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Flashcards covering key concepts of the immune system based on lecture notes.
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What are pathogens?
Disease-causing agents that disrupt the normal physiology of an infected organism.
Give examples of cellular pathogens.
Bacteria, fungi, and parasites.
Give examples of non-cellular pathogens.
Viruses and prions.
What is a virus?
An infective entity that inserts its genetic material into a host cell in order to multiply.
What is a prion?
An infectious protein that has folded abnormally into a disease-causing structure.
What are the three basic lines of defense in the immune system?
Surface barriers, non-specific defense mechanisms, and specific responses.
What does the first line of defense consist of?
Surface barriers that prevent the entry of pathogens into the host body.
What does the second line of defense consist of?
Non-specific defense mechanisms activated after infection occurs.
What does the third line of defense consist of?
Specific responses that target antigens produced by the pathogens.
What are the three distinctive types of barriers to prevent pathogens from accessing body tissue?
Physical barriers, Chemical barriers, and Microbiological barriers.
How does intact skin function as a physical barrier?
Consists predominantly of dead cells that line the body surfaces to prevent pathogen entry.
How do mucous membranes function as a physical barrier?
Consist of living cells that line internal cavities and secrete trapping fluids (mucus).
Give examples of chemical barriers.
Gastric secretions, sweat, tears, and mucus.
What do gastric secretions contain that function to destroy ingested pathogens?
Strong stomach acids (pH < 2).
What biochemical agents that inhibit microbial growth are contained in sweat and tears?
Lysozymes and lactic acid.
What is the function of natural flora (commensals) as a microbiological barrier?
Lines the gut, taking up space and preventing colonization by pathogens.
What initiates clotting when surface barriers are penetrated?
Release of clotting factors from damaged cells or platelets.
What is the primary component of the innate immune system?
Phagocytic leukocytes.
How does innate immune system respond to pathogens?
It does not differentiate between different types of pathogens and responds to an infection the same way every time.
What are phagocytes?
White blood cells (leukocytes) that can engulf foreign bodies.
How are phagocytes recruited to infected tissues?
Damaged cells release chemotactic chemicals.
What is the lymphatic system?
A secondary transport system that functions to drain fluid from all around the body.
Where does lymphatic systems filter fluid?
At sites called lymph nodes.
What are antigens?
Molecular markers (typically glycoproteins) that are usually located on the outer surfaces of pathogens.
What are antibodies?
Specific proteins that target antigens
What cells produce antibodies?
B lymphocytes (and plasma cells)
What are the two types of lymphocytes?
B and T lymphocytes
Which cells are introduced to antigenic fragments by antigen presenting cells in the lymph nodes?
Helper T cells
What is the function of helper T cells?
Releases cytokines to activate naïve B lymphocytes
What is the function of plasma cells?
Produce antibodies that target the antigen and facilitate pathogen elimination.
What is the purpose of memory cells?
Produce a secondary immune response that is faster and more potent
What is Immunodeficiency?
A condition in which the immune system is either compromised or absent.
What causes acquired immunodeficiency syndrome (AIDS)?
human immunodeficiency virus (HIV)
How does HIV transmit?
Through the exchange of bodily fluids.
What is a zoonosis?
An infectious disease that can be transmitted from other species to humans.
What is a vector?
An unaffected intermediate species
What are antibiotics?
Compounds that specifically target prokaryotic features.
What is vaccination?
Involves the injection of a biological preparation (vaccine) to provide active acquired immunity to a specific infectious disease.
What is herd immunity?
When a sufficiently large percentage of a population is immune to infection, there is a reduced risk of infection for individuals who lack immunity.
What is an epidemic?
An outbreak that occurs over a given time period within a particular community or region.
What is a pandemic?
Occurs across a wider geographical area (e.g. global).