Chapter 21 Immune System Flashcards
what is the definition of pathogens?
any disease-causing organism
what are the names of the two “arms” of the immune system that work together to protect the body?
innate immune system
adaptive immune system
in short terms, what is the innate immune system?
the immune system we are born with
in short terms, what is the adaptive immune system?
the immune system we acquire as we encounter pathogens
what is another name of innate immunity that helps describe some of its characteristics?
“non-specific immunity”
- all pathogens are treated the same way
- no recognition (memory) of specific or past infections
what are the pros of innate immunity?
it is always present and working to destroy most of our pathogens
what are the four categories of tools of innate immunity?
barriers
cells
antimicrobial proteins
fever
what specific barriers do the innate immunity system use?
skin
mucous membranes
what specific cells do the innate immunity system use?
phagocytes (such as neutrophils, macrophages, eosinophils, basophils)
Mast cells
natural killer cells
what is another name for adaptive immunity that helps identify its characteristics?
“specific immunity”
has the ability to recognize and remember specific pathogens
what are the pros of adaptive immunity?
has molecular recognition
has memory
is most powerful of the two
what are the cons of adaptive immunity?
takes a few days to fully activate
only initiates after failure of innate immunity
which types of organisms have innate/adaptive immunity?
all organisms have some innate immunity
only vertebrates have adaptive immunity
what are the two category of tools used by adaptive immunity?
cells
proteins
what specifically falls within the cells used by adaptive immunity?
B cells
T cells
what specifically falls within the proteins used by adaptive immunity?
antibodies
what is the first line of defense in immunity?
skin
mucous membranes
normal microbiota
what is the second line of defense in immunity?
natural killer cells
phagocytic white blood cells
inflammation
fever
antimicrobial proteins
what is the third line of defense in immunity?
T cells
B cells
antibodies
We said the adaptive immune system has “specific
molecular recognition”, how do you think a cell can
recognize that a pathogen does not belong?
Molecular recognition - proteins on surface of lymphocytes bind to “non-self” proteins.
When binding occurs, the lymphocyte recognizes that it does not belong. If it quickly attempts to but immediately releases, that means that it is “self” and does belong.
describe the strategy of the innate surface defense
prevent microbes from entering or remaining in the body
list the examples of surface barriers
skin
tears and saliva
ciliary escalator
gastric juices
urine
microbiome
what is the layer of skin that sheds keratin?
Stratum corneum
why do we shed our outermost layer of skin?
keeps microbes from colonizing
what is the function of dermcidin? where is it found?
antimicrobial peptide produced by our sweat glands
how does our sweat protect us from microbes?
low pH
lysozyme
dermcidin
how do our tears and saliva protect us?
constantly rinse out eyes and mouth
contain lysozyme
what does lysozyme do?
break down bacterial cell walls
describe the function of the ciliary escalator? What type of tissue?
mucus membranes of respiratory tract trap microbes within the pseudostratified epithelial tissue and push them out
what two things does the ciliary escalator contain that aids in microbial control?
lysozyme
defensins (antimicrobial peptide excreted by epithelial cells)
how do gastric juices function to protect us?
is apart of the “acid mantel”
maintains acidic conditions and enzymes that break down proteins
what are the organs that are considered the acid mantel?
skin
vagina
stomach
how does urine function to protect us?
flow sweeps away microbes for excretion
how does our microbiome function to protect us?
help out-compete harmful bacteria
(ex: microbiome lines the inside of the stomach in order to outcompete harmful pathogens for space)
even though our gastric juices and saliva are within our bodies, why is it still considered apart of the surface barriers?
surface barriers consist of anything that is not on a cellular level
what is the strategy of the innate internal defense?
neutralize any microbes that get past the first line of defense
what are the examples of cells responsible for innate internal defense?
neutrophils
macrophages (monocytes)
eosinophils
basophils
mast cells
natural killer cells
what are natural killer cells?
large granular lymphocytes capable of killing “self” cancer cells and virus-infected “self” cells
how do natural killer cells cause cell death?
induces target cell to undergo apoptosis (programmed cell death)
what are the two important phagocytic cells?
neutrophils (marines)
macrophages (close second)
which cell attacks pathogens first?
neutrophils
how exactly do neutrophils cause cell death?
respiratory burst - uses the toxic containing granules of neutrophil to kill bacteria before eating it
what toxins do neutrophils have in their granules?
proteases
defensins (antimicrobial peptide)
chemicals that cause hydroxyl radicals
how do macrophages come to be?
- start off as inactive monocytes
- migrate to infected tissues
- differentiate into macrophages
after the neutrophils and macrophages come to ingest pathogens, how does the adaptive immune response know to begin?
macrophage sends signals to activate the adaptive immune response
what role do eosinophils have in the innate immune defense?
attack large parasites by releasing antimicrobial peptides and signals proinflammatory signaling (histamines)
what are the functions of the granules found within basophils and mast cells? name examples for each of the types
their granules contain molecules that:
1. initiate inflammation (histamine, prostaglandins)
2. attract other immune cells (Interleukin-8)
3. have anticoagulant factors (heparin)
what is the difference between a mast cell and basophils?
basophils freely circulate in blood
mast cells are stationary in tissue
what makes natural killer cells different than T cells?
they don’t require MHC in order to target cell for destruction they’re a born killer
what are the two proteins released by natural killer cells that cause cell death?
release 2 proteins:
1. perforin
2. granzymes
what is the function of perforin? what releases it?
natural killer cell
punches holes in the target cell membrane
what is the function of granzymes? what releases it?
natural killer cells
induce the cell to undergo apoptosis (programmed cell death)
what is a complement in terms of immunity?
group of plasma proteins, which, when activated, enhance inflammatory and immune responses
(similar to a catalyst in chemistry)
where are complement proteins synthesized?
liver
what are the three ways to activate complement?
classical pathway
lectin pathway
alternative pathway
where are complement when not active?
in the blood in latent state
what does the classical pathway of complement consist of?
uses antibodies to “turn on” compliment cascade
what does the lectin pathway of complement consist of?
lectin proteins (made in the liver) bond mannose sugars in bacterial cell wall, thereby activating complement proteins
when does the alternative pathway of complement occur?
if antibodies and lectin are not present, compliment will spontaneously activate in the absence of inhibitory proteins found on human cells
in very broad terms, what are the steps of the compliment activation cascade?
domino effect
1. large fragments (b) attach to surface of foreign cell (targeting for desctruction)
2. small fragments (a) float away and act as signaling molecules