18 Questions
What is the pressure in the right atrium typically fluctuating around?
5 mmHg
How does an increase in Right Atrial Pressure (RAP) affect venous return?
Decreases venous return
What determines venous return at steady state?
Cardiac output (CO)
What does the vascular function curve show the relationship between?
Venous return and cardiac output
Which of the following shifts the match between cardiac output and venous return?
Increase in contractility
What does the mean systemic filling pressure (MSFP) represent?
The theoretical pressure if the heart pump is turned off
What is the theoretical pressure that would exist if the heart pump is turned off and blood is allowed to distribute throughout the vasculature until pressure is equal throughout?
Mean circulatory pressure (MCP)
Which part of the cardiovascular system receives 64% of total blood volume in the systemic circulation?
Systemic Venous system
How do changes in blood volume and venous compliance affect the cardiac function curve?
Cause parallel shifts without changing Mean circulatory pressure (MCP)
What does altering systemic vascular resistance (SVR) affect in the systemic function curves?
Alters the slope without changing Mean circulatory filling pressure (Pmc)
Which part of the cardiovascular system receives 7% of total blood volume in the systemic circulation?
Capillaries
What is the structure responsible for receiving blood from the veins and pumping it to the right ventricle of the heart?
Right Atrium
What is the main physiological effect of Natriuretic Peptides on blood vessels?
Promote smooth muscle cell relaxation
Which of the following is NOT a role of Natriuretic Peptides?
Promote vasoconstriction
What is the main downstream effect of Natriuretic Peptides?
Promote smooth muscle cell relaxation
Which receptor type is primarily responsible for the main physiological effect of Natriuretic Peptides on blood vessels?
Receptor type A
What are the main diagnostic markers associated with Natriuretic Peptides?
Troponin and Brain Natriuretic Peptide (BNP)
Which hormone is predominantly involved in promoting diuresis and natriuresis?
ANP (Atrial Natriuretic Peptide)
Study Notes
Venous Return and Cardiac Output
- Venous return (VR) determines right atrial pressure (RAP)
- RAP determines VR
- At steady state, VR = cardiac output (CO)
Mean Systemic Filling Pressure (MSFP)
- Theoretical pressure if heart pump is turned off and blood is distributed throughout vasculature
- Changes with changes in venous compliance or capacitance, and blood volume
Right Atrial Pressure (RAP)
- Typically low, fluctuating around a mean of 0 mmHg
- Required for pressure gradient to drive venous return (VR)
- Difference between central venous pressure (CVP) and RAP is the driving pressure for blood into the atrium (ΔP = CVP-RAP)
Vascular Function Curve
- Shows the relationship between venous return and right atrial pressure
- Changes in blood volume and venous compliance cause parallel shifts in the curve
- Changes in systemic vascular resistance (SVR) alter the slope of the curve without changing MSFP
Cardiac Function Curve
- Shows the relationship between cardiac output and right atrial pressure
- At steady state, venous return = cardiac output
Natriuretic Peptides
- Downstream effect: promote smooth muscle cell relaxation, diuresis, and natriuresis
- Counter regulatory hormones and useful diagnostic markers
- Main physiological effect comes from the NP receptor type A, the predominant receptor on blood vessels
Test your knowledge on the differences between cardiac function curve and vascular function curve. Understand key concepts such as pressure gradients and blood flow in the circulatory system.
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