Final answer:
Approximately 20 complement proteins are inactive in the plasma. They are synthesized continuously by liver cells and macrophages and are capable of responding immediately to infecting microorganisms to destroy extracellular pathogens. 20 complement proteins are inactive in the plasma.
Step-by-step explanation:
In the plasma, there are approximately 20 types of complement proteins that are inactive. These complement proteins are synthesized continuously by liver cells and macrophages, and they are abundant in the blood serum. Once activated by infecting microorganisms, these complement proteins respond immediately to destroy extracellular pathogens.