shock
News •
-
What is shock in physiology?
In physiology, shock occurs when the circulatory system fails to deliver enough blood to peripheral tissues, depriving cells of oxygen and nutrients and preventing waste removal. This can lead to cell damage and, eventually, cell death.
Shock is commonly caused by massive blood loss from trauma or surgery. It can also result from reduced cardiac output, as in a heart attack, or from blood vessel dilation, as in severe infections or allergic reactions.
Symptoms include low blood pressure, rapid pulse, and cold, sweaty skin, though not all symptoms may be present. Treatment of shock involves intravenous fluids, antibiotics, or antihistamines.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What causes shock in the human body?
Shock, in physiology, is the failure of the circulatory system to provide enough blood to peripheral tissues, which impairs oxygen and nutrient delivery and waste removal. It is usually caused by hemorrhage or overwhelming infection and is characterized by a weak, rapid pulse; low blood pressure; and cold, sweaty skin.
Shock can result from sudden reductions in blood volume (as in severe hemorrhage), reduced cardiac output (as in heart attack), and blood vessel dilation (as in some infections). Massive blood loss, plasma loss from burns, and dehydration can also induce shock. Bacterial toxins, foreign substances, and drug overdoses can cause blood vessels to dilate, leading to shock.
The most common cause of shock is massive blood loss through trauma or surgery.
4 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What are the main types of shock?
Shock is a life-threatening condition that occurs when the circulatory system fails to deliver enough blood to the body's tissues and organs, leading to inadequate oxygen and nutrient supply and impaired waste removal.
Types of shock include:
* Hypovolemic shock This type results from a decrease in blood volume caused by hemorrhage, dehydration, or burns.
* Cardiogenic shock This occurs when the heart cannot pump enough blood to meet the body's needs, often due to a heart attack or other heart conditions.
* Septic shock This is caused by a severe infection that leads to widespread inflammation and blood vessel dilation.
* Anaphylactic shock This is a severe allergic reaction that causes blood vessels to dilate.4 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How does shock affect blood flow and organs?
Shock occurs when the circulatory system fails to deliver enough blood to tissues, resulting in inadequate oxygen and nutrient supply, and waste removal. Reduced blood flow through capillaries leads to cell damage and organ dysfunction.
Hemorrhage reduces venous blood return, lowering cardiac output and arterial blood pressure. The body compensates by increasing heart rate and constricting blood vessels to prioritize blood flow to essential organs. Severe blood loss overwhelms these mechanisms, causing blood pressure to drop sharply.
Inadequate blood supply to the heart muscle or noxious products from poorly perfused tissues can impair the heart's pumping action. Arteriolar constriction in shock leads to waste buildup, dilating capillary sphincters and engorging the capillary bed, reducing circulating blood volume.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What are common signs and symptoms of shock?
Shock is a state of acute circulatory failure where tissues don't receive enough blood, oxygen, and nutrients, leading to cell damage and possible death.
Common signs and symptoms include:
* Low blood pressure
* Rapid heart rate
* Pale, cold, and clammy skin
* Confusion or altered mental state
* Weakness
* Light-headedness
* Nausea or vomiting
* Reduced or absent urine output
* Rapid breathing or air hunger
* Dilated pupilsIn severe cases, shock can lead to organ failure, lactic acidosis, and metabolic acidosis. Anaphylactic shock may include itching, difficulty breathing, skin flush, and unconsciousness. Septic shock can also cause a skin rash, heart palpitations, diarrhea, and may result in long-term complications like fatigue and cognitive impairment.
3 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How is shock treated and why is quick action important?
Shock is a life-threatening condition where the circulatory system fails to deliver enough blood to tissues, leading to cell damage or death. Treatment focuses on identifying and addressing the underlying cause, as multiple factors may be involved.
If shock is caused by fluid loss, intravenous fluids are administered. In cases of bacterial infection, antibiotics are used with fluid replacement. Anaphylactic shock requires epinephrine and antihistamines. Quick action is crucial because prolonged shock can cause widespread blood clotting and toxic metabolic products to damage organs, leading to irreversible shock.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
shock, in physiology, failure of the circulatory system to supply sufficient blood to peripheral tissues to meet basic metabolic requirements for oxygen and nutrients and the incomplete removal of metabolic wastes from the affected tissues. Shock is usually caused by hemorrhage or overwhelming infection and is characterized in most cases by a weak, rapid pulse; low blood pressure; and cold, sweaty skin. Depending on the cause, however, some or all of these symptoms may be missing in individual cases.
A brief treatment of shock follows. For further discussion, see cardiovascular disease: Physiological shock.
Shock may result from a variety of physiological mechanisms, including sudden reductions in the total blood volume through acute blood losses, as in severe hemorrhage; sudden reductions in cardiac output, as in myocardial infarction (heart attack); and widespread dilation of the blood vessels, as in some forms of infection. Whatever the central physiological mechanism, the effect of shock is to reduce blood flow through the small vessels, or capillaries, where oxygen and nutrients pass into the tissues and wastes are collected for removal.
" height="20" alt="HEW Logo">
Shock is usually classified on the basis of its presumed cause, although in many cases the true cause of the peripheral circulatory insufficiency may not be apparent. The most common cause of shock is massive loss of blood, either through trauma or through surgery. In the latter case, the blood loss can be anticipated and shock prevented by providing blood transfusions during and after the operation. An acute loss of blood reduces the amount of venous blood returning to the heart, in turn reducing the cardiac output and causing a drop in arterial blood pressure. Pressure receptors, or baroreceptors, in the walls of the aorta and carotid arteries trigger physiological reflexes to protect the central circulation, increasing heart rate to boost cardiac output and constricting small blood vessels to direct blood flow to essential organs. If the blood losses continue, even these mechanisms fail, producing a sharp drop in blood pressure and overt manifestations of shock. Loss of blood plasma in burns or dehydration can also lower blood volume sufficiently to induce shock.
The heart’s output can also be reduced sufficiently to produce shock without blood loss. In coronary thrombosis, the supply of blood to the heart muscle through the coronary artery is interrupted by a blood clot or vascular constriction; the damaged muscle may then lack strength to force a normal volume out of the heart with each stroke. Again, the diminished output triggers the baroreceptors in the arteries to restrict peripheral circulation. Blood clots that block the circulation of blood to the lungs (pulmonary emboli) or increase the fluid that surrounds and cushions the heart (cardiac tamponade) can also impair the pumping of the heart sufficiently to cause shock.
The most common cause of shock by dilation of the blood vessels is massive bacterial infection, which may be further exacerbated by reductions in total blood volume caused by fluid losses secondary to the infection. Generally, toxins produced by the bacteria are the cause of the dilation. Foreign substances in the bloodstream can also produce a form of shock, called anaphylactic shock, through allergic reactions causing blood vessels to dilate. Another possible cause of shock through vascular dilation is drugs; many anesthetic drugs create a controlled shock that must be carefully monitored by adjusting dosage, and overdoses of several such drugs, including barbiturates and narcotics, produce shock symptoms.
The chief problem in treating shock is to recognize the cause of the physiological problem, as several possible causes may coexist in a single patient, especially following an accident. Failure to distinguish between shock caused by inadequate cardiac output and that caused by fluid losses reducing blood volume can result in a therapeutic dilemma, since treatments that are effective for one kind of shock will aggravate the other. Intravenous fluids are the usual treatment for shock caused by loss of blood, but adding extra fluid to the circulation can overload a damaged heart that already has a reduced output, so that the shock deepens. When the cause of shock is unclear, physicians may make a trial using intravenous fluids; if the central venous pressure rises, indicating diminished cardiac capacity, the fluids are stopped before the heart can be further compromised. Shock secondary to bacterial infection may be treated by combined fluid replacement and appropriate antibiotics, while anaphylactic shock is combated with epinephrine and antihistamines, which counter the acute allergic response.
The trusted destination for professionals, college students, and lifelong learners.
SUBSCRIBE
