ABSTRACT
Study objectives List the vascular components of the nephron and describe their function List the tubular components of the nephron and describe their function Distinguish between a cortical nephron and a juxtamedullary nephron Dene the three basic renal processes Describe the components of the ltration barrier Explain how the ltration coefcient and the net ltration pressure determine glomerular ltration Describe the mechanisms by which sodium, chloride, and water are reabsorbed Describe how each segment of the tubule handles sodium, chloride, and water Distinguish between the vertical osmotic gradient and the horizontal osmotic gradient Describe the functions of the vasa recta Describe the process by which potassium ions are secreted and the mechanism that regulates this process Dene plasma clearance Explain how the plasma clearance of inulin is used to determine glomerular ltration rate Explain how the plasma clearance of para-aminohippuric acid is used to determine the effective renal plasma ow Explain how the myogenic mechanism and tubuloglomerular feedback are responsible for the autoregulation of renal blood ow Explain how sympathetic nerves, angiotensin II, and prostaglandins affect the resistance of the afferent arteriole Describe the factors that regulate the release of renin Explain how the control of sodium excretion regulates plasma volume Describe the mechanisms by which sodium excretion is controlled Explain how the control of water excretion regulates plasma osmolarity Describe the mechanisms by which water balance is maintained
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2. Introduction The kidneys are organs specialized to lter the blood. As such, they contribute importantly to the removal of metabolic waste products as well as to the maintenance of uid and electrolyte balance. Specic functions of the kidneys include the following:
Regulation of extracellular uid volume. Regulation of inorganic electrolyte concentration in the extracellular uid. Regulation of the osmolarity of the extracellular uid. Removal of metabolic waste products. Excretion of foreign compounds. Maintenance of acid-base balance. Hormone and enzyme production.
