Chapter 13. The Urinary System
13.8 The Urinary System and Homeostasis
Learning Objectives
By the end of this section, you will be able to:
- state examples of how the kidneys maintain homeostasis; and
- list the two main causes of chronic kidney disease.
The main function of body systems is to maintain a state of homeostasis, and the kidneys are no exception. The kidneys maintain homeostasis in many ways, including by:
- maintaining homeostatic levels of electrolytes in the plasma and regulating total body water content (osmoregulation);
- eliminating nitrogenous wastes;
- controlling blood pressure in the long term via RAAS;
- converting vitamin D to its active form;
- secreting erythropoietin, essential for erythrocyte production and maintaining hematocrit (see Chapter 11);
- regulating plasma pH by altering bicarbonate reabsorption and H+ secretion; and
- maintaining body fluid volume.*
* Maintenance of body fluid volume and acid-base balance are discussed in detail in Chapter 14.
Since the kidneys play a vital role in maintaining homeostasis, if they are damaged in any way, the consequences can be serious.
Disorders of the Urinary System – Kidney Disease
Kidney disease is a condition in which the kidneys are damaged and cannot perform their vital functions. View the videos below to learn more about kidney disease and the link between kidney disease, diabetes mellitus, and hypertension.
What Is Kidney Disease?
Click here to view “What is Kidney Disease? | The Kidney Disease, Heart Disease, and Diabetes Connection | NKF” by National Kidney Foundation (May 12, 2022) in a separate tab.
How Are Kidney Disease, Cardiovascular Disease, and Diabetes Related?
Click here to view “How are CKD, CVD, and Diabetes Related? | The Kidney Disease, Heart Disease, and Diabetes Connection” by National Kidney Foundation (May 12, 2022) in a separate tab.
Section Review
The kidneys play a vital role in maintaining many physiological parameters in homeostasis, including electrolyte levels, total body water content, blood pressure, hematocrit, plasma pH, and body fluid volume.
Critical Thinking Question
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