Chapter 14
Which of these structures conduct(s) action potentials the slowest?
AV node
Which part of the intrinsic conduction system delays the impulse briefly before it moves on to the ventricles?
AV node
Increased pressure in the ventricles would close what valve(s)?
AV valves only
Place these structures in the order that blood returning to the heart from the body would pass through them.1. right ventricle2. left atrium3. right atrium4. pulmonary trunk/pulmonary arteries5. left ventricle6. pulmonary veins
3, 1, 4, 6, 2, 5
Put these phases of the cardiac cycle in the correct order. 1. opening of the semilunar valves 2. isovolumic contraction 3. beginning of atrial systole 4. closure of the AV valves 5. completion of ventricular filling 6. beginning of ventricular systole 7. ventricular relaxation 8. ventricular ejection
3, 5, 6, 4, 2, 1, 8, 7
Put these autorhythmic cells into the correct order for conveying electrical signals through a normal heart. 1. bundle of His 2. internodal pathway 3. Purkinje fibers 4. atrioventricular node 5. sinoatrial nodes 6. left and right bundle branches
5, 2, 4, 1, 6, 3
AV node
Delay(s) occurs here while atria contract
Which of the following causes a decrease in resistance in a vessel?
Vasodilation
Which blood vessels have the lowest blood pressure?
Veins
Which blood vessels return blood to the heart?
Veins
Blood flows through a vessel at a particular flow rate and velocity. What happens to the velocity of the blood flow through that vessel after it constricts, narrowing its diameter? You may assume that the flow rate is unchanged.
Velocity increases.
Drugs known as beta blockers will
decrease heart rate. Submit
Which increases resistance?
decreased flow
How would a decrease in blood volume affect both stroke volume and cardiac output?
decreased stroke volume and no change in cardiac output Submit
Under which circumstances would the diameter of peripheral blood vessels be the greatest?
decreased sympathetic stimulation
Which change will NOT result in increased blood flow to a tissue?
decreased vessel diameter
The P wave of an ECG corresponds to
depolarization of the atria.
Atrial contraction begins
during the latter part of the P wave.
What does the ECG wave tracing represent?
electrical activity in the heart
Match each term with its definition. A. cardiac output (CO)B. heart rate (HR)C. end-diastolic volume (EDV)D. stroke volume (SV)E. end-systolic volume (ESV) the volume of blood in the ventricle available to be pumped out of the heart during one contraction
end-diastolic volume (EDV)
The term used to describe the amount of blood in the ventricle available to be pumped out of the heart during the next contraction is
end-diastolic volume (EDV).
Match each term with its definition. A. cardiac output (CO)B. heart rate (HR)C. end-diastolic volume (EDV)D. stroke volume (SV)E. end-systolic volume (ESV) the volume of blood left in the ventricle after it contracts
end-systolic volume (ESV) Submit
Capillaries are
microscopic vessels in which blood exchanges material with the interstitial fluid.
The action potential in a cardiac contractile cell causes
opening of L-type calcium channels.
The driving force for blood flow is a(n) ________ gradient.
pressure
The importance of the plateau phase of the action potential of myocardial cells is in
preventing tetanus
The cardiac output is equal to the
product of heart rate and stroke volume
As blood vessel length increases,
resistance increases and flow decreases.
Which chamber receives blood from the superior and inferior vena cavae?
right atrium
Which heart chamber pumps unoxygenated blood out the pulmonary trunk?
right ventricle
ECGs
show the summed electrical activity generated by all cells of the heart.
Match the change with the cardiovascular event described. A. increased B. decreased C. unchanged D. stopped The blood pressure in a vessel is 10 units at point A and 10 units at point B. Flow between those points is ________.
stopped
Match each term with its definition. A. cardiac output (CO)B. heart rate (HR)C. end-diastolic volume (EDV)D. stroke volume (SV)E. end-systolic volume (ESV) the volume of blood pumped out of the heart from one ventricle during one contraction
stroke volume (SV)
The volume of blood ejected from each ventricle during a contraction is called the
stroke volume.
As a result of the long refractory period, cardiac muscle prevents
tetanus. Submit
During ventricular systole,
the AV valves are closed.
In order for blood to enter the heart,
the atria must be in diastole but the atrial pressure must be lower than the veins.
The electrocardiogram represents __________.
the electrical activity of all of the cardiac muscle cells Submit
The term myogenic indicates that the heart muscle is the source of
the electrical signal that stimulates heart contraction.
The QRS complex of an ECG represents
the progressive wave of ventricular depolarization.
During ventricular ejection,
the ventricles are in systole.
An artery is a vessel that
transports blood away from the heart.
The heart is actually (one, two, or three) pumps?
two pumps Submit
Autorhythmic cells can generate action potentials spontaneously because they have
unstable membrane potentials.
According to the Frank-Starling law of the heart, the cardiac output is directly related to the
venous return.
What does the QRS complex represent in the ECG wave tracing?
ventricular depolarization
Isovolumetric relaxation and ventricular filling (two phases of the cardiac cycle) take place during __________.
ventricular diastole
Left ventricular pressure is higher than pressure in the aorta during
ventricular diastole only.
In which situation would end-systolic volume (ESV) be the greatest?
when parasympathetic stimulation of the heart is increased
As blood flows away from the heart, how does overall blood pressure in vessels change? Why?
Blood pressure decreases, because of the effects of friction between the vessel walls and the moving blood.
In a cardiac autorhythmic cell, which ion is responsible for the increase in membrane potential from threshold during an action potential?
Ca2+
Which cells act as the heart's pacemaker? Why are they the pacemaker cells?
Cells of the SA node are the usual pacemakers, because they are autorhythmic cells, and set the pace of the heart rate.
Bundle branches
Convey(s) the impulse down the interventricular septum
Purkinje fibers
Convey(s) the impulse throughout the ventricular walls
AV bundle
Electrical link(s) between atria and ventricles
Consider three blood vessel segments of equivalent length and diameter: vessels A, B, and C. Pressure at the beginning of each segment is as follows: A) P = 100 mmHg B) P = 80 mmHg C) P = 60 mmHg Pressure at the end of each segment is as follows: A) P = 70 mmHg B) P = 50 mmHg C) P = 30 mmHg Which vessel has the greatest blood flow through the described segment?
Flow rate is the same in all three segments, because all three vessels have the same resistance and the pressure gradient is the same in all three segments: A) ΔP = 100 - 70 = 30 mmHg; B) ΔP = 80 - 50 = 30 mmHg; C) ΔP = 60 - 30 = 30 mmHg.
Why does the pressure in the arteries and arterioles fall as the blood moves away from the heart?
Friction causes a loss of energy.
What is the role of heart valves?
Heart valves ensure one-way flow of blood through the heart chambers
Internodal pathways
Link(s) between the SA node and AV node
Which of the following is correct about the filling of the ventricles?
Most blood flows passively into the ventricles through open AV valves.
If channels are permeable to
Na+ and K+. Submit
The rapid depolarization phase of the action potentials of myocardial contractile cells is due to which ion(s)?
Na+ only
Contraction of the atria results from which wave of depolarization on the ECG tracing?
P wave
Match the name of the wave with the correlated event.A. P wave B. QRS complex C. T wave D. PR segment E. ST segment atrial depolarization
P wave
Match the name of the wave with the correlated event. A. P wave B. QRS complex C. T wave D. PR segment E. ST segment atrial contraction
PR segment
Describe the pressures in the atria and ventricles that would cause the opening of the AV valves.
Pressure in the atria would be greater than the pressure in the ventricles.
Match the name of the wave with the correlated event A. P wave B. QRS complex C. T wave D. PR segment E. ST segment immediately followed by ventricular contraction
QRS complex
Match the name of the wave with the correlated event. A. P wave B. QRS complex C. T wave D. PR segment E. ST segment ventricular depolarization
QRS complex
Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart?
SA node
Which part of the intrinsic conduction system normally initiates the depolarizing impulse that causes a heartbeat?
SA node
SA node:
Set(s) the pace for the entire heart
Calcium ions are removed from the sarcoplasm of the cardiac cell by the action of the sarcoplasmic reticulum (SR) Ca2+-ATPase pump and which other mechanism?
Sodium-calcium exchanger on the sarcolemma Submit
Match the name of the wave with the correlated event. A. P wave B. QRS complex C. T wave D. PR segment E. ST segment ventricular repolarization
T wave
Which event results in the first heart sound?
The AV valves close.
Manganese ions block the calcium channels in the cardiac muscle membrane. How would the presence of manganese ions in the extracellular fluid affect the contraction of the heart muscle?
The heart would beat less forcefully.
What is an advantage to the longer duration of cardiac action potential compared with the skeletal muscle action potential?
The longer duration prevents tetanus, which allows the heart chambers to relax and refill with blood before the next contraction.
Stretching a myocardial cell
allows more Ca2+ to enter and increases the force of a contraction.
Autorhythmic cells
are also called pacemakers because they set the rate of the heartbeat.
Which valves have chordae tendineae?
bicuspid (mitral) and tricuspid valves
During the plateau phase of the action potentials of myocardial contractile cells, which ion(s) is/are crossing the membrane?
both Ca2+ and K+
Which will increase the heart rate?
both sympathetic stimulation and epinephrine stimulation of the SA node
Match each term with its definition. A. cardiac output (CO)B. heart rate (HR)C. end-diastolic volume (EDV)D. stroke volume (SV)E. end-systolic volume (ESV) the volume of blood circulated from one ventricle in one minute
cardiac output (CO)
The term that describes the volume of blood circulated by the heart in one minute is
cardiac output (CO).
The end of the plateau phase of cardiac contractile cell action potentials is due to the ________ of Ca2+ channels and ________ of K+ channels.
closing, opening
The purpose of valves in the cardiovascular system is to
ensure that blood flows in one direction.
Which of the following would increase heart rate?
epinephrine and norepinephrine
The depolarization of the pacemaker action potential spreads from cell to cell through
gap junctions.
What causes the aortic semilunar valve to close?
greater pressure in the aorta than in the left ventricle
If the membranes of the cardiac muscle cells in the SA node become more permeable to potassium ions,
heart rate will decrease. Submit
How would an increase in the sympathetic nervous system increase stroke volume?
increased contractility
By what mechanism would an increase in venous return increase stroke volume?
increased end diastolic volume Submit
Which of the following would increase cardiac output to the greatest extent?
increased heart rate and increased stroke volume Submit
Put the phases of the cardiac cycle in the correct order, starting after ventricular filling.
isovolumetric contraction, ventricular ejection, isovolumetric relaxation
Ventricular contraction begins
just after the Q wave.
Which heart chamber receives blood from the pulmonary veins?
left atrium
Which chamber pumps oxygenated blood out the aorta to the systemic circuit?
left ventricle
