Representations of the human circulatory system

There is no agreement about the robustness of intuitive representations of the circulatory system and their susceptibility to change by instruction. In this paper, we analyse to what extent students with varying degrees of biology instruction and different ages (High School Health Science and Social Science students and first and final year University Psychology students) have been able to change their intuitive beliefs into scientific representations of the workings of the human circulatory system. We analysed two aspects of the representation of the circulatory system: models of the circulatory system (the relationship between the heart and lungs in the blood pathway) and the circulatory system pattern (the blood pathway between organs). In relation to the models of the circulatory system, we found differences among the different groups of students according to the amount of biological instruction they had. The majority of participants (High School Social Science students and both University Psychology student groups) had an incomplete model, which did not include the lungs while the High School Health Science students group had a scientific representation. As for the circulatory system pattern, we did not find differences among groups. However, we cannot conclude that the representations of the two aspects of the circulatory system (model and pattern) are independent. The data in this study show that compulsory human physiology instruction did not enhance the acquisition of a scientific representation of the human circulatory system.     

脊椎动物循环系统的比较

脊椎动物的循环系统是一个封闭的管道系统 ,分为心血管系统和淋巴系统。心血管系统包括心脏、动脉、毛细血管、静脉和血液 ;淋巴系统包括毛细淋巴管、淋巴管、淋巴导管、淋巴结和淋巴液 (本文略 )。循环系统是体内物质运输和维持体内环境即细胞外液稳定的重要系统。循环系统还是重要的免疫系统 ,并参与体温的调节。1　心脏和血液循环脊椎动物的血液在管道内按一定方向不断地流动 ,即在身体背部从前向后 ,而在腹部是从后向前。但在最低等的脊索动物即尾索动物(urochordates)海鞘中的血液循环属于开管式 ,而且血液不沿固定的方向流动 ,定期改…     

Mechanical circulatory support

Currently, almost five million Americans and 23 million people worldwide are living with congestive heart failure (CHF), with 2 million new cases diagnosed each year. The etiology is mostly ischemic, idiopathic, or viral, and more than $36 billion is spent each year on the care of congestive heart failure patients. Treatment of advanced CHF takes three forms: medical therapy, surgical therapy and cardiac replacement. Medical therapy, including inotropes and vasodilators, relieves symptoms by reducing cardiac work and increasing myocardial contractility. This has helped improve quality of life, but mortality remains unaffected. Surgical therapy, including revascularization, ventricular restoration and valve replacement/repair, relieves symptoms and improves function, but in most cases does not stop the underlying disease process from progressing. When conventional medical or surgical therapies are exhausted, cardiac assist or replacement, including ventricular assist device (VAD), heart transplant or a total artificial heart (TAH) may become the only therapeutic options. This article will not discuss the use of extracorporeal membrane oxygenation for cardiac support that is described in an additional article in this issue of Organogenesis.     

Sinusoids--elements of the circulatory bed of the human heart

The literature concerning the problems of myocyrdial sinusoids has been analysed and morphological investigation of 98 human hearts has been performed. As demonstrates the comparison of the literature data, the term "sinusoid" in the human heart is applied to different structures. In some cases--to designate dilated areas of the venous part of the blood bed in the ventricular walls, in others--"hollow spaces", "intercellular spaces" and Vieussens--Thebesius vessels. Combining methods of intravascular injections and studying serial histological sections, it has been found that the sinusoids--the "hollow spaces", the "intercellular spaces", the "Veussens--Thebesius vessels" present the areas of intertrabcular spaces, which get into the planes of some sections, not being components of the myocardial blood bed. Spatial angioarchitectonics of the sinusoids--dilated areas in the venous part of the myocardial blood bed have been investigated by means of the plastic reconstruction method. It is suggested to apply the term "sinusoids" only to the given parts of the cardiac blood bed.     

The state of the circulatory system in the elderly

Fifty six persons (15 men and 41 women) aged between 90 and 99 years were examined to assess their health determining longevity. Circulatory system was evaluated with the aid of anamnesis, physical examination, chest X-ray and ECG. Clinical symptoms of the circulatory disease were diagnosed in 55.4% of tested persons, including: ischaemic heart disease in 42.9%, arterial hypertension in 35.7%, and circulatory failure in 23.2%. Normal ECG records were noted in 10.7% of the tested elderly persons. The most frequent electrographic abnormalities included: decrease in ST, LAH and atrio-ventricular block of the I degree. Incidence of ECG abnormalities did not depend upon the clinical state. An advanced age (over 90 years) is achieved also by the persons with marked circulatory disorders.     

The circulatory bed of the human uterine tube

By means of combined morphological methods blood vessels have been studied in 54 uterine tubes of child-birth women. The main pathways for carrying and distribution of blood to corresponding parts of the tube are sector arteries. They are situated in the subserous tela along the anterior and posterior semicircles of the organ. The microcirculatory bed (MCB) of the uterine tube is presented by serous, subserous, muscular and mucosal plexuses. The MCB of the serous tunic is characterized by vascular compositions--modules. Angioarchitectonics of the mucosal tunic is determined with differences in vascularization of complex and simple folds. Organospecific for small arteries and veins of the tubes is presence of vascular mechanisms, regulating the blood stream (intimal cushions, muscular-elastic constrictors, valves and others). Blood capillaries of the mucosal tunic possess a number of ultrastructural peculiarities: thickened peripheral part of endotheliocyte cytoplasm, that contains fenestrae; wide continuous basal membrane with pericytes in its duplication; three types of pericytic-endothelial contacts etc.     

Short circulatory residence of the hepatic binding protein

We evaluated the distribution and fate of homologous radioactive Hepatic-binding-protein (125I-HBP) in the rabbit after intravenous (iv) injection and the possibility that this protein may induce interferon production. We demonstrated that only 9% of the injected 125I-HBP remained in the circulation 30 min after injection. The 125I-HBP-Asialoorosomucoid complex displayed a longer half-life than the HBP alone, while 125I-Asialoorosomucoid had a very short half-life and only 1% of the dose was found in the circulation after iv administration. Ten min after iv injection of 125I-HBP the major amount of radioactivity was present in the liver and less in the kidneys and lung. HBP, after iv administration, does not stimulate interferon production and this fact is probably due to its rapid catabolism.     

Corticosteroid side-chain isomerase in the circulatory system

Corticosteroid side-chain (CSC) isomerase catalyzes ketol-aldol interconversion of the corticosteroid side chain. The enzyme was present in the blood of mouse, rat, guinea pig, chicken, pig, horse, sheep, cow, and human. The patterns of substrate specificity, measuring 3H-1H exchange of 21-tritiated forms of 11-deoxycorticosterone, corticosterone, and cortisol, were species specific. Based on enzyme activity and immunostaining of mouse blood fractions, red blood cells had the most isomerase activity, plasma had less, and white blood cells had low but highly variable levels of enzyme. Purified mouse liver CSC isomerase was found to be adsorbed by red blood cells. The results suggest that circulating CSC isomerase is derived in part from tissue sources and is in part an intrinsic blood enzyme.