Human Health and Disease — BIOLOGY STD 12 Science — Question

(A) Immunity and its Types:
Definition: The overall ability of the host body to fight and protect itself against disease-causing organisms (pathogens), conferred by the immune system, is called immunity.
Types: There are two main types of immunity:
1. Innate Immunity: A non-specific type of defense that is present at the time of birth.
2. Acquired Immunity : A pathogen-specific defense characterized by memory, developed after birth.
(B) Brief Notes:
1. Autoimmune Disease: This is a condition where the body's higher immune system loses the ability to distinguish between self-cells and foreign organisms, leading it to attack its own body cells.
Example:Rheumatoid arthritis is a common autoimmune disease in humans.
2. Allergy: The exaggerated or hypersensitive response of the immune system to certain antigens (known as allergens) present in the environment is called an allergy.
Symptoms: These include sneezing, watery eyes, running nose, and difficulty in breathing.
Involvement: It involves IgE type antibodies and the release of chemicals like histamine and serotonin from mast cells.