Changes

'''''Skin'''''

'''''Skin'''''

The simplest way to avoid infection is to prevent microorganisms gaining access to the body. The skin has an external coating of dead cells (cuticle) that, when intact, is impermeable to most infectious agents.

The simplest way to avoid infection is to prevent microorganisms gaining access to the body. The skin has an external coating of dead cells (cuticle) that, when intact, is impermeable to most infectious agents as very few pathogens are capable of penetrating the thick stratified squamous epithelium of the skin (and lower urinary tract).

* Very few pathogens are capable of penetrating the thick stratified squamous epithelium of the skin (and lower urinary tract).

* However, infection becomes a problem when there is:

** Infection becomes a problem when there is:

** Skin loss:  e.g. burns

*** Skin loss:  e.g. burns

** A break in the skin: e.g. wounds

*** A break in the skin: e.g. wounds

'''''Mucous Membranes'''''

'''''Mucous Membranes'''''

* Thin epithelial surfaces are necessary for the normal physiological functions of the body's mucus membranes (ie absorption and gas exchange).They are therefore more susceptible to infection

Thin epithelial surfaces are necessary for the normal physiological functions of the body's mucus membranes (ie absorption and gas exchange).They are therefore more susceptible to infection. But it's ok as the body uses alternative protective mechanisms in these areas:

**  The body uses alternative protective mechanisms in these areas:

*  The '''mucociliary escalator''' of the respiratory tract (assisted by coughing and sneezing)

***  The '''mucociliary escalator''' of the respiratory tract (assisted by coughing and sneezing)

* '''Peristalsis, vomiting & diarrhoea''' when necessary removes microorganisms from the Gastro-Intestinal Tract

*** '''Peristalsis, vomiting & diarrhoea''' when necessary removes microorganisms from the GIT

===Biochemical Barriers===

===Biochemical Barriers===