B4M2Q1 24-25 Flashcards
Which of the following is true of atrial depolarization?
A. Vector is directed from right to left
B. Represented by the PR-interval
C. When abnormal, causes QRS-complex changes
D. Impulse generation comes normally from the AV node
A. Vector is directed from right to left
True of the part of the ECG rhythm strip pointed by the arrow. (See attached figure)
A. Atrial depolarization
B. AV-nodal delay
C. Ventricular depolarization
D. Ventricular repolarization
D. Ventricular repolarization
True of the ECG rhythm strip shown below. (See attached figure)
A. Abnormally prolonged AV-nodal conduction time
B. High-voltage QRS complexes
C. Tachycardia
D. Widened QRS complexes
C. Tachycardia
Which of the following leads has an axis normally directed to +60 degrees?
A. Lead I
B. Lead II
C. Lead III
D. Lead aVL
B. Lead II
The part of the graph pointed by the arrow is primarily caused by which of the
following? (See attached figure.)
A. Na+
B. Ca2+
C. K+ moving intracellularly
D. K+ moving extracellula
B. Ca2+
A conduction block in one of the major bundle branches of the cardiac conduction
system would show primary abnormalities in which part of the ECG?
A. P wave
B. PR interval
C. QRS-T complex
D. ST segment
C. QRS-T complex
True of the part of the ECG rhythm strip enclosed in the box. (See attached figure.)
A. Atrial depolarization
B. Atrial depolarization and repolarization
C. Ventricular depolarization
D. Ventricular depolarization and repolarization
D. Ventricular depolarization and repolarization
Lead III has a positive electrode located at which of the following?
A. Left leg
B. Right leg
C. Left arm
D. Right arm
A. Left leg
Which embryonic vein is responsible for returning poorly oxygenated blood from the
yolk sac?
A. chorionic vein
B. umbilical vein
C. vitelline vein
D. common cardinal vein
C. vitelline vein
Which embryonic structure is the primordium of the heart mainly derived from?
A. splanchnic mesoderm
B. paraxial mesoderm
C. lateral mesoderm
D. neural crest cell
A. splanchnic mesoderm
Which is the primary function of the ductus arteriosus in fetal cuirculation?
A. To shunt blood from the pulmonary artery to the aorta.
B. To shunt blood from the aorta to the pulmonary artery.
C. To shunt blood from the right atrium to the left atrium.
D. To shunt blood from the left ventricle to the right ventric
A. To shunt blood from the pulmonary artery to the aorta.
Which structure in the embryonic heart gives rise to the smooth-walled part of the left atrium and the coronary sinus?
A. Bulbus cordis
B. Truncus arteriosus
C. Sinus venosus
D. Primitive ventricle
C. Sinus venosus
During embryonic development, a mutation occurs that affects the formation of the
endocardial cushions. How might this mutation impact heart development?
A. Atrial and ventricular septation maybe affected, leading to structural heart
defects.
B. The formation of the coronary arteries maybe affected leading to coronary
artery anomalies.
C. The development of aortic arches maybe affected leading to abnormalities in
great vessel connections.
D. The formation of the conduction system may be affected, leading to
arrhythmias
A. Atrial and ventricular septation maybe affected, leading to structural heart
defects.
How do changes in blood flow and pressure at birth lead to the closure of the ductus
arteriosus and foramen ovale?
A. Decreased systemic blood flow leads to ductus arteriosus closure and decreased
right atrial pressure leads to foramen ovale closure.
B. Increased systemic blood flow leads to ductus arteriosus closure and increased
left atrial pressure leads to foramen ovale closure.
C. Decreased pulmonary blood flow leads to ductus arteriosus closure and
increased right ventricular pressure leads to foramen ovale closure.
D. Decreased systemic blood flow leads to ductus arteriosus closure and increased
left ventricular pressure leads to foramen ovale closure.
B. Increased systemic blood flow leads to ductus arteriosus closure and increased
left atrial pressure leads to foramen ovale closure.
Which structure separates the upper part of the heart from the sternum?
A. Lateral margins of the left lung
B. Remnants of the thymus gland
C. Esophagus
D. Fibroserous pleura
B. Remnants of the thymus gland
Which part of the heart primarily forms the cardiac base?
A) Right ventricle
B) Right atrium
C) Left atrium
D) Left ventricle
C) Left atrium
What structure separates the right and left atria?
A) Atrioventricular groove
B) Coronary sinus
C) Interatrial groove
D) Pulmonary trunk
C) Interatrial groove
What anatomical structure predominantly forms the inferior border of the heart?
A) Left ventricle
B) Right atrium
C) Right ventricle
D) Left atrium
C) Right ventricle
The anatomical differences between the right and left borders of the heart influence
their respective functions. Which statement best summarizes this relationship?
A) The left border is more convex, reflecting its role in managing systemic circulation.
B) The right border predominately influences pulmonary circulation due to its straight
profile.
C) Both borders are shaped similarly, thus functioning identically in both circulatory
contexts.
D) The differences in shape between the borders do not affect their functional roles
A) The left border is more convex, reflecting its role in managing systemic circulation.
Which statement best describes the function of the fibrous skeleton of the heart?
A) It provides the heart with electrical continuity.
B) It separates atrial and ventricular muscular walls and supports the valve cusps.
C) It generates rhythmic electrical impulses.
D) It is responsible for the color of the heart itsel
B) It separates atrial and ventricular muscular walls and supports the valve cusps.
Which of the following best describes the primary function of the right atrium in the
human heart?
A) To pump oxygenated blood to the body
B) To collect deoxygenated blood from the body and send it to the right ventricle
C) To direct oxygenated blood from the lungs to the left atrium
D) To separate systemic and pulmonary blood circulatio
B) To collect deoxygenated blood from the body and send it to the right ventricle
Considering the function of the atrioventricular bundle, why is it critical for the heart to
have a coordinated contraction?
A) To minimize energy expenditure.
B) To ensure effective pumping of blood to the body and lungs.
C) To allow for faster heart rates.
D) To enable individual chamber contractions
B) To ensure effective pumping of blood to the body and lungs.
Which heart valve separates the left atrium and the left ventricle?
A. Aortic valve
B. Pulmonary valve
C. Mitral valve
D. Tricuspid valve
C. Mitral valve
Which coronary artery primarily supplies the lateral wall of the left ventricle?
A. Left anterior descending artery
B. Circumflex artery
C. Right coronary artery
D. Posterior descending artery
B. Circumflex artery
The tricuspid valve is located between which two chambers of the heart?
A. Right atrium and right ventricle
B. Left ventricle and aorta
C. Right ventricle and pulmonary vein
D. Left atrium and left ventricle
A. Right atrium and right ventricle
Why do coronary arteries fill during diastole rather than systole?
A. Ventricular contraction compresses the coronary arteries during systole
B. Coronary arterial blood flow requires the aortic valve to be opened
C. Coronary perfusion only occurs during active heart muscle contraction.
D. Ventricular contraction increases the pressure gradient for coronary perfusion
A. Ventricular contraction compresses the coronary arteries during systole
Why are coronary arteries considered as “functional end arteries”?
A. Coronary arteries do not have any form of collateral circulation.
B. The anastomosis is not enough protection against sudden blockage.
C. They rely solely on systemic arterial pressure to maintain blood flow.
D. Their branches has no significant connection with the opposite arte
B. The anastomosis is not enough protection against sudden blockage.
What is the physiological function of the semilunar valves?
A. Prevent the backflow of blood from the ventricles to the atria
B. Keeps the unidirectional flow from ventricles to outside of the heart
C. Regulate the flow of blood between atria and the systemic circulation
D. Separate the pulmonary circulation and the systemic circulatio
B. Keeps the unidirectional flow from ventricles to outside of the heart
A 55-year-old patient presents with chest pain and an ECG reading of ST-segment
elevation in leads II, III, and aVF. Which coronary artery is most likely occluded?
A. Right coronary artery
B. Anterior interventricular artery
C. Circumflex artery
D. Posterior descending artery
A. Right coronary artery
Which vein is the primary structure responsible for venous drainage of the heart into the right atrium?
A. Superior vena cava
B. Coronary sinus
C. Anterior cardiac veins
D. Great cardiac vein
B. Coronary sinus
Which nerve provides parasympathetic innervation to the heart?
A. Phrenic nerve
B. Sympathetic trunk
C. Vagus nerve
D. Accessory nerv
C. Vagus nerve
What is the primary structural component of the cardiac skeleton?
A. Elastic cartilage
B. Hyaline cartilage
C. Dense connective tissue
D. Fibrocartilage
C. Dense connective tissue
What role does the cardiac skeleton play in the structural and functional organization
of the heart?
A. It anchors the heart valves and provides a rigid attachment for the myocardium.
B. It facilitates the propagation of electrical impulses between the atria and
ventricles.
C. It stores calcium ions for myocardial contraction.
D. It acts as a reservoir for coronary blood flow during diastole
A. It anchors the heart valves and provides a rigid attachment for the myocardium.
Which statement best describes the histologic difference between Purkinje fibers and
ordinary cardiac muscle fibers?
A. Purkinje fibers are larger and have abundant myofibrils.
B. Ordinary cardiac muscle fibers lack intercalated discs.
C. Purkinje fibers have fewer myofibrils and more glycogen.
D. Ordinary cardiac muscle fibers are non-striated and multinucleate
C. Purkinje fibers have fewer myofibrils and more glycogen.
What is the distinguishing feature of the epicardium when compared to the
endocardium?
A. Presence of endothelial cells in the epicardium
B. Adipose tissue and mesothelial cells in the epicardium
C. Dense connective tissue in the epicardium
D. Purkinje fibers in the epicardium
B. Adipose tissue and mesothelial cells in the epicardium
A histologic slide of heart tissue shows a layer lined by simple squamous epithelium,
with underlying connective tissue and scattered Purkinje fibers. Which layer of the
heart does this most likely represent?
A. Epicardium
B. Myocardium
C. Endocardium
D. Pericardium
C. Endocardium
What is the resting membrane potential for the ventricles & atria?
A. -60 mV
B. -55 mV
C. -70 mV
D. -90mV
D. -90mV
In which phase of the ventricular muscle action potential is potassium permeability the
highest?
A. PHASE 0
B. PHASE 2
C. PHASE 3
D. PHASE 4
C. PHASE 3
The slow response action potential is responsible for which phase of the ventricular
action potential?
A. PHASE 1
B. PHASE 2
C. PHASE 3
D. PHASE 4
B. PHASE 2
During the relative refractory period, the cardiac muscle cells are:
A. Fully excitable to all types of stimuli
B. Partially excitable to stronger than normal stimuli
C. Completely unresposive to any stimuli
D. In a resting state with no electrical activit
B. Partially excitable to stronger than normal stimuli
Which of the following is the only pathway for cardiac impulse to travel from the atria to
the ventricle?
A. Bundle of His
B. Anterior internodal pathway of Bachman
C. Middle internodal pathway of Wenkebach
D. Posterior internodal pathway of Thorel
Which is the primary pacemaker of the heart?
A. SA NODE
B. AV NODE
C. BUNDLE OF HIS
D. PURKINJE FIBERS
If the SA node discharges at 0.00 sec., when will the action potential normally arrive at
the epicardial surface at the base of the left ventricle?
A. 0.09 SEC.
B. 0.12 SEC
C. 0.18 SEC.
D. 0.22 SEC.
D. 0.22 SEC.
Which of the following statements is true about the characteristics of Cardiac Muscles in
contrast to Skeletal Muscles?
A. Cardiac Muscles are striated muscles while skeletal muscles are non- striated.
B. Muscular contraction of cardiac muscles is voluntary while that of skeletal
muscles are involuntary.
C. The cardiac muscles contain one centrally placed nucleus while skeletal muscles have numerous, peripherally-located nucleus
D. Gap junctions are present both in cardiac and skeletal muscles
C. The cardiac muscles contain one centrally placed nucleus while skeletal muscles have numerous, peripherally-located nucleus
The dark areas crossing the muscle fibers which separate individual cardiac muscle cells
from one another is called?
A. Gap Junctions
B. Intercalated Discs
C. T- Tubules
D. Sarcoplasmic Reticulum
B. Intercalated Discs
Which of the following shows the chronological sequence of excitation- contraction
coupling of cardiac muscles?
A. Sarcoplasmic reticulum releases calcium ions into the sarcoplasm— Action
potential spreads through the Transverse T- Tubules— Sliding of actin and
myosin filaments with one another producing muscle contraction.
B. Action potential spreads through the Transverse T- Tubules— Sarcoplasmic
reticulum releases calcium ions into the sarcoplasm— Sliding of actin and
myosin filaments with one another producing muscle contraction.
C. Sarcoplasmic reticulum releases sodium ions into the sarcoplasm— Sliding of
actin and myosin filaments with one another producing muscle contraction—
Action potential spreads through the Transverse T- Tubules.
D. Sliding of actin and myosin filaments with one another producing muscle
contraction— Action potential spreads through the Transverse T- Tubules—
Sarcoplasmic reticulum releases calcium ions into the sarcoplasm.
B. Action potential spreads through the Transverse T- Tubules— Sarcoplasmic
reticulum releases calcium ions into the sarcoplasm— Sliding of actin and
myosin filaments with one another producing muscle contraction.
The strength of cardiac muscle contraction is highly dependent of which of the following
ions from the extracellular fluid?
A. Sodium
B. Potassium
C. Chloride
D. Calcium
D. Calcium
Eliciting an action potential in a cardiac muscles causes either depolarization along the
entire membrane or no response at all, this response is called?
A. Graded Response
B. Temporal Summation
C. All-or- Nothing Principle
D. Excitation- Contraction Coupling
C. All-or- Nothing Principle
Which of the following steps directly removes the inhibition of the actin- myosin
interaction by troponin- tropomyosin complex?
A. Calcium released from the sarcoplasmic reticulum binding to Troponin C.
B. Removal of bound Calcium from Troponin C.
C. Intracellular Calcium binds to SERCA and is returned to the sarcoplasmic
reticulum.
D. Opening of the voltage- gated sodium channels to allow depolarization
A. Calcium released from the sarcoplasmic reticulum binding to Troponin C.
In Calcium Regulation by the cardiac muscles, which of the following decreases
intracellular calcium?
A. L- Type Calcium Channels
B. Voltage- Gated Sodium Channels
C. T- Type Calcium Channels
D. Calcium ATPase Pump
D. Calcium ATPase Pump
