11.1 Introduction to Electrolytes, Water, and Acid-Base Balance
Figure 11.1 Venus Williams Perspiring on the Tennis Court The body has critically important mechanisms for balancing the intake and output of bodily fluids. An athlete must continuously replace the water and electrolytes lost in sweat. (credit: “Edwin Martinez1”/Wikimedia Commons).
Learning Objectives
After studying this chapter, you will be able to:
- Identify the body’s main fluid compartments
- Define plasma osmolality and identify two ways in which plasma osmolality is maintained
- Identify the six ions most important to the function of the body
- Define buffer and discuss the role of buffers in the body
- Explain why bicarbonate must be conserved rather than reabsorbed in the kidney
- Identify the normal range of blood pH and name the conditions where one has a blood pH that is either too high or too low
Introduction
Homeostasis, or the maintenance of constant conditions in the body, is a fundamental property of all living things. In the human body, the substances that participate in chemical reactions must remain within narrow ranges of concentration. Too much or too little of a single substance can disrupt your bodily functions. Because metabolism relies on reactions that are all interconnected, any disruption might affect multiple organs or even organ systems. Water is the most ubiquitous substance in the chemical reactions of life. The interactions of various aqueous solutions—solutions in which water is the solvent—are continuously monitored and adjusted by a large suite of interconnected feedback systems in your body. Understanding how the body maintains these critical balances is key to understanding good health.
Louisiana Lagniappe: Alkaline Drinking Water
According to the Baton Rouge Water Company, the capital city’s water supply is alkaline, with a mean pH of 8.5. Alkaline water, which has a higher pH level than standard tap water, has gained popularity recently, as advocates claim that it offers such health benefits as enhanced hydration, improved digestion, and increased antioxidant activity. The idea behind these claims is that the higher pH of alkaline water may help neutralize acid in the body, promoting better overall wellness. However, the body maintains a tightly regulated blood pH range of 7.35–7.45, and if the consumption of alkaline water significantly alters blood pH, the kidneys and respiratory system work to counteract this change, adjusting water and electrolyte balance to maintain homeostasis. In this way, the body’s regulatory systems will maintain equilibrium, regardless of the water’s pH.