tailieunhanh - Sabatier Agrawal Machado Advances in Fractional Calculus P14

Công nghệ cơ khí hay kỹ thuật cơ khí là ngành ứng dụng các nguyên lý vật lý để tạo ra các loại máy móc và thiết bị hoặc các vật dụng hữu ích. Cơ khí áp dụng các nguyên lý nhiệt động lực học, định luật bảo toàn khối lượng và năng lượng để phân tích các hệ vật lý tĩnh và động, phục vụ cho công tác thiết kế trong các lĩnh vực như ô tô, máy bay và các phương tiện giao thông khác, các hệ thống gia nhiệt và làm lạnh, đồ dùng gia đình, máy. | 23. The Urinary System I Text Saladin Anatomy Physiology The Unity of Form and Function Third Edition The McGraw-Hill Companies 2003 Chapter 23 The Urinary System 903 In principle we could determine renal clearance by sampling blood entering and leaving the kidney and comparing their waste concentrations. In practice it is not practical to draw blood samples from the renal vessels but clearance can be assessed indirectly by collecting samples of blood and urine measuring the waste concentration in each and measuring the rate of urine output. Suppose the following values were obtained for urea U urea concentration in urine mg mL V rate of urine output 2 mL min P urea concentration in plasma mg mL Renal clearance C is C UV P mg mL 2 mL min mg mL 60 mL min This means the equivalent of 60 mL of blood plasma is completely cleared of urea per minute. If this person has a normal GFR of 125 mL min then the kidneys have cleared urea from only 60 125 48 of the glomerular filtrate. This is a normal rate of urea clearance however and is sufficient to maintain safe levels of urea in the blood. _Think About It_ What would you expect the value of renal clearance of glucose to be in a healthy individual Why Glomerular Filtration Rate Assessment of kidney disease often calls for a measurement of GFR. We cannot determine GFR from urea excretion for two reasons 1 some of the urea in the urine is secreted by the renal tubule not filtered by the glomerulus and 2 much of the urea filtered by the glomerulus is reabsorbed by the tubule. To measure GFR ideally requires a substance that is not secreted or reabsorbed at all so that all of it in the urine gets there by glomerular filtration. There doesn t appear to be a single urine solute produced by the body that is not secreted or reabsorbed to some degree. However several plants including garlic and artichoke produce a polysaccharide called inulin that is useful for GFR measurement. All inulin .