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Exam 3 Study Prep
Advanced Physics
| Question | Answer |
|---|---|
| Which term describes the difference between a vein's intravascular pressure and the pressure exerted by the surrounding tissue? | Transmural Pressure |
| What happens to the Spectral Doppler velocity profile when blood accelerates in a normal artery? | It flattens |
| What can cause a decrease in acceleration or systolic rise time in a spectral doppler waveform? | ? vasovagal response? |
| True or False: Momentary flow reversal in an artery during late systole or early diastole is always abnormal and requires further evaluation | False |
| A normal adult is standing with both arms raised above their head. Where would the highest and the lowest hydrostatic pressure be measured, respectively? | Feet, finger tips |
| What mechanism helps the venous system move blood from the lower extremities to the right atrium of the heart? | Calf muscle pump |
| Where is the "Zero Reference Point" for hydrostatic pressure? | Right atrium of the heart |
| What happens in the vascular system when an arterial stenosis lowers the amount of blood going to the end organs? | Distal arterioles will vasodilate |
| Where would a sonographer expect to see a normal triphasic arterial spectral doppler waveform? | Superficial femoral artery |
| What prevents reverse flow of blood in the veins of the upper and lower extremities? | Numerous one-way valves |
| True or False: A patient can have disease in their vascular system and remain asymptomatic due to the compensatory capabilities of the cardiovascular system. | True |
| What happens in a normal cardiovascular system when the vasomotor tone is increased? | Blood pressure rises, cardiac output increases, venous capacitance decreases (all are correct) |
| What creates hydrostatic pressure in the cardiovascular system? | gravity column of blood |
| What is the significance of an obscured spectral window in a spectral doppler waveform? | Possible turbulent flow |
| What physiological parameter is being calculated when the spectral doppler waveform is measured (in time) from the end of diastole to peak systole? | Acceleration or rise time |
| What mechanism is used to regulate the capacitance of the venous system? | Vasomotor tone |
| What is a result of decreased blood flow to an organ or tissue due to vascular disease? | Ischemia |
| What is the normal venous pressure in the extremities? | 20.0 mmHg? |
| What does a "clear" spectral window indicate in a spectral doppler waveform? | Laminar Flow |
| What happens to venous flow from the lower extremities when a normal patient inhales? | Decreases |
| What physical characteristic of an artery has the greatest influence on its capacitance? | Elasticity |
| True or False: In the human body, the energy lost due to friction between the blood and vessel walls and due to internal friction associated with blood's viscosity in negligible. | False |
| What happens to overall flow resistance when vessels are connected in parallel? | Flow resistance decreases |
| Which of the following statements about flow resistance is true? | Organs with low volumetric flow requirements have high resistance vascular beds, organs with high volumetric flow requirements have low resistance vascular beds, the cardiovascular system can vary flow resistance based on metabolic and physiological need |
| Which statement about hemodynamics is correct for vessels connected in series? | Overall flow resistance increases |
| What causes blood to assume a laminar flow profile in a normal artery? | Friction |
| What is the physiological significance of the dramatic pressure drop and dampened pulsatility distal to the arterioles? | It enhances metabolic exchange in the capillaries by slowing the passage of the RBCs |
| Approximately what percentage of the cardiovascular system's blood is stored in the venous system of a person at rest? | 65% |
| What happens to blood flow when it encounters a "critically stenosed" artery? | Turbulent flow exists distal to the stenosis, most of the blood's energy is lost to friction in the stenosis, resulting in a significant pressure drop, the flow velocity in the stenosis is very high (all are correct) |
| What is the key physiological point to remember during the heart's isovolumetric relaxation and isovolumetric contraction cycles? | All four heart valves are closed |
| Why does the backscattered doppler signal strength decrease as the hematocrit increases? | The RBCs are so close together they can't scatter the beam's energy individually |
| What are the three situations where the echogenicity of blood increases? | Stationary blood, turbulent flow, thrombus |
| What is considered a normal hematocrit value for a healthy female? | 42% |
| Which term describes the aggregation, or clumping, of blood as the flow velocity decreases? | Rouleaux |
| What effect will polycythemia vera have on a patient's hematocrit? | Increase |
| True or False: The "Wisp of Smoke" sign seen in a heart chamber damaged by a myocardial infarction is a result of Rouleaux formation related to the slower flow of the blood | True |
| At higher transmit frequenices, Rayleigh Scatterers in the blood will create a much stronger Doppler signal, which should make blood highly echogenic. However, what factor tends to override this stronger signal as it propagates back to the transducer? | Attenuation |
| True or False: Accurate velocity measurements can be obtained from a blood vessel that's imaged in the transverse plane (short axis) as long as the Doppler angle is known | False |
| What effect will anemia have on a patient's hematocrit? | Decrease |
| According to the lecture, what does turbulent blood flow usually indicate? | Cardiovascular Disease |
| How accurate is dating a thrombus based solely on its sonographic B-mode appearance? | Not very accurate |
| Why are the echoes from blood so weak when compared to the surrounding tissue? | The small size of the RBCs, reflection of the beam energy off the vessel wall due to oblique incidence, specular reflections off the vessel walls, attenuation of the returning echoes (all) |
| What is another name for red blood cells? | Erythrocytes |
| True or False: Veins are more elastric than arteries. | True |
| True or False: Arteries carry about 80% of total blood volume at rest | False |
| True or False: Veins carry about 80% of total blood volume at rest | True |
| What percentage of total blood volume is contained within the veins? | 65% |
| True or False: For flow conduits in series, effective resistance is the sum of resistances of each individual component | True |
| According to hemodynamic principles, when a vessel narrows, velocity through the stenosis will? | Increase |
| True or False: Effective resistance increases with increasing parallel vessels | False |
| A staccato waveform is most commonly associated with? | Near occlusion or very high resistance downstream |
| Bruits are caused by? | Turbulent flow |
| As vessel radius decreases, resistance changes by which relationship? | Inverse to the fourth power |
| Contributing factors to frictional energy losses? | High volume flow, tortuouse vessels, and elevated hematocrit |
| Increased velocity alone can maintain flow across a stenosis when? | The stenosis is mild |
| At what point does velocity increase become insufficient to maintain flow? | Severe narrowing |
| True or False: Increased velocity always guarantees adequate downstream perfusion | False |
| Increased frictional energy loss is primarily due to? | Interaction between blood and vessel wall |
| Which mechanism helps maintain flow when a stenosis becomes hemodynamically significant? | Arterial vasodilation |
| Transmural pressure directly influences? | Vessel diameter |
| True or False: Severe stenosis can lead to turbulence and energy loss, reducing effective flow | True |
| If external pressure exceeds internal pressure in a vessel, the vessel will? | Collapse |
| Collateral circulation develops in response to? | Chronic reduced perfusion |
| Which part of the cardiovascular system provides the pressure needed to overcome resistance of systemic circulation? | Left heart |
| True or False: The velocity of flow is controlled primarily by the varying total cross sectional area of the vessels | True |
| Veins are most sensitive to changes in transmural pressure because they are? | More elastic/compliant |
| During exercise, venous return increases due to? | Calf muscle pump |
| A tardus parvus waveform is characterized by? | Delayed upstroke and reduced amplitude |
| True or False: Collateral vessels form immediately in response to acute stenosis | False |
| A tardus parvus waveform typically indicates? | Proximal stenosis |
| The respiratory pump enhances venous return by? | Decreasing thoracic pressure during inspiration |
Created by:
marissagirl