What is the role of the nephron in excretion?

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I'm studying A2 OCR biology and no matter what I look at/do/read/anything, I cannot seem to get my head around what happens in the nephrons

Can anyone help me please!

Posted Fri 4th January, 2013 @ 19:51 by Fay

2 Answers

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I would recommend you watch this video, excellent description.

https://www.khanacademy.org/science/biology/human-biology/v/the-kidney-and-nephron

or

try this website,

http://www.ivy-rose.co.uk/HumanBody/Urinary/Urinary_System_Nephron_Diagram.php

basically, each nephron is in essence a complete, self-contained 'mini-kidney' that filters blood and forms urine. An individual nephron is composed of two parts: a renal corpuscle that filters the blood, and a renal tubule through which the filtrate travels and becomes modified in the formation of urine.

Renal corpuscle

Consists of two parts - as spherical structure at the inflow end of renal tubules called Bownman's Capsule, and a tuft of capilarrier called the glomerulus. The renal corpuscle if the site where blood is filtered and where tubular fluid, or filtrate, has its origin. Before the blood is filtered, it enters the glmerular capillaries via an afferent arteriole. As the blood flows through the glomerular capillaries , protein-free plasma filters across the walls of the capillaries into the Bowmans' capsule in process called glomerular filtration. Filtrate contains water, flucose, salts and urea. The remaining blood leaves the glomerous via the efferent arteriole.

Renal tubule

As the glomerular filtrate is formed, it flows from the Bowmans capsule to the initial portion of the renal tubule, called the proximal convoluted tubule and then to the proximal straight tubule. Both together are called the proximal tubule. The proximal tubule empties into the loop of Henle for the formation of urine - excess water, salts and urea (see video of detail on this process). All glucose is immediately reabsorbed, and salts needed by the body are reabsorbed into the blood capillaries. The fluid or urine then enteres a short, straight end portion of the nephron called the connecting tubule, which joins the nephron with the collecting duct. The collecting duct collects the urine, which is then transported in the ureters to the bladder.

Hope that helps ;-)

Answered Fri 4th January, 2013 @ 21:18 by Rachel
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That did help - thank you so much the video is really great!

Answered Fri 4th January, 2013 @ 21:47 by Fay