4B.immune system

• Immunity: The overall ability of an organism to fight against disease-causing organisms
• Immunity is the ability of an organism to defend against disease-causing organisms
• Immune System: The network of organs, cells, and proteins that protect the body from harmful infectious agents such as bacteria, fungi, viruses, etc.
• Non-specific lines of defence: The inborn resistance to diseases possessed by all living organisms, also known as innate immunity
• Non-specific lines of defence do not depend on prior contact with microorganisms
• Mature B-cells: Produced in stem cells in the bone marrow of adult mammals, synthesize various types of antibodies displayed on their surface
• Functional B-cells: Developed from mature B-cells in secondary lymphoid organs, change into long-lived memory cells and effector plasma cells
• Complement proteins: Group of inactive plasma proteins and cell surface proteins that, when activated, form membrane attack proteins (MAC) to create pores in the plasma membrane of affected cells
• The pores allow extracellular fluid to enter the cell, causing it to swell and burst
• The complement proteins and their activity are collectively called the complement system
• Colostrum: First milk produced by the mother after delivery, rich in IgA antibodies to protect the infant from infections
• Mononuclear phagocytes:

  • Kupffer cells of the liver
  • Histiocytes of connective tissue
  • Microglia in the brain
  • Osteoclasts of bone
  • Synovial cells of synovial fluid
• These antibodies are transferred from mother to infant, providing natural passive immunity
• Perforins:

  • Form pores in the cell membrane of infected cells
• Granzymes:

  • Enter the infected cell through the pores
  • Cause bursting of the cell by activating certain proteins to destroy the infected cell
• The mechanism of vaccination or immunization is based on the property of memory of the immune system (cells)
• During vaccination:

  • Inactivated or weakened pathogens or antigenic proteins of pathogens are introduced into the body of the host
  • They initiate the production of appropriate antibodies in the host and generate memory-B cells and memory T cells
  • Memory cells recognize the same pathogen when it enters the body and produce antibodies in large scale to kill the pathogen
• Types of Immunological disorders:

  • Immunodeficiency disorder: HIV/AIDS
  • Hypersensitivity disorders: Allergies
  • Autoimmune disorders: Addison's disease, Rheumatoid arthritis
  • Graft rejection: transplantation of organs
• In metro cities of India, more people are prone to allergies due to:

  • Maximum increase in pollution, especially from automobile exhausts
  • Pollution causing allergic reactions in people, with symptoms like sneezing, watery eyes, running nose, and difficulty in breathing
  • Most people suffering from asthma are from cities
• Autoimmune disorders occur when the immune system attacks the body's own proteins:

  • Ex: Addison's disease, Rheumatoid arthritis
• To avoid graft rejections in patients:

  • Tissue matching and blood group matching are essential before transplantation
  • Patients may need to take immuno suppressant drugs throughout life