Ch. 18 Study Guide

[Ch. 18 Specific Question #1] One of the pictures below represents end-diastolic volume (EDV; that is, the volume at the end of ventricular diastole), and the other represents end-systolic volume (ESV). Which is which? Based on these numbers, what is the stroke volume (SV)?

Panel A = EDV, panel B = ESV. SV = 100 mL.

[Ch. 18 RQ #13] What is cardiac output, and how is it calculated?

Cardiac output is the amount of blood pumped out of each ventricle in 1 minute. CO = HR X SV

[Ch. 18 Specific Question #2] Explain why the AV values are open most of the time, while the SL valves are closed most of the time.

For most of the cardiac cycle, pressure is higher on the "upstream" (atrial) side of the AV valves, keeping them open, and higher on the "downstream" (arterial) side of the SL valves, keeping them closed.

[Ch. 18 RQ #11] Draw a normal ECG pattern. Label and explain the significance of its deflection waves.

See figure 18.16 The P wave results from depolarization of the atria. The QRS complex results from ventricular depolarization and precedes ventricular contraction. The T wave is caused by ventricular repolarization and precedes ventricular relaxation.

[Ch. 18 Clicker Question #2] Pressure in the ventricles will be highest near the end of the ______. (a) P wave (b) QRS complex (c) T wave

(b) QRS complex

[Ch. 18 Clicker Question #4] This picture shows pressures in the left atrium, left ventricle, and aorta. Which pressure is represented by the GREEN line? (a) left atrium (b) left ventricle (c) aorta

(c) aorta

[Ch. 18 RQ #4] The sequence of contraction of the heart chambers is (a) random (b) left chambers followed by right chambers (c) both atria followed by both ventricles (d) right atrium, right ventricle, left atrium, left ventricle

(c) both atria followed by both ventricles

[Ch. 18 Specific Question #5] Compare and contrast the roles of Na+, K+, and Ca2+in neuronal and cardiac action potentials.

Na+ entry serves to depolarize both neurons and cardiac pacemaker cells, but in cardiac pacemaker cells some Na+ channels are open at rest, causing the cells to spontaneously depolarize to threshold. In neurons, voltage-gated Na+ channels are responsible for action potentials along axons, but in cardiac pacemaker cells action potentials are due to voltage-gated Ca2+ channels. K+ exit through voltage-gated channels repolarizes both neurons and cardiac pacemaker cells.

[Ch. 18 General Question #8] If given a description of an alteration in cardiac conduction, describe and draw how that would affect the ECG. Example:Premature atrial depolarizations originating outside the SA node.

Occasional premature atrial depolarizations would mean that sometimes a P wave follows the T wave more closely than expected. For a person at rest or in a steady state, the intervals (e.g., T-to-P) should be fairly constant from beat to beat, but this disorder would result in more variability in the length of the T-to-P intervals.

[Ch. 18 CYU #18] DRAW The lines in the graph at right present pressures in the left heart and aorta. Label each of the three lines. Label the points on the graph where AV valves open or close and where SL valves open or close. Label two periods during which all four valves are closed, using the appropriate terms.

See pg A-10

[Ch. 18 CYU #17] If the mitral valve were insufficient, would you expect to hear the murmur (of blood flowing through the valve that should be closed) during ventricular systole or diastole?

The murmur of mitral insufficiency occurs during ventricular systole (because this is when the valve should be closed, and the murmur is due to blood leaking through the incompletely closed valve into the atrium).

[Ch. 18 CYU #7] Which side of the heart acts as the pulmonary pump. The systemic pump?

The right side of the heart acts as the pulmonary pump, whereas the left acts as the systemic pump.

[Ch. 18 CYU #16] The secound heart sound is associated with the closing of which valve(s)?

The second heart sound is associated with the closing of the semilunar valves.

[Ch. 18 Clicker Question #5] Which box best represents the period during which the atria contract? (picture on learning catalytics) A B C D E

B

[Ch. 18 CYU #19] After running to catch a bus, Josh noticed that his heart was beating faster than normal and was pounding forcefully in his chest. How did his increased HR and SV come about?

Exercise activates the sympathetic nervous system. Sympathetic nervous system activity increases heart rate. It also directly increases ventricular contractility, thereby increasing Josh's strok volume.

[Ch. 18 Specific Question #6] Calculate cardiac output from a graph; or, if given any two of the variables in the cardiac output equation, calculate the third one.

Max volume = EDV = 130 mL. Minimum volume = ESV = 70 mL. SV = EDV minus ESV = 130 mL minus 70 mL = 60 mL/beat. HR = 1 beat/sec = 60 beats/min. (Read this off the graph; notice that the cycle repeats about once per second.) CO = HR*SV = (60 beats/min)*(60 mL/beat) = 3600 mL/min. (You wouldn't need to get this exact number, as long as your basic methods were right.)

[Ch. 18 CQ #2] Choose the correct sequence of electrical current flow through the heart wall. (a) SA node, AV node, AV bundle, right and left bundle branches, subendocardial conducting network (b) subendocardial conducting network, AV node, AV bundle, right and left bundle branches, SA node (c) AV node, subendocardial conducting network, AV node, AV bundle, right and left bundle branches (d) AV node, SA node, subendocardial conducting network, AV bundle, right and left bundle branches (e) SA node, subendocardial conducting network, AV node, AV bundle, right and left bundle branches

(a) SA node, AV node, AV bundle, right and left bundle branches, subendocardial conducting network Impulses generated by the SA node spread to the AV node, then to the AV bundle, then to the bundle branches, and finally to the subendocardial conducting network (Purkinje fibers).

[Ch. 18 CYU #8] Which of the following statements are true? (a) The left ventricle wall is thicker than the right ventricle wall. (b) The left ventricle pumps blood at a higher pressure than the right ventricle. (c) The left ventricle pumps more blood with each beat than the right ventricle. Explain.

(a) True (b) True (c) False. Each ventricle pumps the same amount of blood with each beat. If this were not true, blood would back up in either the systemic or pulmonary circulation (because the two ventricles are in series).

[Ch. 18 CYU #4] In the frontal section of the heart at the right, name the structures indicated by a-g. Which heart chamber receives oxygen-poor blood from veins? Which chamber pumps blood into the systemic circulation? Which blood vessel transports blood toward the lungs? (pg. 647)

(a) aorta (b) pulmonary trunk (c) left atrium (d) right atrium (e) left ventricle (f) right ventricle (g) inferior vena cava The (d) right atrium receives oxygen-poor blood. The (e) left ventricle pumps blood into the systemic circulation. The (b) pulmonary trunk transports blood toward the lungs

[Ch. 18 PT #12] The P wave of an electrocardiogram represents __________. (a) atrial repolarization (b) ventricular depolarization (c) ventricular repolarization (d) atrial depolarization

(a) atrial repolarization

[Ch. 18 CQ #10] The inferior vena cava brings blood from the lower regions of the body and empties into the __________. (a) right atrium (b) left ventricle (c) aorta (d) right ventricle (e) left atrium

(a) right atrium The right atrium receives blood both from the superior and inferior venae cavae.

[Ch. 18 CYU #13] Describe the electrical event in the heart that occurs during each of the following: (a) the QRS complex of the ECG (b) the T wave of the ECG (c) the P-R interval of the ECG

(a) the QRS wave occurs during ventricular depolarization. (b) The T wave of the ECG occurs during ventricular repolarization (c) The P-R interval of the ECG occurs during atrial depolarization and the conduction of the AP through the rest of the intrinsic conduction system.

[Ch. 18 CQ #24] What part of the heart is considered the systemic circuit pump? (a) the left ventricle (b) the right ventricle (c) the right atrium (d) the pericardium

(a) the left ventricle

[Ch. 18 Clicker Question #3] Which valves close shortly after the ventricles stop contracting? (a) Atrioventricular (AV) (b) Semilunar (SL) (c) Both AV and SL

(b) Semilunar (SL)

[Ch. 18 CQ #29] An enlarged R wave on an ECG would indicate __________. (a) a myocardial infarction (b) an enlarged ventricle (c) cardiac ischemia (d) repolarization abnormalities

(b) an enlarged ventricle An elevated S-T segment on an ECG indicates cardiac ischemia. A myocardial infarction would appear as elevation of the S-T segment on an ECG. Repolarization abnormalities are represented by a prolonged Q-T interval on an ECG.

[Ch. 18 PT #3] The superior chambers of the heart are called the __________. (a) coronary chambers (b) atria (c) cavae (d) ventricles

(b) atria The heart has four chambers: right atrium, right ventricle, left atrium, and left ventricle. The atria are the superior chambers; the ventricles are inferior to the atria.

[Ch. 18 PT #5] Into which chamber of the heart do the pulmonary veins deliver blood? (a) left ventricle (b) left atrium (c) right ventricle (d) right atrium

(b) left atrium

[Ch. 18 RQ #8] Freshly oxygenated blood is first received by the (a) right atrium (b) left atrium (c) right ventricle (d) left ventricle

(b) left atrium

[Ch. 18 PT #4] Freshly oxygenated blood is delivered to the __________, and then it passes into the __________ to be pumped to the body tissues (systemic circuit). (a) left ventricle; left atrium (b) left atrium; left ventricle (c) right atrium; right ventricle (d) right ventricle; right atrium

(b) left atrium; left ventricle The left side of the heart pumps blood to the body tissues and is known as the systemic circuit pump. Freshly oxygenated blood from the lungs is returned to the left atrium. From the left atrium, the blood flows into the left ventricle. The left ventricle then pumps the blood to the aorta, which distributes it to the body tissues (systemic circuit).

[Ch. 18 RQ #3] An ECG provides information about (a) cardiac input (b) movement of the excitation wave across the heart (c) coronary circulation (d) valve impairment

(b) movement of the excitation wave across the heart

[Ch. 18 RQ #5] The fact that the left ventricular wall is thicker than the right reveals that it (a) pumps a greater volume of blood (b) pumps blood against a greater resistance (c) expands the thoracic cage (d) pumps blood through a smaller valve

(b) pumps blood against a greater resistance

[Ch. 18 CQ #3] During pulmonary circulation, blood leaves the __________. (a) right ventricle and flows directly to the aorta (b) right ventricle and flows directly to the lungs (c) right atrium and flows directly to the left ventricle (d) right atrium and flows directly to the lungs (e) left ventricle and flows directly to the lungs

(b) right ventricle and flows directly to the lungs

[Ch. 18 RQ #7] In the heart, which of the following apply? (1) APs are conducted from cell to cell across the myocardium via gap junctions (2) the SA node sets the pace for the heart as a whole (3) spontaneous depolarization (4) cardiac muscle can continue to contract for long periods in the absence of oxygen (a) all of the above (b) 1, 3, 4 (c) 1, 2, 3, (d) 2, 3

(c) 1, 2, 3,

[Ch. 18 RQ #2] The portion of the intrinsic conduction system located in the superior interventricular septum is the (a) AV node (b) SA node (c) AV bundle (d) subendocardial conducting network

(c) AV bundle

[Ch. 18 PT #13] The second heart sound (the "dup" of "lub-dup") is caused by the __________. (a) opening of the atrioventricular valves (b) opening of the semilunar valves (c) closure of the semilunar valves (d) closure of the atrioventricular valves

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

[Ch. 18 CQ #20] The noncontractile cardiac muscle cells that initiate their own depolarization and cause depolarization of the rest of the heart are called __________. (a) cardioinhibitory centers (b) intercalated discs (c) pacemaker cells (d) desmosomes (e) gap junctions

(c) pacemaker cells

[Ch. 18 CQ #5] From the perspective of blood returning from the systemic circuit, identify the correct sequence of blood flow through the chambers of the heart. (a) left atrium, left ventricle, right ventricle, right atrium, lungs (b) right ventricle, left ventricle, left atrium, lungs, right atrium (c) right atrium, right ventricle, lungs, left atrium, left ventricle (d) left ventricle, left atrium, lungs, right ventricle, right atrium (e) lungs, right ventricle, left ventricle, right atrium, left atrium

(c) right atrium, right ventricle, lungs, left atrium, left ventricle As oxygen-poor blood returns to the heart from the system circuit, it will pass through the right atrium, right ventricle, lungs, left atrium, and left ventricle.

[Ch. 18 PT #10] The role of the atrioventricular node (AV node) is to __________. (a) initiate ventricular depolarization (b) conduct impulses to the sinoatrial node (SA node) (c) slow down impulses so that the atria can contract to fill the adjacent ventricles with blood (d) initiate a sinus rhythm

(c) slow down impulses so that the atria can contract to fill the adjacent ventricles with blood

[Ch. 18 RQ #15] The activity of the heart depends on intrinsic properties of cardiac muscle and on neural factors. Thus, (a) vagus nerve stimulation of the heart reduces heart rate (b) sympathetic nerve stimulation of the heart decreases time available for ventricular filling (c) sympathetic stimulation of the heart increases its force of contraction (d) all of the above

(d) all of the above

[Ch. 18 PT #7] The most muscular chamber of the heart is the __________. (a)right atrium (b) left atrium (c) right ventricle (d) left ventricle

(d) left ventricle

[Ch. 18 PT #15] Which of the following would lead to a decrease in heart rate? (a) exercise (b) sharply decreased blood volume (c) norepinephrine (d) parasympathetic stimulation

(d) parasympathetic stimulation

[Ch. 18 CQ #14] The tricuspid valve is located between the __________. (a) left atrium and left ventricle (b) right ventricle and the aorta (c) right and left ventricles (d) right atrium and right ventricle (e) right and left atria

(d) right atrium and right ventricle

[Ch. 18 CQ #1] Cardiac output is __________. the amount of blood pumped out of the heart during every ventricular contraction (a) the amount of blood filling each ventricle at the end of diastole (b) the number of times the heart beats in one minute (c) the number of impulses fired by the SA node in one minute (d) the amount of blood pumped out of each ventricle in one minute

(d) the amount of blood pumped out of each ventricle in one minute cardiac output = heart rate × stroke volume

[Ch. 18 CQ #13] The normal pacemaker of the heart is the __________. (a) AV node (b) bundle branches (c) subendocardial conducting network (Purkinje fibers) (d) AV bundle (e) SA node

(e) SA node The SA node generates impulses faster than the other node and sets the pace for the heart.

[Ch. 18 CQ #15] When the mitral valve closes, it prevents the backflow of blood from the __________. (a) right atrium into the right ventricle (b) left atrium into the left ventricle (c) right ventricle into the pulmonary trunk (d) left ventricle into the aorta (e) left ventricle into the left atrium

(e) left ventricle into the left atrium

[Ch. 18 CYU #6] Name the valve that just has two cusps.

Bicuspid (mitral) Valve (Left atrioventricular)

[Ch. 18 General Question #7] If given one "line" of a Wiggers diagram, be able to fill in the next "line," according to the following order: •ECG •timing of atrial and ventricular systole and diastole •atrial and ventricular volumes •atrial, ventricular, and aortic pressures •status of heart valves (open or closed) Example: Graph atrial AND ventricular volumes for the periods shown. Don't worry about the exact shapes of the curves, just show whether volume is increasing or decreasing in each chamber during each period.

Each chamber's volume should decrease during its systole and increase during its diastole. Again, the exact shape isn't important.

[Ch. 18 Specific Question #3] List the structures in the heart, specialized for conduction, through which electrical depolarization spreads

Sinoatrial (SA) node => atrial conduction fibers (internodal fibers) => atrioventricular (AV) node => AV bundle / bundle of His => left and right bundle branches => Purkinje fibers (subendocardial conducting network).

[Ch. 18 Specific Question #4] How does the autonomic nervous system affect heart rate through its effects on "funny channels"?

The sympathetic nervous system increases heart rate by opening more of the "funny channels" in the pacemaker cell membranes, allowing faster entry of sodium and quicker attainment of threshold. The parasympathetic nervous system does the opposite: it closes some of the "funny channels" in the pacemaker cells, thus extending the time taken to reach threshold.

[Ch. 18 CQ #4] During systemic circulation, blood leaves the __________. (a) left ventricle and flows directly to the aorta (b) lungs and flows directly to the left atrium (c) right atrium and flows directly to the lungs (d) right ventricle and flows directly to the aorta (e) right ventricle and flows directly to the lungs

a) left ventricle and flows directly to the aorta The movement of oxygenated blood from the left ventricle to the aorta constitutes part of the systemic circuit.