CARDIOVASCULAR SYSTEM QUESTION BANK
Which agent is released or secreted after a hemorrhage and causes an increase in renal Na+ reabsorption? (A) Aldosterone (B) Angiotensin I (C) Angiotensinogen (D) Antidiuretic hormone (ADH) (E) Atrial natriuretic peptide
(A) Aldosterone Angiotensin I and aldosterone are increased in response to a decrease in renal perfusion pressure. Angiotensinogen is the precursor for angiotensin I. Antidiuretic hormone (ADH) is released when atrial receptors detect a decrease in blood volume. Of these, only aldosterone increases Na+ reabsorption. Atrial natriuretic peptide is released in response to an increase in atrial pressure, and an increase in its secretion would not be anticipated after blood loss.
An acute decrease in arterial blood pressure elicits which of the following compensatory changes? (A) Decreased firing rate of the carotid sinus nerve (B) Increased parasympathetic outflow to the heart (C) Decreased heart rate (D) Decreased contractility (E) Decreased mean systemic pressure
(A) Decreased firing rate of the carotid sinus nerve A decrease in blood pressure causes decreased stretch of the carotid sinus baroreceptors and decreased firing of the carotid sinus nerve. In an attempt to restore blood pressure, the parasympathetic outflow to the heart is decreased and sympathetic outflow is increased. As a result, heart rate and contractility will be increased. Mean systemic pressure will increase because of increased sympathetic tone of the veins (and a shift of blood to the arteries).
Propranolol has which of the following effects? (A) Decreases heart rate (B) Increases left ventricular ejection fraction (C) Increases stroke volume (D) Decreases splanchnic vascular resistance (E) Decreases cutaneous vascular resistance
(A) Decreases heart rate Propranolol, a β-adrenergic antagonist, blocks all sympathetic effects that are mediated by a β1 or β2 receptor. The sympathetic effect on the sinoatrial (SA) node is to increase heart rate via a β1 receptor; therefore, propranolol decreases heart rate. Ejection fraction reflects ventricular contractility, which is another effect of β1 receptors; thus, propranolol decreases contractility, ejection fraction, and stroke volume. Splanchnic and cutaneous resistance are mediated by α1 receptors.
Blood flow to which organ is controlled primarily by the sympathetic nervous system rather than by local metabolites? (A) Skin (B) Heart (C) Brain (D) Skeletal muscle during exercise
(A) Skin Circulation of the skin is controlled primarily by the sympathetic nerves. The coronary and cerebral circulations are primarily regulated by local metabolic factors. Skeletal muscle circulation is regulated by metabolic factors (local metabolites) during exercise, although at rest it is controlled by the sympathetic nerves.
The low-resistance pathways between myocardial cells that allow for the spread of action potentials are the: (A) gap junctions (B) T tubules (C) sarcoplasmic reticulum (SR) (D) intercalated disks (E) mitochondria
(A) gap junctions The gap junctions occur at the intercalated disks between cells and are low-resistance sites of current spread.
An increase in contractility is demonstrated on a Frank-Starling diagram by: (A) increased cardiac output for a given end-diastolic volume (B) increased cardiac output for a given end-systolic volume (C) decreased cardiac output for a given end-diastolic volume (D) decreased cardiac output for a given end-systolic volume
(A) increased cardiac output for a given end-diastolic volume An increase in contractility produces an increase in cardiac output for a given end-diastolic volume, or pressure. The Frank-Starling relationship demonstrates the matching of cardiac output (what leaves the heart) with venous return (what returns to the heart). An increase in contractility (positive inotropic effect) will shift the curve upward
An electrocardiogram (ECG) on a person shows ventricular extrasystoles. After an extrasystole, the next "normal" ventricular contraction produces (A) increased pulse pressure because the contractility of the ventricle is increased (B) increased pulse pressure because total peripheral resistance (TPR) is decreased (C) increased pulse pressure because compliance of the veins is decreased (D) decreased pulse pressure because the contractility of the ventricle is increased (E) decreased pulse pressure because TPR is decreased
(A) increased pulse pressure because the contractility of the ventricle is increased The postextrasystolic contraction produces increased pulse pressure because contractility is increased. Extra Ca2+ enters the cell during the extrasystolic beat. Contractility is directly related to the amount of intracellular Ca2+ available for binding to troponin C.
Inspiration "splits" the second heart sound because: (A) the aortic valve closes before the pulmonic valve (B) the pulmonic valve closes before the aortic valve (C) the mitral valve closes before the tricuspid valve (D) the tricuspid valve closes before the mitral valve (E) filling of the ventricles has fast and slow components
(A) the aortic valve closes before the pulmonic valve The second heart sound is associated with closure of the aortic and pulmonic valves. Because the aortic valve closes before the pulmonic valve, the sound can be split by inspiration.
A healthy 35-year-old man is running a marathon. During the run, there is a increase in his splanchnic vascular resistance. Which receptor is responsible for the increased resistance? (A) α1 Receptors (B) β1 Receptors (C) β2 Receptors (D) Muscarinic receptors
(A) α1 Receptors During exercise, the sympathetic nervous system is activated. The observed increase in splanchnic vascular resistance is due to sympathetic activation of α1 receptors on splanchnic arterioles.
When a person moves from a supine position to a standing position, which of the following compensatory changes occurs? (A) Decreased heart rate (B) Increased contractility (C) Decreased total peripheral resistance (TPR) (D) Decreased cardiac output (E) Increased PR intervals
(B) Increased contractility When a person moves to a standing position, blood pools in the leg veins, causing decreased venous return to the heart, decreased cardiac output, and decreased arterial pressure. The baroreceptors detect the decrease in arterial pressure, and the vasomotor center is activated to increase sympathetic outflow and decrease parasympathetic outflow. There is an increase in heart rate (resulting in a decreased PR interval), contractility, and total peripheral resistance (TPR). Because both heart rate and contractility are increased, cardiac output will increase toward normal.
Which of the following is the result of an inward Na+ current? (A) Upstroke of the action potential in the sinoatrial (SA) node (B) Upstroke of the action potential in Purkinje fibers (C) Plateau of the action potential in ventricular muscle (D) Repolarization of the action potential in ventricular muscle (E) Repolarization of the action potential in the SA node
(B) Upstroke of the action potential in Purkinje fibers The upstroke of the action potential in the atria, ventricles, and Purkinje fibers is the result of a fast inward Na+ current. The upstroke of the action potential in the sinoatrial (SA) node is the result of an inward Ca2+ current. The plateau of the ventricular action potential is the result of a slow inward Ca2+ current. Repolarization in all cardiac tissues is the result of an outward K+ current.
Which of the following is an effect of histamine? (A) Decreased capillary filtration (B) Vasodilation of the arterioles (C) Vasodilation of the veins (D) Decreased Pc (E) Interaction with the muscarinic receptors on the blood vessels
(B) Vasodilation of the arterioles Histamine causes vasodilation of the arterioles, which increases Pc and capillary filtration. It also causes constriction of the veins, which contributes to the increase in Pc. Acetylcholine (ACh) interacts with muscarinic receptors (although these are not present on vascular smooth muscle).
In the sinoatrial (SA) node, phase 4 depolarization (pacemaker potential) is attributable to: (A) an increase in K+ conductance (B) an increase in Na+ conductance (C) a decrease in Cl- conductance (D) a decrease in Ca2+ conductance (E) simultaneous increases in K+ and Cl- conductances
(B) an increase in Na+ conductance Phase 4 depolarization is responsible for the pacemaker property of sinoatrial (SA) nodal cells. It is caused by an increase in Na+ conductance and an inward Na+ current (If), which depolarizes the cell membrane.
A person's electrocardiogram (ECG) has no P wave, but has a normal QRS complex and a normal T wave. Therefore, his pacemaker is located in the: (A) sinoatrial (SA) node (B) atrioventricular (AV) node (C) bundle of His (D) Purkinje system (E) ventricular muscle
(B) atrioventricular (AV) node The absent P wave indicates that the atrium is not depolarizing and, therefore, the pacemaker cannot be in the sinoatrial (SA) node. Because the QRS and T waves are normal, depolarization and repolarization of the ventricle must be proceeding in the normal sequence. This situation can occur if the pacemaker is located in the atrioventricular (AV) node. If the pacemaker were located in the bundle of His or in the Purkinje system, the ventricles would activate in an abnormal sequence (depending on the exact location of the pacemaker) and the QRS wave would have an abnormal configuration. Ventricular muscle does not have pacemaker properties.
If the ejection fraction increases, there will be a decrease in: (A) cardiac output (B) end-systolic volume (C) heart rate (D) pulse pressure (E) stroke volume (F) systolic pressure
(B) end-systolic volume An increase in ejection fraction means that a higher fraction of the end-diastolic volume is ejected in the stroke volume (e.g., because of the administration of a positive inotropic agent). When this situation occurs, the volume remaining in the ventricle after systole, the end-systolic volume, will be reduced. Cardiac output, pulse pressure, stroke volume, and systolic pressure will be increased.
The tendency for edema to occur will be increased by: (A) arteriolar constriction (B) increased venous pressure (C) increased plasma protein concentration (D) muscular activity
(B) increased venous pressure Edema occurs when more fluid is filtered out of the capillaries than can be returned to the circulation by the lymphatics. Filtration is increased by changes that increase Pc or decrease πc. Arteriolar constriction would decrease Pc and decrease filtration. Dehydration would increase plasma protein concentration (by hemoconcentration) and thereby increase πc and decrease filtration. Increased venous pressure would increase Pc and filtration.
A 72-year-old woman, who is being treated with propranolol, finds that she cannot maintain her previous exercise routine. Her physician explains that the drug has reduced her cardiac output. Blockade of which receptor is responsible for the decrease in cardiac output? (A) α1 Receptors (B) β1 Receptors (C) β2 Receptors (D) Muscarinic receptors (E) Nicotinic receptors
(B) β1 Receptors Propranolol is an adrenergic antagonist that blocks both β1 and β2 receptors. When propranolol is administered to reduce cardiac output, it inhibits β1 receptors in the sinoatrial (SA) node (heart rate) and in ventricular muscle (contractility).
In a capillary, Pc is 30 mm Hg, Pi is −2 mm Hg, πc is 25 mm Hg, and πi is 2 mm Hg. If Kf is 0.5 mL/min/mm Hg, what is the rate of water flow across the capillary wall? (A) 0.06 mL/min (B) 0.45 mL/min (C) 4.50 mL/min (D) 9.00 mL/min (E) 18.00 mL/min
(C) 4.50 mL/min Kf is the filtration coefficient for the capillary and describes the intrinsic water permeability.Water flow = K X Net pressure= 0.5 mL/min/mmHg X 9 mmHg= 4.5 mL/min
Carbon dioxide (CO2) regulates blood flow to which one of the following organs? (A) Heart (B) Skin (C) Brain (D) Skeletal muscle at rest (E) Skeletal muscle during exercise
(C) Brain Blood flow to the brain is autoregulated by the Pco2. If metabolism increases (or arterial pressure decreases), the Pco2 will increase and cause cerebral vasodilation. Blood flow to the heart and to skeletal muscle during exercise is also regulated metabolically, but adenosine and hypoxia are the most important vasodilators for the heart. Adenosine, lactate, and K+ are the most important vasodilators for exercising skeletal muscle. Blood flow to the skin is regulated by the sympathetic nervous system rather than by local metabolites.
Myocardial contractility is best correlated with the intracellular concentration of: (A) Na+ (B) K+ (C) Ca2+ (D) Cl- (E) Mg2+
(C) Ca2+ Contractility of myocardial cells depends on the intracellular [Ca2+], which is regulated by Ca2+ entry across the cell membrane during the plateau of the action potential and by Ca2+ uptake into and release from the sarcoplasmic reticulum (SR). Ca2+ binds to troponin C and removes the inhibition of actin-myosin interaction, allowing contraction (shortening) to occur.
In which of the following situations is pulmonary blood flow greater than aortic blood flow? (A) Normal adult (B) Fetus (C) Left-to-right ventricular shunt (D) Right-to-left ventricular shunt (E) Right ventricular failure (F) Administration of a positive inotropic agent
(C) Left-to-right ventricular shunt In a left-to-right ventricular shunt, a defect in the ventricular septum allows blood to flow from the left ventricle to the right ventricle instead of being ejected into the aorta. The "shunted" fraction of the left ventricular output is therefore added to the output of the right ventricle, making pulmonary blood flow (the cardiac output of the right ventricle) higher than systemic blood flow (the cardiac output of the left ventricle). In normal adults, the outputs of both ventricles are equal in the steady state. In the fetus, pulmonary blood flow is near zero. Right ventricular failure results in decreased pulmonary blood flow. Administration of a positive inotropic agent should have the same effect on contractility and cardiac output in both ventricles.
An increase in arteriolar resistance, without a change in any other component of the cardiovascular system, will produce: (A) a decrease in total peripheral resistance (TPR) (B) an increase in capillary filtration (C) an increase in arterial pressure (D) a decrease in afterload
(C) an increase in arterial pressure An increase in arteriolar resistance will increase total peripheral resistance (TPR). Arterial pressure = cardiac output × TPR, so arterial pressure will also increase. Capillary filtration decreases when there is arteriolar constriction because Pc decreases. Afterload of the heart would be increased by an increase in TPR.
The physiologic function of the relatively slow conduction through the atrioventricular (AV) node is to allow sufficient time for: (A) runoff of blood from the aorta to the arteries (B) venous return to the atria (C) filling of the ventricles (D) contraction of the ventricles (E) repolarization of the ventricles
(C) filling of the ventricles The atrioventricular (AV) delay (which corresponds to the PR interval) allows time for filling of the ventricles from the atria. If the ventricles contracted before they were filled, stroke volume would decrease.
A 30-year-old female patient's electrocardiogram (ECG) shows two P waves preceding each QRS complex. The interpretation of this pattern is: (A) decreased firing rate of the pacemaker in the sinoatrial (SA) node (B) decreased firing rate of the pacemaker in the atrioventricular (AV) node (C) increased firing rate of the pacemaker in the SA node (D) decreased conduction through the AV node (E) increased conduction through the His-Purkinje system
(C) increased firing rate of the pacemaker in the SA node A pattern of two P waves preceding each QRS complex indicates that only every other P wave is conducted through the atrioventricular (AV) node to the ventricle. Thus, conduction velocity through the AV node must be decreased.
During exercise, total peripheral resistance (TPR) decreases because of the effect of: (A) the sympathetic nervous system on splanchnic arterioles (B) the parasympathetic nervous system on skeletal muscle arterioles (C) local metabolites on skeletal muscle arterioles (D) local metabolites on cerebral arterioles (E) histamine on skeletal muscle arterioles
(C) local metabolites on skeletal muscle arterioles During exercise, local metabolites accumulate in the exercising muscle and cause local vasodilation and decreased arteriolar resistance of the skeletal muscle. Because muscle mass is large, it contributes a large fraction of the total peripheral resistance (TPR). Therefore, the skeletal muscle vasodilation results in an overall decrease in TPR, even though there is sympathetic vasoconstriction in other vascular beds.
The tendency for blood flow to be turbulent is increased by: (A) increased viscosity (B) increased hematocrit (C) partial occlusion of a blood vessel (D) decreased velocity of blood flow
(C) partial occlusion of a blood vessel Turbulent flow is predicted when the Reynolds number is increased. Factors that increase the Reynolds number and produce turbulent flow are decreased viscosity (hematocrit) and increased velocity. Partial occlusion of a blood vessel increases the Reynolds number (and turbulence) because the decrease in cross-sectional area results in increased blood velocity (v = Q/A).
Cardiac output of the right side of the heart is what percentage of the cardiac output of the left side of the heart? (A) 25% (B) 50% (C) 75% (D) 100% (E) 125%
(D) 100% Cardiac output of the left and right sides of the heart is equal. Blood ejected from the left side of the heart to the systemic circulation must be oxygenated by passage through the pulmonary circulation.
The following measurements were obtained in a male patient: Central venous pressure: 10 mm Hg Heart rate: 70 beats/min Systemic arterial [O2] = 0.24 mL O2/mL Mixed venous [O2] = 0.16 mL O2/mL Whole body O2 consumption: 500 mL/min What is this patient's cardiac output? (A) 1.65 L/min (B) 4.55 L/min (C) 5.00 L/min (D) 6.25 L/min (E) 8.00 L/min
(D) 6.25 L/min Cardiac output is calculated by the Fick principle if whole body oxygen (O2) consumption and [O2] in the pulmonary artery and pulmonary vein are measured. Mixed venous blood could substitute for a pulmonary artery sample, and peripheral arterial blood could substitute for a pulmonary vein sample. Central venous pressure and heart rate are not needed for this calculation. Cardiac output = (500 mL/min) / (0.24 mL O2/mL - 0.16 mL O2/mL) = 6250 mL/min, or 6.25 L/min
A hospitalized patient has an ejection fraction of 0.4, a heart rate of 95 beats/min, and a cardiac output of 3.5 L/min. What is the patient's end-diastolic volume? (A) 14 mL (B) 37 mL (C) 55 mL (D) 92 mL (E) 140 mL
(D) 92 mL First, calculate stroke volume from the cardiac output and heart rate: Cardiac output = stroke volume × heart rate; thus, stroke volume = cardiac output/ heart rate = 3500 mL/95 beats/min = 36.8 mL. Then, calculate end-diastolic volume from stroke volume and ejection fraction: Ejection fraction = stroke volume/end-diastolic volume; thus end-diastolic volume = stroke volume/ejection fraction = 36.8 mL/0.4 = 92 mL.
Which of the following agents or changes has a negative inotropic effect on the heart? (A) Increased heart rate (B) Sympathetic stimulation (C) Norepinephrine (D) Acetylcholine (ACh) (E) Cardiac glycosides
(D) Acetylcholine (ACh) A negative inotropic effect is one that decreases myocardial contractility. Contractility is the ability to develop tension at a fixed muscle length. Factors that decrease contractility are those that decrease the intracellular [Ca2+]. Increasing heart rate increases intracellular [Ca2+] because more Ca2+ ions enter the cell during the plateau of each action potential. Sympathetic stimulation and norepinephrine increase intracellular [Ca2+] by increasing entry during the plateau and increasing the storage of Ca2+ by the sarcoplasmic reticulum (SR) [for later release]. Cardiac glycosides increase intracellular [Ca2+] by inhibiting the Na+-K+ pump, thereby inhibiting Na+-Ca2+ exchange (a mechanism that pumps Ca2+ out of the cell). Acetylcholine (ACh) has a negative inotropic effect on the atria.
A 53-year-old woman is found, by arteriography, to have 50% narrowing of her left renal artery. What is the expected change in blood flow through the stenotic artery? (A) Decrease to ½ (B) Decrease to ¼ (C) Decrease to 1⁄8 (D) Decrease to 1⁄16 (E) No change
(D) Decrease to 1⁄16 If the radius of the artery decreased by 50% (1/2), then resistance would increase by 24, or 16 (R = 8ηl/πr4). Because blood flow is inversely proportional to resistance (Q = ΔP/R), flow will decrease to 1/16 of the original value.
In a capillary, Pc is 30 mm Hg, Pi is −2 mm Hg, πc is 25 mm Hg, and πi is 2 mm Hg. What is the direction of fluid movement and the net driving force? (A) Absorption; 6 mm Hg (B) Absorption; 9 mm Hg (C) Filtration; 6 mm Hg (D) Filtration; 9 mm Hg (E) There is no net fluid movement
(D) Filtration; 9 mm Hg The net driving force can be calculated with the Starling equation Net pressure = (Pc - Pi) - (πc-πi) = [(30-(-2)) - (25-2)] mmHg = 32 mmHg - 23 mmHg = + 9 mmHg Because the net pressure is positive, filtration out of the capillary will occur.
Which of the following substances crosses capillary walls primarily through water-filled clefts between the endothelial cells? (A) O2 (B) CO2 (C) CO (D) Glucose
(D) Glucose Because O2, CO2, and CO are lipophilic, they cross capillary walls primarily by diffusion through the endothelial cell membranes. Glucose is water soluble; it cannot cross through the lipid component of the cell membrane and is restricted to the water-filled clefts, or pores, between the cells.
Which of the following changes will cause an increase in myocardial O2 consumption? (A) Decreased aortic pressure (B) Decreased heart rate (C) Decreased contractility (D) Increased size of the heart (E) Increased influx of Na+ during the upstroke of the action potential
(D) Increased size of the heart Myocardial O2 consumption is determined by the amount of tension developed by the heart. It increases when there are increases in aortic pressure (increased afterload), when there is increased heart rate or stroke volume (which increases cardiac output), or when the size (radius) of the heart is increased (T = P × r). Influx of Na+ ions during an action potential is a purely passive process, driven by the electrochemical driving forces on Na+ ions. Of course, maintenance of the inwardly directed Na+ gradient over the long term requires the Na+-K+ pump, which is energized by adenosine triphosphate (ATP).
A 60-year-old businessman is evaluated by his physician, who determines that his blood pressure is significantly elevated at 185/130 mm Hg. Laboratory tests reveal an increase in plasma renin activity, plasma aldosterone level, and left renal vein renin level. His right renal vein renin level is decreased. What is the most likely cause of the patient's hypertension? (A) Aldosterone-secreting tumor (B) Adrenal adenoma secreting aldosterone and cortisol (C) Pheochromocytoma (D) Left renal artery stenosis (E) Right renal artery stenosis
(D) Left renal artery stenosis In this patient, hypertension is most likely caused by left renal artery stenosis, which led to increased renin secretion by the left kidney. The increased plasma renin activity causes an increased secretion of aldosterone, which increases Na+ reabsorption by the renal distal tubule. The increased Na+ reabsorption leads to increased blood volume and blood pressure. The right kidney responds to the increase in blood pressure by decreasing its renin secretion. Right renal artery stenosis causes a similar pattern of results, except that renin secretion from the right kidney, not the left kidney, is increased. Aldosterone-secreting tumors cause increased levels of aldosterone but decreased plasma renin activity (as a result of decreased renin secretion by both kidneys). Pheochromocytoma is associated with increased circulating levels of catecholamines, which increase blood pressure by their effects on the heart (increased heart rate and contractility) and blood vessels (vasoconstriction); the increase in blood pressure is sensed by the kidneys and results in decreased plasma renin activity and aldosterone levels.
Which receptor mediates slowing of the heart? (A) α1 Receptors (B) β1 Receptors (C) β2 Receptors (D) Muscarinic receptors
(D) Muscarinic receptors Acetylcholine (ACh) causes slowing of the heart via muscarinic receptors in the sinoatrial (SA) node.
During which phase of the cardiac cycle is aortic pressure highest? (A) Atrial systole (B) Isovolumetric ventricular contraction (C) Rapid ventricular ejection (D) Reduced ventricular ejection (E) Isovolumetric ventricular relaxation (F) Rapid ventricular filling (G) Reduced ventricular filling (diastasis)
(D) Reduced ventricular ejection Aortic pressure reaches its highest level immediately after the rapid ejection of blood during left ventricular systole. This highest level actually coincides with the beginning of the reduced ventricular ejection phase.
The ventricles are completely depolarized during which isoelectric portion of the electrocardiogram (ECG)? (A) PR interval (B) QRS complex (C) QT interval (D) ST segment (E) T wave
(D) ST segment The PR segment (part of the PR interval) and the ST segment are the only portions of the electrocardiogram (ECG) that are isoelectric. The PR interval includes the P wave (atrial depolarization) and the PR segment, which represents conduction through the atrioventricular (AV) node; during this phase, the ventricles are not yet depolarized. The ST segment is the only isoelectric period when the entire ventricle is depolarized.
A 66-year-old man, who has had a sympathectomy, experiences a greater-than-normal fall in arterial pressure upon standing up. The explanation for this occurrence is: (A) an exaggerated response of the renin- angiotensin-aldosterone system (B) a suppressed response of the renin- angiotensin-aldosterone system (C) an exaggerated response of the baroreceptor mechanism (D) a suppressed response of the baroreceptor mechanism
(D) a suppressed response of the baroreceptor mechanism Orthostatic hypotension is a decrease in arterial pressure that occurs when a person moves from a supine to a standing position. A person with a normal baroreceptor mechanism responds to a decrease in arterial pressure through the vasomotor center by increasing sympathetic outflow and decreasing parasympathetic outflow. The sympathetic component helps to restore blood pressure by increasing heart rate, contractility, total peripheral resistance (TPR), and mean systemic pressure. In a patient who has undergone a sympathectomy, the sympathetic component of the baroreceptor mechanism is absent.
An electrocardiogram (ECG) on a person shows ventricular extrasystoles. The extrasystolic beat would produce (A) increased pulse pressure because contractility is increased (B) increased pulse pressure because heart rate is increased (C) decreased pulse pressure because ventricular filling time is increased (D) decreased pulse pressure because stroke volume is decreased (E) decreased pulse pressure because the PR interval is increased
(D) decreased pulse pressure because stroke volume is decreased On the extrasystolic beat, pulse pressure decreases because there is inadequate ventricular filling time—the ventricle beats "too soon." As a result, stroke volume decreases.
Pulse pressure is: (A) the highest pressure measured in the arteries (B) the lowest pressure measured in the arteries (C) measured only during diastole (D) determined by stroke volume (E) decreased when the capacitance of the arteries decreases (F) the difference between mean arterial pressure and central venous pressure
(D) determined by stroke volume Pulse pressure is the difference between the highest (systolic) and lowest (diastolic) arterial pressures. It reflects the volume ejected by the left ventricle (stroke volume). Pulse pressure increases when the capacitance of the arteries decreases, such as with aging.
A 24-year-old woman presents to the emergency department with severe diarrhea. When she is supine (lying down), her blood pressure is 90/60 mm Hg (decreased) and her heart rate is 100 beats/min (increased). When she is moved to a standing position, her heart rate further increases to 120 beats/ min. Which of the following accounts for the further increase in heart rate upon standing? (A) Decreased total peripheral resistance (B) Increased venoconstriction (C) Increased contractility (D) Increased afterload (E) Decreased venous return
(E) Decreased venous return Diarrhea causes a loss of extracellular fluid volume, which produces a decrease in arterial pressure. The decrease in arterial pressure activates the baroreceptor mechanism, which produces an increase in heart rate when the patient is supine. When she stands up, blood pools in her leg veins and produces a decrease in venous return, a decrease in cardiac output (by the Frank-Starling mechanism), and a further decrease in arterial pressure. The further decrease in arterial pressure causes further activation of the baroreceptor mechanism and a further increase in heart rate.
During which phase of the cardiac cycle does the mitral valve open? (A) Atrial systole (B) Isovolumetric ventricular contraction (C) Rapid ventricular ejection (D) Reduced ventricular ejection (E) Isovolumetric ventricular relaxation (F) Rapid ventricular filling (G) Reduced ventricular filling (diastasis)
(E) Isovolumetric ventricular relaxation The mitral [atrioventricular (AV)] valve opens when left atrial pressure becomes higher than left ventricular pressure. This situation occurs when the left ventricular pressure is at its lowest level—when the ventricle is relaxed, blood has been ejected from the previous cycle, and before refilling has occurred.
During which phase of the cardiac cycle is ventricular volume lowest? (A) Atrial systole (B) Isovolumetric ventricular contraction (C) Rapid ventricular ejection (D) Reduced ventricular ejection (E) Isovolumetric ventricular relaxation (F) Rapid ventricular filling (G) Reduced ventricular filling (diastasis)
(E) Isovolumetric ventricular relaxation Ventricular volume is at its lowest value while the ventricle is relaxed (diastole), just before ventricular filling begins.
At which site is systolic blood pressure the highest? (A) Aorta (B) Central vein (C) Pulmonary artery (D) Right atrium (E) Renal artery (F) Renal vein
(E) Renal artery Pressures on the venous side of the circulation (e.g., central vein, right atrium, renal vein) are lower than pressures on the arterial side. Pressure in the pulmonary artery (and all pressures on the right side of the heart) are much lower than their counterparts on the left side of the heart. In the systemic circulation, systolic pressure is actually slightly higher in the downstream arteries (e.g., renal artery) than in the aorta because of the reflection of pressure waves at branch points.
The greatest pressure decrease in the circulation occurs across the arterioles because: (A) they have the greatest surface area (B) they have the greatest cross-sectional area (C) the velocity of blood flow through them is the highest (D) the velocity of blood flow through them is the lowest (E) they have the greatest resistance
(E) they have the greatest resistance The decrease in pressure at any level of the cardiovascular system is caused by the resistance of the blood vessels (ΔP = Q × R). The greater the resistance is, the greater the decrease in pressure is. The arterioles are the site of highest resistance in the vasculature. The arterioles do not have the greatest surface area or cross-sectional area (the capillaries do). Velocity of blood flow is lowest in the capillaries, riot in the arterioles.
Which of the following parameters is decreased during moderate exercise? (a) Arteriovenous O2 difference (B) Heart rate (C) Cardiac output (d) Pulse pressure (e) Total peripheral resistance (TPR)
(e) Total peripheral resistance (TPR) In anticipation of exercise, the central command increases sympathetic outflow to the heart and blood vessels, causing an increase in heart rate and contractility. Venous return is increased by muscular activity and contributes to an increase in cardiac output by the Frank-Starling mechanism. Pulse pressure is increased because stroke volume is increased. Although increased sympathetic outflow to the blood vessels might be expected to increase total peripheral resistance (TPR), it does not because there is an overriding vasodilation of the skeletal muscle arterioles as a result of the buildup of vasodilator metabolites (lactate, K+ adenosine). Because this vasodilation improves the delivery of O2, more O2 can be extracted and used by the contracting muscle.
When blood volume is increased which of the following hormones would you expect to increase? a) Atrial natriuretic peptide b) aldosterone c) Epinephrine d) angiotensin II
a) Atrial natriuretic peptide
What effect does prolonged standing in one position have on blood pressure? a) it causes blood pooling and a slowing of blood flow b) it causes a compensatory increase in arterial pressure c) it causes a sharp decrease in heart rate d) it causes a sharp decrease in respiratory rate
a) it causes blood pooling and a slowing of blood flow
Predict what would happen to the end systolic volume (ESV) if contraction force was to increase. a) it would decrease b) it would increase c) it would remain constant d) ESV is not affected by contraction force
a) it would decrease
What is the double-walled sac covering the heart termed? a) pericardium b) myocardium c) epicardium d) endocardium
a) pericardium
To predict a change in peripheral resistance as blood vessels diameter increases: a) peripheral resistance decreases b) peripheral resistance increases c) the peripheral resistance remains unchanged d) the peripheral resistance is constant in humans
a) peripheral resistance decreases
In a normal heart, which of the following structures is responsible for setting the heart's pace? a) sinoatrial node b) atrioventricular node c) atrioventricular bundle d) purkinje fibers
a) sinoatrial node
The primary input to the heart by the cardioinhibitory center primarily affects the ____. a) sinoatrial node and atrioventricular node b) purkinje fibers c) the cardiac contractile fibers d) bundle of his
a) sinoatrial node and atrioventricular node
Cardiac muscle cells have several similarities with skeletal muscle cells. Which of the following is not a similarity? a) the cells are each innervated by a nerve ending b) the cells store calcium ions in the sarcoplasmic reticulum c) the cells contain sarcomeres d) the cells become depolarized when sodium ions enter the cytoplasm
a) the cells are each innervated by a nerve ending
Predict what might happen to peripheral resistance in arterioles supplying skeletal muscle when PH levels drop. a) vasoconstriction in vessels supplying skeletal muscles b) vasodilation in vessels supplying digestive viscera c) vasodilation in vessels supplying skeletal muscle vessels d) No change
a) vasoconstriction in vessels supplying skeletal muscles
A decrease in O2 level in skeletal muscle would initiate an auto regulatory mechanism that would stimulate ____ in the arterioles supplying the muscle. a) vasodilation b) vasoconstriction c) constriction of the pre-capillary sphincters d) peristaltic waves
a) vasodilation
An increasing lumen diameter is termed _____, and occurs when smooth muscle ______. a) vasodilation, relaxes b) vasodilation,contracts c) vasoconstriction, relaxes d) vasoconstriction, contracts
a) vasodilation, relaxes
Atrial systole occurs _____ the firing of the sinoatrial node. a) before b) after c) simultaneously with d) alternately with
b) after
The plateau portion of the action potential is contractile cardiac muscle cells is due to: a) an increased potassium permeability b) an influx of calcium ions c) an influx of sodium ions d) exit of calcium ions from the sarcoplasmic reticulum
b) an influx of calcium ions
The left pulmonary artery carries _______ blood and ______blood to/from the _____. a) oxygenated, delivers, heart b) deoxygenated, delivers, lung c) oxygenated, receives, heart d) deoxygenated, receives, lung
b) deoxygenated, delivers, lung
Predict what happens to end diastolic volume when an increase in heart rate is not accompanied by an increase in contractility. a) end diastolic volume is increased b) end diastolic volume is decreased c) end diastolic volume is unchanged d) end diastolic volume not affected by heart rate.
b) end diastolic volume is decreased
What purpose does the coronary circuit serve? a) none; it is a vestigial set of vessels b) it delivers blood to the heart c) it delivers blood to the anterior lung surface for gas exchange d) it feeds the anterior thoracic wall
b) it delivers blood to the heart
Of the following layers of the heart wall, which consumes the most energy? a) epicardium b) myocardium c) endocardium d) visceral pericardium
b) myocardium
Capillary colloid osmotic pressure created by ____ tends to _____. a) blood volume; push fluids out of the capillary b) non-diffusable plasma proteins; draw fluids into the capillary c) interstitial fluid; draw fluids out of the capillary d) proteins in the interstitial fluid; push fluids into the interstitial fluid
b) non-diffusable plasma proteins; draw fluids into the capillary
Why don't platelets form plugs in undamaged vessels? a) platelets aren't formed until vessel damage occurs b) only contact of platelets with exposed collagen fibers and von willebrand factor causes them to be sticky and form plugs c) plugs do form, but are removed by macrophages d) platelets don't form plugs; it is the megakaryocytes that form the plugs
b) only contact of platelets with exposed collagen fibers and von willebrand factor causes them to be sticky and form plugs
The major vessel delivering deoxygenated blood to the lungs in the _____. a) pulmonary trunk b) pulmonary vein c) aorta d) superior vena cava
b) pulmonary vein
Baroreceptors detect changes in_____. a) blood o2 levels b) stretch in arterial walls c) blood co2 levels d) blood H+ levels
b) stretch in arterial walls
In terms of blood flow, why is it important that atrial diastole occurs just as ventricular systole begins? a) the AV valves would remain open if the atria were still contracting. b) the atria need that time to fill with blood in preparation for ventricular filling c) ventricular systole pulls the remaining 20% of blood volume from the atria d) blood would flow too fast otherwise
b) the atria need that time to fill with blood in preparation for ventricular filling
Why does blood velocity decrease as it flows as it goes into the capillary bed? a) the diameter of the capillaries is smaller than that of the arterioles and arteries b) the cross-sectional area of the capillary beds is approximately 2000x than that of the aorta c) the arteries are constricted d) the pressure is much higher in the capillaries
b) the cross-sectional area of the capillary beds is approximately 2000x than that of the aorta
Activation of the extrinsic pathway of coagulation requires exposure of the blood to ____. a) collagen b) tissue factor III c) prothrombin activator d) serotonin
b) tissue factor III
Of the following blood vessel components, which is the most critical in regulating systemic blood pressure? a) tunica intima b) tunica media c) tunica externa d) venous valves
b) tunica media
In what way is pulmonary circulation different from circulation in other body tissues? a) pulmonary circulation does not exhibit vasoconstriction b) pulmonary circulation does not exhibit vasodilation c) as opposed to other tissues, low o2 levels in the lungs induce vasoconstriction d) as opposed to other tissues, low o2 levels in the lungs induce vasodilation
c) as opposed to other tissues, low o2 levels in the lungs induce vasoconstriction
Of the following vessel types, which are responsible for the exchange of gases and nutrients with tissues? a) arteries b) arterioles c) capillaries d) veins
c) capillaries
Why is high blood pressure damaging to the heart? a) with high blood pressure, the blood is more viscous and harder to pump b) the heart rate slows down to dangerously low levels if blood pressure is too high c) due to increased afterload, the left ventricle must contact more forcefully to expel the same amount of blood d) sodium concentration increases during high blood pressure and is toxic to the myocardium
c) due to increased afterload, the left ventricle must contact more forcefully to expel the same amount of blood
Your heart seems to "pound" after you hear a sudden loud noise. This increased contractility is: a) because vagal nerve impulses arrive faster at the heart b) because whena gasp of surprise is emitted, the Frank-Starling law of the heart is evident c) due to norepinephrine causing threshold to be reached more quickly
c) due to norepinephrine causing threshold to be reached more quickly
Which of the following statements is true? a) all arteries transport oxygen rich blood b) the right side of the heart is the systemic circuit pump c) equal volumes of blood are pumped to the pulmonary and systemic circuits at any moment d) the left side of the heart pumps blood to the lungs
c) equal volumes of blood are pumped to the pulmonary and systemic circuits at any moment
The superior vena cava receives systemic blood draining from all areas superior to the diaphragm except the _______. a) lungs b) left upper arm c) heart wall
c) heart wall
Why is vasodilation prominent in the skin when a person increases physical activity? a) it increases delivery of nutrients to the skin to induce sweating b) because skeletal muscles are close to the skin, they receive the oxygen via diffusion c) heat is dissipated across the skin from the blood to help cool the body d) Exercise produces metabolites that induce vasodilation
c) heat is dissipated across the skin from the blood to help cool the body
Blood drained from digestive organs empties into the _____ before going through the liver. a) inferior vena cava b) hepatic vein c) hepatic portal vein d) dural sinus
c) hepatic portal vein
Which vessel receives blood drainage from the liver and returns it to the heart? a) azygos b) hepatic portal vein c) inferior vena cava d) superior vena cava
c) inferior vena cava
The apex of the heart points: a) superiorly toward the right shoulder b) laterally toward the right hip c) inferiorly toward the left hip d) posteriorly toward the left shoulder
c) inferiorly toward the left hip
Of the following cardiovascular components, which contains the majority of the body's blood volume at any one time? a) pulmonary capillaries b) heart c) systemic veins and venules d) systemic capillaries
c) systemic veins and venules
The "lub dub" heart sounds are produced by: a) the walls of the atria and ventricles slapping together during a contraction b) the blood hitting the walls of the ventricles and arteries, respectively c) the closing of the atrioventricular valves ("lub") and the closing of the semilunar valves ("dub") d) the closing of the semilunar valves (lub) and the closing of the atrioventricular valves(dub)
c) the closing of the atrioventricular valves ("lub") and the closing of the semilunar valves ("dub")
Predict the nature of an ECG recording when the atrioventricular node becomes the pacemaker. a) there would continue to be a normal sinus rhythm b) the P wave would be much larger than normal c) the rhythm would be slower d) the T wave would be much smaller than normal
c) the rhythm would be slower
What is the major factor controlling stroke volume during resting periods? a) sympathetic input b) parasympathic input c) venous retreat to the heart d) peripheral resistance changes
c) venous retreat to the heart
The stimulus for the hearts rhythmic contractions comes from _____. a) intercalated discs b) acetylcholine c)a neuromuscular junction d) a pacemaker potential
d) a pacemaker potential
What Is the nature of acetylcholine's inhibitory effect on heart rate? a) acetylcholine induces depolarization in the sinoatrial node b) acetylcholine causes closing of sodium channels in the sinoatrial node c) acetylcholine causes opening of fast calcium channels in contractile cells d) acetylcholine causes opening of potassium channels in the sinoatrial node, thereby hyperpolarizing it.
d) acetylcholine causes opening of potassium channels in the sinoatrial node, thereby hyperpolarizing it.
Cardiac output is determined by _______. a) heart rate b) stroke volume c) cardiac reserve d) both a and b
d) both a and b
The majority (80%) of ventricular filling occurs _____. a) during late ventricular diastole b) passively through blood flow alone c) with atrial systole d) both a and b
d) both a and b
Which of the following structures is an exception to the general principle surrounding blood vessel oxygenation levels? a) pulmonary artery b) aorta c) pulmonary veins d) both a and c
d) both a and c
some of the least permeable capillaries are found in the ____, while some of the most permeable capillaries are found in the _____. a) kidney; brain b) intestines; muscles c) bone marrow; brain d) brain; bone marrow
d) brain; bone marrow
The presence of intercalated discs between adjacent cardiac muscle cells causes the heart to behave as a ______. a) single chamber b) contractile myofibril c) desmosome d) functional syncytium
d) functional syncytium
The primary mechanism driving filtration in capillary beds is _____. a) diffusion b) capillary osmotic pressure c) hydrostatic pressure of the interstitial fluid d) hydrostatic pressure within in the capillaries
d) hydrostatic pressure within in the capillaries
Which type of blood vessel has the largest amount of fibrous tissue? a) Elastic arteries b) venules c) arterioles d) muscular arteries
d) muscular arteries
Pulse pressure decreases by the time that blood reaches the capillary beds because: a) the elastic arteries are too stretchy b) veins are too thing to accommodate pulse pressure c) the diastole lasts longer than the systole d) the muscular arterioles do not exhibit elastic rebound
d) the muscular arterioles do not exhibit elastic rebound
Of the following vessel types, which conduct blood toward the heart, regardless of oxygen content? a) arteries b) arterioles c) capillaries d) veins
d) veins
