Anatomy and Physiology II Practice Test

What type of immunity involves the direct transfer of antibodies from one individual to another?

1. Natural active immunity

2. Natural passive immunity

3. Artificial active immunity

4. Artificial passive immunity

The correct answer is: Natural passive immunity

Natural passive immunity involves the direct transfer of antibodies from one individual to another, which typically occurs through processes like maternal-fetal transfer during pregnancy or through breast milk after birth. This form of immunity provides the recipient with immediate, though temporary, protection against pathogens without requiring their own immune system to actively engage in producing antibodies. During pregnancy, immunoglobulin G (IgG) antibodies can cross the placenta, giving the newborn passive immunity against diseases to which the mother has immunity. Similarly, during breastfeeding, immunoglobulin A (IgA) antibodies are transferred, further protecting the infant from infections. In contrast, natural active immunity occurs when a person is exposed to a pathogen and their immune system produces its own antibodies. Artificial active immunity refers to the introduction of antigens through vaccination, prompting the immune system to create its own antibodies. Artificial passive immunity involves the injection of ready-made antibodies, usually from serum, to provide immediate protection but does not confer long-term immunity since the recipient’s body does not create its own antibodies.