Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Immunity is the overall ability of the host to fight the disease-causing organisms, conferred by the immune system.
Active Immunity: When a host is exposed to antigens, which may be in the form of living or dead microbes or other proteins, antibodies are produced in the host body. This type of immunity is slow and takes time to give its full effective response.
Natural Active Immunity: Occurs during a natural infection when the body manufactures its own antibodies in response to a pathogen.
Artificial Active Immunity: Induced by vaccines (e.g., Polio vaccine, BCG). The body is exposed to weakened or dead pathogens to stimulate antibody production.
Passive Immunity: When ready-made antibodies are directly given to protect the body against foreign agents. It provides immediate relief but does not provide long-lasting protection.
Natural Passive Immunity: Examples include antibodies passing through the mother's milk (colostrum) to the infant, or antibodies crossing the placenta from mother to fetus.
Artificial Passive Immunity: Injection of pre-formed antibodies or antitoxins, such as Anti-tetanus serum (ATS) or anti-venom for snake bites.
The primary response is of low intensity, whereas the secondary (anamnestic) response is highly intensified due to the memory of the first encounter with the antigen.
📐Formulae
💡Examples
Problem 1:
A person is bitten by a poisonous snake and is immediately given an injection of pre-formed antibodies. Identify the type of immunity provided and explain why it is chosen over vaccination.
Solution:
This is a case of Artificial Passive Immunity.
Explanation:
In snake bites, the toxin is fast-acting and potentially lethal. Active immunity (vaccination) would take too long to produce a sufficient concentration of antibodies (). Therefore, pre-formed antibodies (anti-venom) are injected to provide an immediate immune response and neutralize the toxin quickly.
Problem 2:
Why is colostrum considered essential for a newborn baby?
Solution:
Colostrum provides Natural Passive Immunity via .
Explanation:
The yellowish fluid secreted by the mother during the initial days of lactation, called colostrum, has abundant antibodies of the type to protect the infant against various pathogens. Since the infant's own immune system is not fully developed, these ready-made antibodies are crucial for survival.
Problem 3:
Differentiate between the response time of Active and Passive Immunity.
Solution:
Explanation:
Active immunity requires the host's B-cells to identify the antigen, undergo clonal expansion, and differentiate into plasma cells to secrete antibodies, which is a time-consuming process. Passive immunity involves the direct introduction of , making the response time almost instantaneous.