Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Innate Immunity: A non-specific defense mechanism present at birth. It consists of four types of barriers: Physical (Skin, Mucus), Physiological ( in stomach, saliva, tears), Cellular (Phagocytes like -neutrophils, Monocytes), and Cytokine (Interferons).
Acquired Immunity: A pathogen-specific defense characterized by memory. It involves B-lymphocytes (producing antibodies) and T-lymphocytes (mediating cell-mediated immunity).
Primary and Secondary Immune Response: The first encounter with a pathogen produces a low-intensity Primary Response. Subsequent encounters with the same pathogen elicit a highly intensified Secondary (Anamnestic) Response due to memory cells.
Antibody Structure: An antibody is a protein molecule consisting of four peptide chains: two light () chains and two heavy () chains. It is represented by the notation .
Humoral vs. Cell-Mediated Immunity: Humoral immunity is antibody-mediated and found in the blood plasma. Cell-Mediated Immunity () is mediated by T-cells and is responsible for graft rejection during organ transplants.
Active and Passive Immunity: Active immunity is slow and occurs when the host is exposed to antigens (living/dead microbes). Passive immunity is the direct injection of pre-formed antibodies, such as in colostrum for infants or crossing the placenta.
Vaccination and Immunization: Based on the property of 'memory' of the immune system. Vaccines introduce antigenic proteins or weakened pathogens to generate memory B and T cells.
Allergies: An exaggerated immune response to certain environmental antigens (allergens). It involves type antibodies and the release of chemicals like histamine and serotonin from mast cells.
Autoimmunity: A malfunction where the immune system attacks 'self' cells, leading to diseases like Rheumatoid arthritis.
Lymphoid Organs: Primary organs (Bone marrow, Thymus) are where lymphocytes mature. Secondary organs (Spleen, Lymph nodes, Tonsils, - Mucosal Associated Lymphoid Tissue) are where lymphocytes interact with antigens.
📐Formulae
💡Examples
Problem 1:
Why is the secondary immune response much stronger than the primary immune response?
Solution:
Due to the property of immunological memory.
Explanation:
During the first encounter, the body 'records' the identity of the pathogen. When the same pathogen attacks again, memory B and T cells recognize it immediately, leading to a massive and rapid production of antibodies, specifically in later stages, to neutralize the threat.
Problem 2:
A person is suspected to be suffering from a sudden bout of allergy. Which type of antibodies and chemicals will be elevated in their system?
Solution:
Elevated levels of antibodies, histamine, and serotonin.
Explanation:
Allergies trigger the production of immunoglobulins. These antibodies bind to mast cells, causing them to degranulate and release inflammatory mediators like histamine and serotonin, which cause symptoms like sneezing and watery eyes.
Problem 3:
Why are patients who have undergone organ transplantation prescribed immunosuppressants for the rest of their lives?
Solution:
To prevent Cell-Mediated Immunity () from rejecting the graft.
Explanation:
The body's T-lymphocytes can distinguish between 'self' and 'non-self'. In a transplant, the recognizes the foreign tissue (based on markers) and attempts to destroy it. Immunosuppressants dampen this specific response to ensure the survival of the transplanted organ.