04/09/2024
CARDIOVASCULAR SYSTEM || LECTURE-3
Cardiac output (CO) is a crucial measure of heart function, indicating the volume of blood the heart pumps per minute. It’s calculated by multiplying the heart rate (HR)—the number of beats per minute—by the stroke volume (SV), which is the amount of blood ejected by the left ventricle with each beat.
Formula:
Cardiac Output (CO) = Heart Rate (HR) × Stroke Volume (SV)
Key Points:
1. Heart Rate (HR): The number of times the heart beats per minute. A normal resting heart rate is typically between 60-100 beats per minute.
2. Stroke Volume (SV): The amount of blood pumped out of the left ventricle with each heartbeat, usually about 70 milliliters in a healthy adult.
3. Normal Values: In an average adult, the cardiac output is about 4.7 to 5.6 liters per minute, but it can vary based on factors like body size, activity level, and overall heart health.
4. Significance: Cardiac output is essential for delivering oxygen and nutrients to tissues and removing waste products. It can be influenced by factors like exercise, stress, medications, and disease conditions.
5. Clinical Relevance: Monitoring cardiac output is vital in assessing heart function, especially in critical care settings. Abnormal cardiac output, either too high (as in conditions like hyperthyroidism) or too low (as in heart failure), can indicate underlying health issues.
6. Regulation: The autonomic nervous system, circulating hormones, and the intrinsic properties of the heart muscle regulate cardiac output. The heart adjusts stroke volume and heart rate in response to the body's demands to maintain adequate circulation.
Understanding cardiac output helps in diagnosing and managing various cardiovascular conditions, ensuring that the heart is functioning optimally to meet the body's needs.
