The Human Heart Essays - Blood Pressure, Cardiovascular Physiology

The Human Heart Essays - Blood Pressure, Cardiovascular Physiology The Human Heart Biology - Histology The Human Heart. Abstract: Dorland's Illustrated Medical Dictionary defines the heart as "the viscus of cardiac muscle that maintains the circulation of the blood". It is divided into four cavities; two atria and two ventricles. The left atrium receives oxygenated blood from the lungs. From there the blood passes to the left ventricle, which forces it via the aorta, through the arteries to supply the tissues of the body. The right atrium receives the blood after it has passed through the tissues and has given up much of its oxygen. The blood then passes through the right ventricle into the lungs where it gets oxygenated. There are four major valves in the heart; the left atrioventricular valve (also known as the mitral or bicuspid valve), the right atrioventricular valve (tricuspid), aortic valve, and the pulmonary valve. The heart tissue itself is nourished by the blood in the coronary arteries.2 Position of the Heart Within the Body: The heart is placed obliquely in the chest. The two atria are directed upwards and backwards to the right and are at the level of the fifth through the eight dorsal vertebrae. The apex of the heart points downwards and forwards to the left and corresponds to the interspace between the fifth and sixth ribs, two inches below the left nipple. Its atrial border corresponds to a line drawn across the sternum on a level with the upper border of the third costal cartilage. Its lower border (apex) corresponds to a line drawn across the lower end of the same bone, near the xiphoid process. Its upper surface is rounded and convex, directed upwards and forwards, and formed mainly by the right ventricle and part of the left ventricle. The posterior surface of the heart is flattened and rests upon the diaphragm muscle. Of its two borders, the right is the longest and thinnest, the left is shorter but thicker and round. Size: In an adult, the heart measures about five inches in length, three and a half inches in the broadest part of its transverse diameter, and two and a half inches in its antero-posterior. The average weight in the male varies from ten to twelve ounces. In the female, the average weight is eight to ten ounces. The heart will continue to grow in size up to an advanced period of life. This growth is more obvious in men than in women.3 Circulation of Blood in an Adult: The heart is subdivided by a longitudinal muscular septum into two lateral halves which are named right and left according to their position. A transverse muscle divides each half into two cavities. The upper cavity on each side is called the atria/auricle, and the lower side is called the ventricle. The right atrium and ventricle form the venous side of the heart. Dark venous blood is pumped into the right atrium from the entire body by the superior (SVC) and inferior vena cava (SVC), and the coronary sinus. From the right atrium, the blood passes into the right ventricle and from the right ventricle, through the pulmonary artery into the lungs.3 Once the blood becomes oxygenated/arterialized by its passage through the lungs, it is returned to the left side of the heart by the pulmonary veins which open into the left atrium. From the left atrium, the blood passes into the left ventricle where it is distributed by the aorta and its subdivisions through the entire body. Morphology of Each Heart Chamber: The right atrium is a little longer than the left. Its walls are also somewhat thinner than the left. The right atrium is capable of containing about two ounces of fluid. It consists of two parts, a principle cavity/sinus, and an appendix auriculae. The sinus is a large quadrilateral-shaped cavity located between the IVC and the SVC. Its walls are extremely thin and are connected on the lower surface with the right ventricle and internally with the left atrium. The rest of the right atrium is free and unattached. The appendix auricle is a small conical muscular pouch. It projects from the sinus forwards and to the left side, where it overlaps the root of the pulmonary artery.6 There are four main openings into

statue of King Chephren essays

statue of King Chephren essays The extraordinary statue of King Chephren is a masterpiece of sculpture in the round. This work is 168cm tall, 96cm long and 57cm wide, which was the approximate size of the king. The artist who created this sculpture is unknown, as it was found when Mariette's workmen were exploring the favissa of Chephren's valley temple in 1860. The statue was built during the reign of King Chephren, which historians estimate lasted from 2540-2505 BC. The statue is a cut block of Diorite, a granular crystalline igneous rock. This work can be found in the Egyptian Museum in Cairo (Ground Floor, room 42), or if you are unable to visit Cairo, images of the work can be found in the Official Catalogue of The Egyptian Museum of Cairo (pages 64,65) Chephren was the son of Cheops. The enthroned king rests one hand flat on his knee while he holds a folded piece of material in the other. He wears a nemes headdress with pleaded lappets. Attached to his chin is the sign of his dignity, the ceremonial beard. He is also dressed in a shendjyt, a type of short pleated kilt. Two lions support the king's seat, one on each side. The two lions are to provide the king with both power and protection. On each side of the throne the motif of the unity of the two lands, or sema-tawy, is etched in high relief. The sema-tawy, is composed of the heraldic plants of the Two Lands. Lilies, for the south, and papyrus, for the north, are knotted around the hieroglyphic sign for 'union'. The statue of King Chephren contains implied detail, meaning that very few lines in the right positions can make up for a completely textured work. This feature causes your eye to start at the king's face and move around the statue, without being confused by excessive detail. The throne is elevated about a foot above ground level, so the king would appear more powerful to worshippers bowing before the statue. The work is covered with symbolism, including the protection of ...

Paper summary Essay Example | Topics and Well Written Essays - 1000 words

Paper summary - Essay Example The essay hereby aims to explain the points of discussions as structured in the main sections of the article. Further, through the provision of examples and by critically analyzing the contents, the discourse would determine if the authors achieved their objectives through the structure, presentation and discussion of identified concerns. Achieving Learning Effectiveness The authors averred that the way to gauge or measure business gaming simulations (BGS) is through learning effectiveness or educational validity. Two crucial considerations influence learning effectiveness, to wit: effective design and the manner of implementation. The manner of presentation of crucial concerns is perceived to be confusing with intermittent references to various researches conducted on the subject. Sub-topics could have clarified points of discussions. For instance, there could be a sub-heading on problems affecting the design, where algorithmic validity and realism level takes precedence. Under real ism, there are again factors that contribute to difficulties in designing appropriate BGS: the knowledge of the designer and perceived biases. Then, another sub-heading that could give readers a more accurate presentation and understanding of the topic is role of the participator. However, during its discussion, another new topic was discussed: the three types of participant dynamics which should have been discussed separately and in greater detail. The discussion of effective implementation explained the role of experiential learning to achieve effectiveness. By providing a clear definition of the term and the means to actively engage in it, the authors clearly proffered information on the subject. Two relevant factors: the support from a coach and a perceived level of personal motivation were discussed with support from previous researches. Establishing a Research Methodology Framework for Educational Validity Assessment The structure for the discussion of the methodology framewor k was clear, concise and appropriately explained. The section on definition of objectives and the presentation of theoretical propositions identified three propositions referring the previous works conducted on internal educational validity, external representational validity, and external educational validity. Under research design, the authors recommended the multi-case study as the design and explained the rationale by quoting Yin, to wit: â€Å"â€Å"the case study method allows investigators to retain the holistic and meaningful characteristics of real-life events—such as . . .managerial processes† (Yin, 2003, p. 2). This particular research design was chosen in its ability to address the issues that are questioned in terms of ‘why’ and ‘how’. A long discussion on achieving validity in research design ensued qualifying validity in terms of construct, internal and external validity, and their reliability. A tabular illustration effectivel y summarized crucial highlights to enhance the readers’ understanding and preview comparative elements at a glance. Designing and Building an Effective Simulation Model: Objectives and Process Stainton, et.al. (2010)