Cardiovascular System - The Heart CH17
Vagal tone :
Heart rate at rest under both autonomic divisions signaling.
ventricular depolarization
QRS complex
cardiac output
the amount of blood pumped by each ventricle in one minute
Match the following terms to their correct descriptions.: cardiac cycle
the events associated with blood flow through the heart during one complete heartbeat
conduction system cells that delay the impulse for about 0.1 seconds
AV node
A man enters the hospital complaining of chest pain. His history includes smoking, a stressful job, a diet heavy in saturated fats, lack of exercise, and high blood pressure. Although he is not suffering from a heart attack, his doctor explains to him that a heart attack is quite possible. What did the chest pain indicate? Why is this man a prime candidate for further complications? -Myocardial infarction. If the coronary arteries are occluded (atherosclerosis), the heart muscle could be deprived of oxygen, resulting in a heart attack. -Angina pectoris. If the coronary arteries are occluded (atherosclerosis), the heart muscle could be deprived of calcium, resulting in a heart attack. -Angina pectoris. If the coronary arteries are occluded (atherosclerosis), the heart muscle could be deprived of oxygen, resulting in a heart attack. A heart attack. If the coronary arteries are occluded (atherosclerosis), the heart muscle could be deprived of calcium, resulting in endocarditis. -Myocarditis. If the heart continues to become more inflamed, the heart muscle could be deprived of oxygen, resulting in a heart attack.
Angina pectoris. If the coronary arteries are occluded (atherosclerosis), the heart muscle could be deprived of oxygen, resulting in a heart attack.
Which of the following is NOT a difference between cardiac and skeletal muscle? -The plasma membranes of cardiac muscle cells interlock, but skeletal muscle fibers are independent. -Cardiac muscle cells contain more mitochondria than do skeletal muscle cells. -Cardiac muscle does not use the sliding filament mechanism for contraction; skeletal muscle does. -Cardiac muscle cells quickly die in the absence of oxygen; skeletal muscle cells are better able to adapt to oxygen deficiency
Cardiac muscle does not use the sliding filament mechanism for contraction; skeletal muscle does. Both skeletal muscle and cardiac muscle are striated, and both utilize the sliding filament mechanism for contraction.
Asystole is the total absence of ventricular electrical activity. Would defibrillation be effective in this situation? -Defibrillation would not be effective: it interrupts chaotic electrical activity in the heart, and if there is no electrical activity, then there is nothing to interrupt. -Defibrillation would be effective, because it targets the SA node to induce its autorhythmic activity. -Defibrillation would be effective: it repolarizes the cardiac cells, allowing the heart to function normally again. -Defibrillation would be effective, because it resets the heart's electrical activity.
Defibrillation would not be effective: it interrupts chaotic electrical activity in the heart, and if there is no electrical activity, then there is nothing to interrupt.
Which of the following is NOT a role of the pericardium? It anchors the heart to surrounding structures. It protects the heart. It facilitates heart contraction. It prevents the heart from overfilling with blood.
It facilitates heart contraction.
Describe the pressures in the atria and ventricles that would cause the opening of the AV valves. Pressure in the ventricles would be greater than in the atria. Pressures in the atria and ventricles would be equal. Pressure in the atria would be greater than the pressure in the ventricles.
Pressure in the atria would be greater than the pressure in the ventricles. higher pressure in the atria than in the ventricles forces the AV valves to open and blood moves into the ventricles.
The normal pacemaker of the heart is the __________. AV bundle the bundle branches AV node Purkinje fibers SA node
SA node
Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart? AV bundle (bundle of His) Purkinje fibers AV node SA node
SA node the SA Node spontaneously depolarizes, causing the wave of depolarization that spreads through the rest of the conduction system and heart.
Choose the correct sequence of current flow through the heart wall. Purkinje fibers, AV node, AV bundle, right and left bundle branches, SA node SA node, AV node, AV bundle, right and left bundle branches, Purkinje fibers AV node, Purkinje fibers, AV node, AV bundle, right and left bundle branches SA node, Purkinje fibers, AV node, AV bundle, right and left bundle branches AV node, SA node, Purkinje fibers, AV bundle, right and left bundle branches
SA node, AV node, AV bundle, right and left bundle branches, Purkinje fibers
Which of the following statements is NOT true about the shape, position, and location of the heart? Approximately two-thirds of the heart is found to the left of the midline. The heart is located between the two lungs within the mediastinum. The heart is enclosed in a double-layered sac called the pleural membrane. The heart is shaped like a cone with the base facing the right shoulder.
The heart is enclosed in a double-layered sac called the pleural membrane.
Which of the following is NOT a difference between the left and right ventricles? -The left ventricle receives a smaller percentage of coronary blood supply than the right ventricle. -The left ventricle pumps blood to the systemic circuit, while the right ventricle pumps blood to the pulmonary circuit. -The left ventricle is a more powerful pump than the right ventricle. -The walls of the left ventricle are thicker than the walls of the right ventricle.
The left ventricle receives a smaller percentage of coronary blood supply than the right ventricle. Since the demands on the left ventricle are so great, it receives the highest percentage of the coronary blood supply.
Which of the following factors gives the myocardium its high resistance to fatigue? the coronary circulation a very large number of mitochondria in the cytoplasm gap junctions the presence of intercalated discs
a very large number of mitochondria in the cytoplasm
Match each of the following abbreviations with its definition: SV
amount of blood ejected by one contraction of the heart
ESV
amount of blood in the ventricle at the end of contraction
EDV
amount of blood in the ventricle at the end of relaxation
An enlarged R wave on an ECG would indicate __________. a myocardial infarction cardiac ischemia an enlarged ventricle repolarization abnormalities
an enlarged ventricle
The coronary arteries arise from the __________. inferior vena cava superior vena cava right atrium pulmonary trunk aorta
aorta
left ventricle
aortic semilunar valve
The superior chambers of the heart are called the __________. cavea ventricles coronary chambers atria
atria
The ability of some cardiac muscle cells to initiate their own depolarization and cause depolarization of the rest of the heart is called __________. the absolute refractory period automaticity an action potential fibrillation a functional syncytium
automaticity
left atrium
bicuspid valve
The __________ are attached to the AV valve flaps. trabeculae carneae chordae tendineae papillary muscles pectinate muscles
chordae tendineae
The vessels that carry oxygen to the myocardium are called __________. coronary veins pulmonary arteries pulmonary veins aortic arteries coronary arteries
coronary arteries
If cardiac muscle is deprived of its normal blood supply, damage would primarily result from ________. -a lack of nutrients to feed into metabolic pathways -decreased delivery of oxygen -an inadequate supply of lactic acid -a decrease in the number of available mitochondria for energy production
decreased delivery of oxygen
How would a decrease in blood volume affect both stroke volume and cardiac output? -no change in stroke volume and decreased cardiac output -decreased stroke volume and no change in cardiac output -decreased stroke volume and decreased cardiac output -increased stroke volume and increased cardiac output
decreased stroke volume and no change in cardiac output 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 increase because of increased activity of the sympathetic nervous system in an effort to maintain cardiac output.
Which is correctly paired? ectopic focus: an abnormal pacemaker fibrillation: premature contraction arrhythmia: AV node failure heart block: uncoordinated atrial and ventricular contraction
ectopic focus: an abnormal pacemaker
What does the ECG wave tracing represent? electrical activity in the heart contraction of the heart
electrical activity in the heart the ECG waves show the depolarization and repolarization in various areas of the heart.
The lining of the heart chambers is called the __________. epicardium pericardium myocardium endocardium
endocardium
An abnormal P wave could be indicative of ______. an abnormal AV node an abnormal AV bundle incomplete ventricular repolarization enlarged atria
enlarged atria The P wave on an ECG tracing represents SA node firing and subsequent atrial depolarization.
Which is the correct sequence of layers in the heart wall, starting with the outer layer? parietal pericardium, myocardium, endocardium endocardium, epicardium, myocardium myocardium, pericardium, endocardium endocardium, smooth muscle, epicardium epicardium, myocardium, endocardium
epicardium, myocardium, endocardium
Which of the following would increase heart rate? -decreased activity of the sympathetic nervous system -epinephrine and norepinephrine -increased activity of the parasympathetic nervous system -acetylcholine
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.
The cells of the myocardium behave as a single, coordinated unit called a __________. contractile unit cardiac cycle functional syncytium sarcomere pacemaker
functional syncytium
endocardium
glistening white sheet of endothelium lining the inside of the heart
what causes the aortic semilunar valve to close? -greater pressure in the aorta than in the left ventricle -higher ventricular pressure than aortic pressure -equal ventricular and aortic pressures
greater pressure in the aorta than in the left ventricle backflow of blood in the aorta (towards the left ventricle) closes the aortic semilunar valve.
A doctor puts his stethoscope on a patient's chest over the location of the heart and hears a swishing sound. Which of the following conditions is the best diagnosis for the patient's condition? cardiac tamponade angina pectoris myocardial infarction incompetent cardiac valve
incompetent cardiac valve
How would an increase in the sympathetic nervous system increase stroke volume? increased end diastolic volume increased contractility decreased end diastolic volume increased end systolic 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.
By what mechanism would an increase in venous return increase stroke volume? increased end systolic volume decreased end diastolic volume increased end diastolic volume increased contractility
increased end diastolic volume 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).
Which of the following terms refers to a lack of oxygen supply to heart muscle cells? infarction ischemia functional syncytium embolism
ischemia Ischemia refers to a lack of oxygen supply to heart muscle cells
Put the phases of the cardiac cycle in the correct order, starting after ventricular filling. -isovolumetric contraction, ventricular ejection, isovolumetric relaxation -isovolumetric relaxation, ventricular ejection, isovolumetric contraction -ventricular ejection, isovolumetric contraction, isovolumetric relaxation -ventricular ejection, ventricular relaxation, isovolumetric contraction
isovolumetric contraction, ventricular ejection, isovolumetric relaxation the ventricles must contract and eject blood before they relax and fill again.
The interventricular septum forms a dividing wall between the __________. right ventricle and left atrium right atrium and right ventricle left and right ventricles left atrium and right atrium left atrium and left ventricle
left and right ventricles
Into which chamber of the heart do the pulmonary veins deliver blood? right ventricle left ventricle right atrium left atrium
left atrium
left ventricle
left atrium
pulmonary veins
left atrium
Which heart chamber receives blood from the pulmonary veins? Which heart chamber receives blood from the pulmonary veins? left atrium
left atrium the left atrium receives oxygenated blood from the pulmonary veins.
Freshly oxygenated blood is delivered to the __________ and then it passes into the __________ to be pumped to the entire body. left atrium; left ventricle right atrium; right ventricle left ventricle; left atrium right ventricle; right atrium
left atrium; left ventricle
Which chamber pumps oxygenated blood out the aorta to the systemic circuit? Which chamber pumps oxygenated blood out the aorta to the systemic circuit? right ventricle
left ventricle the left ventricle pumps oxygenated blood out the aorta to the entire body (systemic circuit).
During systemic circulation, blood leaves the __________. right ventricle and moves to the lungs lungs and moves to the left atrium right ventricle and goes directly to the aorta right atrium and goes directly to the lungs left ventricle and goes directly to the aorta
left ventricle and goes directly to the aorta
When the mitral valve closes, it prevents the backflow of blood from the __________. right ventricle into the pulmonary trunk left atrium into the left ventricle left ventricle into the left atrium right atrium into the right ventricle left ventricle into the aorta
left ventricle into the left atrium
Match the following structure with its description.: fibrous pericardium
loosely fitting superficial part of the sac enclosing the heart
Guided by powerful signaling molecules, the human heart develops from __________. cardioderm ectoderm mesoderm endoderm
mesoderm
myocardium
middle layer of the heart, composed mainly of cardiac muscle
aorta
most body tissues
coronary artery
myocardium
When viewing a dissected heart, it is easy to visually discern the right and left ventricles by ________. locating the apex noticing the thickness of the ventricle walls tracing out where the auricles connect finding the papillary muscles
noticing the thickness of the ventricle walls
The inner lining of the fibrous pericardium is formed by the __________. myocardium pericardial cavity epicardium endocardium diaphragm parietal layer of serous pericardium
parietal layer of serous pericardium
Cardiac tamponade results in ineffective pumping of blood by the heart because the excessive amount of fluid in the pericardial cavity will______. -prevent the visceral layer of the serous pericardium from properly surrounding the heart -prevent the heart from filling properly with blood -prevent proper oxygenation of the blood -interfere with the ability of this fluid to lubricate the serous membranes
prevent the heart from filling properly with blood The heart is wrapped by a double-walled sac called the pericardium. The pericardial cavity lies between the parietal and visceral layers of the serous pericardium. It is filled with a very small amount of serous fluid. If additional fluid fills the pericardial space, it adds pressure on the outside of the heart, preventing it from filling normally.
aortic semilunar valve
prevents backflow of blood into the left ventricle
pulmonary semilunar valve
prevents backflow of blood into the right ventricle
right ventricle
pulmonary semilunar valve
right ventricle and pulmonary trunk
pulmonary semilunar valve
the right ventricle sends blood into this vessel
pulmonary trunk
Match the following terms with their correct descriptions: brings oxygen-rich blood from the lungs to the left atrium
pulmonary veins
The fact that the left ventricle of the heart is thicker than the right ventricle reveals that it ________. pumps a greater volume of blood sends blood through a smaller valve expands the thoracic cage pumps blood against a greater resistance
pumps blood against a greater resistance
Isovolumetric contraction ________. -occurs immediately after the aortic and pulmonary valves close -occurs only in people with heart valve defects -occurs while the AV valves are open -refers to the short period during ventricular systole when the ventricles are completely closed chambers
refers to the short period during ventricular systole when the ventricles are completely closed chambers
diastole
relaxation
Match each of the following vessels with the correct "destination." superior vena cava
right atrium
The inferior vena cava brings blood from the lower regions of the body and empties into the __________. right ventricle aorta left ventricle left atrium right atrium
right atrium
right ventricle
right atrium
Which chamber receives blood from the superior and inferior vena cavae? left atrium right atrium left ventricle right ventricle
right atrium the right atrium receives unoxygenated blood from the systemic circuit.
The tricuspid valve is located between the __________. left atrium and left ventricle right and left ventricles right ventricle and the aorta right atrium and right ventricle right and left atria
right atrium and right ventricle
Identify the correct sequence of blood flow through the chambers of the heart. right atrium, right ventricle, lungs, left atrium, left ventricle left ventricle, left atrium, lungs, right ventricle, right atrium lungs, right ventricle, left ventricle, right atrium, left atrium right ventricle, left ventricle, left atrium, lungs, right atrium left atrium, left ventricle, right ventricle, right atrium, lungs
right atrium, right ventricle, lungs, left atrium, left ventricle
Which heart chamber sends deoxygenated blood to the lungs? Which heart chamber sends deoxygenated blood to the lungs? left ventricle right atrium left atrium right ventricle
right ventricle The right ventricle sends the deoxygenated blood to the lungs via the pulmonary trunk.
Which heart chamber pumps unoxygenated blood out the pulmonary trunk? Which heart chamber pumps unoxygenated blood out the pulmonary trunk? left ventricle
right ventricle the right ventricle pumps unoxygenated blood out the pulmonary trunk to the lungs.
During pulmonary circulation, blood leaves the __________. left ventricle and moves to the lungs right atrium and goes directly to the lungs right ventricle and moves to the lungs right atrium and goes directly to the left ventricle right ventricle and goes directly to the aorta
right ventricle and moves to the lungs
The endocardium is composed of __________. simple squamous epithelium stratified squamous epithelium simple columnar epithelium simple cuboidal epithelium cardiac muscle cells
simple squamous epithelium
The heart's pacemaker is the __________. atrioventricular bundle sinoatrial node atrioventricular node Purkinje fibers
sinoatrial node The sinoatrial node (SA node), which is in the right atrial wall, is the heart's pacemaker. The autorhythmic cells of this node generate the sinus rhythm that determines heart rate.
Which of the following factors does not influence heart rate? age skin color body temperature gender
skin color
The role of the atrioventricular node (AV node) is to __________. initiate ventricular depolarization slow down impulses so that the atria can contract to fill the adjacent ventricles with blood conduct impulses to the sinoatrial node (SA node) initiate a sinus rhythm
slow down impulses so that the atria can contract to fill the adjacent ventricles with blood
During contraction of heart muscle cells ________. -calcium is prevented from entering cardiac fibers that have been stimulated -the action potential is prevented from spreading from cell to cell by gap junctions -the action potential is initiated by voltage-gated slow calcium channels -some calcium enters the cell from the extracellular space and triggers the release of larger amounts of calcium from intracellular stores
some calcium enters the cell from the extracellular space and triggers the release of larger amounts of calcium from intracellular stores
brings oxygen-poor blood from the upper body to the right atrium
superior vena cava
anterior interventricular artery
supplies blood to the interventricular septum and anterior walls of both ventricles
Match the following terms to their correct descriptions: right marginal artery
supplies blood to the lateral right side of the myocardium
circumflex artery
supplies blood to the left atrium and posterior walls of the left ventricle
CO
the amount of blood ejected from the heart in one minute
Cardiac output is __________. the number of times the heart beats in one minute the amount of blood pumped out of the heart during every ventricular contraction the amount of blood filling each ventricle at the end of diastole the number of impulses fired by the SA node in one minute the amount of blood pumped out of each ventricle in one minute
the amount of blood pumped out of each ventricle in one minute cardiac output = heart rate × stroke volume
Which of the following structures lies on the outside surface of the heart and is an integral part of the cardiac wall? the parietal layer of serous pericardium the pericardial sac the fibrous pericardium the epicardium
the epicardium
B
the frequency at which the heart beats
What part of the heart is considered the systemic circuit pump? the right ventricle the right atrium the left ventricle the left atrium
the left ventricle
pulmonary trunk
the lungs
Which of the following valves is most often faulty in the heart? the aortic semilunar valve the mitral, or bicuspid, valve the tricuspid valve the pulmonary semilunar valve
the mitral, or bicuspid, valve
The absolute refractory period refers to the time during which __________. a skeletal muscle cannot respond to any stimulus and lasts about 250 milliseconds the muscle cell is not in a position to respond to a stimulus of any strength the muscle cell is ready to respond to a threshold stimulus the muscle cell is ready to respond to any stimulus a cardiac muscle cannot respond to any stimulus and lasts only 1 to 2 milliseconds
the muscle cell is not in a position to respond to a stimulus of any strength
The cardiac cycle includes all of the following events EXCEPT __________. the number of times the heart beats in one minute the closing and opening of the heart valves during each heartbeat the movement of impulse from the SA node to all regions of the heart wall the changes in blood volume in all chambers of the heart the changes in pressure gradients in all chambers of the heart
the number of times the heart beats in one minute
Match each area of the heart with the "exit" through which the blood leaves: right atrium
tricuspid valve
right atrium and right ventricle
tricuspid valve
The myocardium receives its blood supply from the coronary arteries. True False
true
Tissues damaged by myocardial infarction are replaced by connective tissue. True False
true
The __________ nerve carries parasympathetic fibers to the sinoatrial (SA) node. accessory facial hypoglossal vagus
vagus
mitral valve
valve between the left atrium and left ventricle
Match the following terms with their correct descriptions: tricuspid valve
valve between the right atrium and right ventricle
Match each area of the heart with the structure from which it receives blood: right atrium
vena cavae
The trabeculae carneae are located in the __________. epicardium endocardium atrium ventricles
ventricles
Isovolumetric relaxation and ventricular filling (two phases of the cardiac cycle) take place during __________. ventricular systole ventricular diastole
ventricular diastole both occur during ventricular diastole when the ventricles are not actively contracting and ejecting blood.
What does the T wave of the electrocardiogram (ECG) represent? atrial depolarizaton ventricular repolarization atrial repolarization ventricular depolarization
ventricular repolarization The T wave of the ECG represents ventricular repolarization as the heart rests and prepares to contract again.
A patient is prescribed a calcium channel blocker to prevent angina (chest pain) by decreasing the demand for oxygen. What is the explanation for this pharmacological effect? -A drug that enhances the entry of calcium ions into the cytoplasm of cardiac cells decreases the force of myocardial contractility, thereby decreasing the oxygen demand, relieving the chest pain. -A drug that inhibits the entry of calcium ions into the cytoplasm of cardiac cells decreases the membrane potential, thereby making the heart beat slower, relieving the chest pain. -A drug that enhances the entry of calcium ions into the cytoplasm of cardiac cells increases the membrane potential, thereby making the heart beat slower, relieving the chest pain. -A drug that blocks the calcium channels prevents the cardiac cells from contracting, thereby relieving the chest pain. -A drug that inhibits the entry of calcium ions into the cytoplasm of cardiac cells decreases the force of myocardial contractility, thereby decreasing the oxygen demand, relieving the chest pain.
A drug that inhibits the entry of calcium ions into the cytoplasm of cardiac cells decreases the force of myocardial contractility, thereby decreasing the oxygen demand, relieving the chest pain
Which part of the intrinsic conduction system delays the impulse briefly before it moves on to the ventricles? bundle branches Purkinje fibers AV node AV bundle (bundle of His) SA node
AV node the AV node slows down the impulse giving the atria time to contract before the ventricles contract.
Tachycardia :
An abnormally fast heart rate.
Bradycardia :
An abnormally slow heart rate.
ventricular repolarization
T wave
Select the correct statement about the heart valves. -The AV valves are supported by chordae tendineae so that regurgitation of blood into the atria during ventricular contraction does not occur. -The tricuspid valve divides the left atrium from the left ventricle. -Aortic and pulmonary valves control the flow of blood into the heart. -The mitral valve separates the right atrium from the right ventricle.
The AV valves are supported by chordae tendineae so that regurgitation of blood into the atria during ventricular contraction does not occur.
Hypercalcemia could cause ______. increased osteoclast activity prolonged T wave hypersecretion of parathyroid hormone All of the listed responses are correct.
The T wave on an ECG tracing represents ventricular repolarization. Repolarization requires the net efflux of K+ ions. Recall that changes in normal ion concentrations, like Ca2+, in the plasma can affect the ability of other ions to move in and out of the cell.
The heart is actually (one, two, or three) pumps?
Two pumps 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 of the following is a difference between cardiac muscle and skeletal muscle? Unlike skeletal muscle cells, cardiac muscle cells do not rely on an influx of calcium ions for depolarization. Unlike skeletal muscle, cardiac muscle does not use a sliding filament mechanism for contraction. Unlike skeletal muscle, cardiac muscle is not striated. Unlike skeletal muscle cells, cardiac muscle cells can be autorhythmic.
Unlike skeletal muscle cells, cardiac muscle cells can be autorhythmic.
Hemorrhage with a large loss of blood causes ________. a lowering of blood pressure due to change in cardiac output no change in blood pressure but a slower heart rate a rise in blood pressure due to change in cardiac output no change in blood pressure but a change in respiration
a lowering of blood pressure due to change in cardiac output
The term for pain associated with deficient blood delivery to the heart that may be caused by the transient spasm of coronary arteries is ________. angina pectoris myocardial infarct pericarditis ischemia
angina pectoris
coronary artery
aorta
the left ventricle sends blood into this vessel
aorta
left ventricle and aorta
aortic semilunar valve
The P wave of an electrocardiogram represents __________. ventricular depolarization atrial depolarization atrial repolarization ventricular repolarization
atrial depolarization
Increased pressure in the ventricles would close what valve(s)? both semilunar and AV valves AV valves only semilunar valves only
av valves only increased pressure in the ventricles would close the AV valves.
Indicate the valve separating the following areas of the heart: left atrium and left ventricle
bicuspid (mitral) valve
During the period of ventricular filling ________. pressure in the heart is at its peak the atria remain in diastole it is represented by the P wave on the ECG blood flows mostly passively through the atria and the open AV valves into the ventricles
blood flows mostly passively through the atria and the open AV valves into the ventricles
Which of these vessels receives blood during ventricular systole? aorta only both the aorta and pulmonary trunk pulmonary veins only pulmonary arteries only
both the aorta and pulmonary trunk
The second heart sound (the 'dup' of 'lub-dup') is caused by the __________. opening of the semilunar valves closure of the atrioventricular valves closure of the semilunar valves opening of the atrioventricular valves
closure of the semilunar valves
systole
contraction
Cardiac muscle has more mitochondria and depends less on a continual supply of oxygen than does skeletal muscle. True False
false
Which of the following would increase cardiac output to the greatest extent? -decreased heart rate and increased stroke volume -increased heart rate and increased stroke volume -increased heart rate and decreased stroke volume -decreased heart rate and decreased stroke volume
increased heart rate and increased stroke volume cardiac output = heart rate x stroke volume.
brings oxygen-poor blood from the lower body to the right atrium
inferior vena cava
epicardium
inner layer of pericardium (called the visceral layer)
The most muscular chamber of the heart is the __________. right atrium left atrium left ventricle right ventricle
left ventricle
Which of the following would lead to a decrease in heart rate? sharply decreased blood volume parasympathetic stimulation norepinephrine exercise
parasympathetic stimulation
stroke volume
the volume of blood pumped by one ventricle with each heartbeat
serous pericardium
thin, slippery, two-layer membrane
Cardiac reserve :
Difference between resting and maximal cardiac output.
Which of the following is correct about the filling of the ventricles? Most blood flows passively into the ventricles through open AV valves. The majority of ventricular filling is caused by contraction of the atria.
Most blood flows passively into the ventricles through open AV valves. most of the ventricular filling is passive; atrial contraction adds just a little more blood.
Match the following terms with their correct descriptions.: atrial depolarization
P wave
Contraction of the atria results from which wave of depolarization on the ECG tracing? T wave QRS complex P wave
P wave the P wave represents atrial depolarization, which leads to atrial contraction.
a faster depolarizing pacemaker cells
SA node
Select the correct statement about the structure of the heart wall. Connective tissue in the heart wall aids in the conduction of the action potential. The myocardium is the layer of the heart that actually contracts. The fibrous skeleton forms the bulk of the heart. The heart chambers are lined by the endomysium.
The myocardium is the layer of the heart that actually contracts.
What does the QRS complex represent in the ECG wave tracing? atrial depolarization ventricular repolarization ventricular depolarization atrial repolarization
ventricular depolarization the QRS complex represents depolarization in the ventricles, which have greater mass than the atria.
The QRS complex on an electrocardiogram represents __________. atrial repolarization ventricular repolarization ventricular depolarization atrial depolarization
ventricular depolarization The QRS complex shows ventricular depolarization
left atrium
pulmonary veins
posterior interventricular artery
runs to the apex of the heart