The Body's Defence Mechanisms

The Body’s Defence Mechanisms

Non-specific (Innate) Defence Mechanisms

The body has several non-specific defence mechanisms, which provide a general defence against various pathogens.

  • Skin: Acts as a physical barrier, preventing the entry of pathogens. Sweat and sebum on our skin also have antibacterial properties.
  • Mucous membranes: These line our respiratory and digestive system, trapping pathogens and preventing their entry.
  • Cilia: These are tiny hair-like structures in the respiratory tract, which move in a coordinated manner to push mucus (and trapped pathogens) out of the lungs and throat.
  • Stomach acid: The strong acids present in the stomach can kill many pathogens that enter the body through food or drink.

Specific (Acquired) Defence Mechanisms

The body also has specific defence mechanisms, which provide a targeted defence against specific pathogens.

  • White blood cells (leucocytes): Different types of white blood cells play key roles in immune response. For example, phagocytes engulf pathogens and destroy them, while lymphocytes produce antibodies.
  • Antibodies: Protein molecules that are produced by lymphocytes. They can identify and neutralise specific pathogens, and aid in their destruction.
  • Immunological memory: After an initial infection, some lymphocytes become memory cells, which help the body to respond more rapidly and effectively to future exposures of the same pathogen.

Inflammatory Response

The inflammatory response is a key part of the body’s defence mechanisms.

  • When tissue is damaged by an injury or pathogen, cells release a chemical called histamine.
  • Histamine dilates the blood vessels in the area, causing them to become more permeable. This allows more blood (carrying immune cells and nutrients) to reach the affected area.
  • The increased blood flow leads to the characteristic signs of inflammation: heat, redness, swelling, and often pain.

Role of Fever in Defence

  • In response to certain infections, the body’s thermostat is reset to a higher temperature, causing a fever.
  • A higher body temperature can inhibit the growth of some pathogens and enhance the body’s immune response.

Remember, these points represent an overview of the body’s defence mechanisms. Always consult a textbook or ask a teacher if you need to understand more about these complex processes.