Bisc 207 Ch.17

What percentage of the total number of cardiac muscle cells are pacemaker cells?

1%

Calculate the end-systolic volume (ESV) if the end-diastolic volume (EDV) in a resting heart is 110 ml and stroke volume (SV) is 70 ml.

40 ml

The amount of blood remaining in each ventricle at the end of the ventricular ejection phase is normally about:

50 ml

Calculate the cardiac output if the heart rate is 100 beats per minute and the stroke volume is 65 ml.

6500 ml/min

Approximately how much blood is pumped from each ventricle during the ventricular ejection phase?

70 ml

What percentage of atria blood flows passively into the ventricles?

80%

According to the Frank-Starling law, a bigger preload will result in __________.

A stronger contraction

Which of the following chemical messengers decreases heart rate?

Acetylcholine

Which of the following terms refers to the force the ventricles must overcome to eject blood into their respective arteries?

Afterload

Where does the left ventricle send blood?

Aorta

What blood vessels do ventricles always pump blood into?

Arteries

Which of the following events is not part of the cardiac cycle?

Atrial contraction phase *Is: Isovolumetric relaxation phase, Ventricular filling phase, & Isometric contraction phase

Which hormone decreases cardiac output by decreasing blood volume and preload?

Atrial natriuretic peptide

What allows the atria and ventricles to depolarize and contract separately?

Atrioventricular (AV) node delay

What might happen if the papillary muscles and/or chordae tendineae stopped functioning?

Blood would leak back into the atria from the ventricles.

What cardiac dysrhythmia does a patient have with a resting heart rate of 50 beats per minute?

Bradycardia

The plateau phase of the cardiac action potential is due to __________.

Ca2++ influx

How do cardiac cells sustain a membrane potential of around 0 mV during the plateau phase?

Calcium channels remain open

Which of the following ion channels are time-gated closing channels?

Calcium ion channels

What condition results from excess fluid in the pericardial cavity compressing the heart and reducing the capacity of the ventricles to fill with blood?

Cardiac tamponade

What structure attaches the cusps of the atrioventricular valves to the papillary muscles?

Chordae tendineae

Which coronary artery supplies the left atrium and parts of the left ventricle?

Circumflex artery

Which of the following events can be heard most easily with a stethoscope?

Closing of atrioventricular valves

Which of the following cell populations does not spontaneously generate action potentials in the cardiac conduction system?

Contractile cells *Do: Atrioventricular node, Purkinjie fibers, & Sinoatrial node

What provides a graphic representation of all the action potentials occurring in the heart?

Electrocardiogram

The visceral pericardium is the same as the ________.

Epicardium

What are the three layers of the heart wall from superficial to deep?

Epicardium, myocardium, and endocardium

T/F: There are two phases of the cardiac cycle in which all four heart valves are open: the isovolumetric contraction phase and the isovolumetric relaxation phase.

False

What is the most superficial layer of the pericardial sac?

Fibrous pericardium

Which opening in the interatrial septum of the fetal heart connects the right and left atrium?

Foramen ovale

Which of the following blood vessels are associated with the coronary sinus?

Great cardiac

What kind of ion channels are unique to pacemaker cells?

HCN channels

Which of the following factors would increase cardiac output to the greatest extent?

Increased heart rate and increased stroke volume

Which of the following statements best describes the apex of the heart?

Inferior tip of the heart and points toward the left side.

Looking in a microscope, what are the visible structures that join cardiac muscle cells?

Intercalated discs

Which of the following structural components is only found in cardiac muscles?

Intercalated discs

During what phase is the S1 heart sound first heard?

Isovolumetric contraction phase

Which of the following statements describes the total refractory period of cardiac muscle?

It is longer than the total refractory period for skeletal muscle.

Which cardiac chamber has the thickest wall?

Left ventricle

Which chamber generates the highest pressure during systole?

Left ventricle

What wave on the electrocardiogram (ECG) occurs during the ventricular ejection phase of the cardiac cycle?

P wave

Which wave on the electrocardiogram (ECG) corresponds with the ventricular filling phase of the cardiac cycle?

P wave

A damaged atrioventricular (AV) bundle or AV node will primarily affect the length of the __________.

P-R interval

Which of the following structures is associated with the atria?

Pectinate muscles

During what part of the action potential will calcium ions enter the contractile cell?

Plateau phase

What is a contractile cell with a membrane potential of 0 mV experiencing?

Plateau phase

The degree of stretch experienced by the sarcomeres in the ventricle cells before they contract is called __________.

Preload

Which of the following blood vessels is not a great blood vessel of the heart?

Pulmonary arteries *Is: pulmonary trunk, superior vena cava, & pulmonary veins

Which vessel is guarded by a semilunar valve at its base?

Pulmonary trunk

Which of the following vessels carries oxygenated blood?

Pulmonary vein

Oxygenated blood is delivered to the left atrium through the ____________.

Pulmonary veins

Which of the following pacemaker cell populations has the slowest intrinsic rate of depolarization at about 20 times per minute?

Purkinjie fiber system

What obscures atrial repolarization on an electrocardiogram (ECG)?

QRS complex

Which wave on the electrocardiogram (ECG) represents ventricular depolarization?

QRS complex

Which electrocardiogram (ECG) finding can be used to measure heart rate?

R-R interval

What is initiated by a rapid influx of sodium ions into contractile cells creating a positive membrane potential inside the cell?

Rapid depolarization phase

What valve prevents the backflow of blood from the right ventricle into the right atrium?

Right atrioventricular valve (tricuspid valve)

Which of the following paths does an action potential in the heart normally take?

SA node atrial contractile cells AV node where it is delayed AV bundle right and left bundle branches Purkinje fibers ventricular contractile cells

What normally serves as the pacemaker of the entire heart?

Sinoatrial (SA) node

Which of the following pacemaker cell populations has the fastest intrinsic rate of depolarization at about 60-70 times or more per minute?

Sinoatrial (SA) node

What is the volume of blood pumped out by one ventricle per heart beat?

Stroke volume (SV)

What two values are needed to calculate cardiac output (CO) for a ventricle?

Stroke volume (SV) and heart rate (HR)

What part of an electrocardiogram (ECG) represents ventricular repolarization?

T wave

What activity is occurring in the heart during the Q-T interval on an electrocardiogram (ECG)?

The ventricular cells are undergoing action potentials.

Which of the following statements best describes how coronary artery anastomoses might help a patient with coronary artery disease?

They provide alternate routes of blood flow when a vessel is blocked.

Which of the following functions is not associated with the heart?

To increase the rate at which erythrocytes are formed *Are: To produce a hormone called atrial natriuretic peptide, To pump blood through two different sets of vessels or circuits, & To help maintain homeostasis of blood pressure

T/F: The sympathetic nervous system increases cardiac output by increasing both heart rate and stroke volume.

True

Which cranial nerves have a negative chronotropic effect on heart rate?

Vagus nerve (CN X)

Which of the following cardiac dysrhythmias is immediately life-threatening and manifests on the electrocardiogram (ECG) with chaotic activity?

Ventricular fibrillation

The electrical impulse is __________ as it passes through the AV node, which permits the atria to contract __________ ventricles.

accelerated; before

The P wave on an electrocardiogram (ECG) represents the depolarization of cells in the __________.

atria

The P wave on an electrocardiogram (ECG) represents the depolarization of cells in the:

atria

Which valve is situated between the left atrium and left ventricle?

bicuspid (mitral) valve

The mitral valve is the clinical name for the ______________.

bicuspid valve

Autorhythmicity in the heart is a function of ________.

cardiac pacemaker cells

Inotropic agents affect:

contractility

Digoxin is a positive inotropic agent derived from the foxglove family of plants. Which of the following is an effect of digoxin?

decreased ESV

The right side of the heart receives:

deoxygenated blood from the systemic circuit

The maximum amount of blood in the ventricles at the end of the ventricular filling phase is called __________.

end-diastolic volume

What largely determines preload?

end-diastolic volume (EDV)

Which of the following volumes should be the greatest?

end-diastolic volume (EDV)

High pressured blood in the ventricles:

forces the semilunar valves open

The concentration gradient for calcium ions...

has the same direction as the concentration gradient for sodium ions.

When is the S2 heart sound heard?

isometric relaxation phase

Which of the following is not a risk factor for coronary artery disease or myocardial ischemia?

low blood pressure *Is: smoking, male gender, & older than age 50 for females

Which of the following is NOT a population of pacemaker cells in the heart?

papillary muscles?

AV valves close when

pressure in the ventricles increases

What is the function of the valves in the heart?

prevent backflow of blood through the heart

Which of the following does NOT return blood to the right atrium of the heart?

pulmonary vein *Does: Superior vena cava, Inferior vena cava, & coronary sinus

The right and left atria depolarize and contract following the arrival of the action potential from the __________.

sinoatrial (SA) node

What two values are needed in order to calculate cardiac output (CO) for a ventricle?

stroke volume (SV) and heart rate (HR)

The vessels that deliver oxygen to the tissues of the body are part of the __________.

systemic circuit

Afterload is described as:

the force the ventricles must overcome to eject blood into their respective arteries.

Blood in the right atrium should travel next past the ________.

tricuspid valve and into the right ventricle

Both the left and right atria receive blood from ________.

veins

The chambers that have just emptied when the second heart sound is heard are the __________

ventricles

Ventricular systole begins during the __________ phase of the cardiac cycle.

ventricular filing