Anatomy 2 Test 3
C
A prolonged Q-T interval on an ECG is indicative of: a) Enlarged ventriclesb) Cardiac ischemiac) Repolarization abnormalityd) Atrial fibrillation
D
At what point does the atrioventricular valve open on the Wiggers diagram? a) During ventricular systoleb) During isovolumetric contractionc) During ventricular diastoled) During atrial systole
B
At which point on the Wiggers diagram do the semilunar valves open? a) Atrial systoleb) Ventricular systolec) Isovolumetric contractiond) Ventricular ejection
A
Cardiac muscle cells have several similarities with skeletalmuscle cells. Which of the following is not a similarity?a) The cells are each innervated by a nerve ending.b) The cells store calcium ions in the sarcoplasmic reticulum.c) The cells contain sarcomeres.d) The cells become depolarized when sodium ions enter thecytoplasm.
B
During isovolumetric contraction in the cardiac cycle, what is the status of the heart valves? a) Both atrioventricular valves are open.b) Both atrioventricular valves are closed.c) Both semilunar valves are open.d) Both semilunar valves are closed.
C
During the depolarization phase of the action potential in contractile cardiac muscle cells, what is the change in membrane potential? a) The membrane potential becomes more negative. b) The membrane potential remains constant at -90 mV. c) The membrane potential becomes more positive, reaching approximately +30 mV. d) The membrane potential becomes more positive, reaching approximately -30 mV.
D
During the sequence of excitation in the heart's intrinsic conduction system, which structure follows the right and left bundle branches? a) Sinoatrial node b) Atrioventricular node c) Atrioventricular bundle d) Subendocardial conducting network (Purkinje fibers)
C
During ventricular ejection in the cardiac cycle, what is the status of the heart valves? a) Both atrioventricular valves are open.b) Both atrioventricular valves are closed.c) Both semilunar valves are open.d) Both semilunar valves are closed.
C
During which phase of the cardiac cycle does the atria contract, pushing blood into the ventricles? a) Atrial diastoleb) Ventricular systolec) Atrial systoled) Ventricular diastole
C
During which phase of the cardiac cycle on the Wiggers diagram does ventricular volume remain constant? a) Atrial systoleb) Ventricular systolec) Isovolumetric contractiond) Ventricular ejection
C
During which phase of ventricular systole does blood get ejected from the ventricles into the pulmonary artery and aorta? a) Atrial systoleb) Isovolumetric relaxationc) Ventricular ejectiond) Atrial diastole
C
During which phase on the Wiggers diagram do both the atrioventricular and semilunar valves remain closed? a) Atrial systoleb) Ventricular systolec) Isovolumetric contractiond) Ventricular ejection
C
Enlarged R waves on an ECG are often associated with: a) Cardiac ischemiab) Ventricular arrhythmiasc) Enlarged ventriclesd) Atrial fibrillation
C
Following the transmission through the atrioventricular bundle, which specific cardiac structures continue the propagation of impulses before reaching the subendocardial conducting network (Purkinje fibers)? a) Sinoatrial node b) Atrioventricular node c) Right and left bundle branches d) Atria
D
From ventricular ejection to isovolumetric relaxation in the cardiac cycle, what happens to the status of the heart valves? a) Both atrioventricular valves open.b) Both atrioventricular valves close.c) Both semilunar valves open.d) Both semilunar valves close.
C
How can changes in patterns or timing of an electrocardiogram (ECG) be indicative of heart-related issues? a) Changes in patterns or timing may indicate increased blood pressure. b) Changes in patterns or timing may reveal diseases affecting the lungs. c) Changes in patterns or timing may suggest abnormalities in the heart's conduction system or damage to the heart. d) Changes in patterns or timing may point to gastrointestinal problems.
D
How do mechanical events in the heart relate to electrical events seen on an electrocardiogram (ECG)? a) They have no relationb) They occur simultaneouslyc) Mechanical events precede electrical eventsd) Mechanical events follow electrical events
A
How does a 12-lead electrocardiogram (ECG) differ from a single-lead ECG? a) A 12-lead ECG records electrical activity from 12 different points on the body, while a single-lead ECG records from only one point. b) A 12-lead ECG measures blood pressure changes, while a single-lead ECG measures heart rate. c) A 12-lead ECG records mechanical contractions of the heart, while a single-lead ECG records electrical activity. d) A 12-lead ECG uses electrodes placed inside the heart, while a single-lead ECG uses electrodes placed on the body.
C
How does ventricular pressure change in relation to ventricular volume on the Wiggers diagram? a) Ventricular pressure decreases as ventricular volume increasesb) Ventricular pressure increases as ventricular volume increasesc) Ventricular pressure and volume have an inverse relationshipd) Ventricular pressure and volume have a direct relationship
B
How is an electrocardiogram (ECG or EKG) different from a tracing of a single action potential? a) ECG records mechanical contractions of the heart, while a single action potential tracing records electrical activity. b) ECG is a composite of all action potentials at a given time, while a single action potential tracing records voltage differences. c) ECG measures blood pressure changes, while a single action potential tracing measures heart rate. d) ECG electrodes are placed inside the heart, while single action potential electrodes are placed on the body.
A
How is the heartbeat modified by the autonomic nervous system (ANS) through the cardiac centers located in the medulla oblongata? a) Direct control over heart rate and contraction strength b) Indirect influence through hormonal regulation c) Coordination of cardiac muscle repair processes d) Regulation of blood pressure within the heart
A
In a normal heart, which of the following structures isresponsible for setting the heart's pace?a) Sinoatrial nodeb) Atrioventricular nodec) Atrioventricular bundled) Purkinje fibers
C
In the absence of input from the AV node, what is the spontaneous depolarization rate of the AV bundle and subendocardial conducting network? a) Accelerated b) Synchronous c) Slowed d) Consistent
A
In which type of muscle does the influx of calcium ions (Ca2+) primarily trigger the release of calcium ions (Ca2+) from the sarcoplasmic reticulum (SR)? A) Skeletal muscle B) Smooth muscle C) Cardiac muscle D) Striated muscle
C
Predict the nature of an ECG recording when theatrioventricular node becomes the pacemaker.a) There would continue to be a normal sinus rhythm.b) The P wave would be much larger than normal.c) The rhythm would be slower.d) The T wave would be much smaller than normal.
C
Repolarization in contractile cardiac muscle cells is primarily due to: a) Closure of voltage-gated sodium channelsb) Opening of voltage-gated calcium channelsc) Efflux of potassium ionsd) Influx of chloride ions
B
The plateau portion of the action potential in contractile cardiacmuscle cells is due to:a) an increased potassium permeability.b) an influx of calcium ions.c) an influx of sodium ions.d) exit of calcium ions from the sarcoplasmic reticulum.
D
The presence of intercalated discs between adjacentcardiac muscle cells causes the heart to behave as a__________.a) single chamberb) contractile myofibrilc) desmosomed) functional syncytium
D
The stimulus for the heart's rhythmic contractions comes from_________.a) intercalated discsb) acetylcholinec) a neuromuscular junctiond) a pacemaker potential
C
What are the benefits of longer action potentials (AP) and contractions in contractile cardiac muscle cells? a) Longer AP and contractions allow for rapid ejection of blood. b) Longer AP and contractions promote relaxation of the heart muscle. c) Longer AP and contractions ensure efficient ejection of blood and prevent tetanic contractions. d) Longer AP and contractions increase the risk of arrhythmias.
C
What characteristic distinguishes the sinoatrial (SA) node from the rest of the myocardium in terms of depolarization? a) It depolarizes at the same rate as the rest of the myocardium. b) It depolarizes slower than the rest of the myocardium. c) It depolarizes faster than the rest of the myocardium. d) It does not depolarize.
A
What characterizes diastole in the cardiac cycle? a) Period of heart relaxationb) Period of heart contractionc) Period of atrial contractiond) Period of ventricular ejection
B
What characterizes the electrical activity observed in ventricular fibrillation? a) Organized pacing by the SA nodeb) Random occurrence of action potentials throughout the ventriclesc) Presence of distinct P, Q, R, S, and T waves on the ECGd) Regular and coordinated contraction of the ventricles
C
What does a normal sinus rhythm on an electrocardiogram (ECG) indicate? a) Abnormal pacing with missing wavesb) Slow heart rate with irregular intervalsc) Normal pacing with all waves presentd) Rapid heart rate with inverted T waves
B
What does an elevated or depressed S-T segment on an electrocardiogram (ECG) typically indicate? a) Enlarged ventriclesb) Cardiac ischemiac) Repolarization abnormalityd) Ventricular arrhythmias
B
What does systole represent in the cardiac cycle? a) Period of heart relaxationb) Period of heart contractionc) Period of atrial relaxationd) Period of ventricular filling
B
What does the aortic pressure represent on the Wiggers diagram? a) Pressure in the left ventricleb) Pressure in the aortac) Pressure in the left atriumd) Pressure in the right ventricle
C
What does the cardiac cycle represent in terms of physiological changes? a) Series of heart rate fluctuationsb) Series of blood pressure variationsc) Series of pressure and blood volume changesd) Series of oxygen saturation fluctuations
B
What does the cardiac cycle represent? a) Period of heart contractionb) Blood flow through the heart during one complete heartbeatc) Electrical activity of the heartd) Contraction of atrial muscles
A
What follows atrial systole and diastole in the cardiac cycle? a) Ventricular systole and diastoleb) Atrial relaxationc) Ventricular relaxationd) Electrical repolarization
D
What is a distinctive feature of the atrioventricular (AV) bundle (bundle of His) in terms of its connectivity with the atria and ventricles? a) It is directly connected to the atria but not to the ventricles. b) It is directly connected to the ventricles but not to the atria. c) It is connected to both the atria and ventricles via gap junctions. d) It is the only electrical connection between the atria and ventricles
D
What is a notable characteristic of the fibers in the atrioventricular (AV) node compared to other cardiac fibers? a) They are larger in diameter. b) They have more gap junctions. c) They are located in the atria. d) They are smaller in diameter and have fewer gap junctions.
B
What is a significant difference in the duration of action potentials (AP) between contractile muscle fibers in skeletal muscle and cardiac muscle? a) AP in skeletal muscle lasts 200 ms, while in cardiac muscle it lasts 1-2 ms. b) AP in skeletal muscle lasts 1-2 ms, while in cardiac muscle it lasts 200 ms. c) AP in skeletal muscle lasts 100 ms, while in cardiac muscle it lasts 50 ms. d) AP in skeletal muscle lasts 50 ms, while in cardiac muscle it lasts 100 ms.
B
What is a significant difference in the duration of contraction between contractile muscle fibers in skeletal muscle and cardiac muscle? a) Contraction in skeletal muscle lasts over 200 ms, while in cardiac muscle it lasts 15-100 ms. b) Contraction in skeletal muscle lasts 15-100 ms, while in cardiac muscle it lasts over 200 ms. c) Contraction in skeletal muscle lasts 50 ms, while in cardiac muscle it lasts 100 ms. d) Contraction in skeletal muscle lasts 100 ms, while in cardiac muscle it lasts 50 ms.
C
What is the approximate pacing rate of the atrioventricular bundle in the heart's electrical conduction system? a) 100 bpm b) 40-60 bpm c) 30-40 bpm d) 20-30 bpm e) 10-20 bpm
C
What is the complete pathway of the subendocardial conducting network, also known as Purkinje fibers, within the heart? a) Through the atria into the interventricular septum b) Through the atrioventricular (AV) node into the ventricular walls c) Through the interventricular septum into the apex and ventricular walls d) Through the atrioventricular (AV) bundle into the atria
C
What is the first phase of the action potential in cardiac pacemaker cells, characterized by the gradual depolarization of the cell membrane? a) Repolarization phase b) Hyperpolarization phase c) Pacemaker potential d) Threshold phase e) Refractory phase
D
What is the function of the atrioventricular (AV) node within the heart's intrinsic conduction system? a) It accelerates the transmission of impulses. b) It initiates the depolarization of the ventricles. c) It conducts impulses across the interventricular septum. d) It delays the transmission of impulses by approximately 0.1 second.
E
What is the pacing rate of the subendocardial conducting network (Purkinje fibers) in the heart's electrical conduction system? a) 100 bpm b) 40-60 bpm c) 30-40 bpm d) 20-30 bpm e) 10-20 bpm
D
What is the primary direction of impulse transmission for the right and left bundle branches within the heart? a) Toward the base of the heart b) Toward the atria c) Toward the interventricular septum d) Toward the apex of the heart
C
What is the primary purpose of electrocardiography? a) To measure blood pressure in the heart b) To detect the mechanical contractions of the heart c) To monitor the electrical currents generated by the heart d) To assess the oxygen levels in the heart
C
What is the purpose of the delay in impulses within the atrioventricular (AV) node? a) To accelerate ventricular contraction b) To initiate atrial contraction c) To synchronize atrial and ventricular contractions d) To slow down the transmission of impulses
D
What is the sequence of contraction initiation within the heart following the activation of the subendocardial conducting network, also known as Purkinje fibers? a) Atrial contraction followed by ventricular contraction b) Simultaneous contraction of both atria and ventricles c) Ventricular contraction followed by atrial contraction d) Sequential contraction from apex towards atria
A
What occurs during isovolumetric relaxation on the Wiggers diagram? a) Ventricular pressure decreases while volume remains constantb) Ventricular pressure increases while volume remains constantc) Ventricular pressure and volume both decreased) Ventricular pressure and volume both increase
B
What occurs during ventricular systole in the cardiac cycle? a) Relaxation of the ventriclesb) Contraction of the ventricles, forcing blood out of the heartc) Relaxation of the atriad) Filling of the ventricles with blood
C
What process occurs during the repolarization phase of the action potential in typical cardiac pacemaker cells? a) Sodium channels open, leading to an influx of sodium ions b) Chloride channels open, allowing chloride ions to enter the cell c) Potassium channels open, resulting in an efflux of potassium ions d) Voltage-gated calcium channels open, causing an influx of calcium ions into the cell e) Voltage-gated calcium channels close, leading to repolarization of the cell
C
What represents atrial pressure on the Wiggers diagram? a) The pressure in the left ventricleb) The pressure in the aortac) The pressure in the left atriumd) The pressure in the right ventricle
C
What structures are responsible for conducting electrical impulses through the interventricular septum? a) Sinoatrial (SA) node b) Atrioventricular (AV) node c) Right and left bundle branches d) Purkinje fibers
C
When do the atrioventricular valves close on the Wiggers diagram? a) During atrial systoleb) During isovolumetric contractionc) During ventricular systoled) During ventricular diastole
C
When do the semilunar valves close on the Wiggers diagram? a) During ventricular systoleb) During isovolumetric contractionc) During ventricular diastoled) During atrial systole
C
When does ventricular pressure reach its peak on the Wiggers diagram? a) During ventricular diastoleb) During isovolumetric contractionc) During ventricular ejectiond) During isovolumetric relaxation
C
Where is the atrioventricular (AV) bundle, also known as the bundle of His, located within the heart? a) In the right atrial wall b) In the left atrial wall c) In the superior interventricular septum d) In the inferior interventricular septum
B
Where is the atrioventricular (AV) node located within the heart? a) In the superior interatrial septum b) In the inferior interatrial septum c) In the interventricular septum d) In the left ventricular wall
B
Where is the sinoatrial (SA) node located within the heart? a) In the left atrial wall b) In the right atrial wall c) In the interventricular septum d) In the left ventricular wall
A
Which component of the heart's electrical conduction system is primarily responsible for setting the pace at approximately 100 beats per minute (bpm)? a) Sinoatrial node b) Atrioventricular node c) Atrioventricular bundle d) Right and left bundle branches e) Subendocardial conducting network (Purkinje fibers)
D
Which component of the heart's electrical conduction system typically sets the pace at approximately 30-40 beats per minute (bpm)? a) Sinoatrial node b) Atrioventricular node c) Atrioventricular bundle d) Right and left bundle branches e) Subendocardial conducting network (Purkinje fibers)
B
Which component of the heart's electrical conduction system typically sets the pace at approximately 40-60 beats per minute (bpm)? a) Sinoatrial node b) Atrioventricular node c) Atrioventricular bundle d) Right and left bundle branches e) Subendocardial conducting network (Purkinje fibers)
B
Which component of the heart's intrinsic conduction system is responsible for transmitting impulses to the atrioventricular bundle? a) Sinoatrial node b) Atrioventricular node c) Right and left bundle branches d) Subendocardial conducting network (Purkinje fibers)
D
Which heart abnormality has no P waves on an otherwisenormal ECG?a) Second-degree heart blockb) Ventricular fibrillationc) Aortic fibrillationd) Junctional rhythm
B
Which nerve carries parasympathetic signals from the cardioinhibitory center to inhibit the SA and AV nodes, thereby decreasing the heart rate? a) Trigeminal nerve b) Vagus nerve c) Optic nerve d) Facial nerve
B
Which of the following best explains why cardiac muscle fibers have a longer absolute refractory period compared to skeletal muscle fibers? A) It facilitates tetanic contractions. B) It prevents tetanic contractions. C) It enhances muscle relaxation. D) It increases muscle endurance.
C
Which of the following characteristics best describes cardiac muscle cells? A) Smooth B) Long C) Striated D) Unconnected
D
Which of the following features is typically observed in cardiac muscle cells? A) Multiple nuclei B) No nucleus C) Two central nuclei D) One central nucleus
C
Which of the following statements accurately describes the difference in mitochondrial content and oxygen dependence between cardiac and skeletal muscle? A) Skeletal muscle has more mitochondria and relies heavily on oxygen, while cardiac muscle has fewer mitochondria and can function without oxygen. B) Both skeletal and cardiac muscle have similar mitochondrial content and oxygen dependence. C) Cardiac muscle has more mitochondria and relies heavily on oxygen, while skeletal muscle has fewer mitochondria and can function without oxygen. D) Skeletal muscle has more mitochondria and can function without oxygen, while cardiac muscle has fewer mitochondria and relies heavily on oxygen.
D
Which of the following statements accurately describes the distribution of the subendocardial conducting network, also known as Purkinje fibers, within the heart? a) It is equally distributed on both sides of the heart. b) It is more elaborate on the right side of the heart. c) It is primarily located in the interatrial septum. d) It is more elaborate on the left side of the heart.
A
Which of the following statements best describes the difference in energy metabolism between skeletal and cardiac muscle? A) Skeletal muscle primarily relies on anaerobic respiration, while cardiac muscle relies on aerobic respiration. B) Cardiac muscle primarily relies on anaerobic respiration, while skeletal muscle relies on aerobic respiration. C) Both skeletal and cardiac muscle rely almost exclusively on aerobic respiration. D) Both skeletal and cardiac muscle primarily rely on anaerobic respiration.
C
Which of the following statements best describes the purpose of the longer absolute refractory period in cardiac muscle fibers compared to skeletal muscle fibers? A) It facilitates rapid contraction of the heart. B) It prevents fatigue during prolonged contraction. C) It allows the heart to relax and fill efficiently for optimal pumping. D) It enables sustained muscle tension for prolonged periods.
C
Which part of the autonomic nervous system is responsible for increasing both the rate and force of the heartbeat by stimulating the SA and AV nodes, heart muscle, and coronary arteries? a) Parasympathetic nervous system b) Somatic nervous system c) Sympathetic nervous system d) Enteric nervous system
D
Which phase of the action potential in contractile cardiac muscle cells involves the influx of calcium ions and the efflux of potassium ions, contributing to the plateau? a) Depolarizationb) Repolarizationc) Hyperpolarizationd) Plateau phase
C
Which phase of the cardiac cycle represents the relaxation of the heart chambers, allowing them to fill with blood? a) Ventricular systoleb) Atrial systolec) Ventricular diastoled) Atrial diastole
C
Which phase of ventricular systole involves the contraction of the ventricles while all valves are closed, preventing blood from entering or leaving the ventricles? a) Atrial contractionb) Ventricular relaxationc) Isovolumetric contractiond) Ventricular diastole
D
Which statement accurately contrasts the metabolic capabilities of skeletal and cardiac muscle under conditions of low oxygen availability? A) Skeletal muscle can perform aerobic respiration when oxygen is not present, while cardiac muscle cannot. B) Both skeletal and cardiac muscle can perform aerobic respiration when oxygen is not present. C) Cardiac muscle can perform fermentation when oxygen is not present, while skeletal muscle cannot. D) Skeletal muscle can undergo fermentation when oxygen is not present, while cardiac muscle cannot.
C
Which statement accurately contrasts the stimulation requirement between pacemaker cells in cardiac tissue and skeletal muscle fibers? A) Pacemaker cells require nervous system stimulation, while skeletal muscle fibers do not. B) Both pacemaker cells and skeletal muscle fibers require nervous system stimulation. C) Skeletal muscle fibers require nervous system stimulation, while pacemaker cells do not. D) Neither pacemaker cells nor skeletal muscle fibers require nervous system stimulation.
C
Which statement accurately describes the T tubules in cardiac muscle cells? A) T tubules are numerous and enter the cell multiple times at the Z disc. B) T tubules are absent in cardiac muscle cells. C) T tubules are wider but less numerous and enter the cell only once at the Z disc. D) T tubules are narrower and enter the cell multiple times at the M line.
B
Which statement accurately describes the chambers of the heart? a) Both atria and ventricles can be contracted simultaneously.b) Both atria and ventricles cannot be contracted at the same time, but both can be relaxed at the same time.c) Only the atria can be contracted during ventricular relaxation.d) Both atria and ventricles contract and relax independently of each other.
B
Which statement accurately describes the difference in absolute refractory period between cardiac and skeletal muscle fibers? A) Cardiac muscle fibers have a shorter absolute refractory period than skeletal muscle fibers. B) Cardiac muscle fibers have a longer absolute refractory period than skeletal muscle fibers. C) Both cardiac and skeletal muscle fibers have similar absolute refractory periods. D) Neither cardiac nor skeletal muscle fibers have an absolute refractory period.
A
Which statement accurately describes the difference in adaptability to alternative fuel sources between skeletal and cardiac muscle? A) Skeletal muscle can use other fuel sources but does not require oxygen, while cardiac muscle is more adaptable to other fuels but must have oxygen. B) Both skeletal and cardiac muscle are equally adaptable to other fuel sources and do not require oxygen. C) Cardiac muscle can use other fuel sources but does not require oxygen, while skeletal muscle is more adaptable to other fuels but must have oxygen. D) Neither skeletal nor cardiac muscle can use alternative fuel sources, and both must have oxygen.
C
Which statement accurately describes the sarcoplasmic reticulum (SR) in cardiac muscle? A) The SR in cardiac muscle is more complex than in skeletal muscle, forming triads. B) The SR in cardiac muscle is absent. C) The SR in cardiac muscle is simpler than in skeletal muscle and lacks triads. D) The SR in cardiac muscle is more extensive than in skeletal muscle, with multiple triads.
B
Which statement accurately describes the self-excitatory nature of the heart and its relationship with the nervous system? a) The heart requires nervous system stimulation for depolarization and contraction. b) The heart depolarizes and contracts without nervous system stimulation, but the rhythm can be influenced by the autonomic nervous system. c) The heart relies solely on nervous system stimulation for both depolarization and contraction. d) The heart does not depolarize or contract in the absence of nervous system stimulation.
D
Which statement accurately describes the valves of the heart? a) The atrioventricular valves (tricuspid and mitral valves) open during ventricular contraction.b) The semilunar valves (pulmonary and aortic valves) remain closed during ventricular relaxation.c) Both sets of valves can be open at the same time.d) Both sets of valves cannot be open at the same time, but both can be closed at the same time.
C
Which statement accurately distinguishes between the physiological characteristics of skeletal and cardiac muscle regarding tetanic contractions? A) Tetanic contractions can occur in both skeletal and cardiac muscles. B) Tetanic contractions cannot occur in skeletal muscles but can in cardiac muscles. C) Tetanic contractions can occur in skeletal muscles but not in cardiac muscles. D) Tetanic contractions are equally likely to occur in both skeletal and cardiac muscles.
D
Which structural component found in intercalated discs of cardiac muscle cells holds the cells together and prevents them from separating during contraction? A) Myofibrils B) Sarcomeres C) Gap junctions D) Desmosomes
D
Which structure found in intercalated discs of cardiac muscle cells allows ions to pass from cell to cell, thus electrically coupling adjacent cells? A) Myofibrils B) Sarcomeres C) Desmosomes D) Gap junctions
C
Which term describes the coordinated contraction of the heart as a single unit? A) Sarcoplasmic reticulum B) Triads C) Functional syncytium D) Skeletal muscle physiology
D
Which term describes the unstable resting membrane potentials exhibited by cardiac pacemaker cells? a) Threshold potentials b) Action potentials c) Resting potentials d) Pacemaker potentials e) Depolarization potentials
C
Which term refers to the gradual depolarization of the cell membrane in cardiac pacemaker cells, leading to the initiation of an action potential? a) Repolarization potential b) Hyperpolarization potential c) Pacemaker potential d) Threshold potential e) Refractory potential
A
Which type of cells are noncontractile and spontaneously depolarize? A) Pacemaker cells B) Smooth muscle cells C) Skeletal muscle cells D) Cardiac muscle cells
C
Which type of muscle cells possess the unique characteristic of being self-excitable? A) Smooth muscle cells B) Skeletal muscle cells C) Cardiac muscle cells D) Striated muscle cells
B
Which type of myocytes are primarily responsible for contraction? A) Smooth myocytes B) Contractile myocytes C) Skeletal myocytes D) Cardiac myocytes
B
Why does the membrane potential of typical cardiac pacemaker cells never flatline? a) Due to the absence of ion channels b) Because of continuous oscillations in ion concentrations c) In response to external electrical stimulation d) To maintain a constant resting potential e) As a result of irreversible depolarization
