Cardiac Output
Cards (6)
- Cardiac output describes the amount of blood the heart pumps through the circulatory system in one minute
- Cardiac output is an important medical indicator of how efficiently the heart can meet the demands of the body
- Two key factors contribute to cardiac output: heart rate and stroke volume
- Equation for Cardiac Output (CO): CO = Heart Rate (HR) × Stroke Volume (SV)
- Heart rate:
- Describes the speed at which the heart beats, measured by the number of contractions per minute (bpm)
- Each ventricular contraction forces a wave of blood through the arteries, detectable as a pulse
- Typical pulse rate for a healthy adult is between 60 – 100 beats per minute
- Can be affected by conditions like exercise, age, disease, temperature, and emotional state
- Body compensates for changes in stroke volume with alterations to heart rate
- Controlled by nervous (sympathetic and parasympathetic systems) and hormonal signals (adrenaline/epinephrine)
- Stroke volume:
- Amount of blood pumped to the body (from the left ventricle) with each beat of the heart
- Affected by blood volume, heart contractility, and resistance from blood vessels
- Changes in stroke volume impact blood pressure
- Blood pressure measurements include systolic (higher) and diastolic (lower) readings
- Systolic pressure is post-contraction, diastolic is during relaxation
- Blood pressure varies based on measurement site, posture, vessel diameter, and fluid retention