Mastering A&P Chapter 18 Criswell Bio 202

The __________ valve is located between the right atrium and the right ventricle. mitral aortic semilunar pulmonary semilunar tricuspid

tricuspid The tricuspid valve is located between the right atrium and right ventricle.

Calculate the stroke volume if the end diastolic volume (EDV) is 135 mL and the end systolic volume (ESV) is 60 mL. 60 mL 75 mL 205 mL 8100 mL

75 mL The SV is calculated by subtracting the ESV from the EDV. You are comparing the volume of the ventricle at its fullest to its emptiest.

At what rate does the sinoatrial (SA) node depolarize? 30 times per minute 40 times per minute 50 times per minute 75 times per minute

75 times per minute The sinoatrial node typically depolarizes spontaneously about 75 times per minute, although this can vary in different individuals. This rate is directly modulated by the autonomic nervous system.

What does the QRS complex represent in the ECG wave tracing? atrial depolarization ventricular repolarization atrial repolarization ventricular depolarization

ventricular depolarization Yes, the QRS complex represents depolarization in the ventricles, which have greater mass than the atria.

At what point in the cardiac cycle is pressure in the ventricles the highest (around 120 mm Hg in the left ventricle)? mid-to-late diastole (ventricular filling) mid-to-late diastole (atrial contraction) ventricular systole early diastole (isovolumetric relaxation)

ventricular systole Left ventricular systole typically produces maximum pressures of around 120 mm Hg during systole.

Which of the following structures collects the depolarization wave from the atria to pass it onto the ventricles? bundle branches SA node atrioventricular bundle AV node

AV node The AV node receives the depolarizing wave from the atria and delays and coordinates that distribution to the ventricles.

Contraction of the atria results from which wave of depolarization on the ECG tracing? QRS complex T wave P wave

P wave Yes, the P wave represents atrial depolarization, which leads to atrial contraction.

Blood enters the left and right coronary arteries directly from which vessel or chamber? circumflex artery aorta left ventricle pulmonary trunk

aorta Blood flows to the right and left coronary arteries directly from the aorta.

The P wave on an electrocardiogram represents __________. atrial depolarization ventricular depolarization ventricular repolarization atrial repolarization

atrial depolarization The P wave reflects the depolarization of the atria.

The first heart sound (the "lub" of the "lub-dup") is caused by __________. atrial contraction closure of the semilunar valves closure of the atrioventricular valves ventricular contraction

closure of the atrioventricular valves The first heart sound (the "lub" of the "lub-dup") is generated by the closure of the atrioventricular valves

Which of the following would cause a DECREASE in cardiac output (CO)? decreasing thyroid function (thyroxine) suddenly standing up from a supine position an increase in adrenal medulla output (epinephrine) heightened use of skeletal muscle

decreasing thyroid function (thyroxine) Thyroxine increases basal metabolic rate, respiratory rate, and both heart rate and contractility.

What does the ECG wave tracing represent? contraction of the heart electrical activity in the heart

electrical activity in the heart Yes, the ECG waves show the depolarization and repolarization in various areas of the heart.

Which of the following would increase cardiac output? parasympathetic stimulation decreased calcium during contraction high blood pressure epinephrine

epinephrine Sympathetic stimulation leads to the release of epinephrine and norepinephrine, both of which increase heart rate and increase contractility, which increases stroke volume. Increasing heart rate and stroke volume increases cardiac output.

Which of the following increases stroke volume? decrease in end diastolic volume (EDV) severe blood loss decrease in preload exercise

exercise Exercise increases venous return, which would in turn increase the amount of blood in the presystolic ventricle (preload).

Which part of the intrinsic conduction system delays the impulse briefly before it moves on to the ventricles? AV node AV bundle (bundle of His) Purkinje fibers bundle branches SA node

AV node Yes, the AV node slows down the impulse giving the atria time to contract before the ventricles contract.

The right side of the heart is considered the systemic circuit pump. True False

False The right side of the heart pumps oxygen-poor blood to the lungs to be re-oxygenated. For this reason, the right side of the heart is considered the pulmonary circuit pump. The left side of the heart pumps blood to the body, and is therefore considered the systemic circuit pump.

The role of the chordae tendineae is to open the AV valves at the appropriate time. True False

False The role of the chordae tendineae is to anchor the AV valves against the large pressure changes that occur as the ventricles contract.

Why are gap junctions a vital part of the intercellular connection of cardiac muscles? Gap junctions form strong intercellular connections. Gap junctions allow calcium to enter the cell, triggering calcium release from the SR. Gap junctions allow action potentials to spread to connected cells. Gap junctions contract when stimulated, strengthening the force of cardiac cell contraction.

Gap junctions allow action potentials to spread to connected cells. Gap junctions are a form of electrical synapse that allow action potentials to spread to connected cells. This property allows the signal to spread efficiently through the heart.

Which statement regarding cardiac muscle structure is accurate? Myofibrils of cardiac muscle tissue vary in diameter and branch extensively. Cardiac cells possess few mitochondria. Cardiac muscle cells are independent of one another both structurally and functionally. Cardiac cells are long, cylindrical, and multinucleate.

Myofibrils of cardiac muscle tissue vary in diameter and branch extensively. The myofibrils of cardiac muscle have various diameters; they also branch in order to maintain connections, via intercalated discs, with other muscle cells.

Which portion of the electrocardiogram represents the depolarization wave received by the atria from the sinoatrial (SA) node? S-T segment P wave QRS complex T wave

P wave The P wave represents the depolarization of the left and right atria and the beginning of atrial systole.

Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart? AV node AV bundle (bundle of His) SA node Purkinje fibers

SA node Yes, the SA Node spontaneously depolarizes, causing the wave of depolarization that spreads through the rest of the conduction system and heart.

The order of impulse conduction in the heart, from beginning to end, is __________. SA node, bundle of His, AV node, bundle branches, and Purkinje fibers SA node, bundle branches, AV node, bundle of His, and Purkinje fibers SA node, AV node, bundle of His, bundle branches, and Purkinje fibers SA node, bundle branches, bundle of His, AV node, and Purkinje fibers

SA node, AV node, bundle of His, bundle branches, and Purkinje fibers The impulses of the heart originate at the SA node (pacemaker). The impulse is then transmitted to the AV node (atrioventricular node), where the impulse slows down to allow the atria to completely contract and thereby fill the adjacent ventricles. The AV node then transmits the impulse to the bundle of His, which branches into left and right bundle branches. The bundle branches give rise to the Purkinje fibers, which transmit the impulse to the ventricle walls and stimulate ventricular contraction.

Adding a chemical that reduces Na+ transport near the sinoatrial (SA) node would have what effect on the heart's intrinsic conducting system? The SA node would depolarize more quickly, increasing the heart rate. The SA node would depolarize more quickly, decreasing the heart rate. The SA node would depolarize less quickly, increasing the heart rate. The SA node would depolarize less quickly, reducing the heart rate. There will be no change.

The SA node would depolarize less quickly, reducing the heart rate. Na+ leaking into the pacemaker cell causes a gradual depolarization of the cells. If that depolarization slows down, the heart rate will slow down.

When threshold is reached at the SA node (an autorhythmic cell), what channels open causing further depolarization of the membrane? potassium slow calcium fast calcium fast sodium

fast calcium Yes, unlike nerve cells or cardiac muscle cells, fast calcium channels are responsible for the depolarization phase of the autorhythmic cell action potential. When the fast calcium channels open, calcium rushes into the cell making it less negative (or more positive).

Action potentials generated by the autorhythmic cells spread to the contractile cells through what structures in the membrane? gap junctions desmosomes intercalated discs tight junctions

gap junctions Yes, action potentials generated by the autorhythmic cells spread waves of depolarization to contractile cells through gap junctions. If the depolarization causes the contractile cells to reach threshold, they will in turn generate an action potential.

Which of these muscles is particularly associated with anchoring the right and left atrioventricular valves? trabeculae carneae papillary muscles myocardium pectinate muscles

papillary muscles Papillary muscles contract to tense the right and left atrioventricular valves via the chordae tendineae just before ventricular systole.

Which of the following does NOT deliver deoxygenated blood to the heart? coronary sinus pulmonary veins superior vena cava inferior vena cava

inferior vena cava The pulmonary veins deliver oxygenated blood to the left atrium.

What structures connect the individual heart muscle cells? intercalated discs trabaculae carneae chordae tendineae anastomoses

intercalated discs Intercalated discs connect the heart muscle cells. They include desmosomes (anchoring junctions) and gap junctions (communicating junctions).

What separates the parietal and visceral pericardium? myocardium fibrous pericardium epicardium pericardial cavity

pericardial cavity The pericardial cavity separates the parietal and visceral pericardium. This cavity contains serous fluid that lubricates the visceral and parietal membranes.

One of the changes that occurs in the pacemaker potential (unstable resting membrane potential) in the SA node (an autorhythmic cell) is a decreased efflux of what ion? sodium potassium calcium

potassium Yes, if there is a decreased efflux of potassium while there is a normal influx of sodium, the inside of the cell would become less negative. Thus, threshold would be reached. The ability of these autorhythmic cells to spontaneously depolarize is what results in the pacemaker potential.

Which of these vessels returns blood to the left atrium of the heart? pulmonary veins pulmonary trunk superior vena cava coronary sinus

pulmonary veins The pulmonary veins transport oxygen-enriched blood from the lungs to the left atrium.

Which of the following terms is correctly matched to its description? stroke volume: amount of blood pumped out by each ventricle in one minute diastole: contraction period quiescent period: total heart relaxation between heartbeats systole: relaxed period

quiescent period: total heart relaxation between heartbeats Between each heartbeat there is a quiescent period in which all the chambers of the heart are relaxed.

The right atrioventricular valve prevents backflow of blood from the right ventricle into the __________. left ventricle right atrium pulmonary trunk left atrium

right atrium Flow from the right ventricle to the right atrium is prevented by the right atrioventricular valve.

Consider the following characteristics of the cells found in muscle tissue. Which feature is shared by both cardiac muscle and skeletal muscle? triads branched cells striations intercalated discs

striations Since both cardiac and skeletal muscles possess arrangements of motor proteins in regularly arrayed sarcomeres, they both display the banding known as striations.

In order to cause cardiac muscle contraction, the contractile cells must also depolarize. What causes the depolarization of the contractile cells? the flow of positive ions from adjacent cells an unstable resting membrane potential in the contractile cells the flow of negative ions from adjacent cells

the flow of positive ions from adjacent cells Yes, the flow of positive ions from the autorhythmic cells (or adjacent cells) brings the membrane to threshold initiating depolarization of the contractile cell.

Repolarization of an autorhythmic cell is due to the opening of which channels? chemically gated calcium channels Chemically gated potassium channels voltage-gated sodium channels voltage-gated potassium channels

voltage-gated potassium channels Yes, opening of voltage-gated potassium channels causes positive potassium ions to move out of the cell. This efflux of potassium causes the cell to become more negative inside thus, repolarizing the cell.