Human kidney structure and substance concentration

Question 1

Where are kidneys located in the human body? Name the filtration unit of them.

Accepted Answer

Kidneys are located in the abdomen, one on either side of the backbone. The functional filtration unit is the **nephron**.

Question 2

List two factors on which reabsorption of water from the filtrate depends.

Accepted Answer

1. Amount of excess water present in the body. 2. Amount of dissolved waste (e.g., urea, salts) to be excreted.

Question 3

Why is there variation in the concentration of given substance in structure P and Q listed in table I and II respectively?

Accepted Answer

Structure P is renal artery carrying blood; structure Q is ureter carrying urine. In nephrons, selective reabsorption occurs where useful substances like glucose and amino acids are 100% reabsorbed back into blood, making their concentration 0% in Q. Waste like urea is concentrated in urine, increasing its concentration from 0.05% to 1.00%.

Question 4

**OR** If a person is suffering from diabetes, concentration of which substance present in structure Q (listed in table II) will be modified and why?

Accepted Answer

The concentration of **glucose** will be modified (increased above 0.00%). In a diabetic person, high blood glucose exceeds the renal threshold of tubular reabsorption, causing unabsorbed glucose to pass into urine (structure Q).

Table I	Structure P concentration %
Urea	0.05
Amino acids	0.06
Salts	1.72
Glucose	0.10

Table II	Structure Q concentration %
Urea	1.00
Amino acids	0.00
Salts	1.60
Glucose	0.00

Human kidney structure and substance concentration

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Question 1 of 4

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Question 3 of 4

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Question 4 of 4

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