What natural defenses do we have against diseases?
Our bodies have several natural defenses against diseases. Here are some key defense mechanisms:
1. Physical Barriers:
- Skin: The outermost layer of our skin acts as a physical barrier, preventing pathogens from entering the body.
- Mucous Membranes: These line the respiratory, digestive, and urogenital tracts, trapping and preventing pathogens from invading.
- Saliva, Mucus, and Tears: These secretions contain substances that can inhibit or kill microorganisms.
2. Innate Immune System:
- Phagocytes: Specialized immune cells (neutrophils, macrophages) engulf and digest foreign particles and microorganisms.
- Natural Killer (NK) Cells: They recognize and eliminate abnormal or infected cells without prior sensitization.
- Inflammation: Occurs in response to tissue damage or infection, promoting blood flow and immune cell recruitment to the affected area.
- Fever: An elevated body temperature can inhibit the growth or kill some pathogens.
- Interferons: Proteins released by infected cells to inhibit viral replication in neighboring cells.
3. Acquired Immune System:
- Antigen Presentation: Specialized cells (antigen-presenting cells) display processed antigens (parts of pathogens) on their surfaces for recognition by immune cells.
- B cells: Produce antibodies that specifically bind to antigens, marking pathogens for destruction or neutralization.
- T cells: Different types of T cells have various functions, including killing infected cells (cytotoxic T cells), regulating immune responses (helper T cells), and providing cellular immunity (memory T cells).
- Memory Cells: After an infection, the immune system retains memory cells that quickly recognize and respond to the same pathogen upon future exposures.
These defense mechanisms work together to protect the body against diseases. If a pathogen breach these defenses, specialized immune responses are triggered to fight off the infection. Understanding these natural defenses helps researchers develop vaccines and therapies to strengthen and enhance the body's ability to combat diseases.