Topics: Nephron, Kidney, Glomerulus Pages: 3 (895 words) Published: December 4, 2012
Nephrons (Greek nephros=kidney) are renal or kidney tubules. Each kidney has over one million nephrons that are responsible for removing waste products from blood and maintaining water, salt and pH balance in the body. This vital job results in the formation of urine.

1.Afferent Arteriole
* receives blood rich in oxygen from the renal artery.
* blood is transported to the glomerulus of the nephron where it is pressure filtered.

* The glomerulus is a knotted up capillary that contains small pores. * The plasma of the blood and the small molecules contained in plasma are pressure filtered into the Bowman's capsule. * Large blood proteins and formed elements like blood cells and platlets are too big to be pressure filtered and remain in the arteriole.

3.Efferent Arteriole
* smaller in diameter than the afferent arteriole and increases the pressure in the glomerulus aiding pressure filtration. * The blood entering the efferent arteriole is thicker, as plasma has entered the tubule, but still contains oxygen that is moved on to the peritubular network to provide for the metabolic needs of the tubule.

4.Bowman's Capsule
The plasma and its' dissolved molecules are transported from the Bowman's capsule into the lumen or inside of the nephron.

5.Proximal Convoluted Tubule
At this point in the nephron, the filtrate from the blood contains both waste molecules like urea and useful molecules like amino acids, glucose, and salt. The filtering process in the glomerulus is not selective (except by size) so the proximal convoluted tubule works to actively transport nutrients (glucose, amino acids, and salts) back into the blood capillaries so they are not lost in the urine. The tubule has a brush border with many villi to increase the surface area for this process of selective reabsorption. The cells of the tubule also contain many mitochondria that produce the ATP required for the large amount of...
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