Anatomy of Defense
What is the skin?
What is the skin? This largest organ of the human body acts as the primary physical barrier against invading pathogens.
What is inflammation?
This rapid, localized response causes redness, heat, swelling, and pain at the site of an injury.
What are antibodies?
These Y-shaped proteins are produced by B-cells to specifically bind to and neutralize foreign invaders.
What is an autoimmune disease?
This is the general term for a misdirected immune response where the body mistakenly attacks its own healthy tissues.
What is a vaccine?
This medical intervention introduces a weakened or harmless part of a pathogen to train the immune system to fight the real thing later.
What are lymph nodes?
Serving as a filtering station, these small, bean-shaped structures swell up in your neck or armpits when you are fighting an infection.
What are neutrophils?
These are the most abundant white blood cells; they rush to the site of infection, eat bacteria, and then rapidly die, forming pus.
What is an antigen?
This term refers to any foreign molecule—often a protein on a virus or bacterium—that triggers an immune response.
What is an allergy?
An overreaction of the immune system to a harmless environmental substance, like pollen or peanuts, is known by this term.
What is herd immunity?
This is the term for the long-term protection achieved when a large enough percentage of a population becomes immune to a disease.
What is the thymus?
This chest gland is the "boot camp" where T-cells go to mature and learn how to distinguish friend from foe.
What is a macrophage?
Meaning "big eater," this type of large white blood cell engulfs debris and pathogens, then "presents" pieces of them to the adaptive immune system.
What is a Helper T-cell (or CD4+ T-cell)?
This specific type of T-cell acts as the "general" of the immune system, secreting cytokines to coordinate both B-cell and killer T-cell responses.
What is histamine?
This chemical, released heavily by mast cells during an allergic reaction, causes blood vessels to dilate and makes your nose run.
What is IgG?
This class of antibody (immunoglobulin) is the most abundant in the human body and can cross the placenta to protect a developing fetus.
What is the spleen?
Located in the upper left abdomen, this organ filters the blood, destroys old red blood cells, and holds a reserve library of white blood cells.
What are Natural Killer (NK) cells?
Unlike other lymphocytes, these "natural" innate cells destroy virus-infected host cells and tumor cells without needing specific activation.
What are plasma cells?
Activated B-cells transform into these cellular factories, dedicated entirely to pumping out thousands of antibodies per second.
What is anaphylaxis (or anaphylactic shock)?
This severe, life-threatening allergic reaction causes a systemic drop in blood pressure and airway constriction.
What are interferons?
These antiviral signaling proteins are released by a virus-infected cell to warn neighboring cells to turn on their defenses.
What are Peyer's patches?
These specialized patches of lymphoid tissue in the small intestine keep tabs on the massive bacterial populations in your gut.
What is the complement system?
This system consists of roughly 30 blood proteins that cooperate to punch holes in bacterial cell walls and coat pathogens for destruction.
What is the Major Histocompatibility Complex (MHC)?
These cell-surface proteins act as "billboards," displaying peptide fragments so T-cells can inspect what is going on inside a cell.
What is a cytokine storm?
In this severe condition, a massive overproduction of immune signaling proteins leads to a dangerous hyper-inflammatory state.
What is cowpox?
British physician Edward Jenner famously created the first vaccine by using this milder disease to immunize people against smallpox.