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Introduction to General Pathology (view source)
Revision as of 20:47, 13 August 2009
, 20:47, 13 August 2009New page: {{review}} {{toplink |linkpage =General Pathology |linktext =General Pathology |maplink = General Pathology (Content Map) |pagetype =Pathology }} <br> ==An Introduction to General Patholog...
{{review}}
{{toplink
|linkpage =General Pathology
|linktext =General Pathology
|maplink = General Pathology (Content Map)
|pagetype =Pathology
}}
<br>
==An Introduction to General Pathology==
* The term '''pathology''' is derived from:
** '''Pathos''', or suffering
** '''Logos''', or reasoning/logic.
* Pathology is defined as the study of disease including:
** '''Aetiology''' - causal factor(s)
** '''Pathogenesis''' - the development of the disease within the body.
** '''Lesions''' - the observable structural changes in the tissues and fluids of the body.
** '''Pathophysiology''' - the functional changes in diseased tissues.
** '''Sequel''' - the consequences of the disease in the body.
** '''Remote effects''' - the effect of disease in one tissue on other tissues in the body.
==Lesions==
* Lesions are the abnormalities or changes seen in living tissues due to disease.
* Observed in
** The live animal
** Tissues surgically removed from the live animal
*** Biopsy/ excision
** Animals soon after death
*** Necropsy, post-mortem examination.
===[[General Pathology - Recognition and Description of Lesions|Description of Lesions]]===
* Descriptions of lesions is very important
* Whole organs, tissues or individual lesions are described under headings such as
*# Size
*# Shape
*# Colour
*# Weight
*#* Generally in relation to body weight
*# Texture and Consistency
*# Appearance of the cut surface
*# Contents of hollow organs
*# Position, relationships and effects on adjacent tissues
==Disease==
===Definition and Type===
* '''Disease''' is a definite morbid (illness producing) process, having a characteristic train of symptoms or signs.
** May affect the whole body or any of its parts.
** The disease's aetiology, pathology and prognosis may be known or unknown.
* There are two main categories of disease.
*# '''Acute'''
*#* Characterised by sudden onset and short duration.
*#* The outcome of acute disease may be:
*#** Death
*#** Resolution due to host defence response or clinical therapy
*#** Progression to chronic disease
*# '''Chronic'''
*#* Characterised by insidious onset and protracted course.
*#* The outcome of chronic disease may be:
*#** Progressive destruction of tissue
*#*** Compromises function and endangers life,
*#** The halting of the course of disease, with tissue repair by scarring.
===Factors Involved in the Development of Disease===
* There are three factors which conspire with each other to produce disease.
*# '''The individual animal'''.
*#* In particular, the animal's nutritional and immune status
*#** This is modified by:
*#*** Recent or concurrent disease
*#*** Previous exposure to the agent(s) responsible
*# '''The disease-causing agent(s)'''.
*#* Most do not cause a uniform pattern of disease
*#** Host defences are important in determining the presentation of the disease.
*#* An agent's capacity to produce disease depends upon:
*#** The dose
*#** The virulence of the agent
*#* Several agents may be involved.
*#** Usually one agent debilitates, allowing others to exert a greater effect within the body
*#* The presence of an agent does not necessarily mean it is the cause of the disease!
*#* A pathogenic agent may be absent from the tissues, due to:
*#** Clinical therapy
*#** Host defence systems
*# '''Environment''', for example:
*#* Overcrowding of animals
*#* Mixing animals from differing origins
*#** Carriers are allowed to infect susceptible animals.
*#*** Carriers are animals which harbour the pathogenic agent but do not show signs of disease.
*#* Changes in management routine
===Types of Agents Causing Disease===
# '''Infectious organisms'''
#* [[Viruses|Viruses]]
#* [[Bacteria|Bacteria]]
#* [[Fungi|Fungi]]
#* [[Parasites|Parasites]]
# '''Physical'''
#* Trauma
#* Pressure
#* Heat
#* Cold
#* Radiation
# '''Chemical'''
#* Toxic organic and inorganic substances
#* Toxins produced by infectious organisms
# '''Nutritional'''
#* Deficiencies of vitamins and trace elements
#* Excess vitamins and trace elements
# '''[[Congenital and Neonatal Disease - Pathology|Genetic defects]]'''
#* There is a very wide range of potential defects.
#** Some are incompatible with life
#** Others affect specific systems within the body
===Aspects of Disease===
* There are many aspects of a disease that must be considered in order to understand it in full.
*# '''Incidence'''
*#* How much of the disease is present?
*#* Where is the disease found?
*#* In what species is the disease seen?
*# '''Aetiology'''
*#* Causal agent(s)
*#* Predisposing factors
*# '''Transmission'''
*#* How is the disease spread between individuals?
*#* Is the disease zoonotic?
*# '''Pathogenesis'''
*#* How the causal agent(s) exert their effect within the body.
*# '''Diagnosis'''
*#* History
*#* Clinical findings
*#** Clinical examination
*#** Clinical pathology
*#* Biopsy or post-mortem examination
*# '''Prognosis and Treatment'''
*# '''Control and Prevention'''
*#* The ideal situation
==Post-Mortem Examination==
* Post-mortem examination (PME) investigates the observable structural changes in the animal.
* Information relating to the disease within the body or specific tissue is gained from PME.
** This includes information on the disease's
*** Aetiology (cause).
*** Pathogenesis (development).
* Several types of [[General Pathology - Post-Mortem Change|changes]] are encountered at post-mortem examination.
*# Those due to the '''disease'''
*#* Lesions
*# Those occuring '''immediately prior to death'''
*#* [[General Pathology - Post-Mortem Change#Agonal Changes|Agonal]]
*# Those occuring '''after death'''
*#* Post-mortem
==Techniques Involved in Pathological Examination==
* '''Fluid examination'''
** E.g. blood, urine, discharges from orifices and so on.
* '''Cytology'''
** Examination of cells in smears, aspirates and fluids.
* '''Necropsy'''
** Visual examination of the gross changes in the dead body.
* '''Histopathology'''
** Microscopic examination of:
*** Tissues selected from the dead body after necropsy.
*** Biopsy/excision materials from lesions in the living animal.
* '''Histochemistry'''
** Microscopic visualisation of enzymatic activity in tissues.
* '''Immunological methods'''
** Specific antibody activity can be detected in tissues and fluids.
*** Examination of serum can show prior exposure to a particular infectious agent (i.e. specific antibodies).
** Specific antigens can be detected in tissues.
*** When linked to a marking agent (e.g. a fluorescent dye), an antibody can localise its antigen in the tissue.
* '''Electronmicroscopy'''
** Electronmicroscopy shows fine detail of the surfaces or internal structures of cells.
* '''Bacteriology/ Virology/ Parasitology'''
** These techniques allow the isolation and identification of pathogenic bacteria, viruses and parasites.
* '''Toxicology'''
** Analysis of tissues for particular poisons and toxins.
{{toplink
|linkpage =General Pathology
|linktext =General Pathology
|maplink = General Pathology (Content Map)
|pagetype =Pathology
}}
<br>
==An Introduction to General Pathology==
* The term '''pathology''' is derived from:
** '''Pathos''', or suffering
** '''Logos''', or reasoning/logic.
* Pathology is defined as the study of disease including:
** '''Aetiology''' - causal factor(s)
** '''Pathogenesis''' - the development of the disease within the body.
** '''Lesions''' - the observable structural changes in the tissues and fluids of the body.
** '''Pathophysiology''' - the functional changes in diseased tissues.
** '''Sequel''' - the consequences of the disease in the body.
** '''Remote effects''' - the effect of disease in one tissue on other tissues in the body.
==Lesions==
* Lesions are the abnormalities or changes seen in living tissues due to disease.
* Observed in
** The live animal
** Tissues surgically removed from the live animal
*** Biopsy/ excision
** Animals soon after death
*** Necropsy, post-mortem examination.
===[[General Pathology - Recognition and Description of Lesions|Description of Lesions]]===
* Descriptions of lesions is very important
* Whole organs, tissues or individual lesions are described under headings such as
*# Size
*# Shape
*# Colour
*# Weight
*#* Generally in relation to body weight
*# Texture and Consistency
*# Appearance of the cut surface
*# Contents of hollow organs
*# Position, relationships and effects on adjacent tissues
==Disease==
===Definition and Type===
* '''Disease''' is a definite morbid (illness producing) process, having a characteristic train of symptoms or signs.
** May affect the whole body or any of its parts.
** The disease's aetiology, pathology and prognosis may be known or unknown.
* There are two main categories of disease.
*# '''Acute'''
*#* Characterised by sudden onset and short duration.
*#* The outcome of acute disease may be:
*#** Death
*#** Resolution due to host defence response or clinical therapy
*#** Progression to chronic disease
*# '''Chronic'''
*#* Characterised by insidious onset and protracted course.
*#* The outcome of chronic disease may be:
*#** Progressive destruction of tissue
*#*** Compromises function and endangers life,
*#** The halting of the course of disease, with tissue repair by scarring.
===Factors Involved in the Development of Disease===
* There are three factors which conspire with each other to produce disease.
*# '''The individual animal'''.
*#* In particular, the animal's nutritional and immune status
*#** This is modified by:
*#*** Recent or concurrent disease
*#*** Previous exposure to the agent(s) responsible
*# '''The disease-causing agent(s)'''.
*#* Most do not cause a uniform pattern of disease
*#** Host defences are important in determining the presentation of the disease.
*#* An agent's capacity to produce disease depends upon:
*#** The dose
*#** The virulence of the agent
*#* Several agents may be involved.
*#** Usually one agent debilitates, allowing others to exert a greater effect within the body
*#* The presence of an agent does not necessarily mean it is the cause of the disease!
*#* A pathogenic agent may be absent from the tissues, due to:
*#** Clinical therapy
*#** Host defence systems
*# '''Environment''', for example:
*#* Overcrowding of animals
*#* Mixing animals from differing origins
*#** Carriers are allowed to infect susceptible animals.
*#*** Carriers are animals which harbour the pathogenic agent but do not show signs of disease.
*#* Changes in management routine
===Types of Agents Causing Disease===
# '''Infectious organisms'''
#* [[Viruses|Viruses]]
#* [[Bacteria|Bacteria]]
#* [[Fungi|Fungi]]
#* [[Parasites|Parasites]]
# '''Physical'''
#* Trauma
#* Pressure
#* Heat
#* Cold
#* Radiation
# '''Chemical'''
#* Toxic organic and inorganic substances
#* Toxins produced by infectious organisms
# '''Nutritional'''
#* Deficiencies of vitamins and trace elements
#* Excess vitamins and trace elements
# '''[[Congenital and Neonatal Disease - Pathology|Genetic defects]]'''
#* There is a very wide range of potential defects.
#** Some are incompatible with life
#** Others affect specific systems within the body
===Aspects of Disease===
* There are many aspects of a disease that must be considered in order to understand it in full.
*# '''Incidence'''
*#* How much of the disease is present?
*#* Where is the disease found?
*#* In what species is the disease seen?
*# '''Aetiology'''
*#* Causal agent(s)
*#* Predisposing factors
*# '''Transmission'''
*#* How is the disease spread between individuals?
*#* Is the disease zoonotic?
*# '''Pathogenesis'''
*#* How the causal agent(s) exert their effect within the body.
*# '''Diagnosis'''
*#* History
*#* Clinical findings
*#** Clinical examination
*#** Clinical pathology
*#* Biopsy or post-mortem examination
*# '''Prognosis and Treatment'''
*# '''Control and Prevention'''
*#* The ideal situation
==Post-Mortem Examination==
* Post-mortem examination (PME) investigates the observable structural changes in the animal.
* Information relating to the disease within the body or specific tissue is gained from PME.
** This includes information on the disease's
*** Aetiology (cause).
*** Pathogenesis (development).
* Several types of [[General Pathology - Post-Mortem Change|changes]] are encountered at post-mortem examination.
*# Those due to the '''disease'''
*#* Lesions
*# Those occuring '''immediately prior to death'''
*#* [[General Pathology - Post-Mortem Change#Agonal Changes|Agonal]]
*# Those occuring '''after death'''
*#* Post-mortem
==Techniques Involved in Pathological Examination==
* '''Fluid examination'''
** E.g. blood, urine, discharges from orifices and so on.
* '''Cytology'''
** Examination of cells in smears, aspirates and fluids.
* '''Necropsy'''
** Visual examination of the gross changes in the dead body.
* '''Histopathology'''
** Microscopic examination of:
*** Tissues selected from the dead body after necropsy.
*** Biopsy/excision materials from lesions in the living animal.
* '''Histochemistry'''
** Microscopic visualisation of enzymatic activity in tissues.
* '''Immunological methods'''
** Specific antibody activity can be detected in tissues and fluids.
*** Examination of serum can show prior exposure to a particular infectious agent (i.e. specific antibodies).
** Specific antigens can be detected in tissues.
*** When linked to a marking agent (e.g. a fluorescent dye), an antibody can localise its antigen in the tissue.
* '''Electronmicroscopy'''
** Electronmicroscopy shows fine detail of the surfaces or internal structures of cells.
* '''Bacteriology/ Virology/ Parasitology'''
** These techniques allow the isolation and identification of pathogenic bacteria, viruses and parasites.
* '''Toxicology'''
** Analysis of tissues for particular poisons and toxins.