Disease Characteristics and Transmission

Glossary of Terms

• Bacteria: A simple, single-celled microbe without a nucleus.
• Fungi: An organism with complex cells that feeds off a living host.
• Microbes: The most abundant and diverse living things on Earth, living in virtually every environment. They include bacteria, viruses, fungi and protozoa. These are microscopic organisms.
• Immune system: The body system that prevents and fights disease.
• Immunity: The body's ability to protect itself from infection.
• Disease: Any medical condition with specific symptoms.
• Pathogens: Microbes and other microscopic agents that cause disease.
• Infectious diseases: Diseases caused by pathogens.
• Infection: When pathogens manage to enter the body and multiply.
• Non-infectious diseases: Diseases not caused by pathogens. They can be caused by lifestyle, environmental or inherited factors.
• Pathogenic: Causing disease.
• Frequency: The number of waves that go by in one second.
• Pseudoscience: A claim that is presented as scientific but does not follow the scientific method.
• Cell: The smallest unit of life.
• B cell: Specialized white blood cell that is part of the third line of defence.
• Clones: Identical copies of a B cell triggered by an antibody.
• Memory cell: A B cell that remains in the bloodstream to recognize pathogens.
• White blood cell: A blood component that helps protect the body from infection.
• Virus: A microscopic, infectious agent made of genetic material and proteins.
• Contagious: When an infectious disease can pass from one person to another.
• Coronavirus: A type of virus that can cause diseases in mammals and birds, including COVID-19 and the common cold.
• Non-contagious: A medical condition that cannot spread from person to person.
• Faeces: Solid waste that remains after food is digested.
• Epidemic: The rapid spread of a disease in a specific community or region.
• Endemic: The continual presence of a disease in a specific community or region.
• Pandemic: The rapid spread of a disease across multiple regions worldwide.
• First line of defence: The body's initial system of barriers to prevent pathogens from entering. It includes physical and chemical barriers.
• Cilia: Microscopic hairs on cells that line the airways, pushing pathogens out..
• Enzyme: A substance that speeds up a chemical reaction, such as chemical digestion in the body.
• Second line of defence: General responses to infection, such as fever and inflammation.
• Membrane: A thin layer that forms a barrier.
• Phagocyte: White blood cells that engulf and destroy pathogens.
• Fever: An increase in core body temperature above 38 degrees.
• Stomach acid: Acid in the stomach that kills many pathogens.
• Negative feedback loop: When one change in a system causes another change in the opposite direction.
• Inflammation: A painful redness or swelling.
• Core temperature: The internal temperature of the body.
• Antibody: A protein that identifies and fights a specific pathogen.
• Polio: An infectious disease caused by a virus that mainly affects the nervous system.
• Vaccination: A treatment that helps build immunity to an infectious disease.
• Paralysis: The inability to move parts of the body.
• Pathogens: Small organisms that cause a disease.
• Microbes: Living organisms that are too small to be seen without a microscope; often referred to as germs.

Infectious and Disease

• Infectious: Pathogens enter the body and multiply, damaging cells and causing symptoms. Many infectious diseases can spread from person to person.
• Disease: Different pathogens cause different diseases with characteristic symptoms

The Spread of Infectious Diseases

• Pathogens spread through various means, such as shaking hands, sharing drinks, coughing, sneezing, contact with contaminated surfaces or bodily fluids, etc.

Comparing Infectious Diseases

• Deadliness (percentage of infected people who die).
• Contagiousness (how easily the disease spreads).

Non-Infectious Diseases

• Diseases not caused by pathogens.
• Caused by lifestyle factors or genetic factors.
• Examples include diabetes, asthma, and cancer.

Classifying Outbreaks

• Epidemic: a rapid spread of disease in a specific community or region
• Pandemic: a rapid spread of disease across multiple regions or worldwide
• Endemic: a continual presence of disease in a specific community or region

The Immune System

• The immune system is a complex system with three lines of defence.
• The first line of defence creates physical and chemical barriers to prevent pathogen entry.
• The second line of defence includes general responses to infections, such as fever, inflammation, and certain cellular responses.
• The third line of defence creates specific responses to infection targeting particular pathogens using specialized B cells and antibodies.

The First Line of Defence

• The barriers to prevent pathogen entry are physical (skin, tears, saliva, mucus) or chemical (stomach acid, enzyme).

The Second Line of Defence

• General responses like fever which slows pathogen reproduction.
• Immune response causing swelling and pain around the site of the infection.
• Phagocytes engulf and destroy pathogens.

The Third Line of Defence

• Specialized cells called B-cells produce specific antibodies to target that particular pathogen.
• Memory cells are created that provide long-term immunity.

Why Negative Feedback Loops are Essential for Controlling Inflammation

• Negative feedback loops act like a brake on the inflammatory response to prevent excessive damage.

Immunity Against Specific Pathogens(Third Line of Defence)

• The immune system responds quickly but in a general way in the first two lines. These two lines aren't specific to the pathogen.
• The third line has specialized responses that target particular pathogens using specialized white blood cells called B-cells that create antibodies.
• It also provides long-term immunity.

How Vaccinations Work

• Vaccination introduces a weakened or dead pathogen into the body.
• The body then creates antibodies and memory cells to fight future encounters.

Herd Immunity

• When enough people are vaccinated, it creates a barrier that prevents the spread of disease to those who cannot or should not be vaccinated.

Test your knowledge of disease characteristics, transmission methods, and the role of pathogens. Assess your understanding of the immune system and its defense mechanisms against infections. Includes matching microbe types with descriptions.