Primary FRCA Course CVS Physiology Exam Prep Questions Flashcards
Coronary blood flow:
A. Is approximately 500 mL/min at rest
False. Resting coronary BF is around 250 mL/min
Coronary blood flow:
Supplies muscle that extracts 40 mL/L of oxygen per minute at rest
False. Coronary O2 extraction is about 110 mL/L/min (55-65% of the available content)
Coronary blood flow:
Is altered directly by vagal activity
False. There is no direct parasympathetic innervation to the coronary vessels
Coronary blood flow:
Ceases in systole
False. Left sided coronary flow is reduced during systole, but does not cease
Coronary blood flow:
Undergoes autoregulation
True. It autoregulates between a MAP range of 50-120 mmHg
In the cardiac cycle:
Left ventricular volume is maximal at the end of atrial systole
True. Atrial contraction contributes to final part of ventricular filling
In the cardiac cycle:
The mitral valve closes by contraction of the papillary muscles
False. The papillary muscles maintain the correct tension in the chordae tendineae and so prevent mitral valve prolapse
In the cardiac cycle:
The left ventricular pressure is maximal just before the aortic valve opens
False. LV pressure continues to rise after aortic valve opening
In the cardiac cycle:
The ejection fraction is normally about 85%
False. Normal ejection fraction is around 70%
In the cardiac cycle:
The dicrotic notch is due to rebound of the aortic valve
False. The elastic aortic wall is stretched during peak ejection and then rebounds after aortic valve closure to produce a slight rise in arterial pressure, creating the dicrotic notch
In a healthy adult human heart the:
Left ventricular end systolic volume is approximately 30 mL
True. Normal LVESV is 30 mL
In a healthy adult human heart the:
First heart sound coincides with the onset of ventricular systole
True. The start of systole is defined by the closure of the mitral and tricuspid valves, which generate the first heart sound
In a healthy adult human heart the:
Stroke volume is approximately 70 mL
True. Normal SV is 70 mL
In a healthy adult human heart the:
Left ventricular end-diastolic pressure is about 50 mmHg
False. Normal LVEDP is 10 mmHg
In a healthy adult human heart the:
Second heart sound is caused by closure of the aortic and pulmonary valves
True. Aortic and pulmonary valve closure generate the second heart sound
Pulmonary vascular resistance:
Is increased in chronic hypoxia
True. Hypoxia produces pulmonary vasoconstriction, increasing PVR
Pulmonary vascular resistance:
Has a value appoximately one-sixth that of the systemic circulation
True. Mean PAP is 15 mmHg (around one sixth of systemic MAP), with both circulations having the same flow
Pulmonary vascular resistance:
Can be measured using a flow-directed balloon catheter with a thermistor tip
True. A Swan-Ganz catheter can measure cardiac output and PA pressure, enabling the PVR to be calculated
Pulmonary vascular resistance:
Is increased by isoprenaline
False. The role of adrenoreceptors in the pulmonary circulation is minor and still remains uncertain, but beta-2 agonism probably leads to modest pulmonary vasodilatation
Pulmonary vascular resistance:
Is decreased by 5-hydroxytryptamine (5-HT)
False. 5-HT produces pulmonary vasoconstriction, raising PAP
In the normal adult heart:
Mitral valve closure occurs before tricuspid valve closure
True. The mitral valve closes fractionally before the tricuspid, although it may well be heard as a single sound
In the normal adult heart:
Pulmonary valve closure occurs before aortic valve closure
False. The pulmonary valve closes fractionally after the aortic valve; this delay is slightly greater during inspiration
In the normal adult heart:
Atrial contraction is of more importance to ventricular filling if the heart rate increases
True. Total diastolic time falls as the HR increases, increasing the importance of active filling by atrial contraction
In the normal adult heart:
There is isovolumetric contraction of the left ventricle after the aortic valve opens
False. Isovolumetric contraction occurs before aortic valve opening
In the normal adult heart:
The aortic valve cusps are immobile during ventricular filling
True. The aortic valve should be closed during ventricular filling
The Pressure:
Drop across major veins is simular to that across the major arteries
True. The largest pressure drop occurs across the arterioles; the drop across the major arteries and major veins are both small
The Pressure:
Drop across the hepatic portal bed is similar to that across the splenic vascular bed
False. The hepatic portal bed is a very low pressure/low resistance one
The Pressure:
In the hepatic portal vein is approximately 3 times higher than that in the inferior vena cava
False. Normal hepatic portal vein pressure is 5-10 mmHg, little different from that in the IVC
The Pressure:
Drop across the vascular bed in the foot is greater when standing than when lying down
False. When standing both the arterial and venous pressures in the foot increase to the same extent, leaving the pressure drop unchanged
The Pressure:
Drop across the pulmonary circulation is the same as across the systemic circulation
False. The drop across the pulmonary circulation is only about a sixth of that in the systemic circulation
In the central venous pressure waveform:
The c wave occurs after ventricular systole
False. The c wave occurs during early ventricular contraction (systole), as the closed tricuspid valve bulges back into the right atrium
In the central venous pressure waveform:
The v wave is caused by atrial contraction
False. The v wave represents atrial filling whilst the tricuspid valve is still closed
In the central venous pressure waveform:
The a wave is absent in atrial fibrillation
True. The a wave results from atrial contraction, so is absent in AF
In the central venous pressure waveform:
The a wave corresponds with the closure of the aortic valve
False. The a wave occurs in late diastole, long after aortic valve closure
In the central venous pressure waveform:
The v wave occurs during diastole
True. The v wave occurs during ventricular relaxation (diastole) but before the tricuspid valve opens - this is according to e-LfH but is debatable. Most time-pressure graphs would have the peak of the v-wave occurring on the cusp of systole and diastole.
With reference to the mechanical events in the cardiac cycle in a normal adult human:
The left ventricle ejects more blood per beat than the right ventricle
False. The ventricles must eject equal volumes of blood
With reference to the mechanical events in the cardiac cycle in a normal adult human:
The mitral valve opens when the left atrial pressure exceeds the left ventricular pressure
True. This is what opens the mitral valve
With reference to the mechanical events in the cardiac cycle in a normal adult human:
During strenuous work, the left ventricular end-diastolic volume may be double than at rest
False. It increases by about 10%. Left-ventricular end systolic volume decreases by about 10% due to increased ejection fraction.
With reference to the mechanical events in the cardiac cycle in a normal adult human:
The pulmonary valve opens when the right ventricular pressure reaches 20-25 mmHg
False. The pulmonary valve opens at a pressure of around 10-12 mmHg
With reference to the mechanical events in the cardiac cycle in a normal adult human:
During diastole, the left ventricular pressure is about 70 mmHg
False. LV pressure during diastole falls to around 5 mmHg
Myocardial contractility:
Is the degree of the inotropic state of heart independent of preload, afterload or heart rate
True. Force of contraction is dependent on preload, but strictly speaking contractility is the ability of the heart muscle to respond to a given preload which is therefore independent.
Myocardial contractility:
determines the rate of development of ventricular Pressure (dp/dt)
True. Contractility defines the rate in rise of pressure
Myocardial contractility:
Can be estimated by ventricular pressure-volume loops
True. Pressure-volume loops include information about contractility
Myocardial contractility:
Is reduced by hypocalcaemia
True. Contractility is calcium dependent
Myocardial contractility:
Accounts for approximately 90% of total mycardial oxygen consumption
True. Cardiac contraction requires a high oxygen consumption
On changing from the upright to the supine position:
Baroreceptor firing rate decreases
False. The rise in venous return increases pulmonary blood volume, stroke volume and arterial BP, resulting in a greater firing rate in the baroreceptors (which respond to stretch)
On changing from the upright to the supine position:
Leg vein pressure is reduced
True. Venous pressure in legs falls as they become at the level of the heart
On changing from the upright to the supine position:
The blood volume in the pulmonary circulation falls
False. The rise in venous return increases pulmonary blood volume, stroke volume and arterial BP, resulting in a greater firing rate in the baroreceptors (which respond to stretch)
On changing from the upright to the supine position:
Stroke volume increases
True. The rise in venous return increases pulmonary blood volume, stroke volume and arterial BP, resulting in a greater firing rate in the baroreceptors (which respond to stretch)
On changing from the upright to the supine position:
Renin activity increases
False. The rise in arterial BP reduces the release of renin from the juxta-glomerular apparatus
The following are true about the fetal circulation:
The PaO2 in the desending aortic is lower than that in the aortic arch
True. Blood in the descending aorta has a lower PO2 because deoxygenated blood has joined via the ductus arteriosus (which contains the deoxygenated blood from SVC which doesn’t go through foramen ovale - whereas most of oxygenated blood from IVC does go through foramen ovale)
The following are true about the fetal circulation:
The ductus venosus contains mixed venous blood
False. The ductus venosus contain blood returning from the placenta via the umbilical vein which is therefore oxygenated.
The following are true about the fetal circulation:
The ductus ateriosus closes due to the rise in the systemic blood pressure
False. Closure of the ductus arteriosus is prostaglandin-mediated
The following are true about the fetal circulation:
Closure of the foramen ovale is due to the change in the left and right atrial pressure
True. Pressure reversal between the atria closes the foramen ovale
The following are true about the fetal circulation:
Blood entering the right atrium can reach the systemic circulation without passing through the left side of the heart
True. Blood from the RA can reach the systemic circulation via the RV, pulmonary artery and ductus arteriosus. It is mostly SVC blood that follows this pathway, which is largely kept separate from IVC blood via streaming in the RA
Chemoreceptors in the arterial system:
Have a higher rate of oxygen consumption per gram than brain tissue
False. The carotid bodies have a very high blood flow per gram of tissue, not oxygen consumption
Chemoreceptors in the arterial system:
Respond to changes in oxygen tension and not content
True. These chemoreceptors respond to the partial pressure of dissolved O2 not total O2 content
Chemoreceptors in the arterial system:
Respond to changes in pH
True. A metabolic acidosis is sensed by these peripheral chemoreceptors
Chemoreceptors in the arterial system:
Conduct afferent information via the glossopharyngeal and vagus nerves
True. Impulses are conducted via IX (carotid) and X (aorta)
Chemoreceptors in the arterial system:
Are found in the carotid sinus
False. Chemoreceptors are found in the carotid and aortic bodies - the sinus contains baroreceptors
The following statements are true:
Of the major organs, the heart has the highest A-V O2 difference
True. Coronary oxygen extraction is high, at an extraction ratio of 0.55-0.6
The following statements are true:
Arterial baroreceptors respond to pressure
True. They are stretch receptors that respond to a rise in pressure
The following statements are true:
Each kidney receives about 10% of the cardiac output
True. Overall renal blood flow is 1000 mL/min, 20% of cardiac output
The following statements are true:
On the ECG, lead II is from the left arm to the left leg
False. Lead II looks at the view from right arm to left leg
The following statements are true:
LV diastolic compliance falls sharply above a volume of 70 mL
False. The LV remains very compliant up to around 120 mL
The vagus:
Innervates the heart primarily via M3 receptors
False. M2 receptors are present in the heart - M3 are mainly located on smooth muscle
The vagus:
Increases L-type calcium channel opening
False. The vagus works mainly by increasing permeability to potassium
The vagus:
Slows conduction through the A-V node
True. It slows A-V conduction
The vagus:
Lowers the trough potential of the sino-atrial node
True. Increasing potassium permeability lowers the trough potential slightly and flattens the rise in phase 4
The vagus:
Is the dominant autonomic effect at rest
True. The natural S-A node rate is 100-110/min, as seen in a denervated heart
Myocardial contractility is enhanced by:
Glucagon
True. Glucagon increases intracellular cAMP via adenylate cyclase activation and phosphodiesterase inhibition
Myocardial contractility is enhanced by:
Noradrenaline
True. Noradrenaline is a potent agonist at beta-2 receptors (though not as potent as adrenaline)
Myocardial contractility is enhanced by:
A decrease in arterial pH
False. Acidosis inhibits myocardial contractility
Myocardial contractility is enhanced by:
An increase in vagal tone
False. Vagal stimulation produces a negative chronotropic action, but has little effect on inotropicity
Myocardial contractility is enhanced by:
A fall in extracellular calcium concentration
False. Calcium is essential component of the contractile process
Regarding the heart and major vessels:
The right ventricle is normally about 8-10 mm thick
False. The RV is normally 3-4 mm thick
Regarding the heart and major vessels:
The right pulmonary artery passes beneath the aortic arch
True. The aorta arches over the right PA
Regarding the heart and major vessels:
The normal pulmonary artery pressure is 25/10 mmHg
True. This is the normal PA pressure
Regarding the heart and major vessels:
All cardiac valves have three leaflets
False. The mitral valve has 2 leaflets
Regarding the heart and major vessels:
The tricuspid valve is anchored by chordae tendineae
True. Both the mitral and tricuspid valves are anchored by chordae tendineae
The following are normal values:
Right ventricular pressure 25/0 mmHg
True. RV systolic pressure is about one fifth of the LV
The following are normal values:
Pulmonary capillary hydrostatic pressure 10 mmHg
True. Pulmonary capillary hydrostatic pressure starts at approximately 12 mmHg, falling to around 7 at the distal end; this is the main reason for minimal fluid loss into the alveoli
The following are normal values:
Glomerular capillary hydrostatic pressure 30 mmHg
False. The glomerular capillary pressure is around 55 mmHg, enabling a large volume of filtrate to be produced
The following are normal values:
Plasma oncotic pressure 25 mmHg
True. Plasma oncotic pressure is around 25 mmHg (just over 1 mOsmol/L), a tiny proportion of the total osmotic pressure (~280 mOsmol/L)
The following are normal values:
Right ventricular end-diastolic volume 110 mL
True. The end-diastolic and end-systolic volumes in the right and left ventricles are similar at around 110 mL and 40 mL respectively
When considering fluid movement at the level of the capillary:
The biggest component of plasma osmotic pressure is generated by electrolytes
True. Electrolytes (mostly sodium and chloride) make up the vast majority of plasma osmotic pressure - it is the number of particles, not their size which counts
When considering fluid movement at the level of the capillary:
Oncotic pressure is approximately one fifth of total plasma osmotic pressure
False. The oncotic pressure, generated by proteins, is less than 0.5% of the total, but is the difference between intravascular and extravascular compartments
When considering fluid movement at the level of the capillary:
Electrolytes can move freely between plasma and interstitial fluid
True. Small particles move freely through the gaps between endothelial cells
When considering fluid movement at the level of the capillary:
There is a net inward movement of fluid at the venous end
True. About 20 L leaves the capillary per day, at the arterial end; 18 L returns at the venous end, with the remaining 2 L returning via the lymphatics
When considering fluid movement at the level of the capillary:
Approximately 2 L of fluid per day return via the lymphatic system
True. About 20 L leaves the capillary per day, at the arterial end; 18 L returns at the venous end, with the remaining 2 L returning via the lymphatics
In a standard cardiac myocyte:
The resting membrane potential is approximately -85 mV
True. Cardiac myocyte RMP is -85 mV intracellularly
In a standard cardiac myocyte:
Sodium inflow is responsible for initial depolarization (phase 0)
True. Sodium inflow initiates phase 0, augmented by calcium inflow through T type channels
In a standard cardiac myocyte:
Calcium inflow is responsible for repolarization (phase 3)
False. Potassium outflow is responsible for phase 3 (repolarization)
In a standard cardiac myocyte:
The action potential lasts approximately 30 ms
False. The AP in a standard cardiac myocyte is approximately 300 ms in length
In a standard cardiac myocyte:
Automaticity is a normal feature
False. Only pacemaker cells normally exhibit automaticity
The following produce a fall in the systemic vascular resistance:
Hypercapnia
True. Hypercapnia produces vasodilatation
The following produce a fall in the systemic vascular resistance:
Pregnancy
True. Vasodilatation occurs during pregnancy, largely mediated by progesterone
The following produce a fall in the systemic vascular resistance:
Increased intracranial pressure
False. As the ICP rises, Cushing’s response leads to vasoconstriction to raise MAP
The following produce a fall in the systemic vascular resistance:
ANP
True. ANP produces vasodilatation as well as natriuresis
The following produce a fall in the systemic vascular resistance:
Changing from fetal to adult circulation
False. Loss of the placental circulation at birth increases SVR
