Final answer:
The major cations in intracellular fluid are potassium and magnesium, while the major anions are phosphate and proteins with negligible chloride. In extracellular fluid, which includes blood plasma and interstitial fluid, the predominant cations are sodium, and the main anions are chloride and bicarbonate.
Step-by-step explanation:
In intracellular fluid (ICF), the chief cations are potassium (K+) and magnesium (Mg++), with a smaller amount of sodium (Na+). The intracellular fluid also contains phosphate and proteins, with negligible chloride ions (Cl-) except in erythrocytes. In extracellular fluid (ECF), which includes blood plasma, interstitial fluid, and lymph, the predominant cations are sodium (Na+) and to a lesser extent, calcium (Ca++), magnesium (Mg++), and potassium (K+). Interstitial fluid has a higher concentration of diffusible anions and a lower concentration of cations than plasma. The main anions in ECF are chloride (Cl-) and bicarbonate (HCO3-). Fluid exchange systems, such as plasma-interstitial fluid, are vital for maintaining osmotic balance, anion-cation balance, and hydrogen ion regulation. The transport of electrolytes across cell membranes is crucial for these processes, with the sodium-potassium pump playing a significant role in maintaining the ionic concentration gradients.