Unit D

Module 8 ~ Lesson 5

Kidney Disorders

The excretory system can experience many different problems. Urinary tract infections can be painful but are easily treated with antibiotics. Kidney stones are formed by the crystallization of excess calcium in the urine. These can be painful to excrete and may cause damage to the kidney.

Kidneys can also be damaged by kidney infections, high blood pressure, diabetes, or blunt force trauma to the lower back where the kidneys are located. Arteriosclerosis can reduce blood flow to the kidneys, and tubules can become blocked. Irreversible damage to the kidneys may require a person to undergo dialysis or a kidney transplant.

Often, the first symptom of a kidney disorder or infection is the amount of urine or the changing characteristics of urine.


Read "Upsetting the Balance of the Excretory System", "Disorders of the Excretory System" and "Problems with Kidney Function" on pages 318 to 321 of your textbook.

Medical Technology

Dialysis is a medical procedure in which the composition of the plasma can be corrected through simple diffusion. Dialyzing fluid (dialysate) is separated from the patient's blood (uremic plasma) by thin semi-permeable membranes. Molecules and ions diffuse into or out of the patient's plasma, depending upon the composition of the dialysate. Thus, careful formulation of dialysate is the key to correcting the composition of uremic plasma.

In hemodialysis, diffusion occurs across artificial membranes. In peritoneal dialysis, it occurs across the intestinal lining (peritoneum). These procedures are illustrated.

Dialysis is not a long-term solution for people with kidney disease. A kidney transplant is often the best solution. Kidney transplants can be done with live donors with very good results.

Adapted from Inquiry into Biology (Whitby, ON: McGraw-Hill Ryerson, 2007), BLM 9.3.5. Reproduced by permission.


Read "Kidney Transplants" and "The Kidney-Coronary Connection" on pages 321 to 325 of your textbook.