Immune system Flashcards
1st line of defense
surface barriers: skin, mucous membranes
2nd line of defense
internal defenses: cells, inflammation, proteins (interferons, complement), fever
3rd line of defense
adaptive/specific system
mucous membranes defenses
acidity, HCl in stomach, lysosyme enzyme in saliva and most fluids, mucin
3 types of phagocytes
macrophages
dendritic (free floating)/Kupffer (fixed)
neutrophils
steps of phagocytosis
i. Adherence: phagocyte adheres to pathogens or debris. Certain pathogens are able to allude adherence due to lacking receptors or having a certain chemical structure. In these cases phagocytes can put a handle on the cell and then grab the handle to pull them in “opsonization”.
ii. Phagocyte forms pseudopods that eventually engulf the particles, forming a phagosome (phagocytic vesicle that is inside the phagosome and contains the pathogenic particles).
iii. Lysosome filled with enzymes and chemicals fuses with the phagocytic vesicle forming a phagolysosome.
iv. Enzymes digest the pathogenic particles, leaving residues.
v. Exocytosis of the vesicle removes the residual material from inside the phagocyte.
respiratory/oxidative burst
vi. Some pathogens are too large or too severe to be phagocytized, instead a respiratory/oxidative burst is used where chemicals similar to bleach/peroxide are released to kill these pathogens. This usually kills the phagocytes in the process.
NK cells
type of lymphocyte
ii. Functions: looks for “not self” on the flag and destroy it
iii. Mechanism of destruction: similar to cytotoxic T-cells but not specific. Cytotoxic which damages the cell membrane. Granzymes cause cells to undergo apoptosis
functions of inflammation (4)
prevents spread, alerts adaptive immune system, disposal of debris, preparation for repair
inflammation mechanism of activation
i. Pattern recognition receptor (toll like receptors) activate
ii. Cytokines which impact another type of cell.
iii. Histamines are released: vasodilation, increases bloodflow. Also increases capillary permeability.
iv. Kinins and prostaglandins do the same thing that histamines do. Kinins also increases sensitivity to pain.
v. 20 proteins are activated “complement”.
vi. Vasodilation causes hyperemia: “a lot of blood”/redness and heat
viii. Leukocytosis-inducing factor (inflammation)
increases WBC and make them migrate to injury
margination
WBC cling to capillary walls
what helps WBC know where to exit the capillary
cellular adhesion molecules and Chemotaxins: cellular debris leading the phagocytes to the right location
selectins and integrins
xi. Endothelial tissue near the injury will sprout selectins which are cellular adhesion molecules.
xii. Phagocytes also sprout cellular adhesion molecules called integrins
pus
cellular debris in the interstitial fluid all mixed together
5 cardinal signs of inflammation
- Redness
- Heat
- Swelling
- Pain
- Impairment
interferon functions
: block protein synthesis and thus virus activity, activate macrophages and NK
complement 3 mechanisms of activation
all activate C3 (the common pathway)
ii. Classical pathway: activated by antibodies.
iii. Lectin pathway: activated by lectin binding to specific sugars on organism’s surface.
iv. Alternative pathway: activated spontaneously when lack of inhibitors on microorganism’s surface allows process to proceed.
common pathway results (OIL)
- Opsonization: coats pathogen surfaces which allows for phagocytosis through adherance.
- Enhances inflammation—more vasodilation, permeability, attraction of leukocytes
- Lysis: Membrane Attack Complex(MACs) insert into the target cell membrane, creating pores which allow for lysis (destruction) of the cell