肾脏主要由肾单位组成，每个肾脏有100万个左右的肾单位。肾单位包括肾小

肾脏主要由肾单位组成，每个肾脏有100万个左右的肾单位。肾单位包括肾小体及其相应的肾小管，肾小体位于肾皮质，肾小管位于肾髓质。莒县人民医院肾内科崔兆山
肾小体由肾小球及肾小囊组成，肾小球是由人球小动脉分出的5～8个分支组成的一团毛细血管网。在这些毛细血管之间有少量的系膜组织充填着，系膜组织由系膜基质和少量系膜细胞组成。肾小球毛细血管壁分3层：内层是内皮细胞、中层为基膜、外层是上皮细胞，这3层合在一起称为“肾小球滤过膜”，它完成肾脏的重要生理功能。在肾小球的人球小动脉和出球小动脉之间有一重要的特殊结构统称为“肾小球旁器”，后者主要由球旁细胞和致密斑组成。球旁细胞的胞浆内含有分泌颗粒，免疫荧光证明这些颗粒中含有肾素，人体90％以上的肾素是由球旁细胞分泌的。当肾缺血、肾小动脉内压下降时就能刺激肾素分泌，故球旁细胞又称 “压力感受细胞”。致密斑是由远端小管上皮细胞演变而来，胞浆内含小颗粒，可感受远曲小管内液的容量和钠离子浓度的变化，故又称“钠敏细胞”，它可调节球旁细胞分泌肾素。
肾小管可分为近端小管(包括近曲小管和髓袢降支粗段)、髓袢细段、远端小管(包括髓袢升支粗段和远曲小管)三部分。近端小管能重吸收肾小球滤过液(原尿)中几乎全部葡萄糖、氨基酸和蛋白质，以及65％的Na+、85％的水和50％的尿素等，还能向管腔分泌H’、氨、肌酐、马尿酸等，是重吸收原尿中大量有用物质和分泌排出某些废物的重要部分。髓袢升支粗段是尿稀释的关键部 位，该段上皮细胞对NaCl主动重吸收而不伴有水的重吸收，从而使该段小管液成为低渗液，使尿稀释成为可能。远曲小管的功能是继续重吸收水和Na。}，并向管腔分泌K+、H+和氨，对维持血液的酸碱平衡起重要作用。醛固酮能促进该段上皮细胞重吸收 Na’，排出K+；抗利尿激素能提高其对水的重吸收，使尿液浓缩、尿量减少。
肾脏的主要生理功能是生成尿液，并借此排泄人体代谢终产物及某些废物、毒物，同时经重吸收保留有用物质，调节水、电解质和酸碱平衡。另外，肾脏尚可分泌一些重要的内分泌激素(如肾素、促红细胞生成素、前列腺素等)，同时也是胰岛素、胃泌素、甲状旁腺素等激素的灭活场所

結果 (中文) 3:

Kidney is mainly composed of kidney units, each of which has 1000000 or so of the kidney. The renal unit includes renal body and its corresponding renal tubules, renal body in the renal cortex, renal tubules in the renal medulla. Ju county people's Hospital Department of Nephrology; Cui Zhaoshan
renal corpuscle by glomerular and renal capsule glomerulus is by the ball separation of arterioles of 5 ~ 8 branch composed of a group of capillary network. A small amount of the capillary was filled with a small amount of the system, and the system was composed of the mesangial matrix and a small number of mesangial cells. The glomerular capillary wall is divided into 3 layers: the inner layer is endothelial cells, basement membrane, the middle layer is epithelial cells,These 3 layers are called "glomerular filtration membrane", which is the important physiological function of kidney. The special structure of the small artery and the small artery of the small artery in the glomerular is a special structure, which is composed of the cells and the dense patches. In the cytoplasm of the cells of the cell, the secretory granules are contained in the cytoplasm. The immune fluorescence shows that these particles contain renin, and more than 90% of the human body is secreted by the cells. When the renal ischemia, renal artery pressure drop can stimulate renin secretion, so the ball next to the cell and said the pressure of the cells". The dense patches are evolved from the distal tubular epithelial cells,The contents of the cell are small particles, which can change the capacity and the concentration of sodium ions in the distal tubule. Therefore, it is called "sodium sensitive cell", which can regulate the secretion of renin in the cell.
kidney tubules can be divided into proximal tubule (including nearly tubule and Henle's loop down a rough section), thin segment of medullary loop, distal tubules (including loops of Henle thick ascending limb and the distal convoluted tubules). Proximal tubular reabsorption of fluid of kidney spherule filtration (urine) in almost all glucose, amino acid and protein, and 65% of the Na, 85% of the water and 50% urea, but also to the luminal secretion H ', ammonia, creatinine, hippuric acid.Is an important part of the heavy absorption of a large number of useful substances in the urine and secretion of certain waste. Mtal is diluted urine is the key, the epithelial cells to NaCl active reabsorption and not associated with water absorption, so that the section of the tubular fluid become hypotonic fluid, urine dilution become possible. The function of the distal tubule is to continue to absorb water and Na. }, and to secrete K, H and ammonia, to maintain the blood acid-base balance. Aldosterone can promote the epithelial cells of the segment to absorb Na, K, anti diuretic hormone can improve its water absorption, so that urine concentration, urine volume decreased.
The main physiological function of the kidney is to generate urine, and to drain the body's metabolic end products and some waste, poison, and at the same time by re absorption of the retention of useful substances, regulating water, electrolyte and acid-base balance. In addition, fair in the kidney secretion some important endocrine hormones (such as renin, erythropoietin (EPO), prostacyclin), and insulin, gastrin, parathyroid hormone and other hormone destroy living place