Podcast
Questions and Answers
What primarily influences stroke volume according to the Frank-Starling law of the heart?
What primarily influences stroke volume according to the Frank-Starling law of the heart?
Which factor is not considered a major determinant of peripheral resistance in the circulatory system?
Which factor is not considered a major determinant of peripheral resistance in the circulatory system?
Which hormone is most likely to increase contractility of the heart muscle?
Which hormone is most likely to increase contractility of the heart muscle?
What is the relationship between preload and stroke volume?
What is the relationship between preload and stroke volume?
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Which of the following factors would likely decrease contractility?
Which of the following factors would likely decrease contractility?
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What is the role of venous pressure in the circulation?
What is the role of venous pressure in the circulation?
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What effect does a slow heartbeat have on stroke volume?
What effect does a slow heartbeat have on stroke volume?
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Which condition could lead to a decrease in peripheral resistance?
Which condition could lead to a decrease in peripheral resistance?
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Which of the following would primarily cause a decrease in stroke volume during rapid heartbeats?
Which of the following would primarily cause a decrease in stroke volume during rapid heartbeats?
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What effect does vasodilation have on systemic vascular resistance (SVR)?
What effect does vasodilation have on systemic vascular resistance (SVR)?
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What role does norepinephrine play in heart contractility?
What role does norepinephrine play in heart contractility?
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Which of the following conditions is most likely a response to severe hypocalcemia?
Which of the following conditions is most likely a response to severe hypocalcemia?
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What is the major impact of the sympathetic nervous system (SNS) during acute stress?
What is the major impact of the sympathetic nervous system (SNS) during acute stress?
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Which type of shock is characterized by inadequate blood flow due to extreme vasodilation?
Which type of shock is characterized by inadequate blood flow due to extreme vasodilation?
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What characterizes chronic hypertension?
What characterizes chronic hypertension?
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How does bradycardia affect heart function?
How does bradycardia affect heart function?
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Which statement best describes the relationship between hyperkalemia and heart function?
Which statement best describes the relationship between hyperkalemia and heart function?
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What is the primary cause of pericarditis?
What is the primary cause of pericarditis?
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What is the effect of the parasympathetic nervous system (PNS) on heart rate?
What is the effect of the parasympathetic nervous system (PNS) on heart rate?
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Study Notes
Cardiac Output (CO) and Reserve
- Cardiac Output (CO) is the amount of blood pumped by each ventricle in one minute
- CO is the product of heart rate (HR) and stroke volume (SV)
- HR is the number of heart beats per minute
- SV is the amount of blood pumped out by a ventricle with each beat
- Cardiac reserve is the difference between resting and maximal CO
Regulation of Stroke Volume
- SV = end diastolic volume (EDV) minus end systolic volume (ESV)
- EDV = amount of blood collected in a ventricle during diastole
- ESV = amount of blood remaining in a ventricle after contraction
Factors Affecting Stroke Volume
- Preload – amount ventricles are stretched by contained blood
- Contractility – cardiac cell contractile force due to factors other than EDV
- Afterload – back pressure exerted by blood in the large arteries leaving the heart
Frank-Starling Law of the Heart
- Preload, or degree of stretch, of cardiac muscle cells before they contract is the critical factor controlling stroke volume
- Slow heartbeat and exercise increase venous return to the heart, increasing SV
- Blood loss and extremely rapid heartbeat decrease SV
Extrinsic Factors Influencing Stroke Volume
- Contractility is the increase in contractile strength, independent of stretch and EDV
- Increase in contractility comes from:
- Increased sympathetic stimuli
- Certain hormones
- Ca2+ and some drugs
- Agents/factors that decrease contractility include:
- Acidosis
- Increased extracellular potassium
- Calcium channel blockers
Venous Pressure
- Venous pressure generally refers to the average pressure within the venous compartment of circulation
- Blood from all the systemic veins flows into the right atrium of the heart, therefore the pressure in the Right atrium is called Central Venous Pressure
Peripheral Resistance
- Peripheral Vascular Resistance (systemic vascular resistance, SVR) is the resistance in the circulatory system that is used to create blood pressure
- It also contributes to the flow of blood and is a component of cardiac function
- When blood vessels constrict (vasoconstriction) this leads to an increase in SVR
- When blood vessels dilate (vasodilation), this leads to a decrease in SVR
- If referring to resistance within the pulmonary vasculature, this is called pulmonary vascular resistance (PVR)
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Description
This quiz explores the concepts of cardiac output (CO) and stroke volume, including definitions, formulas, and factors influencing their regulation. Understand how heart rate, preload, contractility, and afterload impact stroke volume and overall heart function. Test your knowledge on the Frank-Starling Law and its significance in cardiac physiology.
