Cardiac Output

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is cardiac output?

The amount of blood pumped by each ventricle of the heart in an hour

The amount of oxygen pumped by each ventricle of the heart in a minute

The amount of blood pumped by each ventricle of the heart in a minute (correct)

The amount of nutrients pumped by each ventricle of the heart in a minute

What is the normal heart rate in beats per minute (bpm)?

72 bpm (correct)

90 bpm

60 bpm

80 bpm

What is the normal stroke volume in millilitres (mL) per beat?

70 mL per beat (correct)

90 mL per beat

60 mL per beat

80 mL per beat

What is the formula to calculate minute volume?

Stroke volume × heart rate Signup and view all the answers

What is the normal minute volume in liters per minute?

5 L/min Signup and view all the answers

What is the unit of measurement for stroke volume?

Milliliters (mL) per beat Signup and view all the answers

Why is cardiac output important?

To maintain proper blood circulation throughout the body Signup and view all the answers

What can affect heart rate?

All of the above Signup and view all the answers

What is the primary effect of arrhythmias on the heart?

Decreased cardiac output Signup and view all the answers

Which type of shock is caused by heart dysfunction?

Cardiogenic shock Signup and view all the answers

What is the normal resting heart rate below which tachycardia is diagnosed?

100 bpm Signup and view all the answers

What is the primary role of cardiac output in cardiovascular function?

Maintaining hemodynamic stability Signup and view all the answers

What is a potential complication of arrhythmias?

All of the above Signup and view all the answers

What can be indicated by tachycardia at rest?

Underlying issues affecting cardiac output Signup and view all the answers

What is the primary function of the right ventricle?

Pumping deoxygenated blood to the lungs Signup and view all the answers

Which organ receives the most blood supply?

Liver Signup and view all the answers

What is the result of Sympathetic Nervous System (SNS) stimulation on the heart?

Increased heart rate and contractility Signup and view all the answers

What is the effect of Parasympathetic Nervous System (PNS) stimulation on the heart?

Decreased heart rate and contractility Signup and view all the answers

What is the role of epinephrine and norepinephrine in regulating cardiac output?

Increasing heart rate and contractility Signup and view all the answers

What is the primary function of thyroid hormones in regulating cardiac output?

Regulating cells, tissues, and organs in the body Signup and view all the answers

What is the Frank-Starling mechanism involved in?

Regulation of cardiac output Signup and view all the answers

What is the primary function of the baroreceptor reflex?

Regulation of blood pressure Signup and view all the answers

What is the primary function of baroreceptors?

To detect changes in blood pressure Signup and view all the answers

What happens when blood pressure increases?

Baroreceptors detect the stretch in the arterial walls and send signals to the cardiovascular control center Signup and view all the answers

What is the result of increased sympathetic activity and decreased parasympathetic activity?

An increase in heart rate and stroke volume Signup and view all the answers

What influences cardiac output?

Changes in blood pH, oxygen levels, and carbon dioxide levels Signup and view all the answers

What is the result of chemoreceptors sensing changes in carbon dioxide levels and blood pH during exercise?

An increase in sympathetic activity and a decrease in parasympathetic activity Signup and view all the answers

What is a symptom of heart failure?

Fatigue Signup and view all the answers

What is a condition that can cause heart failure?

Hypertension Signup and view all the answers

What is the result of heart failure?

The heart cannot pump enough blood to meet the body's needs Signup and view all the answers

Study Notes

Introduction

Cardiac output is the amount of blood pumped by each ventricle of the heart in a minute.
It is vital for maintaining proper blood circulation throughout the body.
The average resting cardiac output is about 5 L/min, although it varies depending on age, sex, body build, diurnal variations, emotional conditions, exercise, posture, and sleep.

Expression of Cardiac Output

Heart Rate (HR): represents how fast the heart is beating, measured in beats per minute (bpm).
- Normal heart rate: about 72bpm
Stroke Volume (SV): the amount of blood pumped out by the heart with each beat, typically measured in millilitres (mL) per beat.
- Normal stroke volume: 70ml per beat
Minutes Volume: the amount of blood pumped out by each ventricle per 1 minute, calculated by the product of stroke volume and heart rate, measured in liters per minute (L/min).
- Mathematically: Minutes Volume = Stroke Volume × Heart Rate
- Normal minute volume: 5L/min

Distribution of Cardiac Output

The whole volume pumped out of the right ventricle goes to the lungs to become oxygenated.
The left ventricle pumps blood into different parts of the body based on the metabolic activity in that area or region.
The heart itself receives the least amount of blood, while the liver receives the most blood supply.

Regulation of Cardiac Output

Nervous Regulation:
- Sympathetic Nervous System (SNS) stimulation: increases heart rate and enhances myocardial contractility, increasing cardiac output.
- Parasympathetic Nervous System (PNS) stimulation: decreases heart rate, slowing down the heart's pumping action and reducing cardiac output.
Hormonal Regulation:
- Epinephrine (adrenaline) and norepinephrine: increase heart rate and contractility, directly increasing cardiac output.
- Thyroid hormones (THs): regulate the cardiovascular system, exerting several effects on cardiac output.
Baroreceptor Reflex:
- Baroreceptors detect changes in blood pressure, triggering reflex adjustments to maintain blood pressure within the normal range.
Chemical Factors:
- Changes in blood pH, oxygen levels, and carbon dioxide levels can influence cardiac output.

Clinical Correlates

Heart Failure:
- Occurs when the heart cannot pump enough blood to meet the body's needs.
- Caused by conditions like coronary artery disease, hypertension, or heart attacks.
- Symptoms include fatigue, shortness of breath, and fluid retention due to reduced cardiac output.
Arrhythmias:
- Abnormal heart rhythms that disrupt the heart's pumping ability.
- Conditions like atrial fibrillation or ventricular tachycardia can lead to irregular heartbeats.
- Disruption can decrease cardiac output and may cause complications like stroke or heart failure.
Shock:
- Characterized by inadequate blood flow and reduced tissue oxygenation.
- Causes include cardiogenic shock, mechanical/obstructive shock, hypovolemic shock, and distributive shock.
- Decreased cardiac output contributes to insufficient tissue perfusion, potentially leading to organ damage or failure.
Tachycardia:
- A heart rate exceeding the normal resting rate (over 100 bpm).
- Causes can include anxiety, infection, hypoglycemia, hypovolemia, or hyperthyroidism.
- Tachycardia at rest may indicate underlying issues affecting cardiac output.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers the concept of cardiac output, its expression, distribution, regulation, and clinical correlations in maintaining proper blood circulation and tissue oxygenation.