Module 08 Lab Worksheet:  Fluid, Electrolyte, and Acid-Base Balance

Introduction

This week’s lab will examine the dynamics of fluid, electrolyte, and acid-base balance.

Objectives

Objectives for this week’s lab include: 1) Identify the body water content and fluid compartments, 2) Define the factors that influence water balance, 3) Compare and contrast electrolyte imbalances, 4) Describe how the body maintains an acid-base balance, and 5) Compare and contrast the acid-base imbalances.

Overview

A cell’s ability to function and live depends on not only it’s ability to receive nutrients and dispose of wastes but also to maintain homeostasis of the surrounding fluids.  The homeostasis and proper balance of water concentration, electrolytes, and pH regulation is dependent upon a number of mechanisms and organ systems.  Failure on any level will lead to homeostatic imbalances that will cause dysfunction, cellular death and even organism death.

Water occupies and is found in two regions of the body called fluid compartments:  Intracellular fluid (ICF) compartment and the extracellular fluid (ECF) compartment.  About 2/3 of the water volume is found in the ICF compartment which is the water found inside of cells and the other 1/3 of water is found in the ECF compartment, which is water fluid found around the cells.  The ECF is further divided into two regions:  Blood plasma and interstitial fluid (IF).  IF is the water found in the spaces around and in between the cells.  It is important to understand the movement of fluid between the compartments and the effects the gain and loss of water has on each of the compartments.
Water is a universal solvent being able to dissolve many solutes.  Generally, solutes are classified as electrolytes or nonelectrolytes.  Due to their chemical properties, nonelectrolytes, such as urea, glucose, lipids, do not dissolve in water and conduct electricity.  Electrolytes have the ability to dissociate into ions within water and will have the ability to conduct electricity.  Specific electrolyte concentration will vary from ICF to ECF and is important to maintain proper electrolyte concentration to maintain proper resting membrane potential charge of a cell.

Imbalances to the water balance within the body can have significant impacts on electrolyte levels and overall body physiology.  Three common water imbalances are:  Edema- accumulation of fluid in the interstitial space, which leads to swelling of the tissues but not cells, Over-hydration or hypotonic hydration- having too much water within the fluid compartments which leads to severe metabolic disturbances, and Dehydration- the general loss of water from the fluid compartments.  It can include solutes too in the loss.  In any case, electrolyte imbalance will occur with water imbalances.  Sodium (Na+), potassium (K+) and calcium (Ca++) are the three main electrolytes that the body needs to regulate to maintain proper physiology.

Acid-base balance is closely regulated by the body due to the influence pH (H+ ion concentration) can have on functional proteins.  There are three chemical buffer systems that help regulate and resist changes to the body’s pH, which include:  Protein buffer system, Bicarbonate buffer system, and the Phosphate buffer system.  The respiratory and urinary systems also have mechanisms that help regulate acid-base balance within the body.