Summary
The immune system protects the body from harmful pathogens through various mechanisms involving cells like phagocytes and lymphocytes. It distinguishes between self and non-self antigens to mount an appropriate immune response.
- Phagocytes — cells that engulf and digest pathogens through phagocytosis. Example: Neutrophils and macrophages are types of phagocytes.
- Antigens — molecules on the surface of cells that trigger an immune response. Example: Bacterial cell walls have antigens that are recognized as foreign.
- Primary Immune Response — the initial response to a new antigen involving B-lymphocytes and T-lymphocytes. Example: B-lymphocytes produce antibodies, while T-lymphocytes destroy infected cells.
- Memory Cells — cells that remain in the body to provide a faster response upon re-exposure to the same antigen. Example: Memory B cells quickly produce antibodies during a secondary immune response.
Exam Tips
Key Definitions to Remember
- Phagocytes: Cells that engulf and digest pathogens.
- Antigens: Molecules that trigger an immune response.
- Memory Cells: Cells that provide long-term immunity.
Common Confusions
- Confusing phagocytes with lymphocytes.
- Misunderstanding the difference between self and non-self antigens.
Typical Exam Questions
- What is the role of macrophages in the immune system? Macrophages engulf pathogens and present antigens to lymphocytes.
- How do B-lymphocytes respond to antigens? They produce antibodies and form memory cells.
- What happens during a secondary immune response? Memory cells quickly respond to eliminate the pathogen.
What Examiners Usually Test
- Understanding of the roles of different immune cells.
- Ability to explain the primary and secondary immune responses.
- Distinction between self and non-self antigens.