2- Renal Anatomy & Function

Renal Anatomy & Function
Objective 1: Students will be able to identify the component parts of a nephron.
Objective 2: Students can describe the functions of different parts of the nephron.
Objective 3: Students can trace the path of water and ion flow along the length of the nephron
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Model 1: Anatomy of a Nephron (Learning Objective 1)
The nephron is the functional unit of a kidney. There are approximately 1,000,000 nephrons in each kidney.

QUESTIONS:

1. Based on Model 1, where are the two types of nephrons located? (use the terms to distinguish)

2. In words, describe where the proximal convoluted tubule (PCT) is found on the cortical nephron.

3. In words, compare the size/shape of ascending versus the descending limb on the nephron loop on the juxtamedullary nephron.

4. Indicate where you find each part of the nephron with an ”x” in the following table.
Cortex Medulla
PCT
Nephron loop
DCT
Collecting duct

5. Based on Model 1, what is housed in the renal “pyramids”?

6. Using complete, grammatically correct sentences, anatomically describe the differences in location, shape, size, etc. between the cortical and juxtamedullary nephron.

7. What is another name for the glomerular capsule AND what is its role?

Model 2: Function of a Nephron (Learning Objective 2/3)
The three main functions of a nephron in creating urine are filtration, reabsorption and secretion. Reabsorption is defined as putting substances of the filtrate back into the bloodstream. Secretion is defined as moving substances from the bloodstream into the nephron.

QUESTIONS:
1. Based on your work in Model 1, what type of nephron is pictured above, in Model 2?

2. Based on Model 2, and using the “insert” function on your typing program, please fill in the following table with the molecule or ion involved. Then place a circle on the model above around an arrow example of reabsorption. Place a square around an arrow example of secretion on the model above.

Filtration Reabsorption Secretion
Glomerulus
PCT
Nephron Loop
DCT
Collecting Duct

3. After looking at this data in the Table above, what trends or patterns do you see?

4. In the table you made of the filtered substances in Model 2, circle those items that would be considered nutrients.

5. Think about the components of blood. Is there a nutrient you notice that does not become a part of the filtrate and therefore, stays in the blood?

6. What substance is reabsorbed from the descending limb of the nephron loop? (Learning Objective 3)

7. What impact will this have on the concentration of the fluid in the loop? (LO 3)

8. What substance is reabsorbed from the ascending limb of the nephron loop?

9. What impact will this have on the concentration of the fluid in the loop?

10. Concentration of a solution is measured in milliosmoles (mOsm). If the concentration of blood is about 300 mOsm, what happens to the concentration of the filtrate as the nephron dips down into the inner medulla, then comes back up? Draw some fictitious concentrations on the model to indicate your speculation.

11. Look back at Model 1. Why do you think there are different lengths of nephrons in the kidney?

12. The normal pH of urine is typically around 6.0 (slightly acidic). In examining Model 2, can you indicate how the nephron is taking a filtrate that has a normal pH of 7.35 – 7.45 and lowering it to 6.0? Explain how this is happening.