What are the non-specific defence systems of the human body against pathogens?

SouravNovember 13, 2024

Answer

The human body employs a variety of non-specific defense systems to protect against pathogens, which are invaders such as bacteria, viruses, fungi, and parasites. These defenses are innate, meaning they do not require prior exposure to a pathogen to be effective, and they act as the first line of defense against infections.

Primary Non-Specific Defenses

1. Physical Barriers:
   • Skin: The skin serves as a formidable barrier that prevents pathogens from entering the body. It is composed of multiple layers that are tough and impermeable unless damage.
   • Mucous Membranes: These line various body cavities and secrete mucus, which traps pathogens. Mucous membranes are found in the respiratory, gastrointestinal, and urogenital tracts.
2. Chemical Barriers:
   • Tears and Saliva: Both contain enzymes like lysozyme that can break down bacterial cell walls.
   • Stomach Acid: The acidic environment in the stomach can kill many ingested pathogens.
   • Urinary Flow: The normal flow of urine helps flush out microorganisms from the urinary tract.

Secondary Non-Specific Defenses

If pathogens breach primary defenses, the body activates secondary non-specific mechanisms:

1. Inflammatory Response:
   • Inflammation occurs when tissue is damaged or infected. This process involves increased blood flow and the recruitment of immune cells to the site of infection, helping to isolate and eliminate pathogens.
2. Phagocytosis:
   • Phagocytes, including neutrophils and macrophages, engulf and digest pathogens. They play a crucial role in clearing infections by surrounding and breaking down foreign invaders.
3. Natural Killer (NK) Cells:
   • NK cells are a type of lymphocyte that can identify and destroy virus-infected cells or tumor cells without prior sensitization. They release cytotoxic substances that lead to the death of these compromised cells.
4. Fever:
   • An increase in body temperature can inhibit pathogen growth and enhance immune responses. Many pathogens thrive at normal body temperatures; thus, fever acts as a deterrent