Revision: Activation of innate mechanism of immunity

Accuracy is not guaranteed, these are my revision notes.


Question:  Give an account of the activation of innate mechanisms of immunity and evaluate its role in ensuing inflammatory processes

The human body contains many physical barriers to infection and pathogens.  Skin is a major defence barrier.  Mucosal layers in membranes such as the gut, respiratory systems, digestive systems generally,  urinary tract are all protected by the physical barrier.  Eye fluid contains bacterial enzymes.
Peptides in skin prevent bacteria and fungi from entering broken, inflamed areas.  However, at  times, things go wrong.

* Pathogen enters intratissue space
Second lines of defence are needed and the toll like receptors give a reaction. (?)

1. Phagocytes engulf pathogens.
2. Neutrophils (the most abundant type of White Blood Cell) consume pathogens and disintegrate forming pus.
3.  Macrophages - move out of the blood to occupy tissues.  Uses cytoplasmic extensions to engulf and digest.
4. Natural Killer cells (NK cells) - patrol lymph and blood looking for abnormal cells.  Uniquely they can kill your own cells if they are infected with virus or have become cancerous.
- identified by MHC1 (lack of it)
-releases enzyme into the cell to trigger apoptosis.

Internal innate defences include
1. Fever
2. Chemical signals
3. Inflammation

Inflammatory response includes
-Redness
-Swelling
-Heat
-PAin

*Mast cells in connective tissues send out histamine which causes vasodilation.  Allowing more cells to the site to fight the pathogen.
*Heat increases metabolic rate so the cells can heal themselves faster.
*Swelling - forms scabs and triggers lymphatic system which cleans up fluid.
*inflammation also attracts phagocytes and lymphocytes
- neutrophils are beginning to die off at the stage
-skin cells release leukocytosis
-if overrun by virus or serious infection, the hypothalamus raises body temperature into fever.  This also flags the liver and spleen to hold onto iron and zinc which can't contribute to bacterial growth.

When things go wrong:

HIV -

Autoimmunity - attack 'self'