Changes

* The mucosa eroded to produce lesions of darkish-red submucosa covered in dry, crumbly fibrin.

* The mucosa eroded to produce lesions of darkish-red submucosa covered in dry, crumbly fibrin.

* Is usually caused by severe damage due to secondary bacterial infection following an earlier milder insult.

* Is usually caused by severe damage due to secondary bacterial infection following an earlier milder insult.

* Tends to be more severe in the lower [[Small Intestine - Anatomy & Physiology|small intestine]] and upper [[Large Intestine - Anatomy & Physiology|large intestine]].  

* Tends to be more severe in the lower [[Small Intestine Overview - Anatomy & Physiology|small intestine]] and upper [[Large Intestine - Anatomy & Physiology|large intestine]].  

** Many severe infections tend to get worse further down the gut.  

** Many severe infections tend to get worse further down the gut.  

*** Catarrhal change may be seen in the upper [[Small Intestine - Anatomy & Physiology|small intestine]] and fibrinous change in the lower [[Small Intestine - Anatomy & Physiology|small intestine]]s.

*** Catarrhal change may be seen in the upper [[Small Intestine Overview - Anatomy & Physiology|small intestine]] and fibrinous change in the lower [[Small Intestine Overview - Anatomy & Physiology|small intestine]]s.

** In the lower aprt of the bowel, where the inflammation is more severe, disease is more anaerobic.

** In the lower aprt of the bowel, where the inflammation is more severe, disease is more anaerobic.

*** Lesions are caused by anaerobic organisms- convert mild diseases into more serious disease.

*** Lesions are caused by anaerobic organisms- convert mild diseases into more serious disease.