Immune System Flashcards
What is the main difference between innate and adaptive immunity?
innate is very old and adaptive is more recent (evolution)
What are the two parts of the innate immune system?
physical barriers and internal/cell based defenses
What are the two parts of the adaptive immune system?
humoral and cellular immunity
What do physical barriers do for the immune system?
physical walls to protect body (skin and mucous membranes)
How does internal/cell based defenses help the immune system?
cells release chemicals when they recognize a foreign antigen
What are receptors for foreign antigens called?
Pattern Recognition Receptors (PRR)
What happens if there is no PRR to recognize a pathogen?
the innate cell cannot do anything (happens when there’s a new virus.. covid)
What is an antigen?
anything that can be recognized by the immune system… some cause an immune response
What are self antigens?
antigens present on normal human cells that are recognized but not attacked
What is going on in the body if someone has an auto immune disease?
the body is attacking self antigens
What happens when the body recognizes a foreign antigen?
immune response begins
What are the cells of the innate immune system?
neutrophils, macrophages, natural killer cells
Which cells can go in out out of blood and lymph nodes (basically anywhere)?
neutrophils
What are the two types of macrophages?
resident and roaming
What do resident macrophages do?
don’t really move around.. primarily found in digestive tract and lungs
What do roaming macrophages do?
travel throughout body and go to injuries
What do natural killer cells do?
travel through blood and lymph until they find a PRR to attach to cells and cause apoptosis
What chemicals are released by macrophages and neutrophils?
prostaglandins and complement proteins
What chemical is released by mast cells?
histamine
What is released by virus infected cells?
interferons
What do interferons do?
block viral replication and recruit phagocytes
What do prostaglandins do?
activate neurons to cause pain
What does histamine do?
causes vasodilation to increase blood flow which cause redness/heat; causes vessels affected by infection to become leaky and the fluid that leaves is what causes swelling
What are the five cardinal signs of inflammation?
redness, heat, pain, swelling, loss of function
What can cause inflammation?
trauma, chemicals, infection
Why is inflammation a good thing?
helps to prevent spread, debridement, and is the first step in the repair process
What are chemokines?
leukocytosis-inducing factors (bring WBC to infection)
What happens when leukocytosis occurs?
neutrophils quickly come and monocytes follow
How does a fever come about?
neutrophils/macrophages release pyrogens that go to the hypothalamus to tell the body to warm up
What is the complement system?
a part of the innate AND adaptive immune system that is made up of plasma proteins that help fight infections
How is the complement system activated?
1) antibodies from adaptive immune system binding
2) lectin presence on pathogen
3) spontaneous binding to pathogen
What is the Membrane Attack Complex (MAC)?
hole produced by complements that helps with phagocytosis
What are lectins?
sugars found on the membrane that help with adhesion
What is one of the main goals of the adaptive immune system?
create antibodies to bind to foreign ‘stuff’ and activate the MAC in complement
Adaptive immune system:
forms a specific, unique response to each intruder and results in a systemic reaction in which your whole body feels sicks but it has the ability to remember antigens so the next time you’re exposed the reaction will be much quicker
When is the humoral response activated?
when there is a clearly foreign pathogen and its easier to clear
When is the cell mediated response activated?
when the pathogen is ‘hiding’ (virus or cancer cells)
What are the adaptive immune system cells?
T cells, B cells, antigen-presenting cells (APC)
Describe the structure of antibodies.
all antibodies have the same constant region but they also have a variable region and that is the part that binds
How many foreign antigens can each antibody recognize?
one
What does the antibody bind to?
antigen (antibody generating compound)
What cells are activated by the humoral response?
naive B cells
What two cells are formed as a result of B-cell activation?
memory B cells and plasma cells
What are the two conditions in order for a B cell to mature?
have self tolerance and be immunocompetent (recognize only one antigen)
What is negative selection?
if a B or T cell binds to and cannot release from an antigen, it gets killed
What is positive selection?
if a B or T cell binds only weakly to just one antigen, it survives
Does every B cell have the same antibody?
no
What happens when the naive B cell finds its antigen?
activates the B cell (makes clones… memory or plasma cells)
What does a plasma cell do?
release antibodies
What does a memory B cell do?
use antibody as a receptor
Why do all of the activated B cells have the exact same antigen?
somatic recombination
How does somatic recombination ensure that the clones have the same antibody?
cuts out DNA
What are the components of the variable region?
variabel sections (V), diversity sections (D), joining sections (J)
What happens after the naive B cell chooses the 3 sections it wants?
makes an antibody with those three and all unused genes are removed from the genome
What happens during the primary response?
antibodies in blood bind to antigens for the first time and the MAC is activated and neutralization and agglutination occur
What is the secondary response?
second time the foreign antigen enters your body and the memory B cells that were formed during primary are activated to have a quick response (so fast you often time won’t even feel sick)
How do vaccinations work?
utilize the secondary response… your body is given an antigen from the pathogen which activates naive B cells to make memory B cells. after the second exposure your body already has antibodies to fight off the pathogen
Why do we get boosters?
some viruses mutate and antigens change just enough that memory cells no longer bind
