Blood, circulation

As shown in the figure, the blood from the left heart is pumped through the arteries to the various organs and tissues from where, after exchanging various substances, it is returned through the veins to the right heart. This blood circulation is called the major circulation.  

Other required substances are transported from the arterial blood through the walls ofthe arterial capillaries into tissues and organs. In contrast, waste products and unrequired substances produced by the organs and tissues are transported to the venous blood through the walls of the venous capillaries, which combine into venules, and then into larger veins. 

The spleen is an organ, the main functions of which are the formation and purification ofblood. Blood from the spleen and intestine is passed through the portal vein to the liver for further reactions. The functions of the lungs, kidneys, and liver are described later in the chapter. The coronary arteries, which branch from the aorta, supply blood to the muscles of the heart. 

The flow rate of blood through the heart is approximately 4-5lmin for adults. The typical mean blood velocity through the aorta (which is the largest artery with a diameter of 2-3 cm), when pumped from the left heart, is approximately 25 cm s i (mean) the maximum velocity is approximately 60 cm s h The Reynolds number for the maximum velocity is about 3000. In general, the blood flow through arteries and veins is laminar in nature. In capillaries, the typical blood velocity is 0.5-1 mm s , and the Reynolds number is on the order of 0.001. 

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Logically, ADH receptor antagonists, and ADH synthesis and release inhibitors can be effective aquaretics. ADH, 8-arginine vasopressin [113-79-17, is synthesized in the hypothalamus of the brain, and is transported through the supraopticohypophyseal tract to the posterior pituitary where it is stored. Upon sensing an increase of plasma osmolaUty by brain osmoreceptors or a decrease of blood volume or blood pressure detected by the baroreceptors and volume receptors, ADH is released into the blood circulation it activates vasopressin receptors in blood vessels to raise blood pressure, and vasopressin V2 receptors of the nephrons of the kidney to retain water and electrolytes to expand the blood volume. 

Most of the herbal drugs that are used medicinally are comprised in these five groups of indications. Relative few are employed in a limited number of other areas occasionally in skm remedies, liver remedies, coronary remedies, blood circulation remedies, and in other groups of medicines. Summarizing, it can be said that the possibilities of treatment with herbal drugs are limited for a number of reasons for a series of illnesses like severe cardiac insufficiency, tumours, infectious diseases, diabetes, etc., herbal drugs arc not adequate remedies, even though, in contravention of the law, such claims are made in many publications. In a series of further cases, they only find use in support of the actual medical treatment they are nevertheless of value. 

Bloodstream Volume of blood circulating through the heart, arteries, capil... 

According to Gvishiani, in experiments on cats and mice salsoline resembles papaverine in its effects on blood circulation and hydrastinine in its action on smooth muscle. Its use in Russia for the treatment of hypertension has been reported. ... 

Catalyst circulation is like blood circulation to the human body. Without proper catalyst circulation, the unit is dead. Troubleshooting circulation problems requires a good understanding of the pressure balance around the reactor-regenerator circuit and the factors affecting catalyst fluidization. The fundamentals of fluidization and catalyst circulation are discussed in Chapter 5. 

Another consequence of the effect of pressure on gas solubility is the painful, sometimes fatal, affliction known as the bends. This occurs when a person goes rapidly from deep water (high pressure) to the surface (lower pressure), where gases are less soluble. The rapid decompression causes air, dissolved in blood and other body fluids, to bubble out of solution. These bubbles impair blood circulation and affect nerve impulses. To minimize these effects, deep-sea divers and aquanauts breathe a helium-oxygen mixture rather than compressed air (nitrogen-oxygen). Helium is only about one-third as soluble as nitrogen, and hence much less gas comes out of solution on decompression. 

The blood-brain barrier (BBB) forms a physiological barrier between the central nervous system and the blood circulation. It consists of glial cells and a special species of endothelial cells, which form tight junctions between each other thereby inhibiting paracellular transport. In addition, the endothelial cells of the BBB express a variety of ABC-transporters to protect the brain tissue against toxic metabolites and xenobiotics. The BBB is permeable to water, glucose, sodium chloride and non-ionised lipid-soluble molecules but large molecules such as peptides as well as many polar substances do not readily permeate the battier. 

One of the most efficient plasmin inhibitor is a2-PI (70 kDa), which is synthesized by the liver, secreted into the blood circulation, where its concentration is 1 pM. It rapidly forms equimolar complex with plasmin, and in this complex, the active site of the enzyme is irreversibly blocked. The complex, thereafter, is removed by the liver. It is remarkable that when plasmin is bound to its substrate (fibrin), it is protected against its primarily inhibitor, a2-PI the rate of inactivation decreases by 400-fold (Fig. 4) [3]. 

The amide local anaesthetic lidocaine may also be used as an antianhythmic for ventricular tachycardia and exra-systoles after injection into the blood circulation. Drugs with high lipid solubility such as bupivacaine cannot be used for these purposes because their prolonged binding to the channel may induce dysrhythmias or asystolic heart failure [3]. Systemically applied lidocaine has also been used successfully in some cases of neuropathic pain syndromes [4]. Here, electrical activity in the peripheral nervous system is reduced by used-dependent but incomplete sodium channel blockade. 

The a2-plasmin inhibitor, a single-chain glycoprotein (70 kDa), forms rapidly an equimolar complex with plasmin, where the enzyme loses its activity. It is synthesized by the liver and secreted into the blood circulation, where its concentration is 1 pM. 

Plasmin, a serine protease (83 kDa), can degrade fibrin, and its degradation products (FDP) are soluble in the blood. Plasmin is formed from its proenzyme (zymogen, precursor), plasminogen (92 kDa), synthesized by the liver, and secreted into the blood circulation, where its concentration is 2 pM. Plasminogen is converted to plasmin by plasminogen activators (serine proteases). 

Many antihypertensive drug lower the blood pressure by dilating or increasing the size of the arterial blood vessels (vasodilatation). Vasodilatation creates an increase in the lumen (the space or opening within an arteiy) of the arterial blood vessels, which in turn increases the amount of space available for the blood to circulate Because blood volume (the amount of blood) remains relatively constant, an increase in the space in which the blood circulates (ie, the blood vessels) lowers the pressure of the fluid (measured as blood pressure) in the blood vessels. Although the method by which anti-hypertensive drug dilate blood vessels varies, the result... 

Ethanol distributes rapidly, with concentrations in body water 10 times higher than in body fat. The tissues with the greatest blood supply equdibrate most rapidly with arterial blood circulation. Shortly after alcohol ingestion, the ethanol concentration in the brain is higher than the venous concentration. 

Increased accumulation of liposomes, especially small liposomes, has been reported to occur at sites of inflammation (Williams et al., 1986) and in tumors (Turner et al., 1988 Gabizon and Papahadjopoulos, 1988) (cf. Sec. VI.B). However, it is well established that endo-cytosis of liposomes by MPS cells, primarily those located in liver and spleen, accounts for most of the uptake of liposomes—and, in general, uptake of particulate matter—from the blood circulation. 

Capillary phenomena are also essential in tribology and in many biological systems, such as blood circulation and eye irrigation, involving the formation and persistence of the lachrymal film. 

At the Tissue and Organ Level, the Blood Circulation Integrates Metabolism... 

Rimantadine in young adults), utilization of adamantane derivative carriers can probably prolong drug presence time in blood circulation. 

In contrast, the carotenes such as p-carotene and lycopene may position themselves parallel to the membrane surfaces to remain in a more lipophilic environment in the inner cores of the bilayer membranes. To move through an aqueous environment, carotenoids can be incorporated into lipid particles such as mixed micelles in the gut lumen or lipoproteins in the blood circulation and they can also form complexes with proteins with unspecific or specific bindings. 

Both intact carotenoids and their apolar metabolites (retinyl esters) are secreted into the lymphatic system associated with CMs. In the blood circulation, CM particles undergo lipolysis, catalyzed by a lipoprotein lipase, resulting in the formation of CM remnants that are quickly taken up by the liver. In the liver, the remnant-associated carotenoid can be either (1) metabolized into vitamin A and other metabolites, (2) stored, (3) secreted with the bile, or (4) repackaged and released with VLDL particles. In the bloodstream, VLDLs are transformed to LDLs, and then HDLs by delipidation and the carotenoids associated with the lipoprotein particles are finally distributed to extrahepatic tissues (Figure 3.2.2). Time-course studies focusing on carotenoid appearances in different lipoprotein fractions after ingestion showed that CM carotenoid levels peak early (4 to 8 hr) whereas LDL and HDL carotenoid levels reach peaks later (16 to 24 hr). 

The BBB is a complex cellular system which protects the central nervous system (CNS) by separating the brain from the systemic blood circulation. Drugs that act... 

The liver is a wedge-shaped organ of some 1.5 kg in adult humans, which, in terms of blood circulation, is interposed between the gastrointestinal tract and the rest of the body. The blood supply to the liver is from the hepatic portal vein (80%) and the hepatic artery (20%), the former bringing a rich supply of nutrients direct from the intestinal tract and the latter supplying the liver with oxygen. Blood drains from the liver by the hepatic vein. The position of the liver enables it to act as a processor of the absorbed nutrients, and to control their storage... 

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