Chapter 20.3
The resting membrane potential of cardiac contraction cells is A -90mV B: -55mV You got it wrong' C: -70mV D: +30MV
A. -90 mV
The length of time from R to R on an EKG is A: 0.8 seconds B: 0.4 seconds C1 minute D: 0.3 seconds
A. 0.8 seconds
Pacemaker potentials, unlike hyperpolarizing potentials will allow which of the following to occur? A: activate the Sino-atrial node to fire B: acrivate a nerve impulse thrrough the AV bundle C: allow a nerve impulse to pass through the bundle branches D: activate the Auricular-ventricular node to fire
A. Activate the SA node to fire
Contraction of ventricle contractile fibers corresponds to __________ deflection wave on an ECG. A: QRS complex B: P wave C: T wave D: P-Q segment
A. QRS complex
The plateau in the cardiac muscle allows for A: additional time before repolarization B: increased strength of contraction C: immediate muscle contraction D: increased heart rate
A. additional time before repolarization
During cardiac muscle repolarization A. calcium channels close and potassium channels open B. sodium channels open and calcium channels close C. calcium channels open and sodium channels close D. potassium channels close
A. calcium channels close and potassium channels open
Epinephrine enhances the flow of calcium into the heart cells. Which of the following would be expected from an increase in calcium? A: increase strength of contraction You got it right B: slow depolarization C: decrease strength of contraction D: fast repolarization
A. increase strength of contraction
Hypercalcaemia will A: increase the strength of the contraction B: decrease the strength of the contraction C: decrease the firing at the SA node D: increase the firing at the SA node
A. increase the strength of contraction
The refractory period is long in cardiac cells to allow for A: increased filling time B: increased contractions C: decreased filling time D atrial tetany
A. increased filling time
The majority of calcium that causes a cardiac contraction comes from A: interstitial fluid B: cytosol of the cell C: sarcoplasmic reticulum D: nodal cells
A. interstitial fluid
A calcium-induced calcium release from the sarcolemma results in A: plateau B: repolarization C: depolarization D: threshold
A. plateau
Cardiac cells undergo a prolonged depolarization phase called A: plateau B: resting membrane potential C: absolute refractory period D: tetany
A. plateau
Autorhythmicity of the cardiac pacemaker cells occurs because A: the SA node has an unstable resting potential B: the SA node is innervated by the sympathetic nervous system C: the SA node is innervated by the parasympathetic nervous system D: the SA node has a stable resting potential
A. the SA node has an unstable resting potential
The period of sustained depolarization called the "plateau" is due in part by A: voltage gated slow Ca++ channels B: epinephrine C: voltage gated fast NA+ channels D: voltage gated K+ channels
A. voltage gated slow Ca+2 channels
The plateau phase of the cardiac action potential is, in part, due to A: voltage gated slow calcium channels B: ligand channels C: voltage gated fast sodium ion channels D voltage gated potassium channels
A. voltage gated slow calcium channels
From the SA node, the electrical signal travels to the ____ node, located in the interatrial septum.
AV node
The prolonged depolarization (plateau) in cardiac contraction cells is due to A. Inflow of K+ and outflow of Ca+2 B. Inflow of Ca+2 and outflow of K+ C. Inflow of Ca+2 and outflow of Ca+2 D. Inflow of Ca+2 only
B. Inflow of Ca+2 and outflow of K+
When atrial fibers depolarize what deflection wave is present? A. T wave B. P wave C. QRS complex D. S-T segment
B. P wave
Increased parasympathetic simulation results in A: increased heart rate B: a decrease in the rate of depolarization at the SA node C: increased strength of myocardial contraction D: increased stroke volume
B. a decrease in the rate of depolarization at the SA node
The intercalated disk of a cardiac cell A: is the point of attachment for actin and myosin B: contains gap junctions to allow for transmission of ions C: is the point synapse between the nerve and the cardiac cell D: transmits calcium ions into the sarcolemma
B. contains gap junctions to allow for transmission of ions
Unlike skeletal muscle fibers, cardiac muscles A: are arranged in parallel bundles B: contract as a single coordinated unit C: must be stimulated by a nerve to contract D: lack patterns of actin and myosin
B. contract as a single coordinated unit
An increase in extracellular potassium (hyperkalemia) would result in A: increase in heart rate B: decrease in heart rate This is correct answer C: increase in stroke volume D: decrease in afterload
B. decrease in heart rate
Hyperkalemia can be detected on an electrocardiogram by A: elevated P wave B: elevated T wave C: depressed Q wave D: long S-T segment
B. elevated T wave
The heart manufactures ATP primarily by the use of A: glucose B: fatty acids C: creatine phosphate D: lactic acid
B. fatty acids
In order for the Sino-atrial node to fire, which type of nerve impulse is required? A: graded potential B: pacemaker potential C: action potential D: hyperpolarizing potential
B. pacemaker potential
The rapid influx of NA+ into the cardiac contraction fibers results in A: repolarization B: rapid depolarization C: threshold D: plateau
B. rapid depolarization
The delay of the electrical signal at the atrioventricular node (AV) allows for A: the electrical signal to cross both right and left atrium B: the atria to contract and empty the blood into the ventricles C: prolonged resting phase in the atrial chambers D: depolarization of the ventricles
B. the atria to contract and empty the blood into the ventricles
Which is longer? A. the refractory period in skeletal muscle fibers B. the refractory period in cardiac muscle fibers
B. the refractory period in cardiac muscle fibers
Which of the following is not true of cardiac contractile fibers? A: They reach threshold by voltage-gated fast NA+ channels. B: They are groups of cells capable of autorhythmic actions. C They are located in the myocardium. D: They propagate action potential via gap junctions in intercalated discs.
B. they are groups of cells capable of autorhythmic actions
Which of the following are true of cardiac contractile fibers? A: They connect the atria and ventricular chambers. B: They sustain a prolonged depolarization phase called a plateau. C: They spontaneously generate an action potential. D: They branch and send signals down the interventricular septum.
B. they sustain a prolonged depolarization phase called a plateau
Which of the following terms is not associated with cardiac muscle fibers? A: striated B: voluntary C: multinucleated D: intercalated disks
B. voluntary
Place the following components of the conducting system of the heart in the sequence they transmit a signal. 1. AV node. 2. Left and right bundle branches. 3. SA node. 4. Purkinje fibers. 5. AV bundle (bundle of HIS). A: 3, 4, 5, 2, 1 B: 5, 2, 3, 1, 4 C: 3, 1, 5, 2, 4 D: 4, 3, 2, 1, 5
C. SA Node, AV Node, AV bundle, LT RT Bundle Branches, Purkinje Fibers
Which component of the conduction system provides the only electrical connection between the atria and the ventricles? A: AV node B: Purkinje fibers C: bundle of HIS D: SA node
C. bundle of HIS
An action potential spreads across the atrial and ventricular chambers as follows A: depolarization, repolarization, plateau B: plateau, depolarization, repolarization C: depolarization, plateau, repolarization D: repolarization, depolarization, plateau
C. depolarization, plateau, repolarization
Depolarization of cardiac contractile fibers occurs because of A. slow voltage gated Ca+2 channels opening B. Fast voltage gated channels opening C. fast voltage gated Na+ channels opening D. slow voltage gated Na+ channels opening
C. fast voltage gated Na+ channels opening
Which of the following muscle characteristics are found only on cardiac muscle? A. striations B. Sarcoplasmic Reticulum C. Intercalated Disks D. Actin and Myosin
C. intercalated disks
The sinoatrial node's natural rhythm is 100 bpm. What causes the resting heart rate to be 75 beats per minute? A: sympathetic nervous system B: hormones C parasympathetic nervous system D: the action of the atrioventricular node (AV)
C. parasympathetic nervous system
All of the following are true of myocardial heart cells except A: they contract as a single unit B: they undergo depolarization that results in a "plateau" C: they must be innervated by the autonomic nervous system to contract D: they are connected across the atrial walls by intercalated disks
C. they must be innervated by the ANS to contract
Damage is done to the SA node and the patient's heart beat is 50 bpm. Which conduction component is maintaining this rhythm? A: sympathetic nervous system B: parasympathetic nervous system C: Purkinje fibers D: AV node
D. AV Node
If the SA node is damaged which of the following set of nodal cells maintain the heart rhythm. A. Purkinje Fibers B. bundle of HIs C. bundle branches D. AV node
D. AV node
Which of the following statements about SA node is incorrect? A. it can depolarize spontaneously without nervous stimulation B. It is the pacemaker of the heart C. It propagates action potentials that reach the Purkinje cells D. It is in the left atrial wall
D. It is in the left atrial wall
Which component of the conduction radiate into the myocardium in the ventricles? A: SA node B: AV node C: Bundle branches D: Purkinje fibers
D. Purkinje fibers
Which of the following spontaneously generate action potentials the faster? A: Purkinje fibers B: bundle of HIS C: AV node D: SA node
D. SA Node
An ECG electrocardiogram when compared to a previous test can determine all except A. if the conducting pathway is abnormal B. enlarged heart C. If regions of the heart are damaged D. brain waves
D. brain waves
The myocardium of the heart receives oxygenated blood A as blood circulates through the heart chambers B: from the pulmonary veins C: during ventricle systole D: during ventricle diastole
D. during ventricle diastole
If the vagal nerve is severed A: preload increases B: stroke volume decreases C: heart rate decreases D: heart rate increases
D. heart rate increases
Which of the following is not true of the left ventricle? A: It pumps oxygenated blood out of the aorta. B: It contains papillary muscles that anchor the bicuspid valve. C: The myocardial wall is thicker than the other chambers. D: It is depolarized by the AV node (atrioventricular node).
D. it is depolarized by the AV node
All of the following modify the timing or rate of the heart, except A: parasympathetic nerve B: hormones C: sympathetic nerve D: sinoatrial node
D. sinoatrial node
Which of the following cardiac nodal cells establish the normal rhythm and are called "natural pacemaker" cells? A: atrioventricular (AV) node cells B: Purkinje fibers C: atrioventricular node cells D: sinoatrial node cells
D. sinoatrial node cells
The R deflection wave on an electrocardiogram indicates A: ventricular repolarization B: atrial repolarization C atrial depolarization D: ventricular depolarization
D. ventricular depolarization
Identify the type of channels that activate initially during the depolarization of the heart. A: voltage gated slow calcium channels B: voltage gated potassium channels C: ligand channels D: voltage gated fast sodium ion channels
D. voltage gated fast sodium ion channels
the second depolarization wave seen on a normal ECG is a _____ complex, which represents ventricular depolarization.
QRS
The cardiac excitation of the heart normally begins at the ____ node.
SA
The Q-T interval extends from the start of the QRS complex to the end of the ____ wave.
T
The component of the conduction system that provides the only electrical connection between the atria and ventricles is the _____ bundle.
atrioventricular
The T wave on an ECG represents ventricular ______.
repolarization
During the plateau calcium influx is balanced by the efflux of ____ ions.
potassium
The length of time in a normal ECG from R to R is ____ seconds.
0.8
Atrial depolarization occurs in 0.03 sec and is visualized on an ECG as the _____ wave.
P
In a typical ECG the first deflection wave is the ____ wave, which measures atrial depolarization.
P
