Circulatory Shock Lecture 3

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Questions and Answers

What is defined as the stage when no therapy can save a person's life?

Reversible shock

Irreversible shock (correct)

Mild shock

Compensated shock

What is the primary benefit of the head-down position in treating shock?

Reduces blood volume.

Promotes venous return. (correct)

Decreases heart rate.

Increases respiratory rate.

What occurs when positive feedback in shock is mild?

It causes immediate death.

It triggers irreversible shock.

Negative feedback can help recovery. (correct)

It leads to inevitable deterioration.

Which type of drug mimics sympathetic stimulation when treating shock?

Sympathomimetic drugs Signup and view all the answers

Why is oxygen therapy important in the treatment of shock?

It addresses oxygen delivery deficiencies to tissues. Signup and view all the answers

What is the primary function of baroreceptor reflexes in nonprogressive shock?

To stimulate sympathetic circulation Signup and view all the answers

Which compensatory mechanism helps return blood volume to normal during shock?

Absorption of fluid from the intestinal tract Signup and view all the answers

Which of the following best describes progressive shock?

It results from a vicious circle of cardiovascular deterioration Signup and view all the answers

What role does angiotensin play in nonprogressive shock?

It constricts peripheral arteries Signup and view all the answers

In nonprogressive shock, what signals lead to increased thirst and appetite for salt?

Hormonal changes due to kidney function Signup and view all the answers

How does reverse stress-relaxation contribute to shock recovery?

By contracting blood vessels around diminished volume Signup and view all the answers

What is a critical consequence of cardiac depression in progressive shock?

Decreased coronary blood flow Signup and view all the answers

What happens when compensatory mechanisms fail in nonprogressive shock?

Additional shock occurs Signup and view all the answers

What does the term 'shock' refer to in a physiological context?

A situation where blood flow to organs and tissues is insufficient, causing damage. Signup and view all the answers

Which type of shock is characterized by decreased blood volume?

Hypovolemic shock. Signup and view all the answers

What is a primary physiological cause of shock?

Decreased cardiac output. Signup and view all the answers

What describes low-resistance shock?

A decrease in total peripheral resistance. Signup and view all the answers

Which factor is a common cause of decreased venous return?

Diminished blood volume. Signup and view all the answers

Which condition is NOT typically classified as a cause of cardiogenic shock?

Sepsis. Signup and view all the answers

What is one of the required elements to cause shock in the circulatory system?

The heart, blood vessels, or blood can be affected. Signup and view all the answers

Which type of shock can be triggered by an allergic reaction?

Low-resistance shock. Signup and view all the answers

In the progressive stage of shock, what is the expected outcome without therapy?

The individual becomes increasingly worse and can lead to death. Signup and view all the answers

Which physiological response occurs during sympathetic reflex compensations in shock?

Constriction of arterioles. Signup and view all the answers

What characterizes the nonprogressive stage of shock?

Normal circulatory mechanisms enable recovery without outside help. Signup and view all the answers

What is one major effect of increased sympathetic stimulation during shock?

Increased heart rate. Signup and view all the answers

How does sympathetic stimulation affect blood flow to the heart and brain?

It leads to increased flow due to autoregulation. Signup and view all the answers

What ultimately characterizes the irreversible stage of shock?

All known therapies are ineffective despite continued life. Signup and view all the answers

What is the consequence of the sympathetic reflex response to decreased arterial pressure?

Enhanced sympathetic nervous system activity leading to widespread vasoconstriction. Signup and view all the answers

Which statement accurately describes blood flow autoregulation during shock?

It maintains consistent flow in critical regions like the heart and brain. Signup and view all the answers

Study Notes

Definition of Shock

Shock is a state where decreased blood flow to organs and tissues causes damage due to insufficient oxygen and nutrient supply.
Arterial pressure may be low, but not always, during shock.

Physiological Causes of Shock

Inadequate cardiac output is the primary driver of shock.
Cardiac abnormalities, like myocardial infarction, reduce heart's pumping ability.
Decreased venous return can arise from:
- Diminished blood volume.
- Decreased vascular tone in venous reservoirs.
- Obstruction of blood flow.

Classification of Shock

Hypovolemic Shock: Caused by a decrease in blood volume (e.g., hemorrhage, plasma loss from burns).
Low-resistance Shock: Involves decreased total peripheral resistance due to excessive vasodilators (e.g., in allergies and infections).
Cardiogenic Shock: Results from a marked decrease in cardiac output, often seen during heart attacks.

Stages of Shock

Nonprogressive Stage: Compensated stage where the body’s mechanisms allow recovery without any external intervention.
Progressive Stage: Shock worsens without treatment, leading towards potential death.
Irreversible Stage: Shock's progression renders all known therapies ineffective, leading to death even if the patient is still alive at that moment.

Body Responses to Shock

Sympathetic reflex compensations activate due to decreased arterial pressure, stimulated by baroreceptors:
- Constriction of arterioles increases total peripheral resistance.
- Vein constriction helps maintain venous return.
- Increased heart activity can elevate heart rate significantly (up to 160-180 beats/min).

Impact of Sympathetic Stimulation

Sympathetic stimulation does not greatly constrict blood flow to coronary and cerebral vessels, preserving local blood flow through autoregulation.

Compensatory Mechanisms in Nonprogressive Shock

Baroreceptor reflexes stimulate sympathetic circulation.
Reverse stress-relaxation reduces vessel capacity to sustain blood volume.
Formation of angiotensin helps constrict peripheral arteries and regulates fluid output in kidneys, aiding in shock management.
Recovery from shock involves fluid absorption from the intestinal tract and salt intake.

Vicious Circle of Progressive Shock

A decrease in arterial pressure leads to reduced coronary blood flow, weakening heart muscle, and worsening cardiac output, thus perpetuating shock.

Symptoms of Shock

Symptoms should be reviewed from provided visuals or charts for detailed understanding.

Treatment of Shock

Head-Down Position: Helps promote venous return and increases cardiac output.
Replacement Therapy: Includes blood and plasma transfusions to restore volume.
Sympathomimetic Drugs: Drugs like norepinephrine and epinephrine can mimic sympathetic stimulation.
Oxygen Therapy: Addresses oxygen deficiency in tissues, providing essential support during shock.

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Description

This lecture focuses on the definition, types, and physiological causes of circulatory shock. Students will learn about the body's response to shock based on severity, the general symptoms to look for, and an overview of treatment options. It is essential for understanding critical physiological concepts in medical education.