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Acquired Immunity - Practice Questions & MCQ

Edited By admin | Updated on Sep 18, 2023 18:34 AM | #NEET

Quick Facts

  • Types of Acquired Immunity is considered one the most difficult concept.

Concepts Covered - 0

Characteristics of Acquired Immunity
  • It is a pathogen-specific immunity.
  • The immunity that an individual acquires after the birth is called acquired or adaptive or specific immunity. 
  • It is specific and mediated by antibodies or lymphocytes or both which make the antigen harmless.
  • It not only relieves the victim of the infectious disease but also prevents its further attack in future. 
  • Thus acquired immunity consists of specialized В and T lymphocytes and antibodies.

Characteristic Features:

  • Specificity
    • It is the ability to differentiate between various foreign molecules (for­eign antigens).
  • Diversity
    • It can recognize a vast variety of foreign molecules (foreign antigens).
    • Discrimination between Self and Non-self: 
    • It can recognize and respond to foreign molecules (non-self) and can avoid response to those molecules that are present within the body (self) of the animal.
  • Memory
    • When the immune system encounters a specific foreign agent, (e.g., a microbe) for the first time, it generates immune response and eliminates the invader. 
    • This is called the first encounter. 
    • The immune system retains the memory of the first encounter. 
    • As a result, a second encounter occurs more quickly and abundantly than the first encounter.

Components of Acquired Immunity:

  • Acquired immunity has two components: 
    • humoral immunity or Antibody-mediated immune system (AMIS) 
    • cellular immunity or cell-mediated immune system (CMIS).
Types of Acquired Immunity
  • Acquired immunity is of two types: active immunity and passive immunity.

Active Immunity:

  • In this immunity person’s own cells produce antibodies in response to infection or vaccination. 
  • Active immunity may be natural or artificial.
  • A person who has recovered from an attack of smallpox or measles or mumps develops natural active immunity.
  • Artificial active immunity is the resistance induced by vaccines. 

Passive Immunity:

  • When ready-made antibodies are directly injected into a person to protect the body against foreign agents, it is called passive immunity. 
  • It provides immediate relief.
  • Passive immunity may be natural or artificial.
  • Natural passive immunity is the resistance passively transferred from the mother to the fetus through the placenta. 
    • IgG antibodies can cross the placental barrier to reach the fetus.
    • Mother’s milk contains antibodies (IgA) that protect the infant properly by the age of three months.
  • Artificial passive immunity is the resistance passively transferred to a recipient by the administration of antibodies. 

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