Blood levels and Plasma levels

In summary, you do not need to convert the blood concentration into plasma concentration to find the GFR using the given formula in Guyton's textbook.
  • #1
chound
164
0
In my physiology examination, I came across this question:
Find the Glomerular Filtration Rate (GFR), when
Urine Concentration of Urea (U) = 70 (I don't remember the exact values, but it is of no importance),
Urine flow rate (V) = 1ml/min
Blood level of Urea = 20 ( or something)
In Guyton(Physiology textbook), The formula was given as GFR = U*V/P
P is Plasma level of Urea.
My doubt is whether I should convert the Blood Conc into Plasma Conc ( as Blood is 5 L while Plasma is 3 L) and then continue with the problem?
 
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  • #2
No, you do not need to convert the blood concentration into plasma concentration. The formula given in Guyton's textbook is GFR = U*V/P, where U is the urine concentration of urea, V is the urine flow rate, and P is the plasma level of urea. Therefore, you can simply plug in the values given in the question to solve for GFR.
 
  • #3


I would suggest that you first clarify the definitions and differences between blood levels and plasma levels. Blood is a fluid that carries nutrients, hormones, and other substances throughout the body, while plasma is the liquid component of blood that contains these substances. Blood levels refer to the amount of a substance present in the entire blood volume, while plasma levels refer to the concentration of that substance in the plasma specifically.

In order to calculate the GFR using the given formula, you will need to use the plasma concentration of urea. This is because GFR is a measure of the rate at which the kidneys filter blood plasma, not whole blood. Therefore, you will need to convert the blood concentration of urea to plasma concentration by dividing it by the hematocrit (the percentage of red blood cells in the blood). This will give you a more accurate plasma concentration to use in the formula.

In summary, when calculating the GFR, it is important to use the plasma concentration of the substance in question, rather than the blood concentration. This will ensure that your results are accurate and consistent with established scientific principles.
 

1. What are blood levels and plasma levels?

Blood levels refer to the concentration of substances such as hormones, nutrients, and medications in the blood. Plasma levels specifically refer to the concentration of these substances in the liquid component of blood, called plasma.

2. How are blood levels and plasma levels measured?

Blood levels and plasma levels can be measured through a blood test, where a sample of blood is taken and analyzed in a laboratory. This can provide information on the concentration of various substances in the blood.

3. What factors can affect blood levels and plasma levels?

Several factors can affect blood levels and plasma levels, including diet, medication use, and overall health. These levels can also vary throughout the day and can be influenced by factors such as stress and exercise.

4. Why is it important to monitor blood levels and plasma levels?

Monitoring blood levels and plasma levels can provide valuable information about a person's health and the effectiveness of medication or nutrient intake. It can also help identify any imbalances or deficiencies that may need to be addressed.

5. How can one maintain healthy blood levels and plasma levels?

Maintaining a healthy and balanced diet, staying physically active, managing stress levels, and following medication and supplement guidelines can help maintain healthy blood levels and plasma levels. Regular check-ups and blood tests can also help identify any potential issues and allow for early intervention or treatment.

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