Questions and Answers
How is Bernoulli's principle applied to the circulatory system?
The total energy in the vascular system is a balance between potential energy and kinetic energy. Therefore, if blood velocity goes up, there must be a pressure decrease.
In the human circulatory system, when do viscous and inertial losses occur?
Viscous losses occur as the layers of blood rub against each other moving through the vessel, and inertial losses occur whenever blood is forced to change direction or velocity.
Why does the velocity of the blood decrease as the blood travels from the aorta to the arterioles?
Velocity is inversely related to total cross-sectional area, and the total cross-sectional area of blood vessels increases from the aorta to the arterioles.
According to Poiseuille's law, how is volume flow impacted by changes in vessel radius?
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Why is hydraulic filtering necessary in the circulatory system?
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How does capacitance in the arterial system change with age?
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What are the main factors that control peripheral circulation?
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How does a critical stenosis affect pressure and flow?
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How can the ICA and ECA be safely differentiated?
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What is the primary criterion for determining an ICA stenosis? Once the primary threshold has been exceeded, what is the secondary criterion to further categorize diagnosis?
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What did NASCET determine to be the best criteria for determining a >70% stenosis?
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How is stenosis determined in extracranial vessels other than the ICA?
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How can pseudoaneurysm be differentiated from an enlarged lymph node?
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In addition to US findings, what should the vascular technologist pay attention to when assessing a patient suspected of an uncommon vascular pathology?
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With TCD, why is spectral broadening unavoidable?
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What are the main quantitative values used for diagnostic purposes in a transcranial exam?
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Study Notes
Bernoulli's Principle in Circulatory System
- Total energy in the vascular system balances between potential and kinetic energy.
- Increased blood velocity leads to a decrease in pressure.
Viscous and Inertial Losses
- Viscous losses occur from friction as blood layers slide against each other.
- Inertial losses arise when blood changes direction or velocity; depend on blood density and velocity.
- Energy losses due to viscosity are greater than those from inertia in blood vessels.
Blood Velocity and Vessel Cross-Section
- Blood velocity decreases from the aorta to arterioles due to an increase in total cross-sectional area.
Poiseuille's Law on Vessel Radius
- Volume flow correlates directly with the vessel radius to the fourth power.
- Doubling the radius increases volume flow by a factor of 16.
Hydraulic Filtering's Role
- Ensures a steady flow from the heart to capillaries for effective nutrient and waste exchange.
Age-Related Changes in Capacitance
- Arterial capacitance decreases with age due to rigid vessel walls.
- Increased vessel stiffness results in higher systolic and pulse pressure.
Control of Peripheral Circulation
- Peripheral circulation is regulated by the nervous system and local tissue conditions.
- Arterioles play a pivotal role in managing blood flow to specific organs or regions.
Effects of Critical Stenosis
- Increases in stenosis lead to decreases in pressure and flow, especially in low-resistance systems.
Differentiating ICA and ECA
- ECA is usually positioned medial and has branches past bifurcation; characterized by a temporal tap affecting sound waves.
Determining ICA Stenosis
- Primary criterion for >50% stenosis is PSV >125 cm/sec; EDV >140 cm/sec indicates >80% stenosis as a secondary criterion.
NASCET Criteria for >70% Stenosis
- Identified absence of a detectable patent lumen and no flow on grayscale imaging and Doppler assessments.
Stenosis Assessment in Extracranial Vessels
- Detected through a focal velocity increase in PSV >2 times the normal proximal site and poststenotic turbulence.
Differentiating Pseudoaneurysm from Lymph Node
- Pseudoaneurysms connect to a vessel via a neck, showing to-and-fro flow and a swirling "yin-yang" pattern.
- Lymph nodes demonstrate a low-resistance flow pattern and apparent venous flow.
Importance of Patient History in Assessment
- Patient history is crucial for determining potential uncommon vascular pathologies during evaluation.
TCD and Spectral Broadening
- Spectral broadening in TCD is unavoidable due to the larger sample gate size compared to the artery being evaluated.
Quantitative Values in Transcranial Exam
- Mean velocities and pulsatility index are the primary quantitative measures for diagnostic purposes in a transcranial exam.
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Explore key principles related to Bernoulli's principle and energy balance in the circulatory system with these flashcards. Ideal for students studying cardiovascular physiology, this quiz will enhance your understanding of blood flow dynamics and energy losses in vessels.