杏林荟萃之医学英语12—血液系统

1. word elements

2. reading

    Anemia is defined as a decrease in the amount of hemoglobin in the blood. Anemia may result from too few red blood cells, cells that are too small, or too little hemoglobin in the cells. Cells may be normal in size (normocytic) or abnormal (microcytic or macrocytic), and they may be normal in hemoglobin (normochromic)or have too little (hypochromic). Key tests in diagnosing anemia are blood counts, mean corpuscular volume (MCV), and mean corpuscular hemoglobin concentration (MCHC) . The general symptoms of anemia include fatigue, shortness of breath, heart palpitations, pallor, and irritability. There are many different types of anemia, some of which are caused by underproduction of red cells, others by loss or destruction of cells.

    Aplastic anemia results from destruction of the bone marrow and affects all blood cells (pancytopenia). It may be caused by drugs, toxins, viruses, radiation, or bone marrow cancer. Aplastic anemia has a high mortality rate but has been treated successfully with bone marrow transplantation.

Nutritional anemia may result from a deficiency of vitamin B12, folic acid (a B vitamin), or most commonly, iron. A specific form of B12 deficiency is pernicious anemia. This results from the lack of a substance produced in the stomach, intrinsic factor (IF), which aids in the absorption of this vitamin from the intestine. Pernicious anemia must be treated with regular injections of B12. Folic acid deficiency commonly appears in those with poor diet, in pregnant and lactating women, and in those who abuse alcohol. Iron-deficiency anemia result from poor diet, poor absorption of iron, and blood loss. Both folic acid deficiency and iron deficiency respond to dietary supplementation.

In sideroblastic anemia, there is adequate iron available, but the iron is not used properly to manufacture hemoglobin. This disorder may be hereditary or acquired, as by exposure to toxins or drugs, or as secondary to another disease. The excess iron precipitates out in immature red cells (normoblasts).

    Hemorrhagic anemia results from blood loss. This may be a sudden loss, as from injury, or loss from chronic internal bleeding, as from the digestive tract in cases of ulcers or cancer.

Reticulocyte counts are useful in diagnosing the causes of anemia. Reticulocytes are immature red blood cells that normally appear in a small percentage in the blood. An increase in the number of reticulocytes indicates increased red blood cell formation, as in response to hemorrhage or destruction of red cells. A decrease indicates a failure in red blood cell production, as caused by nutritional deficiency or aplastic anemia.

3. words

anemia 贫血

hemoglobin 血红蛋白

aplastic anemia 再生障碍性贫血

folic acid 叶酸

pernicious anemia 恶性贫血

intrinsic factor 内因子

intestine 肠

abuse alcohol 酗酒

sideroblastic anemia 铁粒幼红细胞性贫血

precipitate 沉积

reticulocyte 网织红细胞