L32 Innate Immunity 2

Vocabulary flashcards based on the lecture notes.

Inflammatory Response (student steps on nail)

Mast cells degranulate, send signals attracting more cells to site of injury or infection. Neutrophils enter blood from bone marrow, cling to capillary wall. Mast cells dilate blood vessels so capillaries are leakier. Neutrophils change shape and ‘leak’ through, follow chemical trail to injury site.

Phagocytosis

The process by which cells in the blood ingest and destroy microbes.

Step 1 phagocytosis

Phagocyte adheres to pathogen or disease.

Step 2 phagocytosis

Phagocytes form pseudopods that eventually engulf the particles, forming a phagosome (phagocycitic vesicle).

Step 3 phagocytosis

Lysosome fuses with phagosome forming phagolysosome.

Step 4 phagocytosis

Toxic compounds and lysosomal enzymes destroy pathogens.

Step 5 phagocytosis

Exocytosis of the vesicle removes indigestible and residual material (sometimes).

Phagosome

A phagocytic vesicle formed when a phagocyte engulfs particles.

Phagolysosome

The structure formed when a lysosome fuses with a phagocytic vesicle.

Lysosome importance

Low pH (acidic), reactive oxygen (hydrogen peroxide) and reactive nitrogen intermediates (niitric oxide). Contains enzymes (proteases, lipases, and nucleases) tha digest proteins, fats, and nucleic acids. Hostile environment.

Complement

A system of 9 major proteins/protein complexes (C1-9) that act in sequence to clear pathogens from blood and tissues. (innactive proteins that float around blood)

Complement pathways (triggers)

Classical, alternative and lectin. Triggers activity in component of complement pathway.

classical pathway

antibody bound to pathogen binds complement

alternative pathway

pathogen binds complement to surface/pathogen component.

lectin pathway

carbohydrate components of microbes bind complement.

Complement pathway outcomes

Label, destroy, recruit. Triggers could lead to any of these outcomes.

Label (Opsonisation)

Coating of a microbe with antibody and/or complement fragment C3b to label pathogens which bind to complement receptors on phagocytes (Eat me on its back)

C3 Convertase

Enzyme complex in complement pathways that triggers amplification. (middle of pathway)

Destroy- Membrane Attack Complex (MAC)

Pores in bacterial cells, formed from activated complement components (C5b and C6-C9) that insert into target cell membrane and allow water and ions to rush in (lysis/death).

Recruit

Phagocytes attracted into site, mast cells degranulate by C3a and C5a, inflammatory mediators released (including proteins that attract phagocytes).