Immune System Overview

Immune System

• Pathogens: Microscopic organisms causing disease (e.g., E. coli bacteria, measles virus).
• Virus: Infectious agent with genetic material (protein or fat) inside cells. Chickenpox spreads from skin sores.
• Bacteria: Simple, single-celled microbes without a nucleus. E. coli attaches to cells and releases toxins.
• Antibodies: Proteins identifying and targeting specific pathogens. Produced by B cells targeting one type of pathogens.
• Lines of Defense:
  • Non-Specific (Innate): First line: skin, mucous membranes, secretions; second line: phagocytic leukocytes, inflammatory response, fever, antimicrobial proteins.
  • Specific (Adaptive): Third line: lymphocytes, antibodies, memory cells
• Vaccines: Teach the immune system to recognize and remember pathogens, fighting off specific diseases.

Physical and Chemical Barriers

• First Line of Defence: Protects the body from pathogen entry.
• Physical Barriers:
  • Skin: Tough barrier to pathogen entry.
  • Mucous membranes: Line respiratory, digestive, and urogenital tracts trapping pathogens.
  • Cilia: Hair-like structures moving mucus and trapped particles out of the lungs.
• Chemical Barriers:
  • Stomach acid: Destroys ingested pathogens.
  • Tears and saliva: Washing pathogens from eyes and mouth.
  • Urine flow: Removes pathogens from the urinary tract.
  • Lysozyme: Enzyme in tears and saliva breaking down bacterial cell walls.
  • Sebum: Oily substance with antimicrobial properties (produced by skin)
  • Mucus: Traps and neutralizes pathogens .
  • Acidic pH of Skin: Hostile environment to pathogens.

Vaccination vs No Vaccination

• Vaccinated Person: Possesses memory cells with antibodies ready to fight invading pathogens, resulting in a less severe illness.
• Non-Vaccinated Person: Lacks antibodies fighting the pathogen upon invasion; experiencing a more severe illness while the body produces the antibodies.

Nervous System

• Neuron: Nerve cell with dendrites (receiving information).

Endocrine System

• Hormones: Chemical messengers (e.g., adrenaline, insulin, glucagon) regulating body functions.
• Homeostasis: Maintaining stable internal conditions (temperature, blood glucose etc) through positive and negative feedback mechanisms.
• Endocrine System - functions over longer periods of time with overall slower responses than nervous system that triggers very fast reactions.

Ecosystem

• Predator/Prey: Relationship where one organism consumes another for food; the balance between them affects the ecosystem.
• Competition: Organisms contend for resources (food, shelter, mates)
• Energy Transfer: Energy flows through an ecosystem from producers to consumers. Every step of the food chain incurs some energy loss.
• Energy Losses: Occur as heat, waste products, or incomplete consumption of organism by consumer.

Symbiosis

• Definition: Interaction between two organisms where one benefits, and the other may benefit or not.
• Types:
  • Mutualism: Both benefit (+/+)
  • Commensalism: One benefits, other neutral (+/0)
  • Parasitism: One benefits, other harmed (+/-)

Explore the fundamentals of the immune system, including the roles of pathogens, viruses, and bacteria. Learn about the lines of defense, vaccines, and the body's various physical and chemical barriers against disease. Test your knowledge on how the immune system protects the body.