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前言 Introduction:

肾脏是器官的重要组成部分，构成了尿路系统,尿路系统包括两个肾脏,两个输尿管,膀胱和尿道。肾脏在泌尿系统中发挥着巨大作用。泌尿系统的其他部分主要是通道和存储区域。肾脏是红色的,位于略高于腰部腹膜和腹后壁之间。成人的肾脏的长是10 - 12厘米,宽5 - 7厘米，3厘米厚,质量为135 - 150克。

在正常情况下这两个肾脏可以完成以下功能:

调节血液酸碱度;肾脏排泄氢离子(H +)和碳酸氢保护(HCO3 -);调节血压;肾脏产生凝乳酶;激活凝乳酶-血管紧缩素-醛固酮通路;维持血液渗透性;通过调节水和尿液中的溶质,维持肾脏恒定的血渗透性。

调节血糖,肾脏可以在葡萄糖异生作用中使用氨基酸和谷氨酰胺。所以他们可以释放葡萄糖进入血液，有助于维持正常的血糖水平，促进激素的产生，l(活动形式的维生素D),帮助调节体内平衡，刺激红细胞的生产。排出废物和外来物质,形成尿液，包含在体内没有有用的废弃物质。

Kidney is a part of group of organs that constitute the urinary tract system which consists of two kidneys, two ureters, bladder and urethra. The kidneys do the major function of the urinary system. The other parts of the system are mainly passageways and storage areas. The kidneys are reddish, bean-shaped structure and located just above the waist between the peritoneum and the posterior wall of abdomen. A typical kidney in an adult is 10-12 cm long, 5-7 cm wide and 3 cm thick and has a mass of 135-150 g.

Under normal circumstances the two kidneys are able to do the following functions:

Regulating of blood PH; the kidneys excrete an amount of hydrogen ions (H+) and conserve bicarbonate (HCO3-). Regulating blood pressure; the kidneys produce rennin, which activate the rennin-angiotensin-aldosterone pathways. Maintaining blood osmolarity; by regulating loss of water and loss of solutes in the urine, the kidneys maintain constant blood osmolarity.

Regulating blood glucose; the kidneys can use the amino acids glutamine in gluconegenesis. So they can release glucose into blood to help maintain a normal blood glucose level. Production of hormones; calctirriol (active form of vitamin D) which helps regulate calcium homeostasis and erythropoietinwhich stimulates the production of red blood cells. Excreting waste and foreign substances; by forming urine which contains the waste substances that have no useful functions in the body.

The above mentioned kidney functions based on the functional unit of the kidney called nephron. Each kidney contains about 1 million nephrons. The nephron is a tube closed at one end and open at the other and in between it consists of Bowman's capsule, Glomerulus, Proximal convoluted tubule, Loop of Henle, Distal convoluted tubule and collecting tubule. About 170-200 liters of water are filtered through the kidneys everyday, but about 1-2 liters are excreted from the body as urine.

To produce urine, nephrons and collecting ducts perform three basic processes:

Glomerular filtration: water and most blood solutes in the blood plasma move across the wall of glomerular capillaries into the glomerular capsule and then into the renal tubule.

Tubular reabsorption: as filtered fluid flows along the renal tubule and through the collecting duct, tubule cells reabsorb about 99% of filtered water and many solutes.

Tubular secretion: as the fluid flows along the tubule and through the collecting duct, the tubule and duct cells secrete other materials, such as wastes, drugs and excess ions into the fluid.

Each kidney connects to bladder by ureter, which is tube like structure that provides d本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。