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Postby chenglorraine » Mon May 29, 2006 4:19 pm

Hay Guyz....
PLEASE! Can someone help me. This is one of my GCSE questions and I am not sure whether my answer is right or not! Here is the question
Explain how urine is made in the nephron: 4 marks
Thank you eva so much!!X
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my answer

Postby chenglorraine » Mon May 29, 2006 4:24 pm

HAy's still me! this is my answer:
As the blood passes through the glomerulus, it is filtered through. Some molecules, such as glucose, amino acids, water, ions and urea pass out of the glomerulus, through the Bowman’s capsule into the nephron. All of the glucose summons the ions and much of the water is reabsorbed back into the blood capillaries because they are useful to the body. This is taken place by active transport
The remaining substances are excess ions and urea, which are then released and dissolved in water to form urine
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Postby zalaskit » Mon May 29, 2006 10:03 pm

Real close.
A few things to be revised / added:

-Sugar is not usually filtered by the glomerulus, and if you do find sugar (glucose) in urine, its is commonly a sign to get your kidneys checked out by a doctor.

-you may say that most of the blood plasma is filtered through the glomerulus into the bowmans capsule, as most of it is, except proteins and sugar and a few others that are too large to be filtered.

-you said that the filtrate is passed through the bowmans capsule and into the nephron. keep in mind that the nephron is the whole chain put together; the glomerulus, bowmans capsule, proximal tubule, loop of henle, distal tubule, and collecting duct. what you could have stated was that the filtrate moves from the bowmans capsule to the proximal tubule, leading the the decending limb of the loop of henle.

-I am not sure what u mean by 'the glucose summons the ions' but what i think you are talking about is:
at the point where the filtrate passes into the decending loop of henle, which reaches into the kidneys medulla (both inner and outter). the medulla has a verry high concentration of salt (NaCl) and as a result, draws water out of the filtrate into the medulla via passice transport (osmosis) because of the concentration gradient between the loop of henle and the medulla. this also happens in the collecting duct where most of the remaining water is removed from the filtrate (here there is some active transport occuring).

-last point, the excess filtrate that was not useful to the body and reabsorbed is already in the water, and has been the entire process. so its not that it is then dissolved in water to form urine, its that it's reabsorbed and the remainder is passed into the collecting duct and down to the ureters into the bladder. And, the urine is not technically formed in the kidneys, it is just the waste being concentrated for expulsion by the body. (similar to what i have said above).

So i hope that helps you out... if you have any further questions feel free to email me ([email protected])

and if anyone notices i have goofed up while explaining this please let me know as well.
thanks a bunch

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