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New page: {{review}} {{toplink |linkpage =General Pathology |linktext =General Pathology |maplink = General Pathology (Content Map) |pagetype =Pathology |sublink1=Circulatory Disorders - Pathology ...
{{review}}
{{toplink
|linkpage =General Pathology
|linktext =General Pathology
|maplink = General Pathology (Content Map)
|pagetype =Pathology
|sublink1=Circulatory Disorders - Pathology
|subtext1=CIRCULATORY DISORDERS
}}
<br>
==What is Shock?==
* "Shock" is a clinical term to describe a condition in which:
** The body temperature is subnormal.
** Reflexes are subnormal.
** Respiration is shallow.
** There is a rapid thready pulse.
==Cause of Shock==
* The cause of shock is circulatory failure.
** This leads to impaired perfusion of tissues, resulting in inadequate cellular oxygenation.
==Types of Shock==
===Hypovolaemic shock===
* This is caused by massive reduction in circulating blood volume.
** For example, due to loss in
*** Severe haemorrhage.
*** Extensive body burns.
**** There is excessive loss of tissue fluid from the injured areas.
===Trauma, pain and major surgery===
* Trauma, pain and minor surgery affect the vasomotor control of the peripheral circulation.
* The capillaries become dilated and blood pools in the peripheral circulation.
** A secondary hypovolaemia occurs.
===Endotoxic shock===
* Endotoxic shock occurs in severe infections by Gram negative bacteria.
* The toxins produced by the bacteria are thought to induce clotting of the blood in very small vessels.
** The flow is blocked and blood pools in the peripheral tissues.
thereby blocking the flow and causing pooling of blood in the peripheral
* The condition is known as [[General Pathology - Thrombosis#Disseminated Intravascular Coagulation|Disseminated Intravascular Coagulation]].
===Cardiogenic shock===
* Cardiogenic shock occurs when a suddenly developing cardiac failure causes circulatory collapse, e.g.
** Myocardial infarction
** Severe arrhythmia
** Sudden failure of the valves.
==Pathophysiology of Shock==
* In haemorrhagic and burn shock, there is reflex vasoconstriction of the peripheral and splanchnic blood vessels.
** The body becomes starved of oxygen.
** There is no constriction of the cerebral or coronary blood vessels - this protects the brain and the heart.
* The fall in blood pressure stimulates the release of renin from the kidney.
** Angiotensin from the liver is activated.
*** Causes an increase in blood pressure.
*** Stimulates the adrenal cortex to secrete aldosterone, which causes the kidney to retain sodium and water.
*** The flow of urine may cease.
* The kidney is particularly vulnerable to shock.
** If the condition is prolonged, acute tubular necrosis will develop.
* After a sustained period of oxygen deficit, the vasomotor control over the blood vessels is lost.
** Blood becomes pooled in the capillary beds.
** This state is termed "irreversible shock" and is quickly followed by death.
==Post-Mortem Findings==
* Post-mortem findings are non-specific.
* The lungs are wet and heavy, showing congestion and oedema.
** The alveolar capillaries are distended with blood.
** The alveoli are filled with haemorrhage and oedema fluid.
* A degree of atelectasis (collapse) also develops.
* In the intestine, the blood vessels are congested and there is patchy haemorrhage of the mucosa due to localised anoxia.
** There is also a considerable amount of blood stained fluid within the lumen.
*** May be mistaken for inflammation.
* The kidneys cortex appears pale due to tubular necrosis, while the medulla is darkened by congestion.
** Histologically, the tubular epithelial cells die and fall into the lumen, the basement membranes rupture and irritant material escapes into the interstitium.
{{toplink
|linkpage =General Pathology
|linktext =General Pathology
|maplink = General Pathology (Content Map)
|pagetype =Pathology
|sublink1=Circulatory Disorders - Pathology
|subtext1=CIRCULATORY DISORDERS
}}
<br>
==What is Shock?==
* "Shock" is a clinical term to describe a condition in which:
** The body temperature is subnormal.
** Reflexes are subnormal.
** Respiration is shallow.
** There is a rapid thready pulse.
==Cause of Shock==
* The cause of shock is circulatory failure.
** This leads to impaired perfusion of tissues, resulting in inadequate cellular oxygenation.
==Types of Shock==
===Hypovolaemic shock===
* This is caused by massive reduction in circulating blood volume.
** For example, due to loss in
*** Severe haemorrhage.
*** Extensive body burns.
**** There is excessive loss of tissue fluid from the injured areas.
===Trauma, pain and major surgery===
* Trauma, pain and minor surgery affect the vasomotor control of the peripheral circulation.
* The capillaries become dilated and blood pools in the peripheral circulation.
** A secondary hypovolaemia occurs.
===Endotoxic shock===
* Endotoxic shock occurs in severe infections by Gram negative bacteria.
* The toxins produced by the bacteria are thought to induce clotting of the blood in very small vessels.
** The flow is blocked and blood pools in the peripheral tissues.
thereby blocking the flow and causing pooling of blood in the peripheral
* The condition is known as [[General Pathology - Thrombosis#Disseminated Intravascular Coagulation|Disseminated Intravascular Coagulation]].
===Cardiogenic shock===
* Cardiogenic shock occurs when a suddenly developing cardiac failure causes circulatory collapse, e.g.
** Myocardial infarction
** Severe arrhythmia
** Sudden failure of the valves.
==Pathophysiology of Shock==
* In haemorrhagic and burn shock, there is reflex vasoconstriction of the peripheral and splanchnic blood vessels.
** The body becomes starved of oxygen.
** There is no constriction of the cerebral or coronary blood vessels - this protects the brain and the heart.
* The fall in blood pressure stimulates the release of renin from the kidney.
** Angiotensin from the liver is activated.
*** Causes an increase in blood pressure.
*** Stimulates the adrenal cortex to secrete aldosterone, which causes the kidney to retain sodium and water.
*** The flow of urine may cease.
* The kidney is particularly vulnerable to shock.
** If the condition is prolonged, acute tubular necrosis will develop.
* After a sustained period of oxygen deficit, the vasomotor control over the blood vessels is lost.
** Blood becomes pooled in the capillary beds.
** This state is termed "irreversible shock" and is quickly followed by death.
==Post-Mortem Findings==
* Post-mortem findings are non-specific.
* The lungs are wet and heavy, showing congestion and oedema.
** The alveolar capillaries are distended with blood.
** The alveoli are filled with haemorrhage and oedema fluid.
* A degree of atelectasis (collapse) also develops.
* In the intestine, the blood vessels are congested and there is patchy haemorrhage of the mucosa due to localised anoxia.
** There is also a considerable amount of blood stained fluid within the lumen.
*** May be mistaken for inflammation.
* The kidneys cortex appears pale due to tubular necrosis, while the medulla is darkened by congestion.
** Histologically, the tubular epithelial cells die and fall into the lumen, the basement membranes rupture and irritant material escapes into the interstitium.