Final answer:
Passive immunity provides immediate protection against pathogens through the transfer of antibodies, lasting for a short time, while active immunity develops memory cells for long-term protection.
Step-by-step explanation:
Understanding Passive Immunity
Passive immunity is the kind of immunity that provides immediate immune benefits that can last from several hours up to a few days or months and does not require exposure to the pathogen beforehand. This form of immunity is particularly useful as it offers rapid protection when the body is at risk of infection. Antibodies transferred through passive immunity, either naturally through maternal antibodies or artificially through injections, are responsible for this immediate protection. Unlike active immunity, which takes longer to develop after exposure to an antigen but typically provides long-term protection, passive immunity is temporary as it relies on antibodies that will eventually be catabolized and removed from circulation.
During a first-time infection, an early induced immune response occurs, including the production of antimicrobial proteins. However, it can take days before this protection is fully active. On subsequent exposures to the same pathogen, memory cells facilitate a more rapid response, often within hours, thanks to the body's adaptive immune system retaining a 'memory' of the pathogen. Passive immunity can be an immediate defense while the body's adaptive immune response is being activated.