The Heart
•Circulatory system
-heart, blood vessels & blood
•Cardiovascular system
-heart, arteries, veins and capillaries
-2 major divisions
•Pulmonary circuit - right side of heart
-right heart—lungs—left heart
-carries blood to lungs for gas exchange
•Systemic circuit - left side of heart
-left heart—body—right heart
supplies blood to all organs of the body
Heart Location
In the thoracic cavity, between the lungs in the mediastinum
Size, Shape and Position of the Heart
•Located in thoracic cavity
-specifically in the mediastinum
•area between lungs
-superior to diaphragm
-posterior to sternum
-2/3 of heart to the left of midsagittal plane due to the liver taking space on the right
•Base - broad
superior portion
•Apex - inferior end, tilts to the left, tapers to point
•~size of a fist; weighs 10 oz
Pericardium
•Double walled membraneous sac
•Anchored to diaphragm & connective tissue
•Allows heart to beat without friction, gives it room to expand and resists excessive expansion
•Parietal pericardium
-tough outer, fibrous layer of connective tissue
-inner serous
layer
•Visceral pericardium (a.k.a. epicardium of heart wall)
-serous lining of sac turns inward at base of heart to cover the heart surface
•Pericardial cavity- space between parietal & visceral pericardium
-filled with 5-30ml pericardial fluid to reduce friction
Pericardium Problems
•Pericarditis
-Inflammation of the pericardium
-Painful friction between the two membranes when the
heart beats
•Cardiac Tamponade
-Abnormal accumulation of fluid in the pericardial cavity
-Compresses the heart
-Interferes with ventricular filling
Heart Wall
•Epicardium (a.k.a. visceral pericardium)
-outer membrane covers heart
-fat deposits for protection
-coronary blood vessels travel through this layer
•Myocardium - thick muscular layer
-fibrous skeleton - network of collagenous
& elastic fibers
•provides structural support
•attachment for cardiac muscle
•limits routes of electrical excitation through the heart
•Endocardium- smooth inner lining
-smooth inner lining of chambers & valves
-continuous with endothelium of blood vessels
-direct contact with blood
Spiral Orientation of Myocardial Muscle
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Heart Chambers
•4 chambers
•Right and left atria
-2 superior, posterior chambers
-receive blood returning to heart
-auricles (seen on surface) enlarge chamber
-flaccid walls due to light workload
•only has to pump to ventricles!
•Right and left ventricles
-2 inferior chambers
-pump blood into arteries
-Left ventricle has thickest myocardium
•has to pump to whole body!
Heart External Anatomy- Anterior Chambers
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Question: The chamber of the heart most affected by cardiac tamponade is the ____?
Right ventricle due to the tilt/gravity of the heart
Sulci
•Grooves on outside of heart
•Mark boundaries of chambers
•Atrioventricular (AV) or coronary
sulcus
-Encircles entire heart
-Boundary separating atria from ventricles
•Anterior & posterior interventricular sulcus
-Extend from AV sulcus to the apex of the heart
-Separates right & left ventricles
External Anatomy- Anterior
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External Anatomy- Posterior
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Heart Chambers- Internal
•Interatrial septum
-wall that separates atria
•Interventricular septum
-wall that separates ventricles
•Trabeculae carneae
-internal ridges in ventricles
•Pectinate muscles
-internal ridges of myocardium in right atrium and both auricles
•Chordae tendineae
-cords connect AV valves to papillary muscles on floor of ventricles
Which circuit carries blood from the right ventricle to the lungs for gas exchange and returns it to the left atrium of the heart?
Pulmonary
Heart Internal Anatomy
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Heart Internal Anatomy- Anterior
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Heart Valves
•Ensure one-way blood flow
•Atrioventricular (AV) valves
-right AV valve (tricuspid valve) has 3 cusps
-left AV valve (mitral/bicuspid valve) has 2 cusps (lamb)
-* to remember order, think tri before you bi
•Semilunar valves- control flow into great arteries
-Pulmonary : from right ventricle into pulmonary trunk
-Aortic : from left ventricle into aorta
Blood Flow Through Heart
1-Superior
& Inferior Vena Cava
2-Rt Atrium
3-Tricuspid Valve
4- Rt Ventricle
5-Pulmonary Valve
6-Pulmonary Artery
7- Lungs-pick up oxygen
8-Pulmonary Veins
9- Lt Atrium
10- Mitral Valve (Bicuspid)
11-Lt Ventricle
12- Aortic Valve
13-Aorta
14- Body
What is the study of the heart and its disorders called?
Cardiology
What are the thick inferior chambers of the heart that pump blood into the arteries called?
Ventricles
The passage of blood from the atria to the ventricles is regulated by which valves?
Atrioventricular
What is the ability to rhythmically depolarize without outside stimulation called?
Autorhythmic
Valve Mechanics
AV valves hang open & semilunar valves are closed when the ventricles are relaxed
¯
Ventricles fill with blood and then contract
¯
Pressure & blood in the ventricles push the AV valves closed
(chordae tendinae prevent cusps from bulging into the atria)
¯
The same pressure and blood pushes semilunar valves open
¯
Ventricles relax
¯
Blood flows back down the pulmonary
trunk and aorta; fills cusps to force semilunar valves closed
Operation of AV Valves
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Operation of Semilunar Valves
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Coronary Circulation
•Heart is 0.5% of body weight, but uses 5% of the circulating blood
•Blood vessels of
heart wall nourish cardiac muscle
•Right & left coronary arteries immediately branch off of the aorta by the aortic semilunar valve cusps
•When the ventricles relax and blood flows back down the aorta to fill the cusps, some blood is diverted to the coronary arteries
-Body tissues receive blood when the ventricles contract
-Heart muscle receives blood when the ventricles relax
•Left coronary artery (LCA)
-anterior interventricular branch
•supplies blood to
interventricular septum and anterior walls of ventricles
-circumflex branch
•passes around left side of heart in coronary sulcus, supplies left atrium and posterior wall of left ventricle
•Right coronary artery (RCA)
-right marginal branch
•supplies lateral R atrium and ventricle
-posterior interventricular branch
•supplies posterior walls of ventricles
Venous Drainage
•Route by which
blood leaves an organ
•20% of deoxygenated coronary blood drains directly into right ventricle from coronary veins
•80% of deoxygenated coronary blood returns to right atrium via:
-great cardiac vein
•blood from anterior interventricular sulcus
-middle cardiac vein
•from posterior sulcus
-left marginal vein
-coronary sinus
collects blood and empties into right atrium
Coronary Vessels- Anterior View
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Coronary Vessels- Posterior View
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Question: A blockage in the ______ would cause the most damage to the heart.
Left coronary artery because it supplies the left side of the heart which gets blood out to the entire body
Myocardial Infarction
•Heart attack- sudden death of heart tissue
•Caused by interruption of blood flow from the narrowing or occlusion of an artery supplying the heart with blood
•Usually fat deposits or blood clots are responsible
•Lack of O2 ----> ischemia
•If O2 supply is not restored, necrosis (tissue death) of myocardium occurs
•Responsible for ~1/2 of all deaths in United States
* Anastomoses defend against interruption by providing
alternate blood pathways
Identify each of the heart valves.
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Angina Pectoris
Heart pain due to temporary and reversible myocardial ischemia
•
Hypoxia
¯
Myocardium undergoes anaerobic fermentation
¯
Lactic acid is produced
¯
Pain receptors are stimulated
Identify each component of the electrical conduction system of the heart.
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Coronary Atherosclerosis
•Fatty deposits form in a coronary artery
•Due to abnormal uptake of plasma lipids (ie. cholesterol) by the cells of the blood vessel
•Corrected by:
-By-pass surgery- a blood vessel from elsewhere in the body is used to direct blood flow around the area of
blockage
-Balloon angioplasty- balloon is inflated in the artery to push the fatty deposit up against the blood vessel wall
-Laser angioplasty- laser used to destroy fatty deposit
Structure of Cardiac Muscle
•Involuntary; striated
•Myocytes, cardiomyocytes or cardiocytes
-Short, thick, branched cells, with one nucleus
-¯ Sarcoplasmic reticulum, large T-tubules
•admit more Ca2+ from ECF
•Intercalated discs- join myocytes end to end
-interdigitating folds- surface area
-mechanical junctions (desmosomes)- tightly join myocytes
•Prevent myocytes from pulling apart during contractions
electrical (gap) junctions- form channels allowing ions to flow directly from cytoplasm of one cell into the next cell
The AV valves close in response to the __________.
Contraction of the ventricles and the resulting rise in ventricular pressure
Action potentials received directly from the __________ stimulate the papillary muscles to contract, allowing for the proper __________ of the AV valves.
Subendocardial conducting network (Purkinje fibers); closing
Mitral valve prolapse severe enough to cause regurgitation may directly cause __________ pressure in the __________ atrium.
Increased; left
Intercalated Disks
Specialized cell junctions in the myocardium where one muscle cell connects to the next
Metabolism of Cardiac Muscle
•Aerobic respiration
•Rich in myoglobin and glycogen
•Large mitochondria
•Organic fuels: fatty
acids, glucose, ketones
•Fatigue resistant
•Can undergo anaerobic fermentation for a short period of time
-anaerobic fermentation does not produce enough ATP to sustain cardiac function
•Repair of damage to cardiac muscle is almost all fibrosis (scarring)
Place each label representing a specific electrical event on the appropriate region of the ECG.
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Cardiac Conduction System
•Myogenic- heartbeat originates within heart, not brain
•Autorhythmic- depolarize spontaneously regularly
•Conduction system
-SA Node: pacemaker; initiates heartbeat; sets heart rate; signal spreads through both atria; located in roof of right atrium
-AV Node: electrical gateway to ventricles ; located in side wall of right atria
•can take over as pacemaker if SA node fails
-AV Bundle(Bundle of His): pathway for signals from
AV node
-Right and left bundle branches: divisions of AV bundle that enter interventricular septum and descend to apex
-Purkinje fibers: upward from apex spread throughout ventricular myocardium
Which region of the ECG image aligns with the electrical changes related to atrial repolarization?
Region B
A first-degree block is caused by __________.
delay of the action potential between the SA and subendocardial conducting network (Purkinje fibers)
Cardiac Rhythm
•Systole = contraction; Diastole = relaxation
•Sinus rhythm - normal rhythm set by SA node
-adult at rest is 70 to 80 bpm
•Ectopic foci - region other than SA node sets rhythm
-nodal rhythm - set by AV node; 40 to 50 bpm
-intrinsic
ventricular rhythm - AV bundle; 20-40 bpm
•not enough to sustain normal functioning
•artificial pacemaker is implanted
•Arrhythmia - abnormal cardiac rhythm
-caused by number of things including bundle disease/degeneration
•Ventricular fibrillation (V-fib)- uncoordinated contraction
-ventricles spasm à heart can't pump à cardiac arrest
-defibrillation - strong electrical shock to depolarize myocardium and restore normal heartbeat
The rate of ventricular conduction is best determined by __________ on an ECG.
The number of QRS complexes present within a specific unit of time
An ECG tracing from someone with a third-degree AV block is best described as a tracing with a __________.
2:1 ratio of P waves to QRS complexes
Correctly label the following parts of the pericardium and the heart walls.
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Correctly sequence the pathway of blood flow through the heart, beginning with the venae cavae.
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Contraction of Myocardium
•Myocytes have stable resting potential of -90 mV
•Depolarization (very brief)
-stimulus
opens voltage regulated Na+ gates
-Na+ rushes in (membrane depolarizes rapidly)
-action potential peaks at +30 mV
-Na+ gates close quickly
•Plateau- 200 to 250 msec, sustains contraction
-slow Ca2+ channels open
-Ca2+ binds to fast Ca2+ channels on SR
-SR releases Ca2+ into cytosol
-contraction
•Repolarization - membrane returns to resting potential
-Ca2+ channels close
-K+ channels open
-rapid K+ out returns membrane to resting potential
Action Potential of a Ventricular Cardiocyte
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SA Node Potentials
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Indicate whether each structure is part of the systemic or pulmonary circuit.
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Electrocardiogram (ECG/EKG)
•Composite of all action potentials of nodal and myocardial cells detected, amplified and recorded by electrodes on arms, legs & chest
-In other words: ECG detects electrical currents in the heart
•Invaluable for diagnosing:
-abnormalities in conduction pathways
-enlarged heart
-electrolyte and hormone imbalance
-MI
ECG Components
•P wave -
SA node fires
-signal spreads through atria
-atrial depolarization
•P-Q segment - atrial systole
•QRS complex
-atrial repolarization and diastole (signal obscured)
-AV node fires, ventricular depolarization
•S-T segment - ventricular systole
•T wave - ventricular repolarization
Drag each label to the location of each structure described.
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Drag each statement to the appropriate position to identify the valve being described.
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Drag each statement to the appropriate position to identify the valve being described.
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Principles of Pressure and Flow
•Pressure causes fluid to flow
-pressure gradient
•pressure
difference between two points
•fluid flows from an area of high pressure to an area of low pressure
•Resistance opposes flow
-great vessels have positive blood pressure
-ventricular pressure must rise above this resistance for blood to flow into great vessels
Drag each label to the location of each structure described.
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Drag each label to the appropriate position to identify whether the structure contains oxygenated or deoxygenated blood.
Oxygenated - Coronary arteries, descending arteries, carotid arteries, left ventricle
Deoxygenated - Jugular vein, pulmonary trunk, pulmonary arteries, right atrium, superior vena cava, great cardiac vein
Electrical Activity of the Myocardium
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Correctly label the pathway for the cardiac conduction system.
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Place a single word into each sentence regarding the heart's conduction system.
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Question: A heart rate of 45 bpm and no P wave on an ECG indicates ______?
SA node damage
ECG Diagnostics
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ECGs, Normal & Abnormal
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ECGs, Abnormal
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Abnormal ECG
•Extrasystole or PVC
•absence of a P
wave
•inverted QRS complex
•misshapen QRS and T
•caused by stimulants, stress, lack of sleep or something more serious
Heart Sounds
•Auscultation- listening to sounds made by the body
•1st heart sound (S1) - "lubb" ; louder and longer
-occurs with closure of AV valves
•2nd heart sound (S2) - "dupp"; softer and sharper
-occurs with closure of semilunar valves
•Heart Murmur - sound of blood
flowing backward due to valvular insufficiency
-Valvular stenosis - cusps are stiffened
-Mitral valve prolapse - mitral valve cusps bulge into left atrium
•Hereditary in 1 out of 40 people
•May cause chest pain and shortness of breath
-an incompetent valve can eventually lead to heart failure
-defective valves can be replaced: pig valve or artificial valve
Place a single word into each sentence to make it correct. Then rearrange the sentences into the correct order to explain the process of the cardiocyte action potential.
The action potential of a ventricular CARDIOMYOCYTE beings with opening a voltage gated sodium ion channel.
Na+ inflow depolarizes the membrane, triggering the opening of more channels causing a POSITIVE feedback cycle.
Channels will then close when the voltage reaches +30mV.
Depolarization is then prolonged via slow CALCIUM ION channels.
Once these channels close, potassium ions flow out quickly and restore the RESTING membrane potential.
Place a single word into each sentence to make it correct.
Electrical CURRENTS in the heart can be detected by means of electrode applied to the skin.
An instrument called the electrocardiograph AMPLIFIES these signals and produces a record on a moving paper chart.
The chart includes three principle deflections above and below the baseline; the P wave, QRS complex and the T wave.
The P wave is produced when a signal from the SA node spreads through the atria and DEPOLARIZES them.
The QRS complex is produced when the signal from the AV node spreads through the VENTRICULAR myocardium and depolarizes the muscle.
The T wave is generated by ventricular repolarization immediately before DIASTOLE.
Place a single word into each sentence to make it correct.
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Phases of Cardiac Cycle
•1. Ventricular filling
-During diastole, ventricles expand
-Their pressure drops below that of the atria
-AV valves open and blood flows into the ventricles
-Ventricular filling occurs in three phases
•Rapid ventricular filling: first one-third
-Blood enters very quickly
•Diastasis:
second one-third
-marked by slower filling
-P wave occurs at the end of diastasis when SA node fires
•Atrial systole: final one-third
-atria contract
-ventricles now contain end-diastolic volume (EDV) = ~130 ml blood
•2. Isovolumetric Contraction of Ventricles
-Atria repolarize and relax
-Ventricles depolarize
-QRS complex appears in ECG
-Ventricles contract
-Rising pressure closes AV valves
-Heart sound S1 occurs
-No ejection of blood yet (no change in
volume)
•3. Ventricular Ejection
-Rising pressure opens semilunar valves
-Rapid ejection of blood
-Reduced ejection of blood (less pressure)
-Stroke Volume (SV): amount ejected, about 70 ml
-SV/EDV= ejection fraction, at rest ~ 54%
•during vigorous exercise as high as 90%
•diseased heart ejects less than 50%
-End-systolic volume (ESV): amount left in heart
•4. Isovolumetric Relaxation of Ventricles
-T wave appears in ECG
-Ventricles repolarize and relax
(begin to expand)
-Semilunar valves close
-Heart sound S2 occurs
-AV valves remain closed
-Ventricles expand but do not fill
Classify the following images into the phase of the cardiac cycle they represent.
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Indicate the heart chamber responsible for the given function.
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Overview of Volume Changes
End-systolic volume (ESV) 60 ml
Passively added to ventricle during atrial diastole 30 ml
Added by atrial systole 40 ml
Total: end-diastolic volume (EDV) 130 ml
Stroke volume (SV) ejected by ventricular systole -70 ml
End-systolic volume (ESV) 60 ml
Both ventricles must eject same amount of blood
* You do not have to memorize these values!
Listed are two heart conditions, increased heart rate and decreased heart rate. Classify whether each given factor would increase or decrease heart rate.
Increased Heart Rate- Epinephrine, nicotine, Blood acidosis (decline in pH), thyroid hormone, Hypercapnia (high carbon dioxide levels)
Decreased Heart rate- Hyperkalemia (high potassium concentrations in the ECF), hypercalcemia, Acetylcholine
Congestive Heart Failure (CHF)
1) Right ventricular output exceeds left ventricular output
2) Pressure backs up
3) Fluid accumulates in pulmonary tissue
Congestive Heart Failure (CHF)
1) Left ventricular output exceeds right ventricular output
2) Pressure backs up
3) Fluid accumulates in systemic tissue
Question: In an angiogram, the blood vessels are injected with a dye so that they may be visualized. The angiogram is used to detect ______?
Atherosclerosis
Classify whether each given factor would increase or decrease heart rate.
Increased Heart Rate- cutting the vagus nerve, exercise, sympathetic stimulation, psychological stress
Decreased Heart Rate- Vagal tone, SA node Damage, BBB, Calcium Channel blockers
Place the labels in order denoting the flow of blood through the pulmonary circuit beginning with the right atrium and ending in the left atrioventricular valve. The first and last structures are given.
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Complete each sentence by dragging the labels to the appropriate blanks. Then place each sentence in a logical order beginning with blood entering the right side of the heart.
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Complete each sentence by dragging the labels to the appropriate blanks. Then place each sentence in a logical order beginning with cardiomyocytes in a resting state.
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Drag each label into the appropriate position to characterize the events of a single heart cycle as seen on an ECG tracing.
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Drag each label into the appropriate position to identify the waves of a normal ECG.
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Place the labels in order denoting the sequence of events of the cardiac cycle beginning with resting membrane potential and ending with the beginning of repolarization. The first and last steps are given.
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Indicate whether each item would increase or decrease contractility.
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Which of the following is caused by ventricular contraction?
The atrioventricular valves close, and then the semilunar valves open
When the pressure in the ventricles becomes lower than the pressure in the atria, __________.
The atrioventricular valves open
Which of the following is the correct sequence of events regarding the cardiac cycle?
Isovolumic contraction, ejection, isovolumic relaxation, passive ventricular filling, active ventricular filling
The atria never contract due to passive ventricular filling.
False
In the heart, an action potential originates in the __________.
Sinoatrial node
Which of the following is the correct sequential path of an action potential in the heart?
Sinoatrial node, atrioventricular node, atrioventricular bundle, bundle branches, subendocardial conducting network (Purkinje fibers)
Which of the following is true concerning the heart's conduction system?
Action potentials pass slowly through the atrioventricular node
In the ventricles, the action potential travels along the interventricular septum to the apex of the heart, where it then spreads superiorly along the ventricle walls.
True
Action potentials are carried by the subendocardial conducting network (Purkinje fibers) from the bundle branches to the ventricular walls.
True
Cardiac muscle is not prone to fatigue because it makes little use of anaerobic fermentation or the oxygen debt mechanism.
True
Correctly associate the statements with the three distinct features of an intercalated disc.
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Choose the correct statement(s) that accurately explain(s) impulse conduction to the myocardium. Check all that apply.
Firing of the SA node excites atrial cardiomyocytes and stimulates the two atria to contract almost simultaneously.
In the AV node, the signal slows down to about 0.05 m/sec because the cardiomyocytes have fewer gap junctions over which the signal can be transmitted.
Signals travel through the AV bundle and subendocardial conducting network at a speed of 4 m/sec, the fastest in the conduction system.
Classify the following statement as belonging to either sympathetic or parasympathetic stimulation of the heart.
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Match the components of the cardiac conduction system with their description.
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As a heart chamber contracts, what happens to the pressure of the fluid within it?
It increases
Match the action of the AV and semilunar heart valves with the correct statement regarding pressure differences in the heart chambers.
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Which term refers to relaxation of the heart?
Diastole
Which of the following is the correct formula for calculating cardiac output?
HR x SV
If a person's heart is pumping 5000 mL of blood in one minute and the heart rate is 50 beats per minute, what is the cardiac output?
None of these choices is correct
The difference between the maximum and resting cardiac output is called __________.
Cardiac reserve
The amount of tension in the ventricular myocardium immediately before it contracts is called _________.
Preload
Which of the following has a strong, positive inotropic effect, meaning it increases the strength of each contraction of the heart?
Hypercalcemia
If the right ventricle begins to pump an increased amount of blood, this soon arrives at the left ventricle, stretches it more than before, and causes it to increase its stroke volume and match that of the right. This is an example of __________.
Preload
The Frank-Starling law of the heart states that an additional stretch of the myocardium produces a significant increase in __________ on the next beat.
Contraction force
As exercise progresses, muscular activity __________ venous return. This increases the __________ on the right ventricle.
Increases; preload
Exercise has which of the following effects on cardiac output? Check all that apply.
The main reason the heart rate increases at the beginning of exercise is that proprioceptors in the muscles and joints transmit signals to the cardiac centers.
As the exercise progresses, muscular activity increases venous return.
A sustained program of exercise causes hypertrophy of the ventricles, which increases their stroke volume.
Which of the following is a recording of all nodal and myocardial action potentials in the heart?
ECG
Indicate the heart chamber responsible for the given function.
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Drag each label into the appropriate position to identify the segments and intervals of a normal ECG.
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Identify whether each item would increase or decrease stroke volume.
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Complete each sentence by dragging the labels to the appropriate blanks. Then place each sentence in a logical order beginning with blood entering the right side of the heart.
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Complete each sentence by dragging the labels to the appropriate blanks. Then place each sentence in a logical order beginning with the SA node in a resting state.
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Which of the following statements is not true regarding ventricular systole?
The ventricles relax
The semilunar valves close during __________.
Ventricular diastole
The atrioventricular valves open during __________.
Ventricular diastole
The ventricles begin to fill during ventricular diastole.
True
In a normal ECG, the deflection that is generated by ventricular repolarization is called the __________.
T wave
Which of the following is a feature shared by cardiac muscle and skeletal muscle?
Muscle fiber striations
Which of the following carry oxygen-poor blood?
Venae cavae and pulmonary arteries
The Frank-Starling law of the heart states that stroke volume is proportional to __________.
The end-diastolic volume
The cardiac plexus and cardiac nerves dominate the innervation of the heart and contain both parasympathetic and sympathetic fibers.
True
Which of the following is not a feature of cardiac muscle?
They have about the same endurance as skeletal muscle fibers
Which is the correct path of an electrical excitation from the pacemaker to a cardiomyocyte in the left ventricle (LV)?
Sinuatrial (SA) node → atrioventricular (AV) node → atrioventricular (AV) bundle → subendocardial conducting network → cardiomyocyte in LV
The plateau in the action potential of cardiac muscle results from the action of __________.
Slow Ca2+ channels
The __________ valve regulates the flow of blood between the right ventricle and the vessels leading to the lungs.
Pulmonary
The apex of the heart is found __________ of the midline of the body.
To the left
Correctly label the following structures related to the position of the heart in the thorax.
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Correctly label the following anatomical features of the thoracic cavity.
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Correctly label the internal anatomy of the heart.
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Correctly label the following internal anatomy of the heart.
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Correctly label the following external anatomy of the anterior heart.
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Correctly label the following external anatomy of the posterior heart.
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Correctly label the following external anatomy of the posterior heart.
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Correctly label the external anatomy of the anterior heart.
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Correctly label the following internal anatomy of the heart.
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Correctly label the following internal anatomy of the heart.
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Correctly label the following vessels leading from and toward the anterior heart.
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Correctly label the following vessels leading from and toward the anterior heart.
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Correctly label the following parts of the pericardium and the heart walls.
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Correctly label the following external anatomy of the posterior heart.
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Correctly sequence the pathway of blood flow through the heart, beginning with the venae cavae.
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Correctly label the following coronary blood vessels of the heart.
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Correctly label the following coronary blood vessels of the heart.
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Correctly label the following coronary blood vessels of the heart.
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Identify the unique structural characteristics of cardiac muscle.
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Identify the unique structural characteristics of cardiac muscle.
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Identify the unique structural characteristics of cardiac muscle.
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Drag each label into the appropriate position to indicate which view is necessary to see the indicated structure.
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Place the labels in order denoting the flow of blood through the systemic circuit beginning with the left atrioventricular valve and ending in the right atrium. The first and last structures are given.
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Cardiac Output (CO)
•Amount ejected by each ventricle in 1 minute
•CO= HR x SV
•Resting values: CO = 75 beats/min x70 ml/beat = 5,250 ml/min, usually about 4 to 6L/min
-this means that all of the body's blood is circulated in 1 minute *(an RBC leaving the heart will return in 1 min)
•Vigorous exercise CO to 21 L/min for fit person
and up to 35 L/min for world class athlete
* they have a lower heart rate, but a higher stroke volume
•Cardiac reserve: difference between CO maximum (during exercise) and resting CO
Heart disease = little or no cardiac reserve
Cardiology involves the study of the ______ and its disorders.
Heart
The muscular pump that keeps blood flowing through blood vessels is the ______.
Heart
Heart Rate
•Measured from pulse
•Infants have HR of 120 beats per minute or more
•Young adult females avg. 72 - 80 bpm
•Young adult males avg. 64 to 72 bpm
•HR rises again in the elderly
•Tachycardia: persistent, resting adult HR > 100
-stress, anxiety, drugs, heart disease or body temp.
•Bradycardia : persistent, resting
adult HR < 60
-common in sleep and endurance trained athletes ( SV)
Chronotropic Effects
•Positive chronotropic agents raise HR and negative chronotropic agents lower HR
•Cardiac center of medulla oblongata
-an autonomic control center with 2 neuronal pools
•cardioacceleratory center - sympathetic n.s.
•cardioinhibitory center - parasympathetic n.s.
Sympathetic Nervous System
•Cardioacceleratory center
-stimulates sympathetic cardiac accelerator nerves to SA node, AV node and myocardium
-these nerves secrete norepinephrine, which binds to b-adrenergic receptors in the heart
•+ chronotropic effect
-CO peaks at HR of 160 to 180 bpm
-Sympathetic n.s. can drive HR up to 230 bpm, (limited by refractory period of SA node), but SV and CO are less than at rest
Parasympathetic Nervous System
•Cardioinhibitory center
-stimulates vagus nerves
•right vagus nerve - SA node; left vagus nerve - AV node
-secrete ACh (acetylcholine)
•binds to muscarinic receptors
•opens K+ channels in nodal cells, hyperpolarized, fire less frequently, HR slows down
-vagal tone: background firing rate holds HR to sinus rhythm of 70 to 80 bpm
•severed vagus nerves = SA node fires at intrinsic rate of 100 bpm
maximum vagal stimulation
decreases HR as low as 20 bpm
Blood leaves the left side of the heart through the ______.
Aorta
The _____ side of the heart supplies blood to the pulmonary circuit.
Right
Which side of the heart supplies blood to the systemic circuit?
Left
Inputs to Cardiac Center
•Higher brain centers affect HR
•Chemoreceptors
-sensitive to blood pH, CO2 and oxygen
-aortic arch, carotid arteries and medulla oblongata
•Proprioceptors
-inform cardiac center about changes in activity, HR increases before metabolic demands arise
•Baroreceptors
-pressure sensors in aorta and internal carotid arteries send continual stream of signals to cardiac
center
•if pressure drops, signal rate drops, cardiac center increases HR
if pressure rises, signal rate rises, cardiac center decreases HR
Chronotropic Chemicals
•Neurotransmitters
-norepinephrine and epinephrine (catecholamines) are potent cardiac stimulants
•Drugs
-caffeine inhibits cAMP breakdown
-nicotine stimulates catecholamine secretion
•Hormones
-TH adrenergic receptors in
heart, which the heart's sensitivity to sympathetic stimulation and thus HR
•Electrolytes-potassium has greatest chronotropic effects
- increase K+ myocardium less excitable
•HR slow and irregular due to increased K+ diffusing into the cell, which inhibits repolarization
- decrease K+ cells become hyperpolarized (more negative) because K+ diffuses out of the cells
requires stimulation
Stroke Volume (SV)
•Governed by three factors:
1.Preload
•increase preload or contractility causes increase SV
2.Contractility
3.Afterload
•increase afterload causes decrease SV
Which are components of the cardiovascular system?
Heart
Blood vessels
Preload
•Amount of tension in ventricular myocardium before it
contracts
•increase preload causes increase force of contraction
-exercise increases venous return
-stretches myocardium (increase preload)
-myocytes generate more tension during contraction
-increase CO matches increase venous return
•Frank-Starling law of heart - Stroke Volume = EDV
-ventricles eject as much blood as they receive
more they are stretched ( preload) the harder they contract
Contractility
•Contraction force for a given preload
•Positive inotropic agents
-factors that increase contractility
•hypercalcemia, catecholamines, glucagon, digitalis
•Negative inotropic agents
-factors that decrease contractility are
•hyperkalemia, hypocalcemia
Afterload
•Pressure in arteries above semilunar valves opposes opening of valves
•Increases afterload decreases
SV
-any impedance in arterial circulation increases afterload
•Continuous increases in afterload causes hypertrophy of myocardium
-lung disease, atherosclerosis, etc.
•May lead the heart to weaken and fail
Exercise and Cardiac Output
•Effect of proprioceptors
-HR increases at beginning of exercise due to signals from joints, muscles
•Effect of venous return
-muscular activity increases venous
return causes increase SV
•Increase HR and SV cause increase CO
•Effect of ventricular hypertrophy
-caused by sustained program of exercise
-increase SV allows heart to beat more slowly at rest, 40-60bpm
-increase cardiac reserve, can tolerate more exertion
Which region of the heart is indicated by the letter A in the figure?
Base
The systemic circuit pumps blood from which side of the heart to the body tissues?
Left
The right side of the heart pumps ______ blood to the lungs.
Oxygen-poor
As the heart sits in the thoracic cavity, the superior tip end called the ______.
Base
Which fibrous structure is indicated by the letter A in the figure?
Fibrous pericardium
What is the inferior tapered end of the heart called?
Apex
The ______ is a double-walled sac enclosing the heart.
Pericardium
The heart is ______ the pericardial cavity.
Enfolded by
The serous fluid called _____ fluid fills the pericardial cavity and lubricates the membranes, allowing the heart to beat with minimal friction.
Pericardial
What is the double-layered sac that surrounds the heart called?
Pericardium
Which are layers of the heart wall?
Myocardium
Endocardium
Epicardium
Which type of epithelium makes up part of the endocardium?
Simple squamous
What is the space between the parietal and visceral layers of the pericardium called?
Pericardial cavity
Where does pericardial fluid come from?
The serous pericardium
What is the outermost layer of the heart wall called?
Epicardium
The blood vessel indicated by the letter A in the figure is the superior ______ ______.
Vena cava
Which layer lines the inner chambers of the heart?
Endocardium
The epicardium is also called what?
Visceral layer of the serous pericardium
The blood vessel indicated in the figure has several segments. The initial segment that is indicated by the letter A in the figure is the ______ aorta.
Ascending
The fibrous skeleton of the heart is a ______ of electricity.
Nonconductor
Which blood vessel is a branch off the pulmonary trunk?
Pulmonary artery
A fibrous cord that attaches the pulmonary trunk to the aortic arch is the ______.
Ligamentum arteriosum
Which supports the valves and openings of the great vessels of the heart?
Fibrous skeleton
The framework of collagenous and elastic fibers found in the walls of the heart form the ______ skeleton.
Fibrous
What are the ridges of muscle indicated in the figure?
Pectinate muscles
What are the functions of the fibrous skeleton?
Provides structural support for the heart
Provides electrical insulation between the atria and ventricles
Anchors the cardiocytes and give them something to pull against
What is the earlike extension of each atrium called?
Auricle
What are the internal ridges of myocardium found in the right atrium and auricle?
Pectinate muscles
Which chamber of the heart is indicated here?
Right ventricle
Pulmonary arteries are branches of the ______.
Pulmonary trunk
The thick-walled inferior chambers of the heart that pump blood into the arteries are called ______.
Ventricles
The groove that extends downward from the coronary sulcus on the front of the heart is the anterior _______ sulcus.
Interventricular
Which groove encircles the heart, separating the atria from the ventricles?
Coronary sulcus
Which sulcus overlies the interventricular septum?
Anterior interventricular sulcus
Which groove extends downward from the coronary sulcus on the back of the heart?
Posterior interventricular sulcus
Which valve is indicated in the figure?
Right atrioventricular
The right atrioventricular valve is also called the ______ valve.
Tricuspid
The finger-like muscle indicated in the figure is a _____ muscle.
Papillary
The right atrioventricular valve has ______ cusps.
Three
The left atrioventricular valve has ______ cusps.
Two
Which valves are attached to papillary muscles?
Atrioventricular valves
The mitral valve is also known as what?
Left AV valve
Blood in the left atrium flows directly into the ______.
Left ventricle
The blood vessels that supply nutrients and oxygen only to the heart muscle make up the specific type of circulation called the _____ circulation.
Coronary
What are the string-like structures that attach the AV valves to the papillary muscles called?
Tendinous cords
Which artery travels under the left auricle and then divides into two branches?
Left coronary artery
Which best represents the correct flow of blood through the heart, immediately after it returns from the venous circulation?
Right atrium, right ventricle, left atrium, left ventricle
True or false: The coronary blood vessels are part of the the systemic circulation.
True
The left and right coronary arteries arise from which blood vessel?
Aorta
Which artery runs along the sulcus and supplies blood to the right atrium and SA node?
Right coronary
When does blood flow through the coronary circulation increase?
Ventricular diastole
The right and left coronary arteries arise from the ascending _______.
Aorta
Which vein collects venous drainage from all of the coronary veins and drains into the right atrium?
Coronary sinus
During which phase of the cardiac cycle does blood flow through the coronary circulation?
Ventricular relaxation
_______ are short, thick, branched muscle cells of the heart.
Cardiomyocytes
At rest, the heart gets about 60% of its energy from which of the following?
Fatty acids
The vertebrate heartbeat is said to be ______ because the signal originates within the heart muscle itself.
Myogenic
Cardiomyocytes are jointed end to end by thick connections called ______.
Intercalated discs
Cardiac muscle relies on which process to produce ATP?
Aerobic respiration
Which part of the cardiac conduction system acts as an electrical gateway to the ventricles?
AV node
Which structures are considered to be part of the cardiac conduction system?
SA node
AV node
Purkinje fibers
Where is the SA node located?
The wall of the right atrium
The part of the cardiac conduction system which acts as the pacemaker is the _____ node.
SA
Excitation in the cardiac conduction system leaves the AV node by way of the bundle, also known as the ______ bundle of His.
Atrioventricular
The portion of the cardiac conduction system located in the lower end of the interatrial septum is the _____ node.
Atrioventricular
When the AV node acts as pacemaker, the slower heartbeat has what type of rhythm?
Nodal
What is it referred to as when a portion of the heart wall other than the SA node spontaneously depolarizes?
Ectopic focus
A spontaneously developing local potential that generates action potentials in the SA node is called what?
Pacemaker potential
When a cell in the SA node is depolarized to threshold, voltage-gated ______ channels open.
Calcium
In a healthy person at rest, the SA node normally fires about how many times per minute?
70-80
The depolarization of the SA node (from threshold to peak) is due to the inflow of sodium and ______ ions.
Calcium
Any region of spontaneous firing other than the SA node is a(n) ______ focus.
Ectopic
The pacemaker potential of SA node cells is due to the influx of which ions?
Sodium
When the membrane potential of the SA node reaches threshold, voltage-regulated channels for which ions open?
Calcium
Where does ventricular contraction begin?
Apex
The depolarization of the SA node (from threshold to peak) is due to the inflow of which ions?
Sodium
Calcium
Place the events of an action potential in a ventricular cardiocyte in order.
See image
Impulse conduction through the cardiac conduction system is slowest through which structure, thereby allowing a pause between atrial contraction and ventricular contraction?
AV node
The action potential of a cardiocyte has a plateau due to the opening of which channels?
Slow calcium
Depolarization of a cardiocyte is due to opening of which channels?
Sodium
Repolarization of a cardiocyte is due to opening of which channels?
Potassium
The plateau phase in an action potential of a cardiocyte is caused by which of the following?
Ca2+ entering the cell
The contraction of a cardiocyte occurs during which phase of its action potential?
Plateau
Depolarization in cardiocytes is prolonged probably because ______ channels are slow to close.
Calcium
Firing of the SA node occurs at the beginning of which ECG wave?
P wave
During which stage of an ECG does atrial systole occur?
PQ segment
What does the PQ interval of an ECG represent?
The time required for an impulse to pass from the SA node to AV node
Which is a recording of all nodal and myocardial action potentials in the heart?
ECG
The QRS wave of an ECG represents what event in the heart?
Depolarization of the ventricles
On an ECG, atrial systole begins during the ____ segment.
PQ
Ventricular systole begins shortly after which major deflection on an ECG?
QRS complex
Which of the following best describes what happens during the T wave of an ECG?
The ventricles repolarize
What is an abnormal cardiac rhythm called?
Arrhythmia
A difference in pressure creates a pressure ______ that directs the flow of fluids.
Gradient
Which is a type of arrhythmia?
Ventricular fibrillation
What is the relationship between pressure and volume?
They are inversely proportional
With the onset of ventricular contraction, what happens to the pressure within the ventricles?
It increases
Which instrument is used to measure blood pressure?
Sphygmomanometer
Fluids always flow from an area of ______ pressure to an area of ______ pressure.
Higher, lower
True or false: The papillary muscles contract just before the rest of the myocardium in order to tense the tendinous cords prior to the ejection of blood.
True
Which accounts for the movement of the heart valves during the cardiac cycle?
Pressure changes within the chambers
What is the role of the papillary muscles?
To tense the tendinous cords just prior to ventricular contraction
During ventricular contraction, the ejection of blood out of the heart occurs because the pressure within the ______ exceeds the pressure within the ______.
Ventricles, great arteries
What is the process of listening to sounds made by the body called?
Auscultation
Which best represents the correct order of the following events? 1. Isovolumetric relaxation 2. Ventricular filling 3. Isovolumetric contraction 4. Ventricular ejection
2,3,4,1
The semilunar valves will open when the pressure within the ______ exceeds the pressure within the ______.
Ventricles, great arteries
When the ventricles are relaxed and their pressure is low, which valves are open?
Atrioventricular
The closing of the atrioventricular valves produces which of the heart sounds?
The first
What is the volume of blood ejected from one ventricular contraction called?
Stroke volume
The second heart sound is associated with the closing of which valves?
Semilunar valves
True/False: Each ventricle will eject a volume of blood equal to the amount of blood it received during the ventricular filling phase.
True
True or false: The left ventricle always pumps more blood per beat than the right ventricle.
False
The amount of blood ejected by a ventricle is ______ the amount of blood received during ventricular filling.
The same as
If the volume of blood pumped by the right side of the heart is less than that pumped by the left side of the heart, what would be the result?
Systemic edema
Which autonomic system(s) innervate(s) the heart?
Both sympathetic and parasympathetic nerves
The cardiac nerves convey signals from which nervous system to the heart?
Sympathetic
The vagus nerve conveys signals from which nervous system to the heart?
Parasympathetic
An increase in stimulation by what branch of the nervous system lowers the heart rate?
Parasympathetic
Cardiac output is equal to stroke volume ______ heart rate.
Times
Stimulation of the SA node by the which division of the nervous system raises the heart rate?
Sympathetic
What term describes a consistently elevated resting heart rate above 100 bpm?
Tachycardia
What is the difference between the maximum and resting cardiac output?
Cardiac reserve
Sympathetic stimulation of the heart involves the release of which neurotransmitter?
Norepinephrine
Which describes parasympathetic stimulation of the heart?
Cholinergic
What is a persistent, low resting heart rate below 60 bpm called?
Bradycardia
Which describes sympathetic stimulation of the heart?
Adrenergic
How does an increase in blood calcium ion levels affect heart rate?
It decreases heart rate
Which refers to the steady background firing of the vagus nerve to the heart?
Vagal tone
Which electrolyte has the greatest effect on heart rate?
Potassium
Glucagon and thyroid hormone ______ heart rate.
Increase
What effect does hypocalcemia have on heart rate?
It elevates the heart rate
An increase in venous return to the heart leads to a(n) ______ in preload and therefore a(n) ______ in stroke volume.
Increase, increase
Nicotine increases heart rate by increasing the secretion of what?
Catecholamine
Which law states that stroke volume is determined by the end-diastolic volume?
Frank-Starling
What is the strength of contraction for a given preload called?
Contractility
How do positive inotropic agents affect contractility?
They increase it
An increase in venous return would ______ preload.
Increase
A decrease in venous return to the heart leads to a(n) ______ in preload, and therefore, a(n) ______ in stroke volume.
Decrease, decrease
Which term is used to describe the narrowing of the coronary arteries, usually by atherosclerosis?
Coronary artery disease
Hyperkalemia (high potassium level) reduces the strength of myocardial action potentials, thus reducing the release of calcium. Therefore how will this condition affect contractility?
It will decrease contractility
How do negative inotropic agents affect contractility?
They decrease it
How does the drug digitalis affect heart contractility?
It increases it
Which force impedes the opening of the semilunar valves and opposes ventricular ejection?
Afterload
What is the most common cause of coronary artery disease?
Atherosclerosis
Why does digitalis increase heart contractility?
It increases sarcoplasmic calcium levels
The blood pressure in the great arteries determines which of the following?
Afterload
Which condition involves compression of the heart by an abnormal accumulation of fluid in the pericardial cavity?
Cardiac tamponade
Which condition involves abnormal openings in the interatrial or interventricular septa altering blood flow through the heart?
Septal defect
Which condition involves a seepage of fluid from the pericardium into the pericardial sac?
Pericardial effusion