1st Line
What is the main role of the first line of defence?
Prevent pathogens from entering the body.
Is the second line of defence specific or non-specific?
Non-specific (innate).
Which type of lymphocyte produces antibodies?
B-lymphocytes.
What determines the ABO blood group system?
The presence or absence of A and B antigens on red blood cells.
Which type of immunity is gained through vaccination?
Artificial active immunity.
Name two physical barriers in the first line of defence.
Skin and mucus/cilia.
Name the four major components of the second line of defence.
Inflammation, fever, phagocytes, and the lymphatic system.
What are the two branches of adaptive immunity?
Humoral immunity and cell-mediated immunity.
Which blood type is known as the universal donor?
O−
What is passive immunity?
Immunity gained through receiving pre-made antibodies from another source.
How do cilia help protect the respiratory system?
They sweep mucus and trapped pathogens toward the throat for swallowing or coughing.
Which cell releases histamine during inflammation?
Mast cell.
What is the role of helper T cells?
They coordinate the immune response by activating B cells and other T cells.
Which blood type is known as the universal recipient?
AB+
Why is active immunity generally longer lasting than passive immunity?
Active immunity produces memory cells, while passive immunity does not.
Explain how tears act as both a physical and chemical barrier.
Tears wash pathogens away and contain lysozyme enzymes that kill bacteria.
Explain how fever helps defend the body against infection.
It slows pathogen growth, improves immune cell activity, and promotes recovery.
How do cytotoxic T cells destroy infected cells?
They recognise antigens on MHC I and release perforins that trigger apoptosis.
A patient has blood type A−. Which blood types can safely donate red blood cells?
A− and O−
A baby receives antibodies through breast milk. What type of immunity is this?
Natural passive immunity.
A person cuts their hand while gardening. Explain why the first line of defence has failed.
The skin barrier has been broken, allowing pathogens to enter underlying tissues.
Describe the sequence of events from tissue damage to pathogen destruction during inflammation.
Tissue damage → cytokines released → histamine released → vasodilation and increased permeability → phagocytes enter tissue → phagocytosis destroys pathogens.
Explain why the secondary immune response is faster and stronger than the primary immune response.
Memory B and T cells remain after the first exposure and rapidly activate when the same antigen is encountered again.
Explain why transfusing B+ blood into an A− patient could be dangerous.
Anti-B antibodies would attack B antigens and the Rh antigen may also trigger an immune reaction, causing agglutination and haemolysis.
Compare artificial active immunity and artificial passive immunity.
Artificial active immunity uses vaccines to stimulate antibody and memory cell production, while artificial passive immunity uses injected antibodies that provide immediate protection but no memory cells.