PSIO 431 EXAM I QUESTIONS AND
ANSWERS | 2026 UPDATE | WITH
COMPLETE SOLUTION
what are commensal floras? - ✔️✔️good bacteria, antibiotics, defensins, cathelicidins
that live on skin and protect us from bad bacteria
what structures of the innate immune system are important for starting the inflammatory
process? - ✔️✔️PRRs
(t) or (f): all invertebrates and vertebrates have PRRs - ✔️✔️true
what are the functions of the *innate* immune system? (4) - ✔️✔️1) detect intruders
2) inactivate intruders
3) destroy intruders
4) remove intruders
(t) or (f): invertebrates have an innate immune system. - ✔️✔️true
what are motifs? - ✔️✔️chemical structures that are found in pathogens but not the
host itself
what are 2 examples of motifs? - ✔️✔️1) components of bacterial cell walls
2) microbial nucleic acid structures
what 3 things does the innate immune system recognize? - ✔️✔️1) foreign molecular
structures called pathogen-associated molecular patterns (PAMPs)
2) stress or damage indicator molecules expressed by body cells called damage-
associated molecular patterns (DAMPs)
3) the absence of certain normal cell surface molecules (recognition done by NK cells)
most cells in the body have some _ _ _ on their surface or on inner membranes. -
✔️✔️PRR (pattern-recognition receptor)
what is a subclass of PRRs? - ✔️✔️TLRs; unlike PRRs they are not found on every
cell, but almost every cell
,what does TLR stand for? - ✔️✔️Toll-like receptors (named after the Toll gene in the
fruit fly, which controls innate immunity in invertebrates)
what do TLRs do? - ✔️✔️they recognize foreign molecular structures that we don't
have
what starts inflammation? - ✔️✔️when a TLR binds a PAMP, it starts a signaling
cascade that leads to the expression of factors that cause inflammation
when does a cell release DAMPs? - ✔️✔️when the cell is damaged and/or stressed
what happens when TLRs bind DAMPs? - ✔️✔️it increases local inflammation
what are stimuli for acute inflammation (making cytokines)? (6) - ✔️✔️1) infections
2) trauma
3) physical/chemical agents
4) tissue necrosis
5) foreign bodies
6) immune responses
what are symptoms of acute inflammation? (5) - ✔️✔️1) redness (rubor)
2) heat (calor)
3) swelling (tumor)
4) pain (dolor)
5) loss of function
mast cell degradation leads to what? (4) - ✔️✔️1) vasodilation
2) swelling
3) clotting
4) stimulation of pain receptors
how long does it take to replace the skin? - ✔️✔️7 days
how long does it take to replace the gut lining? - ✔️✔️3 days
what is the first system to be activated when a pathogen enters the body? - ✔️✔️innate
immune system
if the innate immune system cannot get rid of the problem (pathogen), then the body
activates what system? - ✔️✔️adaptive immune system
mast cell degradation releases what substances? (2) - ✔️✔️1) histamine
, 2) cytokines
which is faster: the innate immune system or the adaptive immune system? -
✔️✔️innate immune system (adaptive immune system is slower to get started)
what is the function of histamine in helping with acute inflammation? - ✔️✔️it causes
vasodilation and leakiness
mast-cells can also synthesize what substance to help with acute inflammation? -
✔️✔️PAF
which has the greatest potential: the innate immune system or the adaptive immune
system? - ✔️✔️adaptive immune system
the complement cascade plays a role in what? - ✔️✔️acute inflamamtion
what are the 3 pathways of the complement cascade? - ✔️✔️1) lectin pathway
2) classical pathway
3) alternative pathway
all 3 pathways (classical, alternative, lectin) come together at what component? -
✔️✔️C3
which would you expect to be more serious: C1 or C3 deficiency? - ✔️✔️C3 because
C3 plays a role in 2/3 of the cascades whereas C1 only plays a role in the classical
pathway
the complement cascade results in what structure? - ✔️✔️MAC (membrane-attack
complex)
what does MAC do? - ✔️✔️it pops holes in bacterial cell walls
which pathway in the complement cascade is associated with the innate immune
system only? - ✔️✔️lectin pathway
what does the lectin pathway require? - ✔️✔️MBL
what does MBL bind? - ✔️✔️anything but us
MBL is activated by what? - ✔️✔️MASP-1 and MASP-2
what is the coagulation cascade? - ✔️✔️it plays a role in acute inflammation by
activating platelets (leading to clotting)
ANSWERS | 2026 UPDATE | WITH
COMPLETE SOLUTION
what are commensal floras? - ✔️✔️good bacteria, antibiotics, defensins, cathelicidins
that live on skin and protect us from bad bacteria
what structures of the innate immune system are important for starting the inflammatory
process? - ✔️✔️PRRs
(t) or (f): all invertebrates and vertebrates have PRRs - ✔️✔️true
what are the functions of the *innate* immune system? (4) - ✔️✔️1) detect intruders
2) inactivate intruders
3) destroy intruders
4) remove intruders
(t) or (f): invertebrates have an innate immune system. - ✔️✔️true
what are motifs? - ✔️✔️chemical structures that are found in pathogens but not the
host itself
what are 2 examples of motifs? - ✔️✔️1) components of bacterial cell walls
2) microbial nucleic acid structures
what 3 things does the innate immune system recognize? - ✔️✔️1) foreign molecular
structures called pathogen-associated molecular patterns (PAMPs)
2) stress or damage indicator molecules expressed by body cells called damage-
associated molecular patterns (DAMPs)
3) the absence of certain normal cell surface molecules (recognition done by NK cells)
most cells in the body have some _ _ _ on their surface or on inner membranes. -
✔️✔️PRR (pattern-recognition receptor)
what is a subclass of PRRs? - ✔️✔️TLRs; unlike PRRs they are not found on every
cell, but almost every cell
,what does TLR stand for? - ✔️✔️Toll-like receptors (named after the Toll gene in the
fruit fly, which controls innate immunity in invertebrates)
what do TLRs do? - ✔️✔️they recognize foreign molecular structures that we don't
have
what starts inflammation? - ✔️✔️when a TLR binds a PAMP, it starts a signaling
cascade that leads to the expression of factors that cause inflammation
when does a cell release DAMPs? - ✔️✔️when the cell is damaged and/or stressed
what happens when TLRs bind DAMPs? - ✔️✔️it increases local inflammation
what are stimuli for acute inflammation (making cytokines)? (6) - ✔️✔️1) infections
2) trauma
3) physical/chemical agents
4) tissue necrosis
5) foreign bodies
6) immune responses
what are symptoms of acute inflammation? (5) - ✔️✔️1) redness (rubor)
2) heat (calor)
3) swelling (tumor)
4) pain (dolor)
5) loss of function
mast cell degradation leads to what? (4) - ✔️✔️1) vasodilation
2) swelling
3) clotting
4) stimulation of pain receptors
how long does it take to replace the skin? - ✔️✔️7 days
how long does it take to replace the gut lining? - ✔️✔️3 days
what is the first system to be activated when a pathogen enters the body? - ✔️✔️innate
immune system
if the innate immune system cannot get rid of the problem (pathogen), then the body
activates what system? - ✔️✔️adaptive immune system
mast cell degradation releases what substances? (2) - ✔️✔️1) histamine
, 2) cytokines
which is faster: the innate immune system or the adaptive immune system? -
✔️✔️innate immune system (adaptive immune system is slower to get started)
what is the function of histamine in helping with acute inflammation? - ✔️✔️it causes
vasodilation and leakiness
mast-cells can also synthesize what substance to help with acute inflammation? -
✔️✔️PAF
which has the greatest potential: the innate immune system or the adaptive immune
system? - ✔️✔️adaptive immune system
the complement cascade plays a role in what? - ✔️✔️acute inflamamtion
what are the 3 pathways of the complement cascade? - ✔️✔️1) lectin pathway
2) classical pathway
3) alternative pathway
all 3 pathways (classical, alternative, lectin) come together at what component? -
✔️✔️C3
which would you expect to be more serious: C1 or C3 deficiency? - ✔️✔️C3 because
C3 plays a role in 2/3 of the cascades whereas C1 only plays a role in the classical
pathway
the complement cascade results in what structure? - ✔️✔️MAC (membrane-attack
complex)
what does MAC do? - ✔️✔️it pops holes in bacterial cell walls
which pathway in the complement cascade is associated with the innate immune
system only? - ✔️✔️lectin pathway
what does the lectin pathway require? - ✔️✔️MBL
what does MBL bind? - ✔️✔️anything but us
MBL is activated by what? - ✔️✔️MASP-1 and MASP-2
what is the coagulation cascade? - ✔️✔️it plays a role in acute inflammation by
activating platelets (leading to clotting)
