Into which chamber of the heart will blood flow next after small cardiac vein?
Right atrium
The small cardiac vein empties into the coronary sinus, which drains into the right atrium.
Blood returning to the heart from the pulmonary circuit first enters the __________.
left atrium
The papillary muscles function to __________.
prevent the AV valves from reversing into the atria
The __________ valve prevents backward flow of blood into the left ventricle.
aortic
The pulmonary veins carry __________ blood to the __________ atrium.
oxygenated; left
Which of the valves will open during ventricular systole to allow the flow of blood to the lungs?
The semilunar valve
Blood flows through the pulmonary semilunar valve, toward the lungs, during ventricular systole.
Which of these organs is not found in the mediastinum?
- pericardial sac
- esophagus
- lung
- trachea
lung
The epicardium is also known as the __________.
visceral pericardium
The heart is actually (one, two, or three) pumps?
two pumps
Yes, the right side of the heart pumps to/from the lungs (pulmonary circuit) and the left side of the heart pumps to/from the rest of the body (the systemic circuit).
Which chamber receives blood from the superior and inferior vena cavae?
right atrium
Yes, the right atrium receives unoxygenated blood from the systemic circuit.
Which heart chamber receives blood from the pulmonary veins?
left atrium
Yes, the left atrium receives oxygenated blood from the pulmonary veins.
Which heart chamber pumps unoxygenated blood out the pulmonary trunk?
right ventricle
Yes, the right ventricle pumps unoxygenated blood out the pulmonary trunk to the lungs.
Which chamber pumps oxygenated blood out the aorta to the systemic circuit?
left ventricle
Yes, the left ventricle pumps oxygenated blood out the aorta to the entire body (systemic circuit).
What is the function of the intercalated discs?
#NAME?
Which structure will receive electrical impulses next, after the AV node?
Interventricular septum
The AV node leads to the AV bundle, which carries the stimulus to the interventricular septum.
Which of these is an important difference between cardiac muscle and skeletal muscle?
- Cardiac muscle can't be tetanized.
- Cardiac muscle contracts spontaneously.
- Cardiac muscle lacks troponin.
- Skeletal muscle is striated.
Cardiac muscle can't be tetanized.
Heart rate is controlled by __________.
both the right vagus and sympathetic nerves
The arrow indicates the point of transition from the absolute refractory period to the relative refractory period. Which of the follow occurs just before this point?
Cardiac muscle begins to relax.
Repolarization marks the onset of relaxation, and this occurs shortly before the end of the absolute refractory period.
The P wave of the electrocardiogram is closely followed by __________.
contraction of both atria
During the plateau phase of the cardiac action potential, which ion is entering the cardiac muscle cell?
calcium
Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart?
SA node
Yes, the SA Node spontaneously depolarizes, causing the wave of depolarization that spreads through the rest of the conduction system and heart.
What does the ECG wave tracing represent?
electrical activity in the heart
Yes, the ECG waves show the depolarization and repolarization in various areas of the heart.
What does the QRS complex represent in the ECG wave tracing?
ventricular depolarization
Yes, the QRS complex represents depolarization in the ventricles, which have greater mass than the atria.
Contraction of the atria results from which wave of depolarization on the ECG tracing?
P wave
Yes, the P wave represents atrial depolarization, which leads to atrial contraction.
Which part of the intrinsic conduction system delays the impulse briefly before it moves on to the ventricles?
AV node
Yes, the AV node slows down the impulse giving the atria time to contract before the ventricles contract.
Which wave is the largest in the electrocardiogram?
R
The rapid depolarization phase in the ventricular action potential appears in the electrocardiogram as the __________.
QRS complex
Ventricular systole begins with the __________.
closing of the mitral valve
Compared to the right ventricle, which of these statements about the left ventricle is false?
- It ejects more blood.
- It generates a higher pressure.
- It has a thicker wall.
- It makes a louder heart sound.
It ejects more blood.
During ventricular systole the blood pressure __________ and ventricular volume __________.
increases; decreases
Which of these statements concerning the cardiac cycle is false?
- Aortic pressure is greater than pulmonary trunk pressure.
- AV valves close before semilunar valves open.
- Cardiac cycle begins with atrial systole.
- Ventricular systole begins at the pe
Ventricular systole begins at the peak of atrial systole.
Isovolumetric relaxation and ventricular filling (two phases of the cardiac cycle) take place during __________.
ventricular diastole
Yes, both occur during ventricular diastole when the ventricles are not actively contracting and ejecting blood.
Most blood flows passively into the ventricles through open AV valves. True or false?
True
Yes, most of the ventricular filling is passive; atrial contraction adds just a little more blood.
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.
Yes, higher pressure in the atria than in the ventricles forces the AV valves to open and blood moves into the ventricles.
What causes the aortic semilunar valve to close?
greater pressure in the aorta than in the left ventricle
Yes, backflow of blood in the aorta (towards the left ventricle) closes the aortic semilunar valve.
Increased pressure in the ventricles would close what valve(s)?
AV valves only
Yes, increased pressure in the ventricles would close the AV valves.
The wall of the left ventricle is thicker than the right; the left ventricle pumps more blood than the right. Are these two statements true or false?
The first is true; the second is false.
What is the relaxed state of the ventricle called?
diastole
The resting state of the atrium or ventricle is referred to as diastole. The heart chambers are in diastole for the majority of the cardiac cycle.
The one-way nature of the left AV valve prevents blood flow from _________.
the left ventricle to the left atrium
The atrioventricular valves are one-way valves that allow blood to flow into the ventricle but prevent blood flow back into the atrium. This maintains the movement of blood forward, toward the systemic circulation.
The closing of the left AV valve occurs near the beginning of __________.
ventricular systole
Ventricular systole is the contraction of the ventricle. This causes the pressure within the ventricle to quickly rise above that in the atrium, which in turn causes the AV valve to close. The closed AV valve ensures that blood is ejec
The majority of ventricular filling occurs while the ventricles and atria are in what state(s)?
ventricular and atrial diastole
The majority of ventricular filling occurs while both the ventricle and atrium are relaxed - while both chambers are in diastole. Ventricular filling also occurs during atrial systole, but this phase only contributes about
Which of the following most correctly describes end-diastolic volume?
the volume of the ventricle when it is most full
The end-diastolic volume is the ventricular volume at the end of ventricular diastole. At this point, all ventricular filling (including that from atrial systole) has occurred, and the ventricular volume is
Left ventricular filling occurs __________.
while the AV valve is open
The AV valve allows blood to flow in one direction - from the atrium to the ventricle. Because the ventricle is filled with blood from the atrium, this valve must be open to fill the ventricle.
Heart valves are in what state during isovolumetric contraction?
The AV valves and semilunar valves are closed.
Isovolumetric contraction is the brief period of time at the beginning of ventricular systole where both the AV valves and semilunar valves are closed. Because these closed valves prevent blood from exiting t
The decrease in left ventricular pressure at the end of ventricular systole causes __________.
the semilunar valve to close
The semilunar valve closes when left ventricular pressure drops below aortic pressure. This occurs at the end of ventricular systole and marks the end of ventricular ejection. Blood in the aorta collects in the cusps of the se
Ventricular diastole begins with the closing of the semilunar valves. What phase of the cardiac cycle happens between this event and the later opening of the AV valves?
isovolumetric relaxation
The prefix iso- means "same" so this is a period of "same volume". While the semilunar valve and AV valve are both closed, blood may not enter nor exit the ventricle. Therefore ventricular volume remains constant during this time.
The volume of blood remaining in the ventricle as diastole begins is called the __________.
end-systolic volume
Which of the following factors will decrease cardiac output?
stimulation of the vagus nerve
Which of the following would increase cardiac output to the greatest extent?
increased heart rate and increased stroke volume
Yes, cardiac output = heart rate x stroke volume.
Which of the following would increase heart rate?
epinephrine and norepinephrine
Yes, secreted by the adrenal medulla as a result of sympathetic stimulation, these hormones act as part of the sympathetic response, increasing heart rate.
How would an increase in the sympathetic nervous system increase stroke volume?
increased contractility
Yes, an increase in sympathetic nervous system activity would increase contractility (by increasing available calcium), thus increasing stroke volume. Contractility causes an increase in stroke volume by decreasing end systolic vol
By what mechanism would an increase in venous return increase stroke volume?
increased end diastolic volume
Yes, an increase in venous return increases the end diastolic volume. The fibers are stretched more, resulting in an increase in the force of contraction (preload, or the Frank-Starling Mechanism).
How would a decrease in blood volume affect both stroke volume and cardiac output?
decreased stroke volume and no change in cardiac output
Yes, a decreased blood volume would decrease the end diastolic volume, thus lowering the stroke volume. Although this would initially lead to a decrease in the cardiac output, heart rate would increa
Which of the following will not increase heart rate?
increased parasympathetic stimulation of the SA node
Which of these responses by the heart will sympathetic stimulation not cause?
increased end-systolic volume
Which of these is not needed to determine cardiac output?
- blood pressure
- end diastolic volume
- heart rate
- end systolic volume
blood pressure
If you know both the heart rate and stroke volume, you can calculate the __________.
cardiac output
Action potentials generated by the autorhythmic cells spread to the contractile cells through what structures in the membrane?
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
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?
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 i
When threshold is reached at the SA node (an autorhythmic cell), what channels open causing further depolarization of the membrane?
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 ne
Repolarization of an autorhythmic cell is due to the opening of which 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.
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
Yes, the flow of positive ions from the autorhythmic cells (or adjacent cells) brings the membrane to threshold initiating depolarization of the contractile cell.