Circulatory system 循环系统 The circulatory system is comprised of the heart, the blood vessels, and the blood. It consists of 2 circuits that carry blood around.循环系统由心脏、血管和血液组成。它由负责血液循环的两个回路组成。 The smaller being the pulmonary circuit which runs between the heart and the lungs, and the larger being the systemic circuit which runs between the heart and the peripheral tissues.较小的回路是在心脏和肺之间走行的肺循环，较大的回路是在心脏和周围组织之间走行的体循环。 The cardiac circulatory system functions by providing the tissues of the body with oxygen and nutrients which are transported in the blood.心脏循环系统通过为身体组织提供在血液中运输的氧气和营养物质来发挥作用。 The pulmonary circuit carries the deoxygenated blood into the lungs where the exchange of oxygen and carbon dioxide that the body has produced occurs before the blood returns back to the heart.肺循环将脱氧血液输送到肺，这些脱氧血液在肺内进行气体交换，即吸收氧气，排出身体产生的二氧化碳，然后返回到心脏。 The heart then pumps the newly oxygenated blood around the systemic circuit of the body and delivers the oxygenated blood to the tissues before collecting the deoxygenated blood and sending it back to the heart with unused nutrients and metabolic waste products. These extra substances within the blood filter into the liver for processing.然后，心脏将新含氧血液泵送到身体的体循环，输送到组织，然后收集脱氧血液并将其与未使用的营养物质和代谢废物一起送回心脏。这些血液中多余的物质将被过滤到肝脏进行处理。 The heart is a muscle that acts as a pump. Through electrostimulation, it beats and pushes the blood around the entire body through the circulatory system.心脏是充当泵的肌肉。它通过电刺激跳动，推动血液经由循环系统输送到全身。 The heart is comprised of 4 chambers that consist of 2 pairs on the left and right sides of the heart.心脏由4个腔室组成，心脏左右两侧各有 2 个腔室。 The atria collect blood returning to the heart while the ventricles pump blood out of the heart. The valves in the heart prevent the backflow of blood into the chambers of the heart. The muscular septum divides up the 2 sections of the heart creating a left and right side each containing one atrium and one ventricle.心房收集返回心脏的血液，而心室将血液泵出心脏。心脏中的瓣膜防止血液回流到心腔内。肌肉间隔将心脏的 2 个部分分开，形成左右两侧，每一侧都包含 1 个心房和 1 个心室。 The right side of the heart pumps deoxygenated blood and the left side pumps oxygenated blood. The amount of blood in liters that is pumped out of the heart per minute is known as the cardiac output, which is around 5.6 liters in males and 4.9 liters in females.心脏的右侧泵送脱氧血液，左侧泵送含氧血液。心脏每分钟泵出的血液量（单位：升）称为心输出量，男性的心输出量约为 5.6 升，女性约为 4.9 升。 It can be calculated by multiplying the heart rate which is the number of beats per minute by the stroke volume which is the amount of blood that collects in the ventricles when they are at full capacity and about to contract. The cardiac output varies depending on whether the person is exercising or resting.心输出量=心率（每分钟心脏跳动的次数）× 每搏输出量（心室达到最大容量，且即将收缩时，心室内聚集的血液量）。心输出量根据患者运动或休息而变化。 There are 3 major classes of blood vessels namely arteries, veins, and capillaries and they are categorized according to their histological structure.血管分为动脉、静脉和毛细血管三大类，它们根据其组织结构进行分类。 Arteries transport blood between the tissues and away from the heart and have thick muscular walls with small internal lumina or passageways that can withstand blood under high pressure.动脉在组织之间输送血液，并远离心脏，动脉壁厚，内部管腔或通道小，能够承受高压下的血液。 Veins carry blood away from the tissues and towards the heart and have thin walls. Their internal lumen is larger than that of the arteries due to the fact that they contain blood under low pressure. They also have valves that prevent the blood from flowing backwards.静脉将血液从组织输送到心脏，血管壁很薄。它们的内腔比动脉的内腔大，因为它们在低压下含有血液。它们也有防止血液回流的瓣膜。 Lastly, the capillaries, which are found in the muscles and the lungs, are microscopic and have a one-cell layer thick endothelial lining. In other words, the walls of the capillaries have the width of one single epithelial cell.最后，毛细血管见于肌肉和肺，很微小，毛细血管壁只有一层上皮细胞。换言之，毛细血管壁具有单个上皮细胞的宽度。 They can only tolerate blood under very low pressure due to the fact that it will move slower and gas exchange has a chance to take place. This is also where the exchange of gases, water, nutrients, and waste products takes place because the capillary walls are thin and fenestrated.它们只能承受非常低压力的血液，因为血液移动较慢，气体交换才有可能发生。毛细血管也是气体、水、营养物和废物交换的位置，因为毛细血管壁薄且有孔。 After this, the capillaries collect into venules which are the equivalent to arterioles and fenestrated. Capillaries connect arterioles and venules.然后，毛细血管聚集成小静脉，小静脉相当于小动脉，有孔。毛细血管连接小动脉和小静脉。 The blood is made up of 4 major components.血液由4种主要成分组成。 The plasma is the fluid that surrounds the blood cells and helps transport carbon dioxide, hormones, and the metabolic waste products.血浆是围绕血细胞的液体，有助于运输二氧化碳、激素和代谢废物。 Red blood cells which are also known as erythrocytes are formed in the bone marrow and function mainly as oxygen carriers.红细胞（erythrocytes）在骨髓中形成，主要作为氧载体发挥作用。 White blood cells or leukocytes make up the body’s immune system by producing antibodies and helping destroy harmful microorganisms. These cells are also created in the bone marrow.白细胞（leukocytes）是人体免疫系统的组成部分，可以产生抗体和帮助消灭有害微生物。这些细胞也在骨髓中产生。 Lastly, platelets are cells that clump together to form blood clots and help protect the body by preventing bleeding.最后，血小板是聚集在一起形成血块，并通过防止出血来帮助保护身体的细胞。 （图源：太帅图库） 相关单词学习
Erythrocyte
①发音和释义 e•ryth•ro•cyte/ɪˈrɪθrəsaɪt/红细胞A blood cell of vertebrates that transports oxygen and carbon dioxide, combined with the red pigment haemoglobin, to and from the tissues. 单词 erythrocyte由下列成分构成 erythro-（前缀）红细胞+-cyte（后缀）细胞（图源：太帅图库）
