Specific Defence Mechanisms

Section 1: Introduction to Specific Defence Mechanisms

• The specific defence mechanism, also known as the adaptive or acquired immune system, targets specific pathogens that the body has previously been exposed to.
• It has the ability to ‘remember’ pathogens, providing a quick and efficient response to subsequent infections.
• Specific defence mechanisms are further divided into two main types: cellular immunity and humoral immunity.

Section 2: Cellular Immunity

• Cellular immunity involves immune cells known as T cells.
• T cells include Helper T cells, which assist B cells and Killer T cells, and Killer T cells, which destroy infected body cells.
• This mechanism is primarily effective against cells infected by viruses and cancer cells.

Section 3: Humoral Immunity

• Humoral immunity involves the action of B cells.
• B cells produce antibodies, proteins that recognise and bind to a specific antigen (foreign substance such as a pathogen) in the body.
• By binding to the antigen, antibodies can neutralise the pathogen or mark it for destruction by other immune cells.

Section 4: The Role of Memory Cells

• Following an infection, some T and B cells become memory cells.
• Memory cells remain in the body long after the infection has cleared and facilitate a quicker and stronger response if the same pathogen were to infect the body again, leading to immunity.

Section 5: Vaccination and Immunity

• Vaccination exploits the specific defence mechanism by introducing a harmless form of a pathogen to stimulate an immune response and the formation of memory cells.
• Upon actual exposure to the pathogen, the body can mount a quicker and more effective immune response, preventing or reducing the severity of disease.

It’s important to remember that the specificity and memory of the specific defence mechanism form the basis of immunity, vaccination and allergy responses.