Podcast
Questions and Answers
Which of the following best describes the relationship between vascular distensibility and compliance?
Which of the following best describes the relationship between vascular distensibility and compliance?
- Distensibility refers to the ability of a vessel to stretch, while compliance is the measure of how readily a vessel changes volume with pressure. (correct)
- Distensibility is a dynamic measure, whereas compliance is a static measure of vascular properties.
- Distensibility measures the volume change for a given pressure change, while compliance measures the pressure change for a given volume change.
- Distensibility and compliance are inversely related; as one increases, the other decreases proportionally.
Why is delayed compliance an important mechanism in blood transfusions?
Why is delayed compliance an important mechanism in blood transfusions?
- It immediately increases blood pressure, ensuring adequate perfusion of tissues during the transfusion.
- It allows the circulatory system to accommodate the extra blood volume without causing an immediate large increase in pressure. (correct)
- It stimulates the kidneys to excrete excess electrolytes, maintaining blood composition.
- It rapidly removes excess fluid from the blood, preventing hypervolemia.
How does the compliance of the arterial system contribute to continuous blood flow in capillaries?
How does the compliance of the arterial system contribute to continuous blood flow in capillaries?
- By directly shunting blood from arteries to veins, bypassing the capillaries.
- By dampening the pulsatile flow from the heart, transforming it into a smoother, more continuous flow. (correct)
- By filtering out large blood cells, preventing capillary blockage and promoting smooth flow.
- By actively pumping blood forward, ensuring a constant supply to the capillaries.
What physiological change explains the increase in systolic blood pressure with age?
What physiological change explains the increase in systolic blood pressure with age?
Why is the mean arterial pressure closer to diastolic pressure than systolic pressure during a normal heart rate?
Why is the mean arterial pressure closer to diastolic pressure than systolic pressure during a normal heart rate?
What is the primary determinant of preload?
What is the primary determinant of preload?
How does increased abdominal pressure affect venous blood flow from the legs back to the heart?
How does increased abdominal pressure affect venous blood flow from the legs back to the heart?
How do muscular contractions in the legs assist venous return?
How do muscular contractions in the legs assist venous return?
Why does prolonged standing contribute to the development of varicose veins?
Why does prolonged standing contribute to the development of varicose veins?
How does sympathetic stimulation affect blood volume in venous reservoirs during hemorrhage?
How does sympathetic stimulation affect blood volume in venous reservoirs during hemorrhage?
What effect does vasoconstriction have on vascular resistance and blood flow?
What effect does vasoconstriction have on vascular resistance and blood flow?
In a healthy individual, which of the following factors would decrease pulse pressure?
In a healthy individual, which of the following factors would decrease pulse pressure?
Which of the following is most likely to be observed in a patient with advanced atherosclerosis?
Which of the following is most likely to be observed in a patient with advanced atherosclerosis?
What is the expected effect on right atrial pressure (RAP) from administering a diuretic to a patient with fluid overload?
What is the expected effect on right atrial pressure (RAP) from administering a diuretic to a patient with fluid overload?
How do venous valves counteract the effects of gravity in the lower extremities?
How do venous valves counteract the effects of gravity in the lower extremities?
How does the distensibility of veins compared to arteries affect their function?
How does the distensibility of veins compared to arteries affect their function?
What is the immediate effect of sudden blood loss on right atrial pressure?
What is the immediate effect of sudden blood loss on right atrial pressure?
Which of the following adaptations helps mitigate the effects of prolonged standing on venous pressure in the feet?
Which of the following adaptations helps mitigate the effects of prolonged standing on venous pressure in the feet?
Why does the aorta have a slower blood transmission velocity compared to smaller distal arteries?
Why does the aorta have a slower blood transmission velocity compared to smaller distal arteries?
Which organ primarily regulates long-term arterial pressure?
Which organ primarily regulates long-term arterial pressure?
Flashcards
Vascular distensibility
Vascular distensibility
Measure of volume change per unit pressure change in a vessel.
Vascular Compliance
Vascular Compliance
Total quantity of blood that can be stored in a given vessel or portion of the circulation for each mm Hg pressure increase.
Venous System Dispensability
Venous System Dispensability
Veins can hold a lot more blood without a big pressure change because they stretch more easily.
Delayed Compliance
Delayed Compliance
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Pulse Pressure
Pulse Pressure
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Increased Pulse Pressure
Increased Pulse Pressure
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Dampening of pressure pulses
Dampening of pressure pulses
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Long-term blood pressure regulation
Long-term blood pressure regulation
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Normal Heart Rate: Mean Pressure
Normal Heart Rate: Mean Pressure
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Right Atrial Pressure (CVP)
Right Atrial Pressure (CVP)
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Normal Right Atrial Pressure
Normal Right Atrial Pressure
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Preload determinants
Preload determinants
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Venous constriction cause
Venous constriction cause
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Blood reservoirs
Blood reservoirs
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Study Notes
Vascular Distensibility
- Distensibility refers to the ability of blood vessels to stretch and expand in response to pressure changes.
- Distensibility is calculated by dividing the increase in volume by the increase in pressure.
- Veins are significantly more distensible than arteries.
- Veins can accommodate large volumes of blood.
- Compliance is used to determine the volume of blood that can be stored for a given pressure change.
Pressure-Volume Curve
- The arterial system, which contains approximately 500ml of blood, registers zero pressure.
- Even a small increase in blood volume in the arterial system causes a pressure increase up to 140.
- The venous system accommodates a higher volume of blood without a significant increase in pressure.
- This suggests that the distensibility of the venous system is higher than that of the arterial system.
Delayed Compliance
- Delayed compliance involves the slow stress relaxation of blood vessels.
- An increase in blood volume results in a gradual decrease in pressure over approximately 20 minutes, even without blood removal.
- Delayed compliance enables the circulation to accommodate extra blood, such as during a transfusion.
Arterial System Compliance
- Arterial system compliance converts the heart's pulsatile flow into a near-continuous flow by the time blood reaches the capillaries.
- Pulse pressure is influenced by cardiac output and the compliance of the arterial tree.
- Greater stroke volume requires higher compliance.
- Greater stroke volume also leads to a greater pulse pressure.
- Pulse pressure correlates to the difference between systolic and diastolic pressures.
- As blood vessels become less compliant with age, the same stroke volume can cause a higher pulse pressure.
- As blood is injected into the aorta, the proximal portion of the aorta becomes distended.
- Pulse waves move slower in the aorta and small distal arteries due to greater compliance.
Dampening of Pressure Pulses
- The progressive weakening of pulses in the periphery is due to the resistance and compliance of the vessels.
- Systolic blood pressure typically increases with age.
- Kidneys primarily regulate long-term blood pressure.
- Atherosclerosis generally occurs after age 60.
- During a normal heart rate, mean pressure remains closer to diastolic than systolic pressure due to the longer duration of diastole compared to systole.
Right Atrial Pressure (CVP)
- Right atrial pressure, also referred to as CVP, is balanced between blood return to the atrium and the capacity of the heart to pump blood to the lungs and periphery.
- Normal right atrial pressure is zero, with a range between -5 to 30
- Preload is influenced by changes in blood volume, tone of large vessels, and the diameter of the arterioles.
- Large veins are very dispensable and have little resistance to blood flow.
- When abdominal pressure rises, the pressure in the legs needs to increase above the downward pressure so blood will flow from the legs to the heart.
- The gravitational pressure of water is 1 mmHg for every 13.6 mm.
- A non-moving adult standing has about 90 mmHg in the veins of their feet.
- Valves in the veins and muscular compression of the veins cause blood to return to the heart when the legs move.
- Under ordinary circumstances, venous pressure in the feet remains less than 20 mmHg
- Overstretching of the veins during pregnancy or prolonged standing can cause incompetent valves and varicose veins.
- Constant sanding stretches the veins, but the valve leaflets don't stretch.
- This increases the pressure in one's feet which has to be overcome due to the incompetent valves.
Venous System
- More than 60% of the blood in circulation is typically in the veins.
- Sympathetic stimulation can cause venous constriction, reducing the effects of blood loss by up to 20% of total blood volume.
- Specific blood reservoirs include the spleen, liver, large abdominal veins, and venous plexus beneath the skin.
- Sympathetic stimulation can shrink these organs, increasing blood in circulation.
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