ch 18 a&p 2
Which artery curves to the left around the coronary sulcus, eventually meeting and fusing with small branches of the right coronary artery
circumflex artery
The first blood vessels to branch from the aorta are the ________ arteries
coronary
The great and middle cardiac veins drain blood into the
coronary sinus
Which exterior heart structure returns "used" blood collected from the heart muscle itself (myocardium) back into the flow of blood to be delivered to the pulmonary circuit
coronary sinus
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.
In an ECG recording, which of the following coincides with ventricular repolarization?
t wave
A faster-than-normal heart rate is calle
tachycardia
Blood is supplied to the myocardium by
the (Left and Right) coronary arteries.
The atrioventricular valves permit blood flow
in one direction only
Which description correctly describes the location of the heart
in the mediastinum, superior to the diaphragm
What factor would increase heart rate
increase in thyroxine (T4)
Put the phases of the cardiac cycle in the correct order, starting after ventricular filling.
isovolumetric contraction, ventricular ejection, isovolumetric relaxation Yes, the ventricles must contract and eject blood before they relax and fill again.
Blood returning to the heart from the pulmonary circuit first enters the
left atrium
Which heart chamber receives blood from the lungs
left atrium
The circumflex branch and the anterior interventricular artery are branches of the
left coronary artery
Which vessel(s) supplies/supply the left ventricle, left atrium, and the interventricular septum
left coronary artery
Most of the mass of the heart lies to the ________ the midline
left of
The coronary sulcus is a groove that
marks the border between the atria and ventricles.
Cardiac muscle cells are __________.
mechanically, chemically, and electrically connected to one another
Which option describes the location of the heart
mediastinum
Heart rate is controlled by neurons of the cardiovascular center located in the
medulla oblongata
Which structure provides a rapid-conduction path that tenses the papillary muscles before the ventricular myocardium contracts, preventing "slamming" of the right AV cusps?
moderator band
Which phase of the cardiac cycle is the shortest
atrial systole
During the isovolumetric contraction phase of ventricular systole
atrioventricular valves and semilunar valves are closed.
The earlike extension of the atrium is the
auricle
the muscle layer of the heart is the
myocardium
The interventricular sulci and coronary sulcus contain all of the following except
nerves
What structure is immediately deep to the fibrous pericardium
parietal pericardium
from superficial to deep, name the layers of the heart wall
pericardium myocardium endocardium
Contractions of the papillary muscles
prevent the atrioventricular valves from reversing into the atria
Blood leaves the right ventricle by passing through the
pulmonary valve
Blood returning to the heart from the systemic circuit first enters the
right atrium
The marginal branch and posterior interventricular branch are branches of the
right coronary artery
Identify the correct sequence for blood flow through the heart
right ventricle, through pulmonary valve, pulmonary trunk, pulmonary arteries
The right ventricle pumps blood to the
the right and left lungs
Which event does NOT happen during ventricular diastole?
Atrioventricular valves close because of the contracting ventricles. During ventricular diastole, the ventricles are relaxed. The ventricles have ejected a good portion of their blood into the elastic arteries, and the pressure in the ventricles is now lower than the pressure in the atria and the arteries. This causes the atrioventricular valves to open and the semilunar valves to close.
Define autorhythmicity
Autorhythmicity is the ability of the heart to contract without neural or hormonal stimulation
Activation of which kind of receptor causes heart rate to increase
Beta-one receptor
Compare the base of the heart with the apex.
The base of the heart is the superior portion where the largest veins and arteries are attached. The apex of the heart is located on the inferior aspect of the heart.
What structure prevents the electrical signals generated in the SA node from passing directly from the atrium through to the ventricles below
The cardiac skeleton
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
Describe the location and position of the heart
The heart is located near the anterior chest wall, directly behind the sternum.
Which statement is correct regarding the intrinsic heart rate?
During parasympathetic stimulation, acetylcholine released by parasympathetic neurons opens chemically gated potassium channels in the plasma membrane
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
Which of the following is correct about the filling of the ventricles?
Most blood flows passively into the ventricles through open AV valves. Yes, most of the ventricular filling is passive; atrial contraction adds just a little more blood.
Contraction of the atria results from which wave of depolarization on the ECG tracing?
P wave
Which ECG event demonstrates the depolarization of the atria
P wave
List the important features of the ECG, and indicate what each represents.
P wave (atrial depolarization), QRS complex (ventricular depolarization), T wave (ventricular repolarization)
Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart
SA node
Which of the following is greater during left ventricular systole
The peak pressure in the ventricle.
What statement is true regarding pressures and volumes in the cardiac ventricles?
The pressure is greater in the left ventricle, but the volumes are equal in the two chambers
What superficial landmark identifies the boundary between the left and right ventricles
anterior interventricular sulcus
The left ventricle pumps blood to the
aorta
The inferior point of the heart is called the
apex
Which of the following descriptions matches the phrase "near the left fifth intercostal space
apex of the heart
Which pathology is described as a thickening and toughening of arterial walls
arteriosclerosis
What is the first phase of the cardiac cycle
artial systole
In the non-exercising heart, which event of the cardiac cycle lasts the longest?
atrial diastole There has to be adequate time during the cardiac cycle to provide enough blood return to the heart for adequate cardiac output to the lungs and body systems. Remember the path of blood through the heart
Which valve(s) close(s) during ventricular contraction
both AV valves
Compare the volume of blood each circuit receives from contraction of the ventricles.
both circuits receive the same volume of blood
The heart is innervated by ________ nerves
both parasympathetic and sympathetic
Which heart chamber pumps unoxygenated blood out the pulmonary trunk
Right ventricle
The heart pumps approximately ________ milliliters of blood each minute
6,000
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 Yes, increased pressure in the ventricles would close the AV valves.
What factor would decrease stroke volume
An increase in afterload
Which of the following statements most accurately defines what is happening during the second phase of ventricular systole of the cardiac cycle?
Blood is being ejected from the ventricles through open semilunar valves. The electrical stimulation conducted through the heart causes contraction of the ventricles. During the second phase of ventricular systole, the heart is far enough along in the cycle that the pressure generated by the contracting ventricles has opened the semilunar valves silently and pushed the blood out into the aorta and pulmonary trunk.
What electrolyte (ion) is responsible for the plateau in the cardiac action potential
Calcium
Why is it important that cardiac tissue contain many mitochondria and capillaries
Cardiac tissue is metabolically active and dependent on mitochondrial activity to use aerobic respiration to generate ATP and capillaries provide the oxygen and nutrients for this process
Which statement regarding irreversible shock is true
Circulatory collapse occurs when arteriolar smooth muscles and precapillary sphincters become unable to contract
Which structures collect blood from the myocardium, and into which heart chamber does this blood flow?
Coronary veins collect blood from the myocardium and carry it to the right atrium
When threshold is reached at the SA node (an autorhythmic cell), what channels open causing further depolarization of the membrane
Fast calcium
Which of the following statements is correct concerning the cardiac cycle?
In late ventricular diastole, all chambers are relaxed and filling to about seventy percent of their capacity. The completion of the cardiac cycle occurs when all the chambers of the heart are relaxed which occurs during late ventricular diastole.
Which of the following would decrease heart rate
Increased parasympathetic stimulation of nodal fibers
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
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 structure carries the electrical signal from the septum of the heart through the ventricular myocardium
Purkinje fibers
The portion of the tracing of an electrocardiogram, ECG, that represents ventricular depolarization is the
QRS complex
The portion of the tracing of an electrocardiogram, ECG, that represents ventricular depolarization is the __________.
QRS complex The QRS complex represents the entire events of ventricular depolarization.
List the three stages of an action potential in a cardiac muscle cell
Rapid depolarization, plateau, and repolarization
Which chamber receives blood from the superior and inferior vena cavae?
Right atrium
The heart is actually (one, two, or three) pumps?
Two pumps
Veins are more prone to inappropriate stretching and twisting than arteries, because
Veins have thinner walls than arteries
What does the QRS complex represent in the ECG wave tracing
Ventricular depolarization
Why is ventricular fibrillation fatal?
Ventricular fibrillation is fatal because the ventricles quiver and do not pump blood to the systemic circulation.
What event causes the closing of the AV valves, which results in the first heart sound
Ventricular systole
Isovolumetric contraction is associated with which cardiac cycle phase
Ventricular systole - first phase
Repolarization of an autorhythmic cell is due to the opening of which channels
Voltage-gated potassium channels
The superior portion of the heart where major blood vessels enter and exit is the
base
What structure of the heart contains the largest veins and arteries
base
The term used to describe fluid collecting in the pericardial cavity that restricts the movement of the heart is known as
cardiac tamponade.
The cusps (leaflets) of atrioventricular valves attach directly to
chordae tendineae
What does the ECG wave tracing represent
electrical activity in the heart
Action potentials generated by the autorhythmic cells spread to the contractile cells through what structures in the membrane
gap junctions
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.
The phase in the cardiac cycle when the mitral valve is closed and the aortic valve is open is the
ventricular ejection of ventricular systole
During which phase of the cardiac cycle is the blood pumped to the body
ventricular systole
The long plateau phase of the cardiac muscle action potential is due to
voltage-gated calcium channels remaining open
Intercalated discs serve to transfer all of the following from cell to cell except
z-lines