Cardiac
List the similarities between cardiac and skeletal muscle cells
-AP leads to appearance of Ca++ among myofibrils -Binding of Ca++ to troponin on thin filaments initiates contraction -Actin-myosin cross bridges form, filament slides, contraction occurs
Describe the steps of a cardiac muscle AP
-AP travels down T tubules -At threshold, changes in membrane potential opens FAST SODIUM CHANNELS -Influx of Na+ into cell rapidly depolarizes sarcolemma -As Na+ channels close, voltage-gated Ca++ channels open, SLOW CALCIUM CHANNELS, Ca++ enter sarcoplasm -Slow calcium channels open slowly and remain open for a relatively long period - this is PLATEAU phase -As plateau continues, slow calcium channels begin closing, and slow K+ channels begin opening, K+ rushes out of cell -The extracellular Ca++ also affects the strength of contraction because (T tubules are 5x diameter) -Ca++ in ECF induces Ca++ release from SR, initiates contraction. -Atin, myosin filaments interact -AP lasts ~250-300 msec
What are the 2 types of cardiac muscle cells and their function?
-Specialized muscle cells of conducting system control and coordinate heartbeat -Contractile cells produce contraction that propel blood
How is the AP of SA node different from AP of contractile cells?
-in SA node there is no plateau phase (Ca++) -SA node has a drifting membrane potential - prepotential or pacemaker potential
What is the role of conducting cells and where are they found?
-interconnect the two nodes - SA node & AV node -distribute the contractile stimulus throughout the myocardium. In atria: conducting cells are in internodal pathway (between SA & AV node) In Ventricles: conducting cells are in the AV bundle, bundle branches, and purkinje fibers, which distribute the stimulus to ventricular myocardium.
What defines 1 cardiac cycle?
1 cardiac cycle is from the start of 1 heratbeat to the beginning of the next.
What is the rate of spontaneous depolarization of the Purkinje fibers?
20-40 AP per min.
What is the rate of spontaneous depolarization of the AV node?
40-60 AP per min.
anastamosis
A direct connection between arteries is called a/an
tachycardia
A heart rate in excess of 100 BPM is called __________.
cardiac tamponade
A serious condition in which a large amount of fluid accumulates in the pericardial cavity and puts pressure of the heart is
pacemaker potential
A spontaneously developing local potential in the SA node is called a ________ ___________.
the heart is compressed by blood in the pericardial sac
A stab wound into the heart can result in cardiac tamponade. This means that
The plateau phase of the cardiac contractile cell action potential is caused by A) Ca2+ inflow B) Cl- inflow C) K+ outflow D) Na+ outflow
A) Ca2+ inflow Feedback: The plateau phase slows repolarization by increasing the number of positive ions in the cell.
Calcium is needed for contraction in both skeletal muscle and cardiac muscle. However there are some differences in where it comes from and what it does. Which of these choices correctly describes how calcium works in cardiac muscle cells? A) Extracellular Ca2+ diffuses into the cardiac muscle cells, binds to Ca2+ channels in the sarcoplasmic reticulum and causes Ca2+ release into the cytosol. B) Extracellular Ca2+ diffuses into the cardiac muscle cells, binds to troponin and initiates contraction. C) Ca2+ from the sarcoplasmic reticulum diffuses out of the cell, causing the plateau phase of the action potential. D) Ca2+ from the sarcoplasmic reticulum diffuses out of the cell, causing repolarization.
A) Extracellular Ca2+ diffuses into the cardiac muscle cells, binds to Ca2+ channels in the sarcoplasmic reticulum and causes Ca2+ release into the cytosol. Feedback: In cardiac muscle cells, extracellular Ca2+ has a different job than the Ca2+ from the sarcoplasmic reticulum. The extracellular Ca2+ ions are involved in action potential formation. The ions from the sarcoplasmic reticulum are involved in the contraction mechanism.
In an ECG taken from a person who has no SA node activity, which component will not appear? A) P wave B) QRS complex C) ST segment D) T wave
A) P wave Feedback: The initial wave of an ECG tracing is the P wave, which corresponds to an action potential formed by the SA node.
In which choice are the components of the heart placed in correct order of decreasing intrinsic rhythm? A) SA node, AV node, Purkinje cells B) SA node, Purkinje cells, AV node C) AV node, SA node, Purkinje cells D) Purkinje cells, AV node, SA node
A) SA node, AV node, Purkinje cells Feedback: SA node = 70 - 80 times per minute. AV node = 40 - 60 times per minute. Purkinje cells < 30 per minute.
Which of the following is not a positive chronotrope? A) acetylcholine B) epinephrine C) thyroid hormone D) caffeine
A) acetylcholine
Energy for contraction of myocardial cells comes primarily from A) aerobic respiration in the mitochondria. B) anaerobic respiration in the cytosol. C) glycolysis in the cytosol. D) ATP that is stored while the heart is not contracting.
A) aerobic respiration in the mitochondria. Feedback: The energy demands of the myocardium are very high, therefore cardiac cells require the full ATP production provided by aerobic respiration.
A point where two arteries connect and combine their blood flow is called a(n) A) anastomosis. B) infarction. C) divergence. D) aneurysm.
A) anastomosis. Feedback: Infarctions and aneurysms are pathologies of the cardiovascular system. A divergence would be an antonym of an anastomosis.
The atrioventricular valves open when pressure in the A) atria is greater than pressure in the ventricles. B) ventricles is greater than pressure in the arteries. C) arteries is greater than pressure in the ventricles. D) ventricles is greater than pressure in the atria.
A) atria is greater than pressure in the ventricles. Feedback: The valves open in the direction that blood is flowing.
In the cardiac conduction system, junctional fibers connect the A) atrial syncytium to the AV node. B) AV node to the AV bundle. C) SA node to the Purkinje fibers. D) AV bundle branches to the Purkinje fibers.
A) atrial syncytium to the AV node.
The amount of blood ejected from the heart in one minute is called the A) cardiac output B) end diastolic volume C) end systolic volume D) stroke volume
A) cardiac output Feedback: The difference between EDV and ESV is the stroke volume. Cardiac output is defined as SV times beats per minute.
The amount of blood in the ventricles just before they contract is called the A) end diastolic volume B) end systolic volume C) stroke volume D) cardiac output
A) end diastolic volume Feedback: The end of diastole coincides with the beginning of systole. At the end of ventricular diastole, the ventricles are as full as they are going to be. At the end of ventricular systole, the ventricles are as empty as they are going to be. The difference between EDV and ESV is the stroke volume. Cardiac output is defined as SV times beats per minute.
A needle being inserted into the heart would travel through the layers of the heart wall and coverings in which order, beginning on the outside? A) fibrous pericardium, parietal pericardium, visceral pericardium, myocardium, endocardium B) parietal pericardium, fibrous pericardium, visceral pericardium, myocardium, endocardium C) endocardium, myocardium, fibrous pericardium, parietal pericardium, visceral pericardium D) visceral pericardium, parietal pericardium, fibrous pericardium, endocardium, myocardium
A) fibrous pericardium, parietal pericardium, visceral pericardium, myocardium, endocardium
The atria are electrically isolated from the ventricles by the A) fibrous skeleton B) AV bundle C) visceral pericardium D) Purkinje fibers
A) fibrous skeleton Feedback: The fibrous skeleton of the heart is composed of collagen fibers. It electrically isolates the atria from the ventricles, and serves as the attachment site of the valves and muscle.
Which component of a myocardial cell allows it to electrically stimulate adjoining cells? A) gap junctions B) t-tubules C) desmosomes D) sarcoplasmic reticulum
A) gap junctions Feedback: The only way for a cell to electrically stimulate (as opposed to chemical stimulation) an adjoining cells is to allow ions to pass directly from the cytoplasm of one cell to the next.
Intercalated discs include these structures: A) gap junctions, desmosomes, interdigitating folds B) gap junctions, tight junctions, t-tubules C) gap junctions, desmosomes, t-tubules D) sarcoplasmic reticulum, interdigitating folds
A) gap junctions, desmosomes, interdigitating folds Feedback: Everything at an intercalated disc involves holding two myocardial cells together or allowing them to communicate. T-tubules and sarcoplasmic reticula are located within muscle cells, not between them.
Which ionic imbalance would decrease the strength of cardiac muscle contraction? A) hypocalcemia B) hypercalcemia C) hypokalemia D) hyponatremia
A) hypocalcemia Feedback: Calcium ions are needed for both cardiac action potential formation and for the mechanical events of cardiac muscle contraction.
In response to exercise, the heart would be called upon to _____ the amount of blood pumped, and this would be initiated by signals from ______ fibers. A) increase; sympathetic B) increase; parasympathetic C) decrease; sympathetic D) decrease; parasympathetic
A) increase; sympathetic Feedback: Exercise is a stressful condition which causes the body to use more oxygen and produce more carbon dioxide. These conditions activate the sympathetic nervous system to increase blood flow, and thereby, gas exchange.
The action of acetylcholine after binding to muscarinic receptors on the SA node is to A) open K+ channels, causing hyperpolarization and a decreased rate of spontaneous depolarization B) close K+ channels, causing depolarization and and increased rate of spontaneous depolarization C) open Ca2+ channels, causing increased Ca2+ entry and a stronger contraction D) close Ca2+ channels, causing decreased Ca2+ entry and a faster rate of spontaneous depolarization
A) open K+ channels, causing hyperpolarization and a decreased rate of spontaneous depolarization Feedback: Acetylcholine is released by parasympathetic fibers, and acts to slow the heart rate.
The "skeleton" of the heart A) provides attachment for the heart valves and cardiac muscle B) is made of fibrocartilage C) provides internal support for the cardiac chambers D) is also called the fibrous pericardium
A) provides attachment for the heart valves and cardiac muscle Feedback: The fibrous skeleton of the heart is composed of collagen fibers. It electrically isolates the atria from the ventricles, and serves as the attachment site of the valves and muscle.
The right ventricle of the heart acts as a pump for the A) pulmonary circulation. B) systemic circulation. C) coronary circulation. D) hepatic portal circulation.
A) pulmonary circulation. Feedback: The right ventricle pumps blood through the pulmonary trunk and pulmonary arteries to the lungs.
The function of the pericardial fluid is to A) reduce friction between the pericardial membranes. B) lubricate the heart valves. C) replace any blood that is lost. D) provide oxygen and nutrients to the endocardium.
A) reduce friction between the pericardial membranes
Which of the following commonly increases with age? A) size of the left ventricle B) size of the right ventricle C) heart rate D) flexibility of heart valves
A) size of the left ventricle Feedback: A gradual increase in aortic pressure caused by aging makes it harder for the left ventricle to eject blood, causing it to increase its size to increase its strength.
The cells of the heart's normal pacemaker A) spontaneously generate electrical signals about 70 to 80 times per minute. B) are located in the interventricular septum. C) generate electrical signals only when stimulated by sympathetic fibers. D) are not in contact with other cells of the heart.
A) spontaneously generate electrical signals about 70 to 80 times per minute. Feedback: The SA node has the fastest depolarization/repolarization rate, and is called the pacemaker because it originates the cardiac impulse.
The coronary sinus is a(n) ______ located in the ________. A) vein; posterior atrioventricular sulcus B) vein; posterior interventricular sulcus C) artery; anterior atrioventricular sulcus D) artery; interatrial septum
A) vein; posterior atrioventricular sulcus Feedback: The coronary sinus is located between the atria and the ventricles on the right side of the heart. It drains the veins of the heart into the right atrium.
A blood clot in the circumflex artery would cause a myocardial infarction in part of the A) walls of the left atrium and posterior left ventricle. B) anterior walls of the left and right ventricles, and the interventricular septum. C) posterior walls of the left and right ventricles. D) lateral walls of the right atrium and right ventricle.
A) walls of the left atrium and posterior left ventricle. Feedback: The circumflex artery is a branch of the left coronary artery, and is located in the coronary sulcus.
After the AP passes through AV node and atria contract, The impulse travels along the _________ or _________ which is the only electrical connection between atria and ventricles
AV node=Bundle of His
gap junctions
Action potentials pass from one myocardial cell to another through areas of low electrical resistance called
Describe what happens during Prepotential/pacemaker potential of conducting cells
After each repolarization the membrane drifts towards threshold which leads to spontaneous depolarization - This is prepotential
the arterial pressure that the ventricles must overcome to eject blood
Afterload is
coronary sinus; right atrium
All cardiac veins empty into the _________, which then empties into the _______.
left atrium
An incompetent mitral valve may cause blood to back up into the
lungs
An incompetent pulmonary semilunar valve could result in less blood reaching the
the force of contraction
An increase in extracellular calcium generally increases
blood supply to cardiac muscle
Angina pectoris is chest pain caused by reduced
epicardium
Another name for the visceral pericardium is the
a narrowed opening through the aortic valve
Aortic stenosis results from
aortic semilunar valve opens
As soon as left ventricular pressure exceeds the pressure in the aorta, the
What happens in the first phase of ventricular systole?
As the pressures in the ventricles rise above those in the atria, the AV valves are pushed closed. in Early ventricular systole, the AV valves are pushed closed but pressures are not yet high enough to force open the semilunar valves. This is called isovolumetric contraction
What happens in the 2nd phase of ventricular systole?
As ventricular pressure rises and exceeds pressure in the arteries, the semilunar valves open and blood is ejected. Ventricles contract isotonically.
When does ventricular systole begin?
At the same time as atrial diastole
What happens when Atrial systole begins?
Atrial contraction forces a small amount of additional blood into relaxed ventricles
What does the P wave of an ECG represent?
Atrial depolarization
4 phases of the cardiac cycle
Atrial systole Atrial diastole Ventricular systole Ventricular diastole
Joe's cardiac output at rest is 5 L/min. When he is exercising strenuously it is 20 L/min. What is Joe's cardiac reserve? A) 4 L/min B) 15 L/min C) 25 L/min D) 100 L/min
B) 15 L/min Feedback: Cardiac reserve equals CO during exertion minus CO at rest. The higher the cardiac reserve, the more easily one tolerates strenuous exercise.
The normal rate of spontaneous depolarization of the AV node is A) 20 - 40 per minute B) 40 - 60 per minute C) 70 - 80 per minute D) over 100 per minute
B) 40 - 60 per minute Feedback: The AV node has a depolarization rate of 40 - 60 per minute - a bit slower than the SA node.
If the SA node is damaged, which part of the heart is most likely to take over as a pacemaker? A) atrial myocardial cells B) AV nodal cells C) Purkinje fibers D) ventricular myocardial cells
B) AV nodal cells
What is the effect of norepinephrine on the heart? A) It decreases the rate and strength of contraction. B) It increases the rate and strength of contraction. C) It decreases the amount of blood pumped per minute. D) It has no effect on the heart.
B) It increases the rate and strength of contraction. Feedback: Norepinephrine is released by sympathetic postgangionic fibers.
In which choice are the components of the cardiac conduction system listed in the correct sequence? A) SA node, AV bundle, AV node, Purkinje fibers B) SA node, AV node, AV bundle, Purkinje fibers C) AV node, AV bundle, SA node, Purkinje fibers D) AV node, SA node, Purkinje fibers, AV bundle
B) SA node, AV node, AV bundle, Purkinje fibers Feedback: The SA node has the fastest depolarization/repolarization rate, and is called the pacemaker because it originates the cardiac impulse. The AV node is located at the junction of the interatrial and atrioventricular septa. The AV bundle exits the AV node and enters the interventricular septum. The Purkinje fibers are located in the ventricular myocardium and terminate in the papillary muscles.
Any factor that alters heart rate is called A) a chemotrope B) a chronotrope C) an inotrope D) an isotope
B) a chronotrope
Of the amount of blood entering the ventricles before they contract A) about 70% comes in during atrial contraction. B) about 70% comes in before atrial contraction. C) 100% comes in during atrial contraction. D) 30% comes in during atrial contraction and 70% comes in during ventricular contraction.
B) about 70% comes in before atrial contraction. Feedback: Passive filling occurs during the atrial and ventricular diastole between beats.
An auricle is A) a valve located in a blood vessel B) an extension of the atrial wall C) part of a heart valve D) a blood vessel that carries blood away from the heart
B) an extension of the atrial wall Feedback: "Auricle" means ear-like, and refers to flap-like appearance of the atrium when not filled with blood.
Conduction of the cardiac impulse is slowed as it passes through the AV node. This allows time for the A) ventricles to start contracting before the atria finish contracting. B) atria to contract completely before the ventricles start to contract. C) SA node to catch up. D) last ventricular contraction to finish.
B) atria to contract completely before the ventricles start to contract. Feedback: In order to maintain one-way flow of blood through the heart, it is important that the atria be relaxing before the ventricles begin to contract.
The aorta and pulmonary trunk extend from the heart at its A) apex. B) base. C) interventricular sulcus. D) atrioventricular sulcus.
B) base. Feedback: The apex is at the lower left corner of the heart. A sulcus is a shallow depression on the exterior surface of an organ.
Which of the following vessels is a branch of the left coronary artery? A) left posterior ascending artery B) circumflex artery C) posterior interventricular artery D) left subclavian artery
B) circumflex artery
All cardiac veins empty into the ______, which then empties into the ______. A) coronary sinus; left atrium B) coronary sinus; right atrium C) great cardiac vein; right atrium D) great cardiac vein; left atrium
B) coronary sinus; right atrium Feedback: The great cardiac vein drains the left side of the heart only. The coronary sinus drains into the right atrium.
An electrocardiogram actually records A) the contraction and relaxation of the myocardium B) electrical changes that occur in the myocardial cells. C) blood flow through the heart. D) changes in pressure in the left ventricle.
B) electrical changes that occur in the myocardial cells. Feedback: The term electrocardiogram literally means "electrical heart picture".
The visceral pericardium is also called the A) endocardium. B) epicardium. C) myocardium. D) mediastinum.
B) epicardium.
Which layer of the heart is correctly matched with the tissue of which it is composed? A) endocardium - cardiac muscle tissue B) fibrous pericardium - stratified squamous epithelium C) myocardium - dense irregular connective tissue D) visceral pericardium - a thin layer of epithelium and loose connective tissue
B) fibrous pericardium - stratified squamous epithelium
Slowing the heart while holding the rate of venous return (ml/min) constant would cause A) decreased cardiac output B) increased cardiac output C) no change in cardiac output, because heart rate is not increased D) no change in cardiac output, because stroke volume is not increased
B) increased cardiac output Feedback: Decreasing the heart rate would allow more filling time between ventricular contractions. As a consequence both EDV and SV would be higher.
Which of the following would be an effect of cutting the vagus nerve? A) reduced heart rate B) increased heart rate C) reduced strength of contraction D) increased secretion of acetylcholine
B) increased heart rate Feedback: The vagus nerve is the major carrier of parasympathetic fibers. These fibers act to slow the rate of the heart. By severing the vagus nerve, you remove the "brake" on heart rate, and the rate increases.
Blood from the pulmonary veins enters which heart chamber? A) right atrium B) left atrium C) right ventricle D) left ventricle
B) left atrium
An obstruction in the pulmonary trunk would prevent blood from A) being distributed to the systemic circulation B) picking up oxygen in the lungs C) getting into the right atrium D) leaving the left ventricle
B) picking up oxygen in the lungs Feedback: A trunk is a large vessel. The pulmonary trunk is a large artery that carries blood from the heart toward the lungs.
During ventricular diastole A) pressure in the atria exceeds pressure in the ventricles and the atrioventricular valves open B) pressure in the ventricles eventually exceeds pressure in the arteries and the semilunar valves open. C) the atria contract and pump blood into the ventricles D) no blood enters the arteries
B) pressure in the ventricles eventually exceeds pressure in the arteries and the semilunar valves open.
The chordae tendineae A) attach the semilunar valves directly to the heart wall B) prevent the atrioventricular valve cusps from prolapsing into the atria during ventricular systole C) open the atrioventricular valves during ventricular systole D) attach the heart to the pericardium
B) prevent the atrioventricular valve cusps from prolapsing into the atria during ventricular systole
The presence of arterial anastomoses in the heart A) increases the chance of a myocardial infarction by providing more places for blood clots to lodge. B) reduces the chance of a myocardial infarction by providing alternate sources of blood flow to the myocardium. C) increases the time it takes for blood to flow through the coronary circulation. D) is a sign of cardiovascular disease.
B) reduces the chance of a myocardial infarction by providing alternate sources of blood flow to the myocardium. Feedback: If one vessel is blocked by a blood clot, blood coming through another vessel that joins the first one can make up for the lack of flow in the blocked vessel.
The repair process that occurs in cardiac muscle following injury consists of the replacement of dead myocardial cells by A) mitosis of existing cardiac muscle cells B) scar tissue C) the migration of immature cardiocytes into the damaged area D) the growth of epithelial cells into the damaged tissue
B) scar tissue Feedback: Like all muscle cells, cardiac muscle cells have a much reduced capacity to replicate. When injured, the muscle cells are replaced by collagen fibers, also called scar tissue.
can change heart rate
Baroreceptor reflexes
isovolumetric contraction
Blood does not enter or leave the ventricles during the period called
left ventricle
Blood exiting the aortic semilunar valve is leaving this chamber of the heart
right ventricle
Blood exiting the pulmonary semilunar valve is leaving this chamber of the heart.
right atrium
Blood exits this chamber when it passes through the tricuspid valve
pulmonary veins
Blood flows from the lungs to the left atrium via the ________ ________.
right atrium
Blood from the body returns directly to this chamber of the heart.
left atrium
Blood from the lungs returns directly to this chamber of the heart.
left atrium
Blood from the pulmonary veins is entering this chamber of the heart
left atrium
Blood in the pulmonary veins returns to the
right atrium
Blood in the superior vena cava will enter the _____.
base
Blood vessels enter and exit from the _____ of the heart
The sinus rhythm of a normal adult heart would be about A) less than 40 beats per minute. B) 40 - 50 beats per minute. C) 70 - 80 beats per minute. D) 10 to 120 beats per minute.
C) 70 - 80 beats per minute.
If the heart rate is 70 beats per minute and stroke volume is 70 ml, then A) ESV is 140 ml B) ESV is 1 ml C) CO = 4900 ml/min D) CO = 140 ml/min
C) CO = 4900 ml/min Feedback: Cardiac output (CO) is calculated by multiplying the stroke volume by the heart rate.
What do skeletal muscle cells, cardiac autorhythmic cells, and cardiac contractile cells have in common? A) In all three, depolarization to threshold is caused primarily by K+ outflow B) In all three, depolarization between threshold and peak membrane potential is caused entirely by Na+ inflow C) In all three, repolarization is caused by K+ outflow D) In all three, the depolarization phase is longer than the repolarization phase
C) In all three, repolarization is caused by K+ outflow Feedback: Ca2+ is involved in cardiac muscle cell potentials, but not in skeletal muscle cell potentials.
Which statement is correct concening pulmonary circulation? A) Oxygen rich blood returns from the lungs to the heart through the pulmonary arteries. B) Oxygen poor blood leaves the heart and goes to the lungs through the pulmonary veins. C) Oxygen poor blood returns from the body to the heart through the vena cavae. D) Oxygen rich blood leaves the heart and goes to the body through the vena cavae.
C) Oxygen poor blood returns from the body to the heart through the vena cavae. Feedback: Arteries leave the heart; veins return to the heart.
If lines were drawn on a typical ECG recording showing where atrial and ventricular systole begin and end, then the ventricular systole would be seen as beginning during a ____ and ending during the next ____. A) P wave; QRS complex B) PR segment; T wave C) QRS complex; T wave D) T wave; P wave
C) QRS complex; T wave Feedback: The ECG tracing is a picture of an impulse passing through the cardiac conduction system. Each wave indicates the electrical depolarization or repolarization of a different area. The mechanical contraction of myocardial cells occurs just after the depolarization of the adjacent area of the cardiac conduction system.
Any factor that causes a change in heart contractility is called A) a chemotrope B) a chronotrope C) an inotrope D) an isotope
C) an inotrope Feedback: "Ino" mean fiber, and refers in this case to muscle fiber length. Heart contractility results from changes in fiber length.
Blood leaving the left ventricle goes through which of the following valves? A) biscuspid B) tricuspid C) aortic semilunar D) pulmonary semilunar
C) aortic semilunar Feedback: The bicuspid and tricuspid valves regulate flow between the atria and the ventricles. The left ventricle ejects blood into the aorta; the right ventricle ejects blood to the pulmonary trunk.
The coronary sulcus is a groove on the outside of the heart that marks the division between the A) left and right atria B) left and right ventricles C) atria and ventricles D) aorta and pulmonary trunk
C) atria and ventricles Feedback: The coronary sulcus is also known as the atrioventricular sulcus.
In which choice must the first event occur before the second event for normal cardiac activity during one cardiac cycle? A) Purkinje cells depolarize; atrial myocardial cells contract B) ventricular cells contract; atrial cells contract C) atrioventricular valves close; semilunar valves open D) AV node depolarizes; SA node depolarizes
C) atrioventricular valves close; semilunar valves open
During the isovolumetric phase of the cardiac cycle A) the atria contract and pump blood into the ventricles B) the ventricles contract and pump blood into the blood vessels C) both atria and ventricles are relaxed D) the ventricles contract but ventricular pressure is lower than arterial pressure
C) both atria and ventricles are relaxed Feedback: The isovolumetric phase occurs immediately after the T wave ends. The ventricles relax, but for a short period all the valves in the heart are closed, and no ventricular filling offers. Because the ventricular volume is not changing, this time is said to be isovolumetric (meaning "same volume").
Increased input from the baroreceptors to the cardiac control center would cause which of the following to occur? A) increased sympathetic stimulation and decreased parasympathetic stimulation B) increased sympathetic stimulation and increased parasympathetic stimulation C) decreased sympathetic stimulation and increased parasympathetic stimulation D) decreased sympathetic stimulation and decreased parasympathetic stimulation
C) decreased sympathetic stimulation and increased parasympathetic stimulation Feedback: The baroreceptors are stimulated by high blood pressures. By decreasing the rate and force of contraction, the ANS can reduce the blood pressure.
Which of the following commonly decreases with age? A) the size of the left ventricle B) size of the right ventricle C) heart rate D) oxygen consumption by the myocardium
C) heart rate
The heart is located A) inside the pericardial cavity. B) in the mediastinum, which is located in the pericardial cavity. C) in the mediastinum, which is located in the thoracic cavity. D) in the thoracic cavity, which is located in the mediastinum.
C) in the mediastinum, which is located in the thoracic cavity. Feedback: The mediastinum is the subdivision of the thoracic cavity between the left and right pleural cavities. The pericardial cavity is between the visceral pericardium and the parietal pericardium, and contains only serous fluid.
Which structure is present in the cardiac muscle tissue but not skeletal muscle tissue? A) striations B) nuclei C) intercalated disks D) t-tubules
C) intercalated disks Feedback: Cardiac muscle cells are joined end-to-end, whereas skeletal muscle cells are not.
Which part of the cardiac cycle occurs between the time the AV valves close and the semilunar valves open? A) atrial systole B) atrial diastole C) isovolumetric phase of ventricular systole D) ejection phase of ventricular systole
C) isovolumetric phase of ventricular systole Feedback: While all the valves are closed, no blood moves. The volumes don't change, so the phase is called isovolumetric (meaning "same volume")
In normal individuals, about 2/3 of the total mass of the heart is located A) above the aortic arch B) on the right side of the thoracic cavity C) on the left side of the thoracic cavity D) in the right ventricle
C) on the left side of the thoracic cavity Feedback: The left side of the heart, including the apex, is much larger than the right side.
In response to an elevation in blood pressure, the cardiac control center would attempt to restore homeostasis primarily through A) sympthetic stimuli to the ventricular myocardium B) sympathetic stimuli to the SA node C) parasympathetic stimuli to the SA node D) parasympathetic stimuli to the ventricular myocardium
C) parasympathetic stimuli to the SA node
The heart valves A) contract to pump blood through the heart. B) separate the left and right sides of the heart. C) prevent blood from flowing backward through the heart. D) cause the heart sound when they open.
C) prevent blood from flowing backward through the heart. Feedback: The atrioventricular and semilunar valves are designed to maintain one-way flow of blood through the heart. The "lub-dup" heart sounds are caused by the closing of the valves.
The plateau phase of the cardiac myocardial cell potential A) normally keeps the heart from beating faster than 70 - 80 times per minute B) allows the cell to depolarize spontaneously instead of having to be stimulated by nerve fibers C) prevents tetanus, which would cease pumping action of the heart D) allows the myocardial cells time to rest during the contraction
C) prevents tetanus, which would cease pumping action of the heart Feedback: The plateau phase lengthens the absolute refractory period, preventing a second impulse from forming before the contraction caused by the first has relaxed.
Cardiac output from the left ventricle is A) normally greater than that of the right ventricle B) probably lower than the right ventricle if the person has systemic edema C) probably lower than the right ventricle if the person has pulmonary edema D) probably higher than the right ventricle if the person has pulmonary edema
C) probably lower than the right ventricle if the person has pulmonary edema
Which of the following heart chambers is correctly associated with the blood vessel that enters or leaves it? A) right atrium - pulmonary veins B) left atrium - aorta C) right ventricle - pulmonary trunk D) left ventricle - superior and inferior vena cavae
C) right ventricle - pulmonary trunk Feedback: The right atrium receives blood from the vena cavae. The aorta exits the left ventricle. The pulmonary veins enter the left atrium.
When the right atrium contracts, it pushes blood into the A) superior and inferior vena cavae. B) left atrium. C) right ventricle. D) aorta.
C) right ventricle. Feedback: The main function of the atrial contraction is to make sure there is as much blood as possible in the ventricles before the ventricles contract.
The location of the heart is correctly described as A) lateral to the lungs. B) medial to the sternum. C) superior to the diaphragm. D) posterior to the spinal column.
C) superior to the diaphragm. Feedback: The heart is medial to the lungs, posterior to the sternum, and anterior to the spinal column.
With respect to the effect on cardiac output, the term preload refers to A) the force developed by the myocardial cells during ventricular systole B) the blood pressure in the aorta and pulmonary trunk during ventricular systole C) the amount of tension developed in the myocardium before it contracts D) anything that decreases stroke volume
C) the amount of tension developed in the myocardium before it contracts Feedback: Preload refers to the tension created by the stretching of ventricular fibers as the chambers fill with blood. The longer the fibers, the greater the tension, and the greater the force of the contraction.
The heart would NOT appear on this kind of thoracic section. A) midsagittal section B) transverse section at the level of the 4th rib C) transverse section at the level of the 8th rib D) frontal (coronal) section that also includes the pulmonary trunk
C) transverse section at the level of the 8th rib Feedback: The apex of the heart is located at the 5th intercostal space. A true transverse section at the 8th rib would include the upper abdomen.
The higher the _____, the greater the cardiac output. A) extracellular K+ concentration B) blood pressure in the aorta C) venous return D) level of acetylcholine released at the SA node
C) venous return Feedback: To increase cardiac output, either heart rate or contractile force or both must be increased. An increase in venous return would stretch the walls of the ventricle, increasing the preload and therefore the strength of contraction.
The pericardial cavity is between the A) fibrous pericardium and parietal pericardium B) left atrium and left ventricle C) visceral pericardium and parietal pericardium D) endocardium and myocardium
C) visceral pericardium and parietal pericardium Feedback: The pericardial cavity isolates the heart within the mediastinum.
Which two layers are the most similar in tissue structure? A) fibrous pericardium and visceral pericardium B) fibrous pericardium and endocardium C) visceral pericardium and parietal pericardium D) myocardium and endocardium
C) visceral pericardium and parietal pericardium Feedback: They are most similar because they are continuous with each other and are composed of the same kinds of tissues.
Which of the following is a positive inotrope?
Ca2+
treat tachycardia or other arrhythmias
Calcium channel blockers are frequently used to
What would a prolonged Q-T interval indicate? What is the normal range for Q-T interval?
Can indicate electrolyte disturbances, conduction problems, coronary ischemia, myocardial damage, and some drugs can cause this
stroke volume
Cardiac output is equal to heart rate times ____ _______.
What would cause Tachycardia? How could this be treated?
Caused by part of conduction system being overactive or overstimulated Tx: drugs, beta blockers, something that would slow down the heart
medulla oblongata
Chemoreceptors sensitive to blood carbon dioxide levels are primarily located in the
carotid arteries
Chemoreceptors sensitive to blood oxygen levels are primarily located in the
List the drugs of each Anti-arrhythmic classes I-IV
Class I: sodium channel blockers - lidocaine, quinidine Class II: beta blockers - atenolol, carvedilol, metoprolol Class III: potassium channel blockers - amiodarone Class IV: Calcium channel blockers - diltiazem, verapamil
The first heart sound occurs at the beginning of ventricular systole
Concerning heart sounds, which of the following is correct?
_________ cells cannot maintain stable resting membrane potential
Conducting
Cardiac muscle cells are also called _________
Contractile cells
prevent the AV valves from protruding into the atria
Contraction of the papillary muscles would
systole
Contraction of the ventricles is referred to as ventricular
infarction
Coronary artery disease can diminish myocardial blood flow resulting in the death of myocardial cells. This condition is known as a myocardial
The apex of the heart A) is part of the left ventricle wall. B) points inferiorly and laterally. C) is at the approximate level of the 5th intercostal space. D) All of the above are correct concerning the apex of the heart.
D) All of the above are correct concerning the apex of the heart. Feedback: The apex of the heart is the pointed "bottom" of the heart.
Based on the information given below, which individual has the greatest tolerance for strenuous exercise? Assume they are similar in terms of size and muscular fitness. A) Ann, cardiac reserve = 8 L/min B) Betsy, cardiac reserve = 15 L/min C) Carla, cardiac reserve = 18 L/min D) Donna, cardiac reserve = 25 L/min
D) Donna, cardiac reserve = 25 L/min Feedback: Cardiac reserve equals CO during exertion minus CO at rest. The higher the cardiac reserve, the more easily a person tolerates exercise.
Phophodiesterase is the enzyme that degrades cAMP. A drug that inhibits phosphodiesterase would have what effect on the heart? A) It would decrease cardiac contractility by causing increased removal of Ca2+ from the cell. B) It would increase heart rate but have no effect on contractility. C) It would have no effect, because cAMP is not involved in altering cardiac contractility D) It would increase cardiac contractility by prolonging Ca2+ availability inside the cell.
D) It would increase cardiac contractility by prolonging Ca2+ availability inside the cell. Feedback: Cyclic AMP increases the permeability of the plasma membrane to Ca2+, primarily by opening calcium slow channels in the plasma membrane. Inhibiting the phosphodiesterase would allow prolonged action of cAMP, increasing the Ca2+ concentration of the cell.
Which of the following parts of the cardiac conduction system is correctly matched with its location? A) AV bundle (bundle of His) - upper part of interatrial septum B) AV node - left atrium in the inferior interventricular septum C) Purkinje fibers - epicardium of the ventricles D) SA node - right atrium near the opening of the superior vena cava
D) SA node - right atrium near the opening of the superior vena cava Feedback: The AV node is located at the junction of the interatrial and atrioventricular septa. The AV bundle exits the AV node and enters the interventricular septum. The Purkinje fibers are located in the ventricular myocardium and terminate in the papillary muscles.
Which of the following components of an ECG is not correctly matched with the corresponding event occurring in the heart? A) P wave - atrial depolarization B) PR interval - AV node conduction C) QRS complex - ventricular depolarization D) T wave - atrial repolarization
D) T wave - atrial repolarization
The ANS is the main extrinsic control for cardiac activity, acting through both sympathetic and parasympathetic fibers innervating the heart. This control system is not symmetric--one part of the ANS has less control over the heart. Which of the following statements is NOT correct? A) The sympathetic division has significant control of heart rate through its action at the SA node. B) The sympathetic division has significant control of contractility through its action on the ventricular myocardium. C) The parasympathetic division has significant control of heart rate through its action at the SA node. D) The parasympathetic division has significant control of contractility through its action on the ventricular myocardium.
D) The parasympathetic division has significant control of contractility through its action on the ventricular myocardium. Feedback: The parasympathetic division decreases heart rate, but little effect on contractile force. The sympathetic division increases both heart rate and contractile force.
What is located in the pericardial cavity? A) the heart B) the fibrous pericardium C) the mediastinum D) a small amount of serous fluid
D) a small amount of serous fluid Feedback: The pericardial cavity is the space between the visceral pericardium and the parietal pericardium. The space is lubricated with serous fluid, and allows the heart to move freely without affecting other organs of the thoracic cavity.
Which of the following is not associated with atrioventricular valves? A) chordae tendineae B) cusps C) papillary muscles D) arteries
D) arteries Feedback: Atrioventricular valves control blood flow between atria and ventricles.
Because of the distribution of the cardiac impulse by the conduction system, ventricular contraction begins A) in the semilunar valves and then pushes blood toward the interventricular septum B) in the papillary muscles and causes the atrioventricular valves to open C) in the superior part of the ventricles and pushes blood toward the apex D) at the apex of the heart and pushes blood toward the semilunar valves
D) at the apex of the heart and pushes blood toward the semilunar valves Feedback: Contraction of the superior aspects of the ventricles would push blood toward the apex, making it harder for the ventricles to force the blood up and out through the semilunar valves.
While the atria of the heart are in systole A) the ventricles are also in systole. B) the atrioventricular valves are closed. C) blood is being pumped into the aorta and pulmonary trunk. D) blood is being pumped into the ventricles.
D) blood is being pumped into the ventricles. Feedback: Atrial systole and ventricular systole must alternate in order for blood to flow through the heart.
The alternate contraction and relaxation of the atria and ventricles are referred to as the A) cardiac output B) coronary circulation C) cardiac conduction system D) cardiac cycle
D) cardiac cycle Feedback: Correct Answer
Stroke volume times heart rate equals A) blood pressure B) afterload C) end systolic volume D) cardiac output
D) cardiac output
Which choice would not increase cardiac output? A) increase heart rate, increase stroke volume B) increase heart rate, no change in stroke volume C) no change in heart rate, increase stroke volume D) decrease heart rate, no change in stroke volume
D) decrease heart rate, no change in stroke volume Feedback: CO = SV x HR
At a heart rate above 180 beats per minute, all of these decrease except A) cardiac output B) filling time C) stroke volume D) end systolic volume
D) end systolic volume Feedback: The ESV is affected by contraction force, and not by heart rate. The others are all factors dependent on heart rate.
The Frank-Starling law of the heart says that the higher the end diastolic volume, the A) lower the cardiac output B) higher the end systolic volume C) lower the blood pressure D) higher the stroke volume
D) higher the stroke volume Feedback: The Frank-Starling law says that, within limits, the more the myocardial contractile cells are stretched prior to contraction, the stronger the resulting contraction will be.
Which of the following would not increase stroke volume? A) increased venous return B) increased sympathetic stimulation of the myocardium C) increased end diastolic volume D) increased arterial blood pressure
D) increased arterial blood pressure Feedback: An increase in arterial blood pressure would make it harder for the ventricle to open the semilunar valves to eject blood. As a consequence, the end systolic volume would be higher, leading to a lower stroke volume.
The anterior and posterior interventricular sulci mark the position of which internal heart structure? A) bicuspid and tricuspid valves B) semilunar valves C) fossa ovalis D) interventricular septum
D) interventricular septum Feedback: A sulcus is a groove visible on the surface of an organ.
Which chamber of the heart has to work the hardest (pump against the highest pressure)? A) right atrium B) left atrium C) right ventricle D) left ventricle
D) left ventricle Feedback: Both gravity and the length of the aorta cause pressures to be higher for the left ventricle. For this reason, the left ventricle has a much thicker, and therefore stronger, myocardium than the right ventricle.
Damage to which of the following parts of the brain would cause the body to have less control over cardiac activity? A) cerebral cortex B) thalamus C) basal nuclei D) medulla oblongata
D) medulla oblongata Feedback: The cardiac control centers are in the medulla oblongata.
The Purkinje fibers are found in which layer of the heart wall? A) endocardium B) epicardium C) fibrous pericardium D) myocardium
D) myocardium Feedback: The Purkinje fibers are modified cardiac muscle cells that carry impulses as part of the cardiac conducting system.
The cardiac pacemaker potential is caused by cyclic changes in membrane potential that occur in which of the following sequences? A) slow inflow of Na+ ; rapid K+ inflow; slow K+ outflow B) slow inflow of Ca2+ ; rapid Na+ inflow; rapid K+ outflow C) slow inflow of K+ without Na+ outflow; rapid Na+ inflow; rapid K+ outflow D) slow inflow of Na+ without K+ outflow; rapid Ca2+ inflow; rapid K+ outflow
D) slow inflow of Na+ without K+ outflow; rapid Ca2+ inflow; rapid K+ outflow
Contraction of a ventricular chamber is called A) diastole. B) diastasis. C) hypertrophy. D) systole.
D) systole. Feedback: The term systole means "to contract". The term diastole means "to dilate".
Inhibition of the SA node by the parasympathetic division of the ANS is called A) cardioacceleration B) inotropia C) bradycardia D) vagal tone
D) vagal tone Feedback: Vagal tone refers to the action of the parasympathetic fibers in the vagus nerve on the heart. These fibers reduce the rate of SA node depolarization from 100 per minute to 70 - 80 per minute.
Damage to cells of the AV bundle would prevent the cardiac impulse from reaching the A) SA node B) atria C) AV node D) ventricles
D) ventricles Feedback: The AV bundle is located in the interventricular septum, and conducts impulses from the AV node to the ventricular myocardium.
The semilunar valves close at the beginning of A) atrial systole B) atrial diastole C) ventricular systole D) ventricular diastole
D) ventricular diastole Feedback: The reduction of ventricular pressure below arterial pressure allows the force of arterial blood "falling back" toward the ventricles to close the semilunar valves.
Pressure in the ventricles would be highest during A) atrial diastole B) atrial systole C) ventricular diastole D) ventricular systole
D) ventricular systole Feedback: Pressure is highest when they are contracting and no blood is leaving.
the opening of voltage-gated sodium channels and voltage-gated calcium channels
Depolarization of a cardiac muscle cell occurs as the result of
ECGs are helpful in diagnosing ________ ________, what does this indicate?
Diagnosing cardiac arrhythmias -May indicate: Damage to myocardium; injuries to pacemakers or conduction pathways; Exposure to drugs; abnormalities in electrolyte composition of ECF
List the drugs that may affect ECGs
Digoxin Antiarrhythmics classes I-IV tricyclic antidepressants H1 antagonists methylxanthines doxorubicin lithium catecholamines diuretics
increased sympathetic stimulation of the heart
During hemorrhagic shock in which blood pressure is decreased, which of the regulatory mechanisms is most important is increasing cardiac output to help maintain blood pressure?
aorta
During the ejection phase of the cardiac cycle, blood exits the left ventricle through the
AV and semilunar valves are closed
During the isovolumetric contraction period of the cardiac cycle,
the inner lining of the heart
E.Z. Goen is admitted to the cardiac unit with a diagnosis of endocarditis. When E.Z. asks the nurse where the infection is located, the nurse replies that the infection is in
What happens in Ventricular diastole?
Early -
stroke volume
End-diastolic volume minus end-systolic volume is equal to
aerobic respiration in the mitochondria
Energy for contraction of myocardial cells comes primarily from
a decrease in the frequency of action potentials in the conduction system
Excess potassium ions in cardiac tissue cause
nitroglycerin
Fred was admitted to the cardiac unit with chest pains. No arrhythmias and no large changes in the heart rate were observable. Blood samples taken over the next few days showed no increase in enzymes such as creatine phosphokinase. A possible treatment of the condition is
pulmonary trunk
From the right ventricle, blood flows directly into the _____.
the heart rate to decrease. It might cause cardiac arrest
If cardiac muscle cells are unable to repolarize, this would cause
Another portion of the heart will become the pacemaker
If the SA node is nonfunctional, which of the following is most likely to occur?
increase its rate and force contraction
If the heart receives more sympathetic stimulation than parasympathetic stimulation, the heart will
Describe the Atrial fibrillation Arrhythmia
Impulses move over atrial surfaces in uncoordinated fashion -Heart can still pump blood because ventricles are still contracting - Not life-threatening Tx: blood thinners
Describe the Ventricular Fibrillation Arrhythmia
Impulses travel around ventricles in uncoordinated fashion -PVCs and ventricular tachycardia can precede fibrillation -Can lead to cardiac arrest - heart stops pumping blood -Cannot live with this condition Tx: Defibrillator. Goal is to reset heart to reestablish its rhythm; Defibrillator is shocking the heart to get cells in the same electrical state - depolarizing the whole heart and allowing the SA node to take over.
QRS complex results from ventricular depolarization
In a normal electrocardiogram, the
both decreased heart rate and increased stroke volume
In a physiology lab, the students designed an experiment to illustrate how the heart responds to changes in blood pressure. Everyone relaxed and then did a headstand. Which of the following observations are consistent with the change in the function of their hearts?
all four chambers of the heart are in diastole at the same time
In the cardiac cycle,
the two atria relax while the two ventricles contract
In the cardiac cycle,
the heart rate to decrease
Increased vagal stimulation would cause
In a healthy young adult, what happens to cardiac output when heart rate increases above 160 bpm?
It decreases.
What happens to preload when there is venous constriction in the veins?
It increases.
The __________ the diameter of a conducting fiber, the _______ the resistance for propagation = FASTER conduction
Larger diameter = lower resistance = FASTER conduction
Compare/contrast the right and left bundles branches
Left branch is larger (because left ventricle myocardium is larger) Both extend toward apex and fan out deep to endocardial surface; as branches diverge they conduct AP to purkinje fibers and moderator band
the resting membrane potential is hyperpolarized
Lowered extracellular potassium levels will lower the heart rate because
cardiac output times peripheral resistance
Mean arterial pressure is
What is the major difference between cardiac and skeletal muscle cells?
Nature and duration of AP - the source of Ca++, duration of resulting contraction
circumflex artery
Occlusion of which of the following would primarily damage the posterior wall of the heart?
left bundle branch block
Of the types of damage resulting from a myocardial infarction, which is most likely to cause the greatest increase in the Q-T interval?
What does the Q-T interval represent on an ECG?
One complete cycle of ventricular depolarization and repolarization; Usually measured from end of P-R interval instead of from the bottom of the Q wave.
Which of the following is unique to cardiac muscle cells?
Only cardiac muscle is capable of autorhythmicity
pulmonary trunk
Pressure in the right ventricle must exceed pressure in the ____ before the right ventricle can eject blood
Which component of the heart conduction system would have the slowest rate of firing?
Purkinje fibers
________ _______ conduct AP very rapidly to ventricular muscle (_________ cells)
Purkinje fibers; contractile
During which portion of ECG are the atria repolarizing even though it is not strong enough to be recorded on ECG?
QRS complex
Tachycardia is _____ HR, or greater than _____ BPM at rest.
Rapid; >100 BPM
a heart murmur
Regurgitation of blood flow through the aortic semilunar valve would give rise to
From AV bundle AP travels to interventricular septum and enters the _________________.
Right and left bundle branches.
the _________ dominates conduction pathway in normal conditions because it spontaneously depolarizes first before other parts of conducting system.
SA node
List the parts of the conducting system
SA node AV node Conducting Cells: Internodal pathways, AV bundle, bundle branches, Purkinje fibers
Where is the fastest rate of spontaneous depolarization?
SA node at a rate of 80-100 AP per min.
_______ of an ECG extend from the end of one wave to the start of another. ________ are more variable, but always include at least one entire wave.
Segments; intervals
What does the P-R interval represent?
Start of atrial depolarization (P) to start of ventricular depolarization/start of QRS complex.
increase the force of ventricular contraction
Stimulation of the heart via the sympathetic nerves would
SA node
The "pacemaker" of the heart is the
bicuspid or mitral valve
The AV valve that is located on the same side of the heart as the origin of the aorta is the
atrial depolarization
The P wave of an ECG indicates
aorta
The _______ carries blood from the left ventricle to the body.
atria to complete their contraction
The action potentials are slowed at the AV node to allow the
increased parasympathetic stimulation of the heart
The baroreceptor reflex would cause which of the following events to occur if the reflex was caused by an increase in blood pressure?
this area produces action potentials more rapidly than any other portion of the conduction system
The cardiac electrical impulse normally begins spontaneously in the SA node because
medulla oblongata
The cardioregulatory center of the brain is located in the
left ventricle
The chamber of the heart that endures the highest pressure is the
systemic
The delivery of oxygen and nutrients to the tissues of the body is accomplished through ________ circulation.
backflow of blood toward the ventricles
The dicrotic notch in the aortic pressure curve is due to the
vibrations that occur when the valves close
The first and second heart sounds are most directly related to
reduce friction between the pericardial membranes
The function of the pericardial fluid is to
coronary sinus
The great cardiac vein and middle cardiac vein empty into a venous cavity called the
prevents tetanic contractions of the cardiac muscle
The long refractory period observed in cardiac muscle
What is isotonic contraction and where in the cardiac cycle does this occur?
The muscle cells shorten, and tension production remains relatively constant. This occurs in the 2nd phase of ventricular systole.
parietal pericardium
The pericardial sac is lined with
the period of ejection
The period of isovolumetric contraction is immediately followed by
absolute refractory period
The period of time in which the myocardium is insensitive to further stimulation is called the
continuing to have open calcium channels
The plateau phase seen during the action potential of a cardiac muscle cell is due to the
angioplasty
The procedure whereby a small balloon is placed into a partially occluded coronary artery and then inflated to increase blood flow through the artery is called a(n)
cardiac output
The product of the stroke volume times the heart rate is known as the
Starling Law of the heart
The relationship between preload and stroke volume is known as
the body and the heart
The right atrium receives blood from
pulmonary
The right side of the heart receives blood from the body and pumps through _________ circulation to the lungs.
endocardium
The smooth inner lining of the heart chambers is the __________.
depolarization
The spontaneous opening of sodium channels marks the beginning of ____ of a myocardial cell
during ejection
The tricuspid valve is closed
pulmonary semilunar valve
The valve located between the right ventricle and the pulmonary trunk is the
stroke volume
The volume of blood pumped during each cardiac cycle is the
right ventricle
This chamber pumps blood to the pulmonary circuit.
left ventricle
This chamber pumps blood to the systemic circuit.
left ventricle
This chamber pumps to the coronary circuit
What is isovolumetric contraction and where in the cardiac cycle does this occur?
This occurs in early phase of ventricular systole. -All the heart valves are closed, the volumes of the ventricles do not change, and ventricular pressure are rising.
TRUE
True or false: Blood flow through the coronary blood vessels decreases during myocardial contraction and increases during myocardial relaxation.
sinus arrhythmia
Variations in respiratory rate is a symptom of
apex of the heart
Ventricular contraction begins at the
What does the QRS complex of ECG represent?
Ventricular depolarization
tachycardia
What abnormal heart rhythm could be caused by an elevated body temperature, excessive sympathetic stimulation, or toxic conditions?
movement of K+ through voltage-gated K+ channels
What action is most responsible for the resting membrane potential in cardiac muscle cells?
ventricular fibrillation
What cardiac arrhythmia will have no QRS complex as a symptom?
depolarization of the ventricles and repolarization of the atria
What event(s) occur during the QRS complex of an ECG?
An opening between the right and left atria in the embryo and fetus
What is the foramen ovale?
It allows an action potential to reach the left atrium so both atria contract together
What is the importance of the delay in the action potential in the AV node?
ventricular systole
What occurs during the time between the first heart sound and the second heart sound?
aorta
What vessel exits the left ventricle?
many voltage-gated Ca2+ channels open
When a pacemaker potential in the SA node reaches threshold,
Describe the Ectopic Pacemaker Arrhythmia
When a purkinje or ventricular muscle cell depolarizes to threshold and triggers an abnormal conduction pathway or premature ventricular contraction (PVC); starts its own little conduction pathway wherever ectopic pacemaker is triggered
left ventricle
When blood passes through the bicuspid valve, it enters this chamber of the heart
action potentials are conducted from cell to cell only in cardiac muscle
When comparing cardiac muscle cells and skeletal muscle cells,
the bicuspid (mitral) valve opens
When left atrial pressure exceeds left ventricular pressure,
AV valves close
When ventricular pressure exceeds atrial pressure, the
aorta
Which blood vessel carries blood from the left ventricle?
AV node
Which of the following areas of the conduction system would produce spontaneous action potentials most frequently if the SA node were not functioning?
pacemaker potential
Which of the following events occurs first?
increased epinephrine release from the adrenal medulla
Which of the following factors would cause an increase in heart rate?
right ventricle - pulmonary trunk
Which of the following heart chambers is correctly associated with the blood vessel that enters or leaves it?
providing a location for gas exchange between oxygen and carbon dioxide
Which of the following is NOT a function of the heart?
pulmonary vein
Which of the following is NOT a major opening into the right atrium?
nitroglycerin
Which of the following is NOT an enzyme given to someone experiencing a myocardial infarction to break up blood clots?
The apex of the heart is directed superiorly and to the left
Which of the following is NOT true about the heart?
All of the choices are functions of the heart skeleton. Provides electrical insulation between the atria and ventricles, Supplies support and reinforcement for the valves, Provides a rigid site for cardiac muscle attachment.
Which of the following is a function of the heart skeleton?
closing of calcium channels - plateau phase
Which of the following is mismatched?
Most ventricular filling occurs before the atria contract
Which of the following is true?
myocardium
Which of the following layers forms the bulk of the heart wall?
chronic stress
Which of the following might increase the risk for cardiovascular disease?
pectinate muscles - muscles that close valves
Which of the following pairs is mismatched?
possess special cell-to-cell contacts called intercalated discs
Which of the following phrases would apply to cardiac muscle cells?
SA node, AV node, AV bundle, bundle branches, Purkinje fibers
Which of the following sequences for the conducting system is correct?
If cardiac muscle fibers are slightly stretched, they have a stronger contraction force.
Which of the following statements regarding intrinsic regulation of the heart is true?
the AV bundle
Which of the following will depolarize immediately after the AV node depolarizes?
an increase in the level of carbon dioxide in the blood
Which of the following will increase the heart rate?
depolarization would be delayed and the heart rate would decrease
Which of the following would result from a reduced function of the sodium channels in the SA node?
The great cardiac vein collects blood from the left anterior surface of the heart.
Which of these statements is true?
pulmonary veins
Which vessels empty blood into the left atrium?
pulmonary arteries
Which vessels transport blood to the right and left lungs?
to decrease heart rate
Why is body temperature sometimes reduced during heart surgery?
an increase in cardiac output and force of left ventricular contraction
Within normal limits, an increase in preload leads to
fossa ovalis
a depression in the atrial septum
The force the heart must overcome to pump blood is known as ________.
afterload
cardia muscle cells
are maintained by an extensive capillary network.
What happens when Atrial diastole occurs?
atrial are relaxed and filling with blood, this continues until the start of the next cardiac cycle. Ventricular systole begins at the same time as atrial diastole.
Most blood enters the ventricle during ________.
atrial diastole
In which septum is it normal to find openings in the adult?
atrioventricular septum
Cardiac muscle has the unique quality of _______, which is the ability to contract on its own without neural or hormonal stimulation.
automaticity
Which primitive area of the heart will give rise to the right ventricle?
bulbus cordis
The influx of which ion accounts for the plateau phase?
calcium
The two tubes that eventually fuse to form the heart are referred to as the ________.
cardiogenic tubes
aorta
carries blood from the left ventricle into systemic circulation
pulmonary trunk
carries blood from the right ventricle to the lungs
The first heart sound represents which portion of the cardiac cycle?
closing of the atrioventricular valves
The Chordae tendineae
connect the flaps of the AV valves to the papillary muscles
The epicardium
covers the surface of the heart
If P-R interval is over 200 msec, what does this indicate? What is the normal range for P-R interval?
damage to conducting pathways or AV node; Normally 0.12-0.20 seconds.
What would cause Bradycardia? How could this be treated?
damage to conduction pathway: damage to SA node or AV node: heart block; TX: not with drugs, but with a pacemaker; don't use drugs to overstimulate heart
What would happen to the heart rate if the SA node was damaged & unstable to function?
decreased HR because the AV node would have to take over which is the next fastest rate o AP per min; slower spontaneous depolarization than SA node
The ________ layer secretes chemicals that help to regulate ionic environments and strength of contraction and serve as powerful vasoconstrictors.
endocardium
Which of the following is not important in preventing backflow of blood?
endocardium
The AV node is located ______________. Impulse conduction _______ when passing though AV node. Why/How does this happen and what is the importance of this delay?
floor of right atrium near the opening of the coronary sinus at the base of the inf. vena cava; slows; As the signal enters the AV node its rate of travel slows down, due in part to the smaller diameter of the cells of the AV node and in part because the connection between nodal cells are less efficient at propagating the signal. The signal is delayed at the AV node to allow the signal to reach both right and left atria and for the atria to contract (about 25msec after this signal is sent) simultaneously and so that atria can contract slightly before ventricles
bicuspid valve
has only two valve flaps
The earliest organ to form and begin function within the developing human is the ________.
heart
The heart
is a four-chambered muscular pump
The cardiac cycle consists of a distinct relaxation and contraction phase. Which term is typically used to refer ventricular contraction while no blood is being ejected?
isovolumic contraction
The myocardium would be the thickest in the ________.
left ventricle
aortic semilunar valve
located at the opening to the aorta
tricuspid valve
located between the right atrium and the right ventricle
The cardiovascular centers are located in which area of the brain?
medulla oblongata
Of the three germ layers that give rise to all adult tissues and organs, which gives rise to the heart?
mesoderm
Which valve separates the left atrium from the left ventricle?
mitral
Because the bundle branches deliver the impulse across the _______ _______ to the papillary muscles directly, rather than by way of _____ ______, the papillary muscles begin contracting before the rest of the ventricular musculature does.
moderator band; purkinje fibers
Which portion of the ECG corresponds to repolarization of the atria?
none of the above: atrial repolarization is masked by ventricular depolarization
The SA node is located in the __________________ and contains _____ cells. It is connected to the AV node by _________ _______
posterior wall of the right atrium; pacemaker cell; internodal pathways
From the Right and Left bundle branches the AP travels to _____________ and through the _______ _______.
purkinje fibers; moderator band
superior vena cava
returns blood to the heart from the head and neck
inferior vena cava
returns blood to the heart from the lower extremities
pulmonary veins
returns blood to the heart from the lungs
trabeculae carneae
ridges and on the interior walls of ventricles
Which chamber initially receives blood from the systemic circuit?
right atrium
Bradycardia is ______ HR, or less than ______ BPM at rest.
slow; <60 BPM
Which of the following lists the valves in the order through which the blood flows from the vena cava through the heart?
tricuspid, pulmonary semilunar, bicuspid, aortic semilunar
The pulmonary trunk and aorta are derived from which primitive heart structure?
truncus arteriosus
Ventricular relaxation immediately follows ________.
ventricular repolarization
What does the T wave of ECG represent?
ventricular repolarization