MICR 270 EXAM 3 QUESTIONS WITH ALL ANSWERS UPDATED
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Course
MICR 270
Institution
MICR 270
MICR 270 EXAM 3 QUESTIONS WITH ALL ANSWERS UPDATED
Physical barriers (type of immune barrier) - Answer-- Made of every structure at interface between inside and outside of body (Like skin, cilia and bodily secretions)
- Made of physical and chemical components
- Function to prevent or slow down ...
MICR 270 EXAM 3 QUESTIONS WITH
ALL ANSWERS UPDATED
Physical barriers (type of immune barrier) - Answer-- Made of every structure at
interface between inside and outside of body (Like skin, cilia and bodily secretions)
- Made of physical and chemical components
- Function to prevent or slow down invasion of pathogens
- Physical components include skin and mucous membranes (Skin provides barrier
pathogens can't cross unless breached; Mucous membranes cover body cavities and
contain specialized structures)
- Chemical components include secretions with active antimicrobial substances
Soluble barriers (type of immune barrier) - Answer-- Made of complement system and
cytokines (These macromolecules contribute to mediation of an innate immune
response)
- Complement system (Causes lysis of microbes, increased inflammatory response)
Cellular barriers (type of immune barrier) - Answer-- Made of neutrophils, macrophages,
dendritic cells and natural killer cells (These cells have critical roles in the innate
immune response like inflammation and phagocytosis)
- Primary function is to prevent or slow down invasion of pathogens
Innate immunity as first line of defence - Answer-- Operates non-specifically during early
phases of an immune response (Doesn't need prior exposure to invading pathogen)
- Fights all pathogens in same way
- Ready to be mobilized upon first signs of infection
inflammation overview - Answer-- Series of biological reactions in response to invasion
of harmful infectious agents
- It occurs as localized tissue response to injury/invasion (It has both local and systemic
effects within body)
- Characterized by redness, heat, pain, swelling
- Its purpose is to localize and eliminate the invading pathogen (Prevents pathogen from
spreading; Removes harmful stimuli - damaged cells, irritants or pathogens)
Breach (inflammatory response step) - Answer-- Pathogens need to find a breach in the
sealed physical barrier to enter the body (A wound provides such a breach → it will
damage cells and give pathogens opportunity to break through physical barrier)
Vasodilation (inflammatory response step) - Answer-- First major event in inflammation
,- Increase in diameter of blood vessels and permeabilization of capillaries near affected
area (Redness and heat are consequence of a higher blood volume around the area of
the infected tissue)
- These physiological changes are induced by vasoactive and chemotactic factors
(Damaged tissues and activated immune cells secrete these factors)
Permeabilization (inflammatory response step) - Answer-- Vasodilation causes
increased capillary permeability, causing entrance of fluids in tissues
- Coupled with vasoconstriction of vessels carrying blood away from affected area,
excess fluid (exudate) accumulates at infection site (A consequence of this is the
swelling characteristic of inflammation (edema))
- Exudate has proteins which help mediate the inflammatory response (Has pro-
inflammatory cytokines, specifically chemokines; Has complement proteins)
- Complement proteins are activated in presence of extracellular pathogens (They
function to attract the key players of the cellular barrier to the infection site)
Extravasation (inflammatory response step) - Answer-- Chemotactic factors induce
recruitment of more immune cells to infection site (These factors were released by cells
in vasodilation and permeabilization)
- Neutrophils are first cell type to arrive by chemotaxis
- When neutrophils circulate in blood to get to infection site, they adhere to endothelial
walls (this process is called margination)
- They then migrate between capillary-endothelial cells into infected tissue (This process
is called extravasation/diapedesis)
Phagocytosis (inflammatory response step) - Answer-- At infection site, neutrophils and
other phagocytes engulf pathogens (Other phagocytes include macrophages and
dendritic cells)
- Phagocytosis is one of the main processes used by innate immune cells to destroy
extracellular pathogens
Order of events in the immune response - Answer-- Breach
- Vasodilation
- Permeabilization
- Chemotaxis
- Margination
- Extravasation/diapedesis
- Phagocytosis
Pattern recognition receptors - Answer-- Innate immune cell receptors
- Capable of recognizing repeated molecular patterns of pathogens (Molecular patterns
can be PAMPs or DAMPs)
- Various families: most studied are Toll Like Receptors/TLRs
- Can be expressed by both innate and adaptive immune cells (However they are an
integral signalling component of innate immunity)
, Repeated molecular patterns (overview) - Answer-- Those recognized by PRRs are
conserved motifs
- Certain subsets can be found in various pathogen groups, called pathogen-associated
molecular patterns/PAMPs (Another category is called danger-associated molecular
patterns (DAMPs))
- Both types of molecular pattern are critical in innate immune cells ability to recognize
invaders
Pathogen Associated Molecular Patterns (PAMPs) - Answer-- Molecules associated
with pathogen groups recognized by immune cells (Include functional structures of a
pathogen; Include repeated sequences (protein, lipoprotein etc.) conserved across
specific groups of microbes; Enables quick infection response by inducing innate
immune response)
- These patterns are not found in host cells
- Molecular structures either expressed on surface, or found inside pathogens (LPS is
found on cell surface of bacteria, dsRNA found inside viruses; Other Examples: PG,
flagellin, other viral nucleic acids)
Damage/Danger Associated Molecular Patterns (DAMPs) - Answer-- Molecules
released by stressed cells undergoing necrosis
- They are host biomolecules (They indicate damage to the body, and initiate an
inflammatory response)
- Examples: abnormal location of a cell structure, cell-stress indicator molecules
(Abnormal location can be DNA found outside of mitochondria or nucleus; Example of
cell-stress indicator molecules are heat-shock proteins)
Toll-Like Receptors (TLRs) - Answer-- Class of PRRs whose signalling plays critical role
in innate immune response
- Expressed either on plasma membrane or endosomal/lysosomal membranes of
mammalian cell
- Upon activation, they initiate transcription of genes encoding for inflammatory
cytokines, chemokines and costimulatory molecules
- Have 2 major roles: recognize PAMPs and/or DAMPs, induce expression of signaling
to activate T-cells
Phagocytosis overview - Answer-- It is a type of endocytosis (Cell takes up material
from environment by invaginating its membrane to form a vacuole)
- Can be induced from recognition of a PAMP by a phagocyte through its PRR (Can
also be induced by pathogen opsonization)
- Neutrophils, macrophages and dendritic cells are the main innate immune cells with
phagocytic functions (They are involved in maintaining the cellular barrier)
- Next line of defence after breach and pathogen recognition
Primary lymphoid organs - Answer-- Thymus
- Bone Marrow
Secondary lymphoid organs - Answer-- Spleen
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