Alterations in Urinary/Renal Functioning

Reading:

Porth, C.M. (2007)  Essentials of Pathophysiology:  Selected portions of chapters 23-26.

Purposes:

Review the normal anatomy and physiology of the urinary system as a basis for understanding the pathophysiological changes that occur in disease;

Understand the pathophysiology that underlies clinical manifestations in disease states;

Contrast infectious and inflammatory urinary/renal problems;

Describe causes of acute renal failure and compare acute and chronic renal failure.

Reading Guide:

To help you determine which parts of the chapters are to be emphasized, refer to the written syllabus for guidance on included topics. 

Also, review the textbook website at http://thePoint.LWW.com/PorthEssentials for links to chapter-related resources with animations and chapter review questions.

Terminology:

Use the syllabus, your textbook, and the links suggested below to familiarize yourself with the major pathophysiology of the system.

Study Questions:

In addition to the end-of-chapter questions listed earlier, consider the following questions.

1. Though inulin measures GFR most exactly, why is the creatinine clearance used most frequently as a useful measure of GFR? What characteristic of creatinine makes GFR as measured by creatinine clearance slightly high? (Think about whether its freely filtered, reabsorbed, or secreted).
2. In what part of the tubular system of the nephron is the final regulation of water balance accomplished?
3. Pyelonephritis is inflammation caused by an infection; is this true of glomerulonephritis? Is the damage to the kidneys in glomerulonephritis due to the kidneys becoming infected with beta hemolytic streptococcus bacteria?
4. Is acute or chronic glomerulonephritis more likely to be reversible?
5. Of the three categories of acute renal failure (prerenal, postrenal, or intrinsic), which is commonly due to nephrotoxic drugs and chemicals? Which is a perfusion problem? Which is due to obstructions to urine flow?
6. What are the normal levels of BUN, serum creatinine, osmolarity of the blood, BUN/creatinine ratio, and urine specific gravity?
7. If fractional excretion of sodium (FE%) is normally less than 1% of the sodium filtered by the glomeruli (since normally 99% of the filtered sodium is reabsorbed), would you expect the FE% to be increased or decreased in acute tubular necrosis? Remember that in acute tubular necrosis (intrinsic failure), the kidney tubules would be less able to accomplish their normal function of reabsorbtion of sodium.
8. In renal failure, why do BUN levels rise faster than serum creatinine levels in a situation of reduced renal perfusion such as prerenal acute renal failure?
9. What are the three stages of chronic renal failure in the course of progressive irreversible destruction of the kidneys leading to chronic renal failure? In which of the three stages do BUN and creatinine increase to a measurable level?

Exercise:

Test your knowledge of some of the physiology of the system by answering the questions on Module Exercise 5. Complete this exercise in Angel. You will get an extra credit point for completing this exercise.

Discussion Group:

The deadline for participation in the Module 5 discussion group is midnight, Sunday, Oct. 22nd.

Try to finish this module by Oct. 6 to stay on schedule. This material will be tested on the exam on Oct. 26, 2006,  3-5 p.m. in Room 1050 SON.