Cholesterol is the central compound m any discussion of steroids Its name is a combination of the Greek words for bile (chole) and solid (stereos) preceding the characteristic alcohol suffix ol It is the most abundant steroid present m humans and the most important one as well because all other steroids arise from it An average adult has over 200 g of cholesterol it is found m almost all body tissues with relatively large amounts present m the brain and spinal cord and m gallstones Cholesterol is the chief constituent of the plaque that builds up on the walls of arteries m atherosclerosis... 

Cholesterol is biosynthesized in the liver trans ported throughout the body to be used in a va riety of ways and returned to the liver where it serves as the biosynthetic precursor to other steroids But cholesterol is a lipid and isn t soluble in water How can it move through the blood if it doesn t dis solve in if The answer is that it doesn t dissolve but IS instead carried through the blood and tissues as part of a lipoprotein (lipid + protein = lipoprotein) The proteins that carry cholesterol from the liver are called low density lipoproteins or LDLs those that return it to the liver are the high-density lipoproteins or HDLs If too much cholesterol is being transported by LDL or too little by HDL the extra cholesterol builds up on the walls of the arteries caus mg atherosclerosis A thorough physical examination nowadays measures not only total cholesterol con centration but also the distribution between LDL and HDL cholesterol An elevated level of LDL cholesterol IS a risk factor for heart disease LDL cholesterol is bad cholesterol HDLs on the other hand remove excess cholesterol and are protective HDL cholesterol IS good cholesterol... 

As of early 1992, the market for ceU culture-derived products approached 1 billion per year. The market is expected to grow substantially throughout the 1990s. CeU culture products include erythropoietin, 1991 sales of approximately 400 million, for the treatment of anemia associated with kidney dialysis, and tissue plasminogen activator, 1991 sales approximately 200 million, for treating heart attack victims with blocked arteries (see Cardiovascularagents). 

Thrombolytic Enzymes. Although atherosclerosis and the accompanying vascular wall defects are ultimately responsible for such diseases as acute pulmonary embolism, arterial occlusion, and myocardial infarction, the lack of blood flow caused by a fibrin clot directly results in tissue injury and in the clinical symptoms of these devastating diseases (54). Thrombolytic enzyme therapy removes the fibrin clot by dissolution, and has shown promise in the treatment of a number of thrombo-occlusive diseases (60). 

There are a number of tissue adhesives currently approved as adjuncts to hemostasis. Each agent has specific properties which enhance intraoperative hemostasis in particular situations. All forms of surgical bleeding are not alike. Bleeding can be fast or slow, diffuse or punctate, arterial or venous, capillary or larger vessel. Thus one agent may be more efficacious than another in a specific clinical situation. 

Meticulous care needs to be used in the application of this tissue adhesive. Only a very thin layer of adhesive should be used to assist with reapproximation of the intima and adventitia. It is important to remember that the material should not be allowed to drip into or onto critical areas such as the ostium of the coronary arteries. Inadvertent placement of this agent in such areas can result in blockage of a critical artery and a potentially fatal myocardial infarction. In addition. 

Anoxia Anoxia is the absence of oxygen in inspired gases or in arterial blood and/or in the tissues. This is closely related to hypoxia, which is a severe oxygen deficiency in the tissues. One can think of anoxia as the most extreme case of hypoxia. 

Baroreceptor. Specialized pressure-sensitive tissue located in carotid arteries. Nerve impulses proportional to arterial blood pressure are conducted from this tissue to the brain which in turn exerts control over the blood pressure. 

Although blood pressure control follows Ohm s law and seems to be simple, it underlies a complex circuit of interrelated systems. Hence, numerous physiologic systems that have pleiotropic effects and interact in complex fashion have been found to modulate blood pressure. Because of their number and complexity it is beyond the scope of the current account to cover all mechanisms and feedback circuits involved in blood pressure control. Rather, an overview of the clinically most relevant ones is presented. These systems include the heart, the blood vessels, the extracellular volume, the kidneys, the nervous system, a variety of humoral factors, and molecular events at the cellular level. They are intertwined to maintain adequate tissue perfusion and nutrition. Normal blood pressure control can be related to cardiac output and the total peripheral resistance. The stroke volume and the heart rate determine cardiac output. Each cycle of cardiac contraction propels a bolus of about 70 ml blood into the systemic arterial system. As one example of the interaction of these multiple systems, the stroke volume is dependent in part on intravascular volume regulated by the kidneys as well as on myocardial contractility. The latter is, in turn, a complex function involving sympathetic and parasympathetic control of heart rate intrinsic activity of the cardiac conduction system complex membrane transport and cellular events requiring influx of calcium, which lead to myocardial fibre shortening and relaxation and affects the humoral substances (e.g., catecholamines) in stimulation heart rate and myocardial fibre tension. 

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