4.1: What Is Homeostasis?
By the end of this section, you should be able to:
- 4.1.1 Define homeostasis.
- 4.1.2 Compare and contrast intracellular fluid and extracellular fluid and their effects on the body’s cells.
- 4.1.3 Discuss the major cations and anions and their essential functions.
Homeostasis is the ability of the body to maintain a stable and constant internal environment despite changes in the external environment (Billman, 2020). This means that the body can regulate and balance its various physiologic processes, such as body temperature (see Figure 4.2), fluid balance, pH levels, blood sugar levels, and hormone levels, to ensure they remain within a narrow range that is optimal for the body’s functioning.
Ions
An ion is an atom or molecule that has an unequal number of protons and electrons. This inequality gives the ion an electrical charge, either positive or negative. Ions are critical to maintaining homeostasis within the body.
Anions
An anion is a negatively charged ion, meaning it has more electrons than protons. This happens when an atom gains one or more electrons, leaving it with a negative net charge. Chloride (Cl – ), bicarbonate (HCO 3 – ), phosphate (PO 4 – ), and sulfate (SO 4 – ) are anions.
Cations
A cation is a positively charged ion, meaning it has fewer electrons than protons. This happens when an atom loses one or more electrons, leaving it with a positive net charge. Calcium (Ca 2+ ), magnesium (Mg 2+ ), potassium (K + ), and sodium (Na + ) are cations. Cations are important for acid–base reactions (reactions that affect pH).