Understanding Infectious Diseases in Biology
Pathogens are microorganisms that cause diseases through various mechanisms. The main types include bacteria, viruses, fungi and protists, each with distinct characteristics and transmission methods.
Definition: Pathogens are disease-causing microorganisms that can infect living organisms and cause illness through different mechanisms like producing toxins or damaging cells.
Bacteria are relatively large pathogens around1000nm that reproduce by binary fission and release toxins into the body. They can be treated with antibiotics, though antibiotic resistance is becoming a major concern due to bacterial mutations and improper antibiotic use. Common bacterial infections include Salmonella and Gonorrhoea, which require specific preventive measures and treatments.
Viruses are much smaller pathogens 20−40nm that invade host cells and hijack cellular machinery to replicate. Unlike bacteria, they cannot be treated with antibiotics. Instead, antiviral medications may help slow viral replication. Notable viral infections include HIV and measles, which are prevented through different strategies like vaccines and avoiding exposure.
The immune system responds to pathogens through white blood cells, specifically phagocytes and lymphocytes. Phagocytes engulf pathogens directly, while lymphocytes produce specific antibodies to target invaders. Vaccines work by stimulating this immune response using weakened or dead pathogens, allowing the body to develop immunity before encountering the actual disease.