Anglický jazyk
3.3 Medical English -Blood and blood flow
Blood is the red liquid that flows through the vessels. It contains formed elements = blood cells and a fluid portion called plasma. The formed elements are the erythrocytes = red blood cells, leukocytes = white blood cells, and thrombocytes = platelets = clotting cells. All blood cells originate from immature cells called stem cells = haemocytoblasts. These stem cells mature in the red bone marrow tissue of adults and in the liver and spleen of the growing fetus. As the cells mature, they differentiate and specialise. Red blood cells lack a nucleus and carry haemoglobin which is oxygen carrying pigment. When the blood cells wear out, they are destroyed by special liver and spleen cells. Bile pigments including bilirubin are formed as waste products from the breakdown of haemoglobin and are excreted out of the body.
Leukocytes are called white blood cells because they do not carry pigmentation and contain a large nucleus. There are two major types: granulocytes which contain large granules in their cytoplasm, and agranulocytes which do not have any. Granulocytes are then divided into eosinophils, basophils and neutrophils. Neutrophils fight diseases by swallowing up germs. This process is called phagocytosis.
Agranulocytes are monocytes and lymphocytes. Monocytes are also phagocytic. Lymphocytes are made in lymphatic tissues such as lymph nodes, the spleen and the thymus gland, and the bone marrow. They are a source of antibodies which can neutralise and destroy antigens that might enter the body (bacteria, viruses).
Thrombocytes are the smallest cells. Their primary function is haemostasis = blood clotting.
Plasma contains 91% of water and proteins, salts and sugars, hormones, waste and food substances. Four major plasma proteins are albumin, globulin, fibrinogen and prothrombin.
The blood and lymphatic systems have many functions. Blood carries vital materials such as oxygen, nutrients and hormones to tissue cells and transports waste materials such as carbon dioxide and urea away. Lymph transports needed proteins which leaked out of blood capillaries back to the bloodstream through the veins. Molecules can leak because capillary walls are permeable. Blood and lymph protect the human body by carrying disease-fighting cells and antibodies which combat infection.
But sometimes even blood can become ill. In the investigation of blood diseases, the simplest test is a full blood count (FBC). In a sample of blood, it measures the amount of haemoglobin, the number of the three kinds of cells, the volume of the cells, and the erythrocyte sedimentation rate (ESR) which measures how quickly erythrocytes fall down to the bottom of the sample.
One of the commonest blood diseases of blood is anaemia. It may be due to blood loss for example from a chronic bleeding ulcer, excessive destruction of red cells, or low production for example because the diet lacks iron.
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vessel
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céva
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formed element
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pevná částice
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fluid, liquid
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tekutý
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clot
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srážet se
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(im)mature
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(ne)zralý
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stem cell
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kmenová buňka
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bone marrow
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kostní dřeň
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wear out
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opotřebovat
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waste products
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odpadní látky
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breakdown
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rozklad, rozkládat
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excrete
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vylučovat
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germs
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choroboplodné zárodky
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nutrient
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živina
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carbon dioxide
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CO2
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urea
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močovina
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bloodstream
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krevní řečistě
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fight, combat
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bojovat
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blood loss
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ztráta krve
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ulcer
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vřed
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excessive
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nadměrný
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The heart ensures the blood are circulate. Without circulation, blood would not be able to carry oxygen to the tissue cells. The normal resting heart rate is about 65 – 75 beats per minute. In athletes it may be as low as 40 bpm. In extreme athletic activity, the heart rate can go up as high as 200/min.
The heart rhythm can be regular or irregular = arrhythmia. There may be early beats which interrupt the regular rhythm = premature beats, or the rhythm may vary with respiration, or it may be completely irregular as in fibrillation. When patients are aware of the irregularity, they describe it as palpitations.
Heart failure occurs when the heart is unable to maintain sufficient cardiac output = the amount of blood pumped by the heart each minute. It may involve the left side of the heart, the right side, or both. In the left heart failure the main symptom is breathlessness. In the right heart failure it is peripheral oedema = swelling which starts in the feet and ankles. Breathlessness is shortness of breath, or dyspnoea. At first this is caused by exertion = exercise, effort, but in severe cases it may be present even at rest. A patient who is breathless when lying flat in bed (orthopnoea) will tend to sleep on two or more pillows. The abbreviation SOBOE is used (short of breath on exertion/on exercise/on effort).
The commonest heart disorders are a heart attack and ischaemic heart disease (IHD). Ischaemia means lack of blood supply in a particular region. It happens when a vessel is blocked by pieces of fat.
There are two types of circulation in the human body: the systemic circulation and the pulmonary circulation. There are similarities and differences between then. The systemic circulation begins at the aorta, leads oxygenated blood into the body tissues and comes back into the right atrium through the superior and inferior vena cava. The blood then continues to the right ventricle through the tricuspid valve. Then it heads for the main pulmonary artery through the pulmonary valve. This is where the pulmonary circulation starts. The artery receives the mixed venous blood and branches along the system of airways. The pulmonary capillaries form a dense network in the alveolar wall which makes a very efficient arrangement for gas exchange. The oxygenated blood is then collected by the small pulmonary veins that in the end unite to form four large veins which drain in the left atrium. Through the mitral valve the blood continues into the left ventricle and to the aorta through the aortic valve.
At first sight, the pulmonary circulation appears to be simply a smaller version of the systemic circulation. But there are some differences. The pressures in the pulmonary circulation are very low. The mean pressure in the main pulmonary artery is only about 15 mm Hg, and the systolic and diastolic pressures are about 25 and 8 mm Hg respectively. By contrast, the mean pressure in the aorta is about 100 mm Hg while the pressures in the atria are about 2–5 mm Hg. The pulmonary arteries are thus very thin and contain quite little smooth muscle. On the other hand, the systemic arteries and the left heart have thick walls and a lot of smooth muscle. That is because the systemic circulation needs to supply blood to various organs which may be far above the level of the heart. The thickness of the left ventricle wall can be up to 1,5 cm!
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ensure
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zajišťovat
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rate
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míra
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beats per minute (bpm)
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údery za minutu
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vary
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měnit se, kolísat
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respiration
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dýchání
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be aware of
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uvědomovat si
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cardiac output
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srdeční výdej
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swelling
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otok
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exertion, effort
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námaha
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heart attack
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infarkt myokardu
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tend to
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mít tendenci
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systemic
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tělní
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pulmonary
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plicní
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atrium
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síň
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vena cava
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dutá žíla
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ventricle
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komora
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tricuspid valve
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trikuspidální chlopeň
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mixed venous blood
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smíšená venózní krev
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semilunar valve
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poloměsíčitá chlopeň
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branch
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větvit se
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arrangement
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uspořádání
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gas exchange
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výměna plynů
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oxygenated
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okysličená
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mean pressure
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střední tlak
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smooth muscle
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hladká svalovina
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supply
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dodávat
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