AP 2 CH 18 REVIEW
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
Which best describe the isovolumetric contraction phase of the cardiac cycle?
As ventricular systole starts, the AV valves are closed and the semilunar valves are closed. Because the ventricles are contracting and both valves are closed, pressure increases rapidly leading to ejection.
_______ control blood flow into the ventricles.
Atrioventricular valves
In contrast to a skeletal muscle cell action potential, why does the action potential for a cardiac muscle cell contain a "plateau" phase?
Cardiac muscle cells contain slow Ca2+ channels in their sarcolemma that continue to allow influx of Ca2+ ions after Na+ channels are inactivated. Fast voltage-gated Na+ channels are open only for a very brief time before they are inactivated, but the resulting depolarization opens slow Ca2+ channels that start a positive feedback cycle that temporarily keeps the membrane potential high. Both Na+ and Ca2+ ions help in depolarizing cardiac muscle cells. The plateau is caused by the low number of open K+ channels and the positive feedback effect on the membrane potential caused by the inflow of Ca2+ ions.
What fibrous structure functions to anchor the atrioventricular valves in a closed position?
Chordae tendineae Chordae tendineae are the fibrous cords that attach the atrioventricular valves to papillary muscles. They help anchor the atrioventricular valves in a closed position during ventricular contraction.
Name the inner lining of the heart.
Endocardium; The endocardium is the smooth, slick lining of the chambers of the heart. Endocardium is a continuation of endothelium that lines blood vessels. Both endocardium and endothelium are composed of simple squamous epithelial tissue, which minimizes friction between the wall of the chamber/vessel and the blood.
Why does a graph of the membrane potential of living pacemaker cells never demonstrate a flat line?
Hyperpolarization of pacemaker cells triggers the opening of slow Na+ channels and starts a new slow depolarization phase. At the end of an action potential, as repolarization and hyperpolarization occur, slow Na+ channels open, causing the membrane potential to immediately start to increase again (called the pacemaker potential), eventually triggering another action potential.
Which chamber of the heart sends oxygenated blood directly to the systemic circuit via the aorta?
Left ventricle
Failure in a particular structure of the heart tends to cause a backup of blood in the lungs, known as pulmonary congestive heart failure. Failure of which structure of the heart would lead to such a backup?
Left ventricle Failure in the left ventricle can cause increased blood hydrostatic pressure in the lungs, causing fluid buildup in the alveoli.
Blood on the right never mixes with blood on the left, once the heart is fully developed.
Once fetal modifications (i.e. foramen ovale, ductus arteriosus) close following delivery of the infant, blood on the right side of the heart should not mix with blood on the left side of the heart.
Contraction of the atria results from which wave of depolarization on the ECG tracing?
P wave
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
Which of these vessels returns blood to the left atrium of the heart?
Pulmonary veins The pulmonary veins transport oxygen-enriched blood from the lungs to the left atrium.
Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart?
SA node
blood flow pathway
Superior/inferior vena cava -> right atrium -> right ventricle -> pulmonary artery -> lungs -> pulmonary veins -> left atrium -> left ventricle -> aorta -> body Blood moves from the aorta, through smaller systemic arteries, and into systemic capillaries. From there it moves through systemic veins, into the right atrium, and through the tricuspid valve.
_____ is a faster than normal heart rate.
Tachycardia
Which of the following is true during ventricular systole?
The AV valves are closed At the beginning of ventricular systole, the one-way AV valves are forced shut. The AV valves remain shut throughout ventricular systole. This prevents blood from flowing back into the atria when the ventricles contract.
What is the role of the atrioventricular bundle?
The atrioventricular bundle provides the only pathway for electrical signals to pass from the atria to the ventricles. The atrial cardiac cells are not connected by gap junctions to the ventricular cardiac cells. The only means by which the electrical signals of the heart can pass from atria to ventricles is the atrioventricular bundle.
why does a patient with left-sided heart failure have a low systolic blood pressure?
The left side of the heart pumps blood into the body, so when it fails, less blood will be pumped into the arteries.
Isovolumetric relaxation is characterized by which of the following?
The semilunar and AV valves are closed.
Name the irregular ridges of muscle lining the ventricles.
Trabeculae carneae Trabeculae carneae are the small elevated ridges of muscle arranged in a web type fashion found in both the right and left ventricles.
Identify the right atrioventricular valve.
Tricuspid valve The tricuspid valve is the atrioventricular valve located on the right side of the heart. It separates the right atrium from the right ventricle.
Excessive vagal stimulation of the heart will result in _______
a decrease in heart rate and, eventually, a temporary cessation of the heartbeat
Blood enters the left and right coronary arteries directly from which vessel or chamber?
aorta
The vessel that carries oxygen-rich blood to tissues is the ___
aorta.
The structure that is located anatomically between the aorta and the left ventricle is the _____
aortic semilunar valve.
The prefix _____ means atrium.
atri-
Atrial pressure is greater than ventricular pressure during which phase of the cardiac cycle?
atrial contraction Blood always flows from high to low pressure. During atrial contraction, blood flows from atria (high pressure) to ventricles (low pressure). Similarly, this same pressure gradient exists during ventricular filling.
Identify the ear like flaps that are attached to the top chambers of the heart.
auricle
Identify the valve found between the left atrium and left ventricle.
bicuspid, mitral valve
During the ejection period, _______
blood is pumped into the aorta and the pulmonary trunk
What causes the abnormal swishing or whooshing sound that is heard as blood regurgitates back into an atrium from its associated ventricle?
blood turbulence
The prefix _____ means heart or heart action.
cardi
The ______ carries oxygen-poor venous blood of the coronary circulation into the right atrium.
coronary sinus
How would a decrease in blood volume affect both stroke volume and cardiac output?
decreased stroke volume and no change in cardiac output
Which of the following would cause a DECREASE in cardiac output (CO)?
decreasing thyroid function (thyroxine) Thyroxine increases basal metabolic rate, respiratory rate, and both heart rate and contractility.
What does the ECG wave tracing represent?
electrical activity in the heart
The prefix _____ means electricity.
electro-
A test that records the electrical activity of the heart is a(n) _____
electrocardiogram.
Which of the following is equivalent to the ventricular volume during isovolumetric relaxation?
end systolic volume (ESV) Isovolumetric relaxation occurs at the beginning of ventricular diastole when the ventricular volume is at its minimum value−the end systolic volume (ESV). Because no volume changes occur during isovolumetric relaxation, ventricular volume remains at this value throughout the phase.
Which of the following would increase heart rate?
epinephrine and norepinephrine secreted by the adrenal medulla as a result of sympathetic stimulation, these hormones act as part of the sympathetic response, increasing heart rate.
Cardiac output is _______.
equal to blood flow and equal to heart rate times stroke volume equal to heart rate times stroke volume equal to blood flow equal to heart rate times (EDV minus ESV)
Which of the following INCREASES stroke volume?
exercise Exercise increases venous return, which would in turn increase the amount of blood in the presystolic ventricle (preload)
In what direction does blood flow through the heart?
from a region of high pressure to a region of low pressure Blood moves through the heart from atria to ventricles and out large arteries, always from areas of high pressure to areas of lower pressure through one-way valves.
What causes the aortic semilunar valve to close?
greater pressure in the aorta than in the left ventricle
What variable(s) can the cardiovascular system alter to maintain blood pressure?
heart rate, stroke volume and resistance
The sinoatrial node is located _______.
in the right atrial wall of the human heart
The effect of the sympathetic nervous system on the heart is to _______.
increase the heart rate and increase the force of contraction
An increased preload is equivalent to, or causes, a(n) ______
increased EDV
How would an increase in the sympathetic nervous system increase stroke volume?
increased contractility 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 volume; it does not change end diastolic volume.
Increase in stroke volume is a result of _______.
increased contractility of the heart, increased EDV and increased preload
By what mechanism would an increase in venous return increase stroke volume?
increased end diastolic volume
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.
Aortic valve stenosis is characterized by ______
increased resistance to blood flow, thickening of the myocardium and narrowing of the aortic semilunar valve
Patients with aortic valve stenosis experience _______.
increased thickness in the myocardium and a decrease in chamber volume
Increasing the left flow tube radius corresponds to _______.
increasing preload
The _____ carries oxygen-poor venous blood from below the diaphragm from the areas of the lower body and extremities into the right atrium.
inferior vena cava
The structure dividing the two atria of the heart is called the _______
interatrial septum.
What structures connect the individual heart muscle cells?
intercalated discs
Put the phases of the cardiac cycle in the correct order, starting after ventricular filling.
isovolumetric contraction, ventricular ejection, isovolumetric relaxation
Which heart chamber receives blood from the pulmonary veins?
left atrium
Which heart chamber receives oxygenated blood from the lungs?
left atrium
The pulmonary veins deliver oxygenated blood to the ______
left atrium.
What heart chamber pushes blood through the aortic semilunar valve?
left ventricle
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).
Identify the most muscular chamber.
left ventricle; The left ventricle is responsible for pumping blood out to the body. This requires a lot of force. The left ventricle is the most muscular in order to pump the blood with adequate force
1. The structure that prevents backflow of blood into the left atrium is the _____
mitral (bicuspid) valve.
Which layer of the heart wall contracts and is composed primarily of cardiac muscle tissue?
myocardium The myocardium is composed of cardiac muscle and a dense network of connective tissue.
Which branch of the autonomic nervous system dominates after a large meal?
parasympathetic branch
Name the ridged bundles of muscle found projecting inside the right atrium
pectinate muscles The pectinate muscles are ridge like elevations of muscle. They are parallel to each other and resemble teeth of a comb. They are easily observed inside the right atrium.
What is the main function of heart valves?
prevent the backward flow of blood Heart valves are one-way valves that prevent blood from flowing backward. For example, the AV valves only allow blood to flow from the atria to the ventricles. And the semilunar valves only allow blood to flow from the ventricles to the aorta and pulmonary trunk. When valves do not completely close, blood flows backward through the heart, creating an abnormal "sloshing" sound known as a heart murmur.
Identfiy the valve located at the exit of the right ventricle.
pulmonary semilunar valve
The presence of an incompetent tricuspid valve would have the direct effect of causing ______.
reduced efficiency in the delivery of blood to the lungs The tricuspid valve separates the right atrium and the right ventricle. It must remain tightly closed during ventricular contraction so blood can be pumped out of the ventricle and into the pulmonary arteries.
Into which chamber of the heart do the superior vena cava, inferior vena cava, and coronary sinus return deoxygenated blood?
right atrium
The right tricuspid valve prevents backflow of blood from the right ventricle into the __________.
right atrium Flow from the right ventricle to the right atrium is prevented by the right tricuspid valve.
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 chamber of the heart exits into the pulmonary trunk?
right ventricle
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.
During the ventricular ejection phase of the cardiac cycle, which of the following is true?
semilunar valves are open During ventricular ejection, blood flows from the ventricles into the arteries. To do so, the blood must pass through the semilunar valves, which must be open during this phase. Narrowing of the left semilunar valve reduces blood flow out of the heart, a disease condition known as aortic stenosis.
Consider the following characteristics of the cells found in muscle tissue. Which feature is shared by both cardiac muscle and skeletal muscle?
striations
The ______ carries oxygen-poor venous blood from above the diaphragm from areas of the upper body and extremities into the right atrium.
superior vena cava
The capillaries receiving blood flow from the left side of the heart are the ______
systemic capillaries.
Afterload is the pressure threshold that must be exceeded to open _______.
the aortic semilunar valve and the pulmonary semilunar valve
Which of the following is equivalent to the ventricular volume during isovolumetric contraction?
the end diastolic volume (EDV) Isovolumetric contraction occurs at the beginning of ventricular systole when the ventricular volume is at its maximum value−the end diastolic volume (EDV). Because no volume changes occur during isovolumetric contraction, ventricular volume remains at this value throughout the phase.
What structure in the intrinsic cardiac conduction system determines heart rate?
the sinoatrial (SA) node The SA node is composed of pacemaker cells that initiate and set the initial pace, or the sinus rhythm, of the heartbeat.
When the atria contract, which of the following is true?
the ventricles are in diastole Atrial contraction fills each of the ventricles to their maximum capacity−the end diastolic volume (EDV). This occurs towards the end of ventricular diastole while the ventricles are still relaxed.
The left side of the heart pumps blood _______.
through the aortic valve
The heart is actually (one, two, or three) pumps?
two 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).
What is happening during the "pause" phase when the heart is resting (relaxing)?
ventricles are filling
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
Ventricular pressure is greater than aortic pressure during which phase of the cardiac cycle?
ventricular ejection
Most of the decrease in ventricular volume takes place during which phase of the cardiac cycle?
ventricular ejection As the ventricles contract, blood is forced through the semilunar valves and out into the arteries, resulting in a reduction in ventricular blood volume. At the end of this phase, ventricular volume is at a minimum−the "end-systolic volume" (ESV).
Most of the increase in left ventricular volume takes place during what phase of the cardiac cycle?
ventricular filling During ventricular filling the AV valves remain open, which allows blood to flow from the atria into the ventricles. The passive flow of blood during this phase (before atrial contraction) accounts for roughly 80 percent of the increase in ventricular volume.
The prefix ______ means ventricle of the heart.
ventriculo-
At what point in the cardiac cycle does the AV valve open?
when atrial pressure becomes greater than ventricular pressure
At what point in the cardiac cycle does the semilunar valve close?
when pressure in the ventricle becomes less than aortic pressure
At what point in the cardiac cycle does the semilunar valve open?
when ventricular pressure becomes greater than aortic pressure
At what point during the cardiac cycle does the AV valve close?
when ventricular pressure becomes greater than atrial pressure
