Aorta

Poiseuille was a physician-physiologist interested in the flow of blood through blood vessels in the body. Estimate the viscosity of blood from the fact that blood passes through the aorta of a healthy adult at rest at a rate of about 84 cm sec , with a pressure drop of about 0.98 mmHg m". Use 9 mm as the radius of the aorta for a typical human. 

Two AT-II receptors, AT and AT2 are known and show wide distribution (27). The AT receptor has been cloned and predominates ia regions iavolved ia the regulation of blood pressure and water and sodium retention, eg, the aorta, Hver, adrenal cortex, and ia the CNS ia the paraventricular nucleus, area postrema, and nucleus of the soHtary tract. AT2 receptors are found primarily ia the adrenal medulla, utems, and ia the brain ia the locus coeruleus and the medial geniculate nucleus. AT receptors are GCPRs inhibiting adenylate cyclase activity and stimulating phosphoHpases C, A2, and D. AT2 receptors use phosphotyrosiae phosphatase as a transduction system. 

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. 

Grafts are also frequently employed in the upper part of the body to reconstmct damaged portions of the aorta and carotid arteries. In addition, grafts are used to access the vascular system, such as in hemodialysis to avoid damage of vessels from repeated needle punctures. Most grafts are synthetic and made from materials such as Dacron or Teflon. Less than 5% of grafts utilized are made from biological materials. 

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. 

There are other glycosaminoglycans. Hyaluronic acid [9004-61-9] occurs both free and in noncovalent association with proteoglycan molecules. Heparin [9005-49-6] and heparan sulfate [39403-40-2] also known as heparitin sulfate [9050-30-0] occur in mast cells and in the aorta, Hver, and lungs. 

The 9,11-azo analog of PGH2, compound A, is stable indefinitely and is substantially more active than PGH2 in stimulating muscle contraction in the isolated rabbit aorta strip. 

Haupt-satz, m. fundamental principle or law main theorem axiom, -schalter, m. main (or master) switch, -schlagader, /. main artery aorta, -schluss, m. (Elec.) main circuit. -schliissel, m. master key. -schnitt, m. principal section, -schwlngung, /. principal vibration, -serie, /. principal series, -tlcherung,/. (Elec.) main fuse, main cutout. 

In 1948 Einstein was found to have a large intact aneurysm of the abdominal aorta. In 1950 he wrote his testament, willing his papers and manuscripts to Hebrew University (where they are now). On April... 

Plastics have made many major contributions to the contemporary scene. Health-care professionals depend on plastics for everything from intravenous bags to wheelchairs, disposable labware to silicone body parts, etc. The diversity of plastics allows them to serve in many ways, improving and prolonging lives, such as a braided, corrugated Dacron (Du Pont s polyester) aorta tube (24). 

Other surgical implants are essentially plastic repair products for worn out parts of the body. It is possible to conceive of major replacements of an entire organ such as a kidney or a heart by combining the plastic skills with tissue regeneration efforts that may extend life. This is used to time the heart action. Extensively used are plastic corrugated, fiber (silicone or TP polyester) braided aortas (24). 

Postmastectomy reconstruction Artificial hip. knee 18. Artificial finger, toe joints Tom ligaments Natural-action Seattle Foot Aorta... 

Rosato, D. V., Plastic Replaces Aorta Permits Living Normal-Long Life, Newton-Wellesly Hospital-Massachusetts, Mar. 1987. 

Defects of the Ductus arteriosus Botalli (short circuit connection between arteria pulmonalis and aorta non-closure after birth)... 

Kawamoto, S. Adelstein, R.S. (1987), Characterization of myosin heavy chains in cultured aorta smooth muscle cells. A comparative study. J. Biol. Chem. 262, 7282-7288. 

Finally, a 150 kDa calmodulin binding protein, caldesmon is found bound to actin filaments at low calcium concentrations. The ratio of caldesmon to actin molecules seems to vary from 1 20 in the aorta to as much as 1 200 in chicken gizzard. It has been reported and disputed that caldesmon crosslinks actin filaments into large bundles. 

The vasorelaxant activity, which was assessed as the inhibition of calcium-induced contraction of K-depolarised rat aorta has a IC50 of 3368 tiM compared with 5.6 nM for SR 33557. 

Another example was done by Opitz et al. They utilized P4HB scaffolds to produce viable ovine blood vessels, and then implanted the blood vessels in the systemic circulation of sheep. Enzymatically derived vascular smooth muscle cells (vSMC) were seeded on the scaffolds both under pulsatile flow and static conditions. Mechanical properties of bioreactor-cultured blood vessels which were obtained from tissue engineering approached those of native aorta. 

They also seeded autologous vSMC and ECs obtained from ovine carotid arteries to study autologous tissue-engineering blood vessels in the descending aorta of juvenile sheep. They found that after three months implantation, grafts were fully patent, without dilatation, occlusion, or intimal thickening. A continuous luminal EC layer was formed. However, after six months ... 

Shum-Tim D, Stock U, Hrkach J, Shinoka T, Lien J, Moses MA, Stamp A, Taylor G, Moran A, Landis W, Langer R, Vacanti JP, and Mayer JE Jr. Tissue engineering of autologous aorta using a new biodegradable polymer. Ann Thorac Surg, 1999, 68(6), 2298-304. 

Cardiovascular Effects. No studies were located regarding cardiovascular effects in humans after inhalation exposure to endosulfan. Routine gross and histopathologic examination of the heart and aorta of rats exposed (nose-only) to concentrations of endosulfan of up to 2 mg/m for 6 hours/day,... 

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