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Flashcards in The Innate Immune System Deck (8)
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1

The immune system actually consists of 2 systems

- The innate immune system
- The adaptive immune system

2

THE INNATE IMMUNE SYSTEM OVERVIEW

- Non-specific responses
- These responses are “hard-wired”
- These responses does not change during the lifespan of the person

3

THE ADAPTIVE IMMUNE SYSTEM OVERVIEW

- Individualised responses that vary from pathogen to pathogen
- Need to be exposed to the pathogen

4

THE INNATE IMMUNE SYSTEM
2 of the major parts of the innate immune system

- Phagocytic cells
- Plasma proteins such as the complement proteins

5

Phagocytes

- White blood cells of the neutrophil and macrophage type
- Due to a combination of signals and changes in the barrier function of the capillary wall: the phagocytes leave the bloodstream and migrate to the site of infection
- They engulf infectious agents (but also dead and dying cells and cell debris) and this leads to destruction of the foreign material

6

Cytokines

- Locally released protein factors which regulates the activity of cells
- The are secreted by cells of the immune systems as well as other local non-immune cells types
- All of the cells involved in the immune response communicate via cytokines
- Cytokines stimulate or inhibit, the activity of innate and adaptive immune systems

7

THE COMPLEMENT SYSTEM

- A set of plasma proteins that circulate in their inactive form
- Each protein is named C plus a number related to the order that they were discovered
- Several possible starting points

When activated there is a cascade of activation
- The the first protein activates the second and so on…
- Activation can involve splitting the inactive protein into fragments
- Sometime the activated components combine together in a complex

8

FUNCTIONS OF THE COMPLEMENT SYSTEM

- The formation of a protein complex (the Membrane Attack Complex) on the surface of the pathogen which causes membrane lysis
- Formation of protein fragments which can stimulate other immune responses for example :
- Opsonization: coating a cell in molecules to improve the chance that is phagocytosed by immune cells
- Chemotaxis: Some complement fragments will attract immune cells out of the circulation and into the site of infection or cell damage