Author, Donkey, Bureaucrats, Administrators
53,803
edits
Changes
Created page with "* Antigenic material is transported in phagocytes via the tissue lymphatics to the local lymph node. * In the subcapsular sinusoids of the lymph node, antigens are exposed to t..."
* Antigenic material is transported in phagocytes via the tissue lymphatics to the local lymph node.
* In the subcapsular sinusoids of the lymph node, antigens are exposed to the reticular cell macrophages.
** These macrophages form a meshwork around the subcapsular, cortical and medullary sinusoids.
** These reticular cells present the antigen to the appropriate lymphocyte population.
*** To B-cells in the follicular centres
*** To T-cells in the parafollicular areas.
* When stimulated by antigen presentation, the respective areas undergo an increase in size by hperplasia.
** The lymphocytes produced later leave the lymph node to seek out the source of the antigen in the damaged portion.
* Bacteria surviving the initial local inflammatory reaction also travel to the lymph node.
** Travel either in macrophages or as a bacteraemia/septicaemia.
** In the lymph node, many bacteria are trapped, degraded and killed, or exposed to antibody produced by plasma cells in the medullary area.
** Bacteria set up an acute inflammatory response in the lymph node.
*** If they are pyogenic, baceria can produce abscessation in the lymph node.
**** E. g. Strangles.
***** An upper respiratory tract pathogen in the horse.
***** Abscesses in the cervical lymph nodes burst to the exterior.
***** Abscesses in the retropharyngeal node burst into the pharynx
***** Infection is usually localised to the head and neck, but can spread to cause abscessation elsewhere in the body.
===Bacteraemia===
* Bacteria may continue through the lymph nodes and circulate in the blood.
* These are generally cleared from the blood by other organs containing phagocytes.
** E.g. the [[Liver - Anatomy & Physiology|liver]], [[Spleen - Anatomy & Physiology|spleen]] and lungs.
* There are species differences in the ability to remove bacteria.
** In most species, the majority of clearance is carried out by the [[Liver - Anatomy & Physiology|liver]] and spleen.
** However, in the pig, the lung removes 60-80% of such bacteria.
===Septicaemia===
* Septicaemia is a condition where there are highly pathogenic bacteria circulating and rapidly multiplying in the blood.
** Accompanied by severe signs of clinical illness due to the liberation of bacterial toxins.
*** High fever
*** Rapid respiration
*** Shock
** Can result in the death of the animal.
====Gross Appearance====
* The lymph nodes, [[Liver - Anatomy & Physiology|liver]] and spleen are very hyperaemic and swollen.
====Histological Appearance====
* Capillaries in tissues taken immediately after death show bacteria in their lumens.
[[Category:Lymph Nodes]]
* In the subcapsular sinusoids of the lymph node, antigens are exposed to the reticular cell macrophages.
** These macrophages form a meshwork around the subcapsular, cortical and medullary sinusoids.
** These reticular cells present the antigen to the appropriate lymphocyte population.
*** To B-cells in the follicular centres
*** To T-cells in the parafollicular areas.
* When stimulated by antigen presentation, the respective areas undergo an increase in size by hperplasia.
** The lymphocytes produced later leave the lymph node to seek out the source of the antigen in the damaged portion.
* Bacteria surviving the initial local inflammatory reaction also travel to the lymph node.
** Travel either in macrophages or as a bacteraemia/septicaemia.
** In the lymph node, many bacteria are trapped, degraded and killed, or exposed to antibody produced by plasma cells in the medullary area.
** Bacteria set up an acute inflammatory response in the lymph node.
*** If they are pyogenic, baceria can produce abscessation in the lymph node.
**** E. g. Strangles.
***** An upper respiratory tract pathogen in the horse.
***** Abscesses in the cervical lymph nodes burst to the exterior.
***** Abscesses in the retropharyngeal node burst into the pharynx
***** Infection is usually localised to the head and neck, but can spread to cause abscessation elsewhere in the body.
===Bacteraemia===
* Bacteria may continue through the lymph nodes and circulate in the blood.
* These are generally cleared from the blood by other organs containing phagocytes.
** E.g. the [[Liver - Anatomy & Physiology|liver]], [[Spleen - Anatomy & Physiology|spleen]] and lungs.
* There are species differences in the ability to remove bacteria.
** In most species, the majority of clearance is carried out by the [[Liver - Anatomy & Physiology|liver]] and spleen.
** However, in the pig, the lung removes 60-80% of such bacteria.
===Septicaemia===
* Septicaemia is a condition where there are highly pathogenic bacteria circulating and rapidly multiplying in the blood.
** Accompanied by severe signs of clinical illness due to the liberation of bacterial toxins.
*** High fever
*** Rapid respiration
*** Shock
** Can result in the death of the animal.
====Gross Appearance====
* The lymph nodes, [[Liver - Anatomy & Physiology|liver]] and spleen are very hyperaemic and swollen.
====Histological Appearance====
* Capillaries in tissues taken immediately after death show bacteria in their lumens.
[[Category:Lymph Nodes]]