Study Notes
The body's defense against infectious diseases involves various mechanisms to prevent and combat pathogens like bacteria, viruses, fungi, and protozoa. Bacteria — Prokaryotes that divide by binary fission. Example: Salmonella causes food poisoning. Viruses — Acellular entities requiring a host cell for reproduction. Example: Influenza virus causes the flu. Fungi — Eukaryotic organisms reproducing via spores. Example: Athlete's foot is caused by fungi. Protozoa — Simple parasites. Example: Malaria is caused by protozoa. Skin — Acts as a physical barrier with biochemical defenses. Example: Sebaceous glands secrete chemicals to inhibit microbial growth. Mucous Membranes — Protect internal structures by trapping and removing pathogens. Example: Mucus in the trachea traps pathogens. Blood Clotting — Seals wounds to prevent pathogen entry. Example: Platelets and fibrin form a clot at wound sites. Phagocytes — White blood cells that ingest pathogens. Example: Phagocytes engulf bacteria through phagocytosis. Antibodies — Proteins produced by B lymphocytes to target specific antigens. Example: Antibodies bind to antigens to neutralize pathogens. Antibiotics — Drugs that target bacterial processes but not viruses. Example: Penicillin disrupts bacterial cell wall synthesis.
Exam Tips
Key Definitions to Remember
- Bacteria: Prokaryotes that divide by binary fission
- Viruses: Acellular entities needing a host cell
- Fungi: Eukaryotic organisms reproducing via spores
- Protozoa: Simple parasites
- Antibodies: Proteins targeting specific antigens
Common Confusions
- Viruses vs. Bacteria: Viruses are acellular and need a host, while bacteria are prokaryotic cells
- Antibiotics: Effective against bacteria, not viruses
Typical Exam Questions
- What is the role of the skin in defense against pathogens? The skin acts as a physical barrier with biochemical defenses.
- How do phagocytes contribute to immunity? Phagocytes ingest pathogens through phagocytosis.
- Why are antibiotics ineffective against viruses? Antibiotics target bacterial processes not present in viruses.
What Examiners Usually Test
- Understanding of different pathogen types and examples
- Mechanisms of the body's primary defenses like skin and mucous membranes
- The process and importance of blood clotting in preventing infections