Английский в медицине. Чтение и перевод текста по теме Blood and its elements

Blood is considered a modified type of connective tissue. Mesodermal in origin, it is composed of cells and cell fragments (erythrocytes, leukocytes, platelets), fibrous proteins (fibrinogen – fibrin during clotting), and an extracellular amorphous ground substance of fluid and proteins (plasma). Blood carries oxygen and nutrients to all cells of the body and waste materials away from cells to the kidney and lungs. It also contains cellular elements of the immune system as well as humoral factors. Now we talk about different elements of blood and the processes by which they are formed. 

The formed elements of the blood include erythrocytes, leukocytes and platelets. 

Erythrocytes, or red blood cells, are important in transporting oxygen from the lungs to tissues and in returning carbon dioxide to the lungs. Oxygen and carbon dioxide carried in the RBC combine with hemoglobin to form oxyhemoglobin and carbaminohemoglobin, respectively. 

Mature erythrocytes are denucleated, biconcave disks with a diameter of 7-8 mm. The biconcave shape results in a 20-30% increase in sur face area compared to a sphere. 

Erythrocytes have a very large surface area: volume ratio that allows for efficient gas transfer. Erythrocyte membranes are remarkably pliable, enabling the cells to squeeze through the narrowest capillaries. In sickle cell anemia, this plasticity is lost, and the subsequent clogging of capillaries leads to sickle crisis. The normal concentration of erythrocytes in blood is 3,5-5,5х1012/liter in women and 4,3-5,9х1012/liter in men. Higher counts in men are attributed to the erythrogenic androgens. The packed volume of blood cells per total volume of known as the hematocrit. Normal hematocrit values are 46% for women and 41- 53% for men. 

When aging RBCs develop subtle changes, macrophages in the bone marrow, spleen, and liver engulf and digest them. The iron is carried by transferring in the blood to certain tissues, where it combines with apoferritin to form ferritin. The heme is catabolized into biliver-din, which is converted to bilirubin. The latter is secreted with bile salts. 

Leukocytes, or white blood cells, are primarily with the cellular and humoral defense of the organism foreign materials. Leukocytes are classified as granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lympmonocytes). 

Granulocytes are named according to the staining properties of their specific granules. Neutrophils are 10-16 mm in diameter. They have 3-5 nuclear lobes and contain azurophilic granules (lysosomes), which contain hydrolytic enzymes for bacterial destruction, in their cytoplasm. Specific granules contain bactericidal enzymes (e.g., lysozyme). 

Neutrophils are phagocytes that are drawn (chemo-taxis) to bacterial chemoattractants. They are the primary cells involved in the acute inflammatory response and represent 54- 62% of leukocytes.  Eosinophils: they have a bilobed nucleus and possess acid granulations in their cytoplasm. These granules contain hydrolytic enzymes and peroxidase, which a discharged into phagocytic vacuoles. Eosinophils are more numerous in the blood during infections and allergic diseases; they normally ascent only 3% of leukocytes. 

Basophils: they possess large spheroid granules, which are basophilic and metachromatic, due to heparin, a glycosaminoglycan. Their granules also contain histamine. Basophils degranulate in certain immune reaction, releasing heparin and histamine into their surroundings. They also release additional vasoactive amines 29 and slow reacting substance of anaphylaxis (SRS-A) consisting of leukotrienes LTC4, LTD4, and LTE4. They represent less than 1% – of leukocytes. 

1. How is the blood considered?

Blood is conidered under a microscope.

 2. What is the blood composed of? 

Blood is considered a modified type of connective tissue. Mesodermal in origin, it is composed of cells and cell fragments (erythrocytes, leukocytes, platelets), fibrous proteins (fibrinogen – fibrin during clotting), and an extracellular amorphous ground substance of fluid and proteins (plasma).

3. What does blood carry? 

Blood carries oxygen and nutrients. 

4. Where does the blood carry oxygen and nutrients? 

Blood carries oxygen and nutrients to all cells of the body.

5. What does the blood contain in the immune system? 

Leukocytes, or white blood cells, are primarily with the cellular and humoral defense of the organism foreign materials. Leukocytes are classified as granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lympmonocytes).