SUMMARY
The work is related to the subject of learning Hemodynamics in the Morphophysiology V subject that is taught in the second year of the Medicine career. Reference is made to aspects related to the problem and to some authors who have investigated the problem. Concepts are assumed or criticized and based on them, an analysis of the learning of Hemodynamics is developed from the perspective of the base of Fluid Theory. A referential framework is constructed that analyzes aspects related to the teaching-learning process of Morphophysiology V and also supports the interdisciplinary link between the Theory of Fluids, as part of Physics, and Hemodynamics.The author found that there is little presence of research work related to the learning of Hemodynamics contents and its relationship with those of Fluid Theory.
Summary
The investigation is related whit the theme of the apprenticeship of Hemodynamic contents in the subject of Morphophysiology V which is part of the study plan in the Medicine Career. In this work it appears the antecedents of the problem and the opinion of some authors that have studied this theme. It is analyzed the apprenticeship of the Hemodynamic from the absence of Theory of the Fluids which is related.All this with the present methodology and the didactic principles included.
Keywords
- Hemodynamics Fluid Theory Interdisciplinarity
Introduction
In the Medicine career, Morphophysiology is included in the study programs as a guiding discipline. It studies the form, structure and function of the human organism, as well as the laws and principles that govern its organization, development and relations with the external environment. It integrates the subjects Embryology, Anatomy, Histology, Physiology and Biochemistry. Known as Basic Medical Sciences, they constitute the biological foundation of the Health Sciences since "… with the knowledge of the normal structure and function, one has the ability to understand the disease and design a rational treatment." (McPhee and Ganong, 2007: 1)
Hemodynamics, within the subject Morphophysiology V, is in charge of the study of the circulatory system. Possessing solid knowledge and understanding of the biological and physical foundations, allow developing capacities and abilities to act in the fields of prevention, promotion and recovery of health; as well as supports the diagnosis and treatment of pathologies that affect man and his environment.
“Physics is essential to understand the mechanism of many biological processes, such as the flow of blood. Perhaps the mystery of life itself can one day be understood in terms of the fundamental laws of Physics. " (Cromer, 2011: 3). Many models of this science can be applied to living things. Such is the case of Fluid Theory as it is used to describe the blood circulation process and the description of the parameters of Hemodynamics.
In the teaching of Morphophysiology V there are factors that negatively influence the assimilation of the contents and the fulfillment of the objectives. The little base of the concepts and laws of Natural Sciences that students have constitutes one of these factors (Cañizares, 2006).
The previous analysis led the author to formulate the following problem: What interdisciplinary relationship exists between the contents of Hemodynamics, in the subject Morphophysiology V, and those of Fluid Mechanics as part of Physics?
The objective of this work is declared: to argue the contribution of the Theory of Fluids for the learning of the contents of Hemodynamics in the subject Morphophysiology V from its interdisciplinary link.
The importance of this work lies in the fact that the Fluid Theory that links basic contents of this part of Physics with those of Hemodynamics within Morphophysiology V, responds to a need for the satisfactory learning of the latter, for students of the medical career. Also having as a scientific novelty the scarce reference to this subject in Medical Sciences.
DEVELOPING.
During the first years of the medical degree, Basic Sciences are received. The origin of these dates back to the emergence of medical knowledge, when human beings felt the need to act on diseases. They include those sciences that constitute the biological foundations for the health professions. Its contents are related to the knowledge of the structure and functions of the human organism. Some of them have become firmly established over time, others are more recent (Viciedo, 2010).
From the gnoseological and pedagogical point of view in Basic Sciences, according to the opinion of a group of specialists headed by Dr. Roberto Gallego Fernández (2008), four trends are identified:
-To the growing interdisciplinarity: what constitutes an effective way that contributes to the achievement of the mutual relationship of the system of facts, phenomena, concepts, laws and theories from different sciences. (Gallegos, 2008: 63).
Being Human Morphophysiology an integrative discipline, "… encompasses the study of molecules and subcellular components to the study of the organic system and the interrelation that allows living beings to function as an organism, all the information it collects has a great practical application." (Guyton, 2011: 9). Its purpose is the structural and functional analysis of the human body related to the healthy individual and the main health problems and a humanistic approach in professional training in order to develop the ability to acquire knowledge, habits and skills in the different attention scenarios (Cañizares, 2006).
The Morphophysiology V subject is part of the Morphophysiology discipline. It addresses the morphofunctional characteristics of the different organs and structures as a system and the regulatory mechanisms of their functions. Among its objectives is to explain the morphofunctional characteristics of the cardiovascular system taking into account its origin, development and macroscopic and microscopic particularities of its components. This is achieved by highlighting the functional interrelation between the components, as well as the main mechanisms of regulation of their functions, which It can be potentiated from a problematic teaching and the link of its knowledge with that of other sciences.
In the text: The Scientific Research Process, a call is made to search for an effective method that corresponds to the scientific level of the content. That stimulates creative activity, cognitive interest and achieves the development of faculties in medical students (Losada, 2007). One way to achieve this is to consider the contents of the subject Morphophysiology V with an integrative and linked nature those who serve as a base.
In (Viciedo, 2010), it is considered that currently there is a growing interdisciplinarity that has epistemological and pedagogical sources. It starts from the recognition that certain objects of study cannot be adequately interpreted with the cognitive arsenal of isolated particular sciences.
The hemodynamics as part of the Morphophysiology V and its link with the theory of fluids.
The circulatory system as an anatomical structure constitutes a specialized system, with a complex constitution. The first concepts about its structure and function were referred to by William Harveyen in 1628. Although Aristotle already in the fourth century BC deduced the communication of blood vessels with the heart (Duque, 2011). The dynamics of blood movement is studied by a part of Morphophysiology V called Hemodynamics.
In the program of the subject Morphophysiology V it is stated that the contents of Hemodynamics in the instructional framework, contribute to explain the characteristics of the circulation. The objectives are defined as:
-Interpret the hemodynamic effects on systemic circulation of various factors, characteristic of the blood.
-Predict the expected hemodynamic effects on the systemic circulation in general, of various characteristic factors of the blood and structural vessels, under normal and pathological conditions (Morphophysiology Program V, 2012: 3).
It is important to take into account the functional interrelation between the parameters that characterize blood circulation and the manifestations they produce. All as a consequence of alterations in the normal functioning of the system, emphasizing the morphofunctional characteristics of each of the components. The regulation of arterial pressure, cardiac output and venous return as an adaptive response to internal and external changes, taking into account hemodynamic principles and the general mechanisms of regulation of circulation.
The study of Hemodynamics becomes effective when it is accompanied by the analysis, from the point of view of Physics, of the phenomena associated with blood circulation, from the perspective of interdisciplinarity. This will allow students to have consolidated knowledge and be more efficient in their professional development. In this way, objectives such as the explanation and application of the contents will be fully met. The formative influence in this case will consist in discovering the logical essence that exists behind each phenomenon related to blood circulation from the physical point of view as cause and effect.
For Dr. Fernando Perera Cumerma: "Interdisciplinarity is a didactic strategy that prepares the student to transfer content that allows them to holistically solve the problems they will face in their future professional performance" (Perera, 1999: 14.). This definition fits the case of the teaching-learning process of Hemodynamic contents associated with a complex system such as blood circulation, which, without the establishment of interrelationships between disciplines, would lack a comprehensive study of the phenomenon.
Interdisciplinarity is an important way to create motivations and interests towards learning; It can make the teaching of the contents related to a complex subject such as Hemodynamics pleasant when the foundations of the same contributed by other sciences are recognized. Learning can be activated and the knowledge thus assimilated can be linked to practical professional situations in a more consolidated way.
Dr. I. Barrios examines the role of interdisciplinarity in Medical Sciences, such as:
«… Intervention based on teaching scientific knowledge relevant to the understanding of the health-disease process… based on its link with other sciences, without wasting an excellent opportunity to educate students in a comprehensive view of the human being. » (Barrios, 2002: 33).
Physics studies laws so general that, in one way or another, they are closely related to the other Natural Sciences. It serves as theoretical support for many aspects of Physiology and therefore Medical Sciences, which contributes to a better understanding by students of the contents of Hemodynamics. Such is the case of the Fluid Theory, which includes aspects that can be used to describe the circulation of the blood.
Mastering these contents will allow the student to master models and methods that can be used for a thorough understanding of Hemodynamics. To better understand blood circulation, the relationship between flow and velocity must be understood (which can be studied considering the fluid as Newtonian) and which is given by the pressure difference established between the ends of the blood vessel (Gayton, 2011).
In Hemodynamics, essential phenomena and properties of blood movement through the vascular system are treated that the Fluid Theory can describe from its laws and equations. These notions are treated under the conditions of their relationship with the properties of blood and blood vessels: The Law of Pressure of Liquids and the Laws of Equilibrium of the same, the Equations of Continuity and Bernoulli, the Torricelli Theorem, the Laws of Laminar and Turbulent Flows and that of Communicating Vessels are some of them.
Pascal's Law as a fundamental content of Hydrostatics is essential to understand the transmission of pressure inside the blood vessels and its relationship with other hemodynamic parameters. The Communicating Vessels Law is important as one of the operating principles of the venous system, which guarantees adequate circulation during venous return and helps to explain varicose vein problems and venous insufficiency in the lower limbs.
One of the characteristics of a fluid in motion is that it exerts a force parallel to the surface that limits it, directed in the direction of movement, the viscous force being its reaction, which opposes the movement. To maintain a permanent flow, an external motive force must be applied to balance the viscous force. In the circulatory system, the heart plays this role, which it performs periodically to keep the closed blood system in constant motion.
The rest of the movement is determined by the relationships between the areas of the cross-sections of the ducts and the speed of circulation and its influence on the pressure. The areas in the arteries, arterioles and capillaries are different, this implies pressure differences and a resulting movement according to the gradient of the same.
The behavior between velocity and cross-sectional area is determined by the Continuity Equation, which constitutes a conservation law and predicts that the product of these magnitudes remains constant. The relationship between velocity and pressure will be established by the equation Bernoulli, which is the law of conservation of energy for a fluid.With a constant heart rate, the flow that occurs through displacement in an artery will be subjected as it passes through a thinner vessel, and therefore greater will be its speed.
Venous return seems to contradict this analysis, if one takes into account the pressure drop that occurs in these ducts and the opposite action of the force of gravity to the movement of the blood. The presence of valves accompanied by muscular contractions drives the blood in this part of the system, allowing it to return to the heart.
Torricelli's Theorem is a consequence of Bernoulli's equation, and its importance in explaining the speed of fluid outflow through an orifice, constitutes a basis for elucidating how the outflow of blood through the heart valves occurs (phenomenon of diastole in the heart).
Poiseulli's law establishes the relationship between flow with another series of parameters: pressure variation, vessel configuration and viscosity. Explain the pressure drop that occurs as we approach the capillaries where the reduction in radius is evident. In the case of stenosis, this law predicts that a sudden increase in localized pressure will occur in the area, due to the decrease in radius and can be linked to the variation of red blood cells and the appearance of diseases such as anemia and polysitemia.
The laminar regimes appear when, by the action of the viscosity force, the fluid layers slide over the adjacent layers, producing a displacement of homogeneous lines with almost constant speed. According to this regime, the fluid layers closest to the walls make it slower than the inner layers. Property by which they can by diffusion and osmosis through the action of the pressures to pass the alimentary substances and the dioxygen from the arterial lumen to the extracellular space.
Alterations in the circulatory system due to pressure differences is another aspect that the Continuity Equation helps to understand: phenomena such as ischemia as a regulator of blood pressure and its metabolic effects on neuronal cells when the accumulation of atheroma is too intense., its relationship with pressure and arteriosclerosis, the production of edema as a result of the elevation of capillary pressure and oncotic pressure, etc.
Turbulent flow considers the particles of the fluid moving in all directions without maintaining a fixed direction, but irregularly, colliding with each other in a chaotic manner, resulting in rapid and irregular velocity pulsations at any point. This is what happens in the valve mechanism that facilitates the ascent of the blood through the veins when passing from one to another in the opposite direction to gravity and where the motor energy that drives the blood from the heart has disappeared.
CONCLUSIONS.
The bibliography consulted and the critical assessment carried out for this work on the teaching-learning process of Hemodynamics and its link with the Theory of Fluids allowed to verify that there are theoretical and methodological foundations that allow to support the importance of treating these contents from the optics of interdisciplinarity as an effective way to deepen the knowledge and implementation of the biological and physical foundations that constitute the basis of the blood circulation system.
BIBLIOGRAPHY
- Barrios, I. Rivera, N. (2002) The logical-intellectual and ethical-reflective vision of skills in higher medical education: Selected readings. Study material for the Master of Medical Education. La Habana. Cañizares, O. Sarasa, N. Labrada, C. (2006) Integrated teaching of Basic Biomedical Sciences in Comprehensive Community Medicine. Rev Cubana EducMedSuper. Jan-Apr. 2006, vol. 20, no. 1.Cromer, A. (2011) Physics for life sciences. Barcelona, Ediciones Toray.Duque, JR (2011) Hemodynamic modeling and simulation in vascular networks. Title to opt for the academic master's degree. Faculty of Mathematical Sciences, Madrid.Gallegos, R. Palés, J. Escanero, E. (2008)Educational innovation in the university: the teaching of Physiology in the degree of medicine. Valencia: Publications of the University of Valencia. Guyton, A. (2011) Manual of Medical Physiology. Madrid, Ed. Interamericana de España, SAV.Hernández, D. (2013) Physical processes that guarantee hemodynamics in man. Available at http: //www.sld.cuLosada, JL (2007) The scientific research process. U. East. CEES. Electronic support. Mc Phee, S and Ganong, M. (2007) Medical pathophysiology: an introduction to clinical medicine. Bogotá, Editorial El Manual Moderno.Perera, F. (1999)The interdisciplinary training of science teachers: an example in the teaching-learning process of Physics. Thesis as an option to the scientific degree of Doctor of Pedagogical Sciences. Morphophysiology V program. (2012) University of Medical Sciences of Havana.Viciedo, A. (2010) Integrative methodological theoretical conception for the psychopedagogical diagnosis of medical students. Thesis as an option to the scientific degree of doctor of pedagogical sciences. ICBP "Victoria de Girón".
