Final answer:
Sodium, calcium, and bicarbonate are all described as plasma ions, which are electrolytes important for functions such as nerve impulse regulation, muscle contractions, and maintaining the body's osmotic balance.
Step-by-step explanation:
Sodium, calcium, and bicarbonate are all described as plasma ions, not proteins, cells, or enzymes.
These substances are electrolytes that are crucial for numerous physiological functions, including the regulation of nerve impulses, muscle contractions, and the control of the body's osmotic balance.
The balance of these ions in the plasma is essential for maintaining homeostasis, as they contribute to the buffering systems such as the bicarbonate buffer, which helps to maintain blood pH within a narrow range.