The Immune System Flashcards
The immune system protects our bodies from foreign ____, or infectious agents.
pathogens
The ____ arm is quick to respond, but it is not specific to individual pathogens nor does it form memory cells.
innate
The ___ arm is slower to activate, but it specifically targets a pathogen and forms memory cells.
adaptive
The largest physical barrier is the skin, part of the integumentary system, which prevents most pathogens from entering the body.
The skin also has a moderately acidic pH, between 3 and 5, which discourages replication of most pathogens.
The skin is inhabited by ___, nonpathogenic microbes that compete for resources and thus prevent pathogen occupancy.
flora
In addition to the physical barriers, there are several chemical barriers to infection. Saliva, tears, and mucus all contain the enzyme ____, which degrades bacterial cell walls and causes them to ____, or burst.
lysozyme; lyse
Cells continuously secrete ____ into the bloodstream. These small molecules are broad-spectrum antimicrobials that target and kill many bacterial, viral, and fungal pathogens to prevent infection.
antimicrobial peptides
If a cell becomes infected, it will secrete ____, a small chemical messenger, to signal to nearby cells the presence of a foreign pathogen and activate innate defenses in those cells.
interferon (is a type of protein)
The innate immune system is quick to respond to incoming pathogens but is unable to form ____, or the ability to remember a pathogen that has been previously encountered.
memory
____ are named for the dense granules, containing reactive oxygen compounds and cytokines, in their cytoplasm and include basophils, eosinophils, and neutrophils.
Granulocytes
____ are responsible for releasing histamine and mediating allergic reactions.
basophils
____ are cells responsible for killing parasites.
eosinophils
____ are the most common of the granulocytes and are responsible for phagocytosing, or eating, bacteria and mediating inflammatory responses.
neutrophils
____ leads to swelling of the tissue and fever, as well as recruitment of immune cells.
Inflammation
____ leads to swelling of the tissue and fever, as well as recruitment of immune cells.
Inflammation
They recognize pathogen-associated molecular patterns (PAMPs), common proteins and carbohydrates found on the surface of pathogens that are not specific to one ____, the term for a microbial protein.
antigen
____ also digest dying cells, especially in the ____ where red blood cells die.
macrophages; spleen
____ cells attack and kill cells that contain intracellular pathogens or display abnormal surface antigens (i.e. tumor cells).
natural killer (NK)
____ cells attack and kill cells that contain intracellular pathogens or display abnormal surface antigens (i.e. tumor cells).
natural killer (NK)
The adaptive immune system is slower to respond because it must first be activated by antigen presentation by cells of the innate immune system. Once activated, it will specifically target pathogens and host cells displaying the presented antigen.
Following clearance of the infection, memory cells are formed, which will activate quickly following a secondary encounter with the same pathogen.
The quick activation of memory cells underlies the usefulness of ____. During ____, the immune system is challenged by a weakened pathogen and forms memory cells. These cells will quickly activate and kill the pathogen when exposed a second time, preventing or minimizing infection and the development of symptoms.
vaccination
____ are born in the bone marrow; released into the bloodstream as immune cells; and travel to the ____, a lymphoid organ, for maturation.
T cells; thymus
____, following activation by antigen-presenting cells, help to activate other adaptive immune cells such as cytotoxic T and B cells.
Helper T cells
Helper T cells are targeted and killed by the human immunodeficiency virus (HIV), the virus responsible for acquired immunodeficiency syndrome (AIDS), leading to a loss of immune function.
When a cause of death is written as complications related to AIDS, this indicates that the individual succumbed to infections caused by pathogens that are typically harmless to relatively healthy individuals.
____, when activated, will kill a host cell that expresses a foreign antigen. ____ are antigen specific, meaning that they will only kill a cell that displays the single antigen they were primed to recognize.
Cytotoxic T cells
____ are both born in and mature in the bone marrow.
B cells
Following activation, they develop into ____ cells and secrete ____, proteins that specifically bind to viral antigens.
plasma; antibodies
Antibodies can be acquired either by ____ immunity, through production by plasma cells, or ____ immunity, through the introduction of antibodies from an external source.
active; passive
Antibodies can be acquired either by ____ immunity, through production by plasma cells, or ____ immunity, through the introduction of antibodies from an external source.
active; passive
The adaptive immune system is normally self-tolerant, in that it does not respond to normal cellular antigens. However in some cases, it targets healthy host cells, leading to autoimmune disease.
Autoimmune disorders include type 1 diabetes, in which the immune system targets the pancreas, and lupus, in which the immune system targets multiple organs.
