Difference between revisions of "Host invasion by microorganisms"

From WikiVet English
Jump to navigation Jump to search
 
(28 intermediate revisions by 7 users not shown)
Line 1: Line 1:
{{toplink
+
===Introduction===
|backcolour = FFE4E1
 
|linkpage =WikiBlood
 
|linktext =WIKIBLOOD
 
|maplink = Haematopoiesis and Blood Cells (Concept Map) - WikiBlood
 
|tablelink = Haematopoiesis and Blood Cells (Table) - WikiBlood
 
|sublink1 =Immunology - WikiBlood
 
|subtext1 =IMMUNOLOGY
 
|pagetype =Blood
 
}}
 
 
 
=Introduction=
 
  
 
One of the main causes of disease is infection by microorganisms, with four types so far identified:
 
One of the main causes of disease is infection by microorganisms, with four types so far identified:
*Viruses
+
*[[Viruses]]
*Bacteria
+
*[[Bacteria]]
*Fungi
+
*[[Fungi]]
*Parasites- comprising protozoa and helminths
+
*[[Parasites]]- comprising [[protozoa]] and [[helminths]]
  
 +
A fifth controversial type are Pirons, which are infectious proteins that are believed to be the cause of bovine spongiform encephalopathy (BSE) and the human variant  Creutzfeldt–Jakob disease (vCJD).<br />
 +
<br />
 
All exist as either:
 
All exist as either:
 
*Primary pathogens ('''obligate'''): presence always corresponds with disease
 
*Primary pathogens ('''obligate'''): presence always corresponds with disease
Line 27: Line 18:
 
*'''Orofecal''':typically enteric infections
 
*'''Orofecal''':typically enteric infections
  
 +
{{Learning
 +
|flashcards = [[Host Invasion by Microorganisms Flashcards|Host Invasion Flashcards]]
 +
}}
  
=[[Viruses - WikiBlood|Viruses]]=
+
===References===
 +
*<div id="Janeway">{{citation|initiallast = Murphy|initialfirst = K|2last = Travers|2first = P|finallast = Walport|finalfirst = M|year = 2008|title = Janeway's Immunobiology|ed = 7th |city = New York|pub = Garland Science Publishing}}</div>
  
=[[Bacteria - WikiBlood|Bacteria]]=
+
*http://www.cellsalive.com
[[Image:Bacterial structure.png|thumb|right|150px|Bacteria Structure - Wikimedia Commons 2008]]
 
==Structure==
 
Bacteria offer the immune system a greater range of foreign components with which to be recognized, including:
 
*Flagellum
 
*Pili
 
*Capsule
 
*Cellular components: membrane, cell sap containing enzymes, genetic material, cell wall
 
  
==Pathogenesis==
 
Bacterial invasion can be either:
 
*'''Localized''', such as an '''abscess'''
 
*'''Systemic''', such as '''septicemia'''
 
  
Some bacteria also produce toxins:
+
{{review}}
*'''Endotoxogenic''': cell wall degradation products (lipopolysaccharide) released into the blood stream, causing toxic shock
+
<br><br>
*'''Exotoxogenic''': bacteria produce and secrete toxin (such as tetanus and botulism)
+
{{Jim Bee 2007}}
 
+
[[Category:Immunology]]
==Replication==
 
The lifespan of bacteria differs from that of viruses in that it includes a '''colonization''' phase, which occurs on epithelial surfaces.  As bacteria are capable of self-replication (i.e. they don't require host cellular machinery), this colonization phase allows them to develop a highly skilled and lethal army before invading the body.  Once invasion occurs, spread can occur via the vascular or lymphatic systems.  The pathogenesis of a particular strain of bacteria very much depends upon its location in the body: "''Streptococcus pneumoniae'' in the lung causes pneumonia...whereas in the blood it causes a rapidly fatal systemic illness, pneumoncoccal sepsis." (Murphy, et al, 43)
 
 
 
==Immunity to Bacteria==
 
*Bacterial evasion of immunity
 
**Bacterial capsules can avoid phagocytosis and complement activation
 
**Some bacteria are able to survive phagocytosis and evade digestion (such as mycobacterium and ''Leptospira'')
 
 
 
*[[Innate Immune System - WikiBlood#Innate Immunity to Bacteria|Innate Immunity to Bacteria]]
 
*Adaptive Immunity to Bacteria:
 
Phagocytosis and digestion are the primary tools of the Immune System to conquering bacterial infection.  These are enhanced by the production of [[Immunoglobulin G - WikiBlood|IgG]] and CD8+ Tcells, as well as by [[Complement - WikiBlood|complement]] activation.
 
 
 
==Prevention and control==
 
'''Antibiotics''' can be used to prevent and control bacterial invasion, replication, and dissemination.
 
 
 
=[[Parasites - WikiBlood|Parasites]]=
 
 
 
==Types==
 
Parasites broadly include:
 
*Helminths (worms)
 
*Arthropods (insects)
 
*Protozoa (single-celled eukaryotes)
 
 
 
==Immunity to Parasites==
 
The immune system relies on granulocytes ([[Mast Cells - WikiBlood|mast cells]] and [[Eosinophils - WikiBlood|eosinophils]]) and the production of [[Immunoglobulin E - WikiBlood|IgE]] antibody to combat parasitic infection.  Once produced in response to danger signals, IgE attaches to circulating granulocytes.  IgE then binds to the parasite, signals mast cell and eosinophil degranulation, and causes enzymatic digestion of the intruder.
 
 
 
=References=
 
*<div id="Janeway">{{citation|initiallast = Murphy|initialfirst = K|2last = Travers|2first = P|finallast = Walport|finalfirst = M|year = 2008|title = Janeway's Immunobiology|ed = 7th |city = New York|pub = Garland Science Publishing}}</div>
 

Latest revision as of 09:28, 24 May 2012

Introduction

One of the main causes of disease is infection by microorganisms, with four types so far identified:

A fifth controversial type are Pirons, which are infectious proteins that are believed to be the cause of bovine spongiform encephalopathy (BSE) and the human variant Creutzfeldt–Jakob disease (vCJD).

All exist as either:

  • Primary pathogens (obligate): presence always corresponds with disease
  • Secondary (opportunistic): prerequisites must be fulfilled before disease occurs

Microorganisms can enter the body by three routes:

  • Contact: typically seen in dermatological infections
  • Aerosol: typically respiratory infections
  • Orofecal:typically enteric infections


Host invasion by microorganisms Learning Resources
FlashcardsFlashcards logo.png
Flashcards
Test your knowledge using flashcard type questions
Host Invasion Flashcards


References

  • Murphy, K., Travers, P. and Walport, M. (2008) Janeway's Immunobiology. 7th ed. New York: Garland Science Publishing.





LIVE logo Originally funded by the RVC Jim Bee Award 2007