Heart bodies

A well-rounded exercise program addresses three separate physical needs. Aerobic exercise develops the legs, heart, body composition, and stamina. Strength exercise develops the arms, upper and lower torso, and improves body appearance. 

Transgenic mice with specific cardiac expression of constitutively active a[[, adrenoceptors showed cardiac hypertrophy, as reflected by an increased heart/body weight ratio and increases in diacylglycerol and atrial... 

Using MRI as a substitute for X ray tomography IS only the first of what are many medical applica tions More he on the horizon If for example the rate of data acquisition could be increased then it would become possible to make the leap from the equivalent of still photographs to motion pictures One could watch the inside of the body as it works— see the heart beat see the lungs expand and con tract—rather than merely examine the structure of an organ... 

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... 

Some scientific studies indicate that the gam in performance obtained through the use of anabolic steroids is small This may be a case though in which the anecdotal evidence of the athletes may be closer to the mark than the scientific studies The scientific studies are done under ethical conditions in which patients are treated with prescription level doses of steroids A 240 pound offensive tackle ( too small by todays standards) may take several ana bolic steroids at a time at 10-20 times their pre scribed doses in order to weigh the 280 pounds he (or his coach) feels is necessary The price athletes pay for gams in size and strength can be enormous This price includes emotional costs (friendships lost because of heightened aggressiveness) sterility testicular atro phy (the testes cease to function once the body starts to obtain a sufficient supply of testosterone like steroids from outside) and increased risk of prema ture death from liver cancer or heart disease... 

Biomedical Applications. In the area of biomedical polymers and materials, two types of appHcations have been envisioned and explored. The first is the use of polyphosphazenes as bioinert materials for implantation in the body either as housing for medical devices or as stmctural materials for heart valves, artificial blood vessels, and catheters. A number of fluoroalkoxy-, aryloxy-, and arylamino-substituted polyphosphazenes have been tested by actual implantation ia rats and found to generate Httle tissue response (18). 

Most iron salts and compounds may be safely handled following common safe laboratory practices. Some compounds are irritants. A more serious threat is ingestion of massive quantities of iron salts which results in diarrhea, hemorrhage, fiver damage, heart damage, and shock. A lethal dose is 200 250 mg/kg of body weight. The majority of the victims of iron poisoning are children under five years of age. 

Selenium. Selenium, thought to be widely distributed throughout body tissues, is present mostly as selenocysteine in selenoproteins or as selenomethionine (113,114). Animal experiments suggest that greater concentrations are in the kidney, Hver, and pancreas and lesser amounts are in the lungs, heart, spleen, skin, brain, and carcass (115). 

Florfenicol concentrations in tissues and body fluids of male veal calves were studied after 11 mg/kg intramuscular doses adininistered at 12-h intervals (42). Concentrations of florfenicol in the lungs, heart, skeletal muscle, synovia, spleen, pancreas, large intestine, and small intestine were similar to the corresponding semm concentrations indicating excellent penetration of florfenicol into these tissues. Because the florfenicol concentration in these tissues decreased over time as did the corresponding semm concentrations, it was deemed that florfenicol equiUbrated rapidly between these tissues and the blood. Thus semm concentrations of florfenicol can be used as an indicator of dmg concentrations in these tissues. 

One of the remarkable features of the heart, which is about the size of a fist, is that the pumping action or contractions (- 70 times/min) of atria and ventricles are simultaneous. Deoxygenated blood is pumped out to the lungs from one side of the heart at the same time oxygenated blood is pumped out from the other side to the aorta and onward through the body. The entire process of blood flow between the atria, ventricles, and the principal vessels is in unison, controlled in part by four one-way valves. The atrioventricular valves, tricuspid on the right and mitral on the left, prevent blood from flowing... 

In addition to its internal blood flow operation, the heart has its own system of blood vessels to keep the muscle wall of the heart, the myocardium, supphed with oxygenated blood (Fig. 3a). The coronary arteries, which branch from the aorta to the right and left sides of the heart, are vital to maintaining that supply. The heart is an extraordinary electromechanical muscle that can be trained to increase blood flow to the body sixfold. It can range from 5 to 30 L /min during exertion. 

Valve Problems. The primary solution to valve problems has been implantable replacement valves. The introduction of these devices necessitates open-heart surgery. There are two types of valves available tissue (porcine and bovine) and mechanical. The disadvantage of tissue valves is that these have a limited life of about seven years before they calcify, stiffen, and have to be replaced. The mechanical valves can last a lifetime, but require anticoagulant therapy. In some patients, anticoagulants may not be feasible or may be contraindicated. Of the valves which require replacement, 99% are mitral and aortic valves. The valves on the left side of the heart are under much greater pressure because the left ventricle is pumping blood out to the entire body, instead of only to the lungs. Occasionally, two valves are replaced in the same procedure. 

Cardiomyopathy. The best available solution to cardiomyopathy may be one that is less sophisticated than transplant surgery or the artificial heart. The cardiomyoplasty-assist system combines eariier electrical stimulation technology with a new surgical technique of utilizing muscle from another part of the body to assist the heart. 

One of the more intriguing cardiovascular developments is cardiomyoplasty where implantable technologies are blended with another part of the body to take over for a diseased heart. One company, Medtronic, in close collaboration with surgeons, has developed a cardiomyoplasty system to accompany a technique of wrapping back muscle around a diseased heart which can no longer adequately pump. A combination pacemaker and neurological device senses the electrical activity of the heart and correspondingly trains and stimulates the dorsal muscle to cause the defective heart to contract and pump blood. Over 50 implants have been performed to date. 

One successful total artificial heart is ABIOMED s electric TAH. This artificial heart consists of two seamless blood pumps which assume the roles of the natural heart s two ventricles (Fig. 7). The pumps and valves are fabricated from a polyurethane, Angioflex. Small enough to fit the majority of the adult population, the heart s principal components are implanted in the cavity left by the removal of the diseased natural heart. A modest sized battery pack carried by the patient suppHes power to the drive system. Miniaturized electronics control the artificial heart which mns as smoothly and quietly as the natural heart. Once implanted, the total artificial heart performs the critical function of pumping blood to the entire body (6). 

In the tissues of animals, most thiamine is found as its phosphorylated esteis (4—6) and is piedominandy bound to enzymes as the pyrophosphate (5), the active coen2yme form. As expected for a factor involved in carbohydrate metaboHsm, the highest concentrations ate generally found in organs with high activity, such as the heart, kidney, Hver, and brain. In humans this typically amounts to 1—8 p.g/g of wet tissue, with lesser amounts in the skeletal muscles (35). A typical healthy human body may contain about 30 mg of thiamine in all forms, about 40—50% of this being in the muscles owing to their bulk. Almost no excess is stored. Normal human blood contains about 90 ng/mL, mostly in the ted cells and leukocytes. A value below 40 ng/mL is considered indicative of a possible deficiency. Amounts and proportions in the tissues of other animal species vary widely (31,35). 

Table 21.1 Likely intensities of body currents when lasting for more than a heart beat (- 60-300 ms)...

To enable the body to sustain a high fault current it is essential that the fault interrupting device (relay or release) is quick responding. For domestic applications, it is recommended to be less than a heart beat. 

To extract die EPBC liquids, die plant employs a cryogenic temperature process in combination with a refluxed demedianizer process in two trains. The two turboexpander trains are die heart of die process and bodi have operated at efficiencies higher dian originally expected at die design stage. 

Bradycardia Bradycardia is a slow heart rate (60 beats per minute or slower) that does not meet the body s metabolic demands. Symptoms of bradycardia include dizziness, extreme fatigue, shortness of breath, or fainting spells. This can be compared to tachycardia, which is an extremely rapid heart rate, usually signified by a pulse of over 100 beats per minute. Adults usually have a resting heart rate of 70-80 beats per minute, although well-trained athletes can have resting rates in the 50 s or 60 s. Newborn babies have a normal heart rate of 120-160 beats per minute. A slowed heart rate can lead to a variety of other problems. First aid treatment may include administration of oxygen. 

HOT Tblood flow to. skin (vasodilation), heart rate T, sweating T, skin moisture T, body temperatures T, metabolism T... 

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