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Healing and Repair - Pathology (view source)
Revision as of 16:45, 14 September 2010
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==Introduction==
==Introduction==
* There are several factors on which the ability to heal and repair depends:
* There are several factors on which the ability to heal and repair depends:
*# '''Species'''
*# '''Species'''
==Repair==
==Repair==
* Repair occurs through one of two mechanisms:
* Repair occurs through one of two mechanisms:
** '''Regeneration'''
** '''Regeneration'''
===Regeneration===
===Regeneration===
* In mammals, only epithelial and connective tissues regenerate extensively.
* In mammals, only epithelial and connective tissues regenerate extensively.
* The ability of tissue to regenerate depends upon whether the tissue is
* The ability of tissue to regenerate depends upon whether the tissue is
====Labile Tissues====
====Labile Tissues====
* Labile tissues constantly replenish their cells throughout life.
* Labile tissues constantly replenish their cells throughout life.
** For example skin and mucous epithelia normally desquamate their outer layer of cells during life, maintaining their overall composition by division of their basal layers.
** For example skin and mucous epithelia normally desquamate their outer layer of cells during life, maintaining their overall composition by division of their basal layers.
====Stable Tissues====
====Stable Tissues====
* Stable tissues have a limited ability to replace themselves.
* Stable tissues have a limited ability to replace themselves.
* They retain the ability to
* They retain the ability to
====Permanent====
====Permanent====
* Permanent tissues have poor or no regenerative capacity.
* Permanent tissues have poor or no regenerative capacity.
* This group includes tissues in which the cells are highly specialised and generally have only one function, for example:
* This group includes tissues in which the cells are highly specialised and generally have only one function, for example:
===Replacement===
===Replacement===
* Replacement is essentially endothelial and fibrous tissue proliferation to replace severely damaged tissue.
* Replacement is essentially endothelial and fibrous tissue proliferation to replace severely damaged tissue.
** This classical dual replacement gives rise to granulation tissue.
** This classical dual replacement gives rise to granulation tissue.
===Healing by First Intention===
===Healing by First Intention===
* Healing by first intention occurs when the incised ends remain in close apposition to each other anf bacterial contamination is minimal.
* Healing by first intention occurs when the incised ends remain in close apposition to each other anf bacterial contamination is minimal.
** This may be induced by suturing.
** This may be induced by suturing.
====Process====
====Process====
* Initially, the incision ruptures the dermal blood vessels.
* Initially, the incision ruptures the dermal blood vessels.
** The exuded blood forms a fibrinous clot between and above the incision.
** The exuded blood forms a fibrinous clot between and above the incision.
====Factors Inhibiting Healing====
====Factors Inhibiting Healing====
* Factors inhibiting proper wound healing include:
* Factors inhibiting proper wound healing include:
*# '''Protein deficiency'''
*# '''Protein deficiency'''
===Healing by Second Intention===
===Healing by Second Intention===
* Healing by second intention occurs when the gap between the ends of the incision is too wide to allow close approximation of the ends.
* Healing by second intention occurs when the gap between the ends of the incision is too wide to allow close approximation of the ends.
* This process of granulation tissue repair in a large wound is also the underlying process in the repair of:
* This process of granulation tissue repair in a large wound is also the underlying process in the repair of:
====Process====
====Process====
* In comparison to healing by first intention, there is a more massive fibroblastic and endothelial proliferation in the wound which fills and repairs the defect.
* In comparison to healing by first intention, there is a more massive fibroblastic and endothelial proliferation in the wound which fills and repairs the defect.
* There is also considerable surface exudation.
* There is also considerable surface exudation.
==== Factors Inhibiting Healing====
==== Factors Inhibiting Healing====
* Several factors inhibit healing by second intention.
* Several factors inhibit healing by second intention.
*# '''Movement'''
*# '''Movement'''
====Scarring====
====Scarring====
* As the fibroblasts mature into fibrocytes, the collagen also matures and contracts and there may be extensive scar formation.
* As the fibroblasts mature into fibrocytes, the collagen also matures and contracts and there may be extensive scar formation.
** There may be considerable depression of the surface in such a scar.
** There may be considerable depression of the surface in such a scar.
==Repair in the Bones==
==Repair in the Bones==
===Causes of Fracture===
===Causes of Fracture===
* The causes of fracture fit into two distinct categories:
* The causes of fracture fit into two distinct categories:
*# '''Fracture of trauma'''
*# '''Fracture of trauma'''
===Description of a Fracture===
===Description of a Fracture===
* There are various terms to describe a fracture's appearance.
* There are various terms to describe a fracture's appearance.
* Separation of the ends of the fracture may be '''complete''' or '''incomplete'''.
* Separation of the ends of the fracture may be '''complete''' or '''incomplete'''.
===Complications===
===Complications===
* There are several possible complications that may arise in the repair of bone.
* There are several possible complications that may arise in the repair of bone.
# Inadequate immobilisation of the fractured ends will lead to incomplete repair by callus formation.
# Inadequate immobilisation of the fractured ends will lead to incomplete repair by callus formation.
# Infection delays healing due to the effects of the toxins on theproliferating cells.
# Infection delays healing due to the effects of the toxins on theproliferating cells.
#* May give rise to a systemic infection affecting the rest of the body.
#* May give rise to a systemic infection affecting the rest of the body.
==Repair in the Respiratory Tract==
==Repair in the Respiratory Tract==
* Severe damage to the alveolar wall results in fibrous tissue organisation of the entire alveolus.
* Severe damage to the alveolar wall results in fibrous tissue organisation of the entire alveolus.
* The appearance of inflammation in the respiratory tract varies with the route of entry of the agent.
* The appearance of inflammation in the respiratory tract varies with the route of entry of the agent.
===Airborne Agents===
===Airborne Agents===
* Infectious droplets tend to deposit in the anterior ventral portions of the lobes.
* Infectious droplets tend to deposit in the anterior ventral portions of the lobes.
** I.e. in the apical, cardiac and anterior portions of the diaphragmatic lobes.
** I.e. in the apical, cardiac and anterior portions of the diaphragmatic lobes.
===Blood-borne Agents===
===Blood-borne Agents===
* Blood-bourne agents tend to have a patchy distribution throughout the lung.
* Blood-bourne agents tend to have a patchy distribution throughout the lung.
* Cause '''interstitial pneumonia'''.
* Cause '''interstitial pneumonia'''.
====Circulating Toxins====
====Circulating Toxins====
* For example, "Fog Fever" in adult cattle.
* For example, "Fog Fever" in adult cattle.
** Interstitial emphysema.
** Interstitial emphysema.
====Micro-organisms====
====Micro-organisms====
* A predominantly mononuclear reaction in the alveolar wall can be caused by:
* A predominantly mononuclear reaction in the alveolar wall can be caused by:
** Viruses
** Viruses
====Parasites====
====Parasites====
* Lungworms (''Dictyocaulus vivipara'') tend to affect the dorsocaudal areas of the diaphragmatic lobes in their invasion stage as larvae in the blood.
* Lungworms (''Dictyocaulus vivipara'') tend to affect the dorsocaudal areas of the diaphragmatic lobes in their invasion stage as larvae in the blood.
* Later adult stages irritate the airways and also release larvae which are inhaled deeper into the lung.
* Later adult stages irritate the airways and also release larvae which are inhaled deeper into the lung.
===Traumatic Implantation===
===Traumatic Implantation===
* Traumatic implantation is fairly rare.
* Traumatic implantation is fairly rare.
* Initially causes a pleural inflammation, with some extension to the adjacent lung tissue.
* Initially causes a pleural inflammation, with some extension to the adjacent lung tissue.
==Repair in the Alimentary Tract==
==Repair in the Alimentary Tract==
===The Gut===
===The Gut===
* The gut is quite prone to infections.
* The gut is quite prone to infections.
** These are generally kept at bay by the profuse gut associated lymphoid tissue and the continuous movement of ingesta.
** These are generally kept at bay by the profuse gut associated lymphoid tissue and the continuous movement of ingesta.
===The Liver===
===The Liver===
* The [[Liver - Anatomy & Physiology|liver]] retains limited powers to regenerate and has considerable functional reserve.
* The [[Liver - Anatomy & Physiology|liver]] retains limited powers to regenerate and has considerable functional reserve.
* Acute inflammation is often due to viruses and bacteria.
* Acute inflammation is often due to viruses and bacteria.
===The [[Pancreas - Anatomy & Physiology|Pancreas]]===
===The [[Pancreas - Anatomy & Physiology|Pancreas]]===
* The [[Pancreas - Anatomy & Physiology|pancreas]] suffers both acute and chronic disease.
* The [[Pancreas - Anatomy & Physiology|pancreas]] suffers both acute and chronic disease.
* The acute form called acute pancreatic necrosis is the important type in dogs.
* The acute form called acute pancreatic necrosis is the important type in dogs.
==Repair in the Urinary Tract==
==Repair in the Urinary Tract==
* The kidney has a great functional reserve.
* The kidney has a great functional reserve.
** Only 30% of the tissue is required to function properly.
** Only 30% of the tissue is required to function properly.
===Glomerulonephritis===
===Glomerulonephritis===
* Glomerulonephritis and glomerular deposition of amyloid may cause loss of substantial quantities of protein into the urine.
* Glomerulonephritis and glomerular deposition of amyloid may cause loss of substantial quantities of protein into the urine.
* Oedema develops in the body, generally first in the back legs, then the ventral subcutis, and perhaps in the abdominal cavity.
* Oedema develops in the body, generally first in the back legs, then the ventral subcutis, and perhaps in the abdominal cavity.
===Pyelonephritis===
===Pyelonephritis===
* Important in the cow and sow.
* Important in the cow and sow.
** It tends to be quite acute in the sow, and chronic in the cow.
** It tends to be quite acute in the sow, and chronic in the cow.
* Arises from infection ascending the urinary tract.
* Arises from infection ascending the urinary tract.
* There is progressive loss of tissue.
* There is progressive loss of tissue.
** Starts with necrosis in the pelvic area, then the inflammation spreads up into the cortex. *P oor prognosis even with therapy.
** Starts with necrosis in the pelvic area, then the inflammation spreads up into the cortex.
*Poor prognosis even with therapy.
===Cystitis===
===Cystitis===
* Bladder inflammation.
* Bladder inflammation.
* Common in females.
* Common in females.
==Repair in the Genital Tract==
==Repair in the Genital Tract==
===Female===
===Female===
* '''Inflammation of the uterus''' in livestock can take place at two periods:
* '''Inflammation of the uterus''' in livestock can take place at two periods:
*# At service.
*# At service.
===Male===
===Male===
* '''Prostatitis'''
* '''Prostatitis'''
** Inflammation of the prostate.
** Inflammation of the prostate.
==Repair in the Central Nervous System==
==Repair in the Central Nervous System==
* '''Encephalitis'''
* '''Encephalitis'''
** Inflammation of neural tissue of the brain.
** Inflammation of neural tissue of the brain.