8.2 The Innate Immue System Flashcards
What are defensins?
They are an antibacterial enzyme found in the skin.
How does the gut protect against infection?
- Stomach acid kills bacteria.
- Competition from normal gut flora
What ways can the complement system be activated?
How does it work on the bacteria?
- Classical pathway: requires binding of an antibody
- Alternative pathway: does not require antibodies.
It works by essentially punching holes in the cell wall, making the osmotically unstable.
Although it can be activated by antibodies, it is considered non-specific defense because it cannot be modified to target a specific organism over others.
What are interferons?
These are products of cells that have been infected with viruses. They cause nearby cells to decrease production of both viral and cellular proteins.
They also decrease the permeability of these cells, making viruses more difficult to infect them.
They also regulate MHC class I and class II molecules, resulting in increased antigen presentations.
Responsible for many of the flu like symptoms that occur during viral infection.
What is the first cell that is activated when a bacteria attacks and what three thing happen?
Macrophages, progeny of monocytes. (microglial cells, Langerhans cells, osteoclasts)
- Phagocytizes the invader.
- Digests the invader.
- Presents peptides of the invader (antigen) to other cells using a protein called MHC or major histocompatibility complex.
What does MHC 1 do
MHC= major histocompatibility complex
MHC 1= found in all nucleated cells, bind antigens from inside the cell (like a virus). If a cell is infected with a pathogen, it can express this, and be targeted by cytotoxic T lymphocytes to be killed.
Also referred to as the endogenous pathway.
What does MHC 2 do?
MHC= major histocompatibility complex
MCH II= professional antigen presenting cells. Pick up cells from the environment that can be displayed by MCH II.
Also referred to as the exogenous pathway.
What are some specialized cells that use the exogenous pathway (i.e. MCH II)?
Macropahges, dendritic cells, some b-cells, certain activated epithelial cells.
is the MHC complex system considered part of the innate or adaptive immune system?
Innate!
What do mast cells do?
They release histamine and other chemicals that promote inflammation.
What do dendritic cells do?
They present antigens, fragments of protein or other molecules from pathogens or cancer cells- to adaptive immune cells, inducing them to attack bearers of the displayed antigen.
What do NK Cells do?
It destroys the body’s own cells that have been infected with pathogens, it also goes after cancer cells.
They target cells that have downregulated MHC molecules, either from viruses or cancer
What are toll like receptors?
They are a pattern recognition receptor (PRR) that allows the cell to recognize the category of the invader (bacteria, virus, fungus, or parasite) to allow for the production of appropriate cytokines to recruit the right type of immune cells.
How to neutrophils follow bacteria?
Using chemotaxis.
Also once the have been opsonized.
What do eosinophils release? Why is this useful?
They release histamine.
This is useful because it increases the leakiness of the blood vessels, allowing additional immune cells to move out of the bloodstream and into the tissue.
