Тексты для мединститута 4 (перевод)
Содержимое: 50131002749557.rar (15,05 Кбайт)
качественный перевод текстов преподавателем английского языка, также продаётся по частям
According to their functions different organs of the human body are divided into several systems: the bones, the muscular system, the alimentary tract, the respiratory system, the urogenital1 system, the vascular system, and the nervous system.
The muscles and the bones are under the layer of subcutaneous2 fat. The muscles are connected with the bones.
The heart and the large blood vessels connected with it, as well as the lungs and the esophagus are in the thoracic cavity. The spleen, the liver and the stomach are in the abdominal cavity under the diaphragm. The small and large intestines are in the abdominal cavity lower than the stomach, the liver and the spleen. The kidneys are on the posterior side of the abdominal cavity.
Text A. Work of the Human Heart
The human heart contracts from the first moment of life until the last one. The contractions of the heart pump the blood through the arteries to all the parts of the body. Scientists have determined that the total weight of the blood pumped by the heart daily is about ten tons.
The rate of heart contractions is regulated by two groups of nerve fibers. It varies in different persons and at different age.
Physiologists have determined that in the adult the heart makes from 60 to 72 beats per minute. In children the rate of heartbeat is much higher. Research work of many scientists has helped to determine that the rate of heartbeat increases depending on different emotions.
Each beat of the heart is followed by a period of rest for the cardiac muscle. Each wave of contraction and a period of rest following it compose a cardiac cycle.
Research work has given physiologists the possibility to find out that the heart muscle works or contracts about one third of the time of the person’s life. The period of rest is shorter during greater physical exertion and longer when the body is at rest.
Each cardiac cycle consists of three phases: physiologists have called the first phase of short contraction of both atria—the atrial systole. They have called the second phase of a more prolonged contraction of both ventricles—the ventricular systole. The period of rest of the cardiac muscle is called the diastole.
The left ventricle discharges out the blood received by the left atrium from the pulmonary circulation through the aorta to the systemic circulation.
The blood received from the systemic circulation by the right atrium is discharged out of the right ventricle to the lungs through the pulmonary arteries.
Prolonged research work of many physiologists has given the possibility to estimate the role of the ventricles which serve as the main pump. The atria act as receiving chambers. The contraction of the atria which sends the final portion of the blood into the ventricle is considerably less.
Text B. The Circulation of the Blood
Now we know that the venous blood from the systemic and portal circulation is brought to the right atrium of the heart. When the pressure in the right atrium has increased the blood passes into the right ventricle from the right atrium.
During the systole of the ventricle the blood is pumped from the right ventricle into the pulmonary artery. When the right ventricle has pumped the venous blood into the pulmonary artery it enters the pulmonary circulation. The blood is brought to the lungs through the pulmonary artery. In the lungs the venous blood discharges out carbon dioxide. When the blood has discharged out carbon dioxide it takes in oxygen in the lungs.
The blood which has become oxygenated passes from the venous part of the pulmonary capillary system into the venules and veins. When the oxygenated blood has passed the four pulmonary veins it is brought to the left atrium of the heart.
Under the pressure in the left atrium the arterial blood which the pulmonary veins have brought to the heart is pumped into the left ventricle. During the prolonged contraction of the left ventricle, the so-called ventricular systole, the arterial blood is pumped into the aorta — the main artery of the vascular system. When the left ventricle has pumped the arterial blood into the aorta it is carried through the arteries to all the parts of the body.
Text C. The Corpuscular Elements of Blood
Blood is a fluid tissue with many various functions. Not only important physiological process takes place in the blood but it determines the activity of widely separated body cells.
Blood is composed of plasma and the corpuscular elements which are called red corpuscles or erythrocytes, white corpuscles or leucocytes and blood platelets or thrombocytes.
It is generally considered that no sex differences exist in the count of white corpuscles or leucocytes. The count of leucocytes in the blood of a healthy person is 4,500 to 9,500 per cu mm (cubic millimetre). When the number of white blood cells (WBC) is counted after mental or physical exertion, meals and mild activity it may increase to 10,000 and more per cu mm.
It is estimated that the erythrocytes are the most numerous cellular elements, ranging from 4,000,000 to 5,000,000 per cu mm. The red blood cell count (RBC) may change with age; when the red blood cell count is done after physical exertion and emotions it may increase.
One knows that red corpuscles have two physical features which are very important in the function of respiration. They have great elasticity and flexibility. These features give them the possibility to pass through very small capillaries. The discoid form of the corpuscle gives it a maximal surface for a given mass.
The most important part of the red cell is its red colouring substance or hemoglobin which on an average forms about 36% of its mass.
The total blood volume is divided into circulating and reservoir volumes.
The average human blood volume is not less than 7.5% but not more than 10% of the body weight. It is generally stated that the circulating volume averages smaller in the females than in the males. The circulating volume of the blood depends on the changes of the air temperature.
Text D. The Heart Sounds
When we listen to the heart we can hear two sounds. The third sound is also heard in some young persons before the age of 30.
The first heart sound is the longest one. It is heard at the moment of contraction of the ventricles when the atrio-ventricular valves close.
The second sound lasts for a shorter period of time. It is heard at the moment when the pulmonary and aortic semi lunar valves close.
The third heart sound is heard when the blood is passing from the atria into the ventricles.
The first and the second cardiac sounds are heard over all the portions of the heart and often over the large vessels. The first heart sound is greater over the surface of the ventricles and it is the greatest over the surface of the mitral and tricuspid valves. The second heart sound is heard loudest over the aorta and the pulmonary artery.
Heart sounds are also heard over some portions of the chest. Normally the first heart sound is heard best over the apex of the heart in the fifth costal interspace. The second sound is heard best over the pulmonary artery and the aorta, that is in the second left and right costal interspaces. The aortic sound is normally louder than the pulmonic sound.
The heart sounds are very important in the clinical diagnosis and the doctors determine many cardiac diseases by heart sounds.
|1 мес||3 мес||12 мес|
В целях исключения необоснованных и заведомо ложных сообщений о фактах нарушения указанных прав, администрация будет отказывать в предоставлении услуг на торговой площадке Plati, только после получения от Вас письменных заявлений о нарушении с приложением копий документов, подтверждающих ваши авторские права или права собственности, по адресу: 123007, г. Москва, Малый Калужский пер. д.4, стр.3, Адвокатский кабинет «АКАР №380».
В целях оперативного реагирования на нарушения Ваших прав и необходимости блокировки действий недобросовестных продавцов, Plati просит Вас направить заверенную телеграмму, которая будет являться основанием для блокировки действий продавца, указанная телеграмма должна содержать указание: вида нарушенных прав, подтверждения ваших прав и ваши контактные данные (организиционно-правовую форму лица, Ф.И.О.). Блокировка будет снята по истечение 15 дней, в случае непредставления Вами в Адвокатский кабинет письменных документов подтверждающих ваши авторские права или права собственности.