Microorganisms which are typically one-celled, have no chlorophyll, multiply by simple division, and can be seen only with a microscope.
Bacteria
What is a virus?
It's a tiny, nonliving particle that can infect cells and cause diseases and cannot be killed with antibiotics.
Disease is…
It's a pathological condition of a part, organ, or system of an organism characterized by an identifiable group of signs or symptoms.
What is a pathogen?
It is an organism or particle that causes disease (viruses, bacteria, etc.)
What is an infectious disease?
a contagious disease caused by pathogens (flu, measles, chickenpox, malaria)
What is a noninfectious disease?
a disease that is not caused by pathogens and is not contagious (Alzheimer's, cancer)
What is a substance that provokes allergies (pollen, mold, dust, certain foods) ?
Allergen
What are the components of the immune and lymphatic systems?
Lymph nodes, adenoids, spleen, bone marrow, lymphatic vessels, tonsils, thymus, appendix.
What are the body systems that work together to defend the body against disease?
the immune system, lymphatic system, and cardiovascular system
What is an allergy?
It is an abnormal reaction to a foreign substance .
What is an acute disease?
It begins suddenly and lasts for a short time (colds, flu)
What is chronic disease?
It lasts for a long time and/or recurs frequently (cancer, arthritis, diabetes)
What is the lymphatic system?
a major component of the immune system that protects the body from pathogens
It is a rounded mass of tissue that filters fluids from other body tissues and traps pathogens.
lymph node
The body's ability to protect itself from pathogens before they cause disease
Immunity
The type of immunity in which the immune system produces antibodies in response to the presence of a pathogen. It can last a few years or up to a lifetime
Active immunity
