Chapter 20- The Heart

Systemic Circulation?

(left side of heart) it receives bright red oxygenated blood from the lungs. ventricle ejects blood into aorta →to separate streams entering progressively smaller system arteries → to all organs throughout body except alveoli of lungs Arteries to small diameter arterioles to extensive beds of systemic capillaries

What is the cardiac output of a patient with a stroke volume of 70 mL/ventricular contraction whose heart rate is 90 beats/minute?

6300 mL/minute

Where in the conduction system do action potentials propagate most slowly?

Action potentials propagate most slowly through the AV node.

Which are correct? Valves open and close in response to pressure changes The chordae tendineae and papillary muscles stop the atrioventricular valves from everting in response to high ventricular pressure. The atrioventricular valves are closed by filling of cusps by backflow of blood. All of these statements are correct.

All are correct

What is the significance of an enlarged Q wave?

An enlarged Q wave may indicate a myocardial infarction (heart attack).

self excitable, pacemakers, Form the conduction system of the heart Describe what?

Auto rhythmic fibers of the heart

The plateau phase of the action potential in cardiac muscle is due to the inflow of what?

Ca2+ Calcium ions

Veins in the myocardium drain into the

Coronary Sinus

Which diagnostic procedure for CAD is used to visualize coronary blood vessels?

Coronary angiography is used to visualize many blood vessels.

The left ventricle refills with blood in preparation for initiation of the next cardiac cycle during ventricular?

Diastole

K+ moves out of the cell

During repolarization of a cardiac muscle fiber

T of F: The left ventricular pressure must be greater than the aortic pressure during ventricular ejection so that blood will move out through the pulmonary arteries.

False

T or F: Baroreceptors monitor changes in blood chemistry.

False

T or F: During fetal development, an opening called the foramen ovale allows blood in the right and left ventricles to mix.

False

T or F: The coronary artery carries blood to the right atrium

False

T or F:A top endurance athlete could have a cardiac reserve half their resting cardiac output.

False

T or F:Blood enters the systemic circuit of blood flow by passing through the pulmonary valve.

False

T or F:Blood pressure is highest in the aorta during ventricular diastole.

False

T or F:Cardiac muscle fibers produce much of their energy by way of anaerobic respiration

False

T or F:Skeletal muscle fibers are more branched than cardiac muscle fibers.

False

T or F: During plateau, depolarization is maintained because potassium inflow balances sodium outflow.

False - Calcium inflow

T or F: Bradycardia is a condition in which the resting heart rate is greater than 80 beats per minute.

False - under 50 beats per minute

What is the role of HDL?

HDL removes excess cholesterol from body cells and transports it to the liver for elimination.

The closing of the semilunar valves corresponds with the second?

Heart sound

Release of norepinephrine from nerve fibers causes

Increase heart rate and increase force of contraction

During exercise, increased muscle contraction helps return more blood to the heart. This would lead to

Increased stroke volume

Which patients are candidates for cardiac transplantation?

Individuals with end‐stage heart failure or severe coronary artery disease are candidates for cardiac transplantation.

Internally, the right and left halves of the heart are separated by the?

Interatrial and Interventricular septa

During which two periods of the cardiac cycle do the heart muscle fibers exhibit isometric contraction?

Isovolumetric contraction and relaxation

Nervous regulation of the heart originates in the

Medulla

What are the heart membrane and wall layers

Membrane = Pericardium (outer), Serous Pericardium of parietal layer(inner) Pericardial cavity (empty space), Serous layer of visceral layer Heart Wall = Epicardium (serous pericardium visceral layer), Myocardium, and Endocardium

Embryologically, the heart is a derivative of the

Mesoderm

From which tissue does the heart develop?

Mesoderm

Would more blood flow through the heart during ventricular systole or ventricular diastole?

More blood would flow during ventricular diastole because the vessels are open.

Which numbers constitute the pulmonary circulation? Which constitute the systemic circulation?

Numbers 2 (right ventricle) through 6 (left atrium) depict the pulmonary circulation; numbers 7 (left ventricle) through 1 (right atrium) depict the systemic circulation.

When is the partitioning of the heart complete?

Partitioning of the heart is complete by the end of the fifth week.

Tachycardia refers to

Rapid Heart Rate

Which is incorrect? S1, the first heart sound, is associated with blood turbulence associated with closure of the atrioventricular valves at the beginning of ventricular diastole. S2, the second heart sound, is associated with blood turbulence associated with closure of the semilunar valves at the beginning of ventricular diastole. S3, the third heart sound, is due to blood turbulence during rapid atrial filling. S4, the fourth heart sound is due to blood turbulence during atrial systole.

S3, the third heart sound, is due to blood turbulence during rapid atrial filling

What represents the correct sequence of flow of an electrical impulse through the heart?

SA node, AV node, AV bundle, Purkinje fibers

Preload Contractility of the individual ventricular muscle fibers Afterload or the pressure that must be exceeded before ejection of blood from the ventricles can occur. All effect

Stroke Volume

Which of the following statements is correct? The auricles are extensions of the ventricles which serve to increase the ventricular volume. The coronary sulcus marks the boundary between the two ventricles. Sulci contain coronary blood vessels. Trabeculae carneae are muscular ridges on the interior wall of the right atrium

Sulci contain coronary blood vessels.

Which four developmental defects occur in tetralogy of Fallot?

Tetralogy of Fallot involves an interventricular septal defect, an aorta that emerges from both ventricles, a stenosed pulmonary valve, and an enlarged right ventricle.

The left anterior descending artery supplies blood to:

The Walls of both ventricles

How much blood remains in each ventricle at the end of ventricular diastole in a resting person? What is this volume called?

The amount of blood in each ventricle at the end of ventricular diastole—called the end‐diastolic volume—is about 130 mL in a resting person.

Which coronary blood vessel delivers oxygenated blood to the walls of the left atrium and left ventricle?

The circumflex artery delivers oxygenated blood to the left atrium and left ventricle.

Whats Incorrect? The coronary sinus empties into the left atrium. Portions of the interior wall of the right atrium have pectinate muscles while the walls of the left atrium are smooth. The left atrium receives blood from 4 pulmonary veins. The left and right ventricles contain chordae tendineae and trabeculae carneae.

The coronary sinus empties into the left atrium

The coronary sulcus forms an external boundary between which chambers of the heart?

The coronary sulcus forms a boundary between the atria and ventricles.

How does the duration of an action potential in a ventricular contractile fiber compare with that in a skeletal muscle fiber?

The duration of an action potential is much longer in a ventricular contractile fiber (0.3 sec = 300 msec) than in a skeletal muscle fiber (1-2 msec).

In what two ways does the fibrous skeleton contribute to the functioning of heart valves?

The fibrous skeleton attaches to the heart valves and prevents overstretching of the valves as blood passes through them.

Which heart sound is related to blood turbulence associated with closure of the atrioventricular valves?

The first heart sound (S1), or lubb, is associated with closure of the atrioventricular valves.

How does thickness of the myocardium relate to the workload of a cardiac chamber?

The greater the workload of a heart chamber, the thicker its myocardium.

When during embryonic development does the primitive heart begin to contract?

The heart begins to contract by the twenty‐second day of gestation.

What are the functions of intercalated discs in cardiac muscle fibers?

The intercalated discs hold the cardiac muscle fibers together and enable action potentials to propagate from one muscle fiber to another.

What is the mediastinum

The mediastinum is the anatomical region that extends from the sternum to the vertebral column, from the first rib to the diaphragm, and between the lungs.

Which component of the conduction system provides the only electrical connection between the atria and the ventricles?

The only electrical connection between the atria and the ventricles is the atrioventricular bundle.

How do papillary muscles prevent atrioventricular valve cusps from everting (swinging upward) into the atria?

The papillary muscles contract, which pulls on the chordae tendineae and prevents cusps of the atrioventricular valves from everting and letting blood flow back into the atria.

What node contains autorhythmic fibers that repeatedly generate action potentials

The sinoatrial node

When you are exercising, contraction of skeletal muscles helps return blood to the heart more rapidly. Would this tend to increase or decrease stroke volume?

The skeletal muscle "pump" increases stroke volume by increasing preload (end‐diastolic volume).

What region of the heart is innervated by the sympathetic division but not by the parasympathetic division?

The ventricular myocardium receives innervation from the sympathetic division only.

Which layer is both a part of the pericardium and a part of the heart wall?

The visceral layer of the serous pericardium (epicardium) is both a part of the pericardium and a part of the heart wall.

T or F: An ECG is helpful in determining if the cardiac conduction path is abnormal, if the heart is enlarged, if certain regions of the heart are damaged, or the cause of chest pain.

True

T or F: Chordae tendineae stabilize the bicuspid valve and prevent it from prolapsing.

True

T or F: Deoxygenated blood is found in the right ventricle.

True

T or F: Gap junctions in the intercalated disks allow action potentials to pass from one cardiac muscle cell to another.

True

T or F: In a mitral valve prolapse, a portion of the bicuspid valve protrudes into the left atrium.

True

T or F: Is this the correct flow of blood through the heart? Right atrium, tricuspid valve, right ventricle, pulmonary semilunar valve, pulmonary artery, lungs, pulmonary veins, left atrium, bicuspid valve, left ventricle, aortic semilunar valve.

True

T or F: Purkinje fibers transmit the action potential from the apex of the heart to the ventricles.

True

T or F: Regular exercise increases cardiac output, decreases blood pressure, aids in weight control and increases fibrinolytic activity.

True

T or F: The fibrous skeleton of the heart consists of four dense connective tissue rings surrounding the valves of the heart.

True

T or F: The interatrial septum septum separates the ventricles from the atria.

True

T or F: The pericardium consists of a fibrous and serous layer. The visceral layer of the serous pericardium may be referred to as the epicardium.

True

T or F: The right atrium receives blood from the coronary sinus.

True

T or F: The right ventricle is not as thick as the left ventricle since the left ventricle pumps blood throughout the body.

True

T or F:Cardiac output equals the stroke volume multiplied by the heart rate.

True

T or F:The right atrium receives blood from the superior and inferior vena cava and the coronary sinus while the left atrium receives blood from the 4 pulmonary veins.

True

Why is ventricular fibrillation such a serious arrhythmia?

Ventricular fibrillation is such a serious arrhythmia because ventricular pumping stops, blood ejection ceases, and circulatory failure and death can occur without immediate medical intervention.

What occurs during that portion of the EKG designated as the P wave?

atrial myocardium depolarizes

Tension in the chordae tendineae and papillary muscles during ventricular systole prevent

backflow of blood into the atria

The first heart sound is associated with

both atrioventricular valves closing during ventricular systole

Which of the following is NOT a congenital heart defect? coarctation of the aorta coronary artery disease atrial septal defect tetralogy of Fallot patent ductus arteriosus

coronary artery disease

Positive inotropic agents

increase contractility of the heart

The atrioventricular (AV) bundle (bundle of His)

is the only site where action potentials can conduct from the atria to the ventricles.

Nerve impulses that reach the heart by means of the vagus nerve are

parasympathetic and cause decreased heart rate

When the left ventricle fails, blood backs up in the lungs, causing

pulmonary edema

Pulmonary Circulation?

receives all dark red deoxygenated blood returning from systemic circulation. Blood ejected from right ventricle → pulmonary trunk which branches → pulmonary arteries that carry blood → lungs.

increased maximal cardiac output during strenuous exercise comes from...

regular aerobic training

What represents the correct pathway of blood moving from the superior vena cava to the lungs?

right atrium, tricuspid valve, right ventricle, pulmonary semilunar valve

Which of the following is a risk factor for developing coronary artery disease? getting 20 minutes of aerobic exercise three times a week maintaining a weight proportionate to your height not smoking sedentary life style having high HDL levels and low LDL levels

sedentary life style

The right atrium receives blood directly from 3 vessels. They are the

superior vena cava, inferior vena cava, and coronary sinus

The plateau phase of depolarization of muscle fibers in the ventricles of the heart extends from

the QRS to the T wave of the ECG

The Frank-Starling law of the heart states that

the volume of blood that enters the heart during diastole directly affects the force of contraction at systole

Most of the heart lies in what direction

to the left of midline of the thoracic cavity

The ridges formed by raised bundles of cardiac muscle fibers on the internal surface of the ventricles are called the?

trabeculae carneae

Blood flows from the right atrium to the right ventricle through the _____ valve.

tricuspid

T or F: Cardiac output is the volume of blood ejected from the left ventricle into the aorta each minute.

true

T or F:The relationship between preload and end diastolic volume is referred to as the Frank-Starling law.

true

T or F; The cardiovascular system is one of the first to develop because the rapidly growing embryo needs to obtain oxygen and nutrients and get rid of waste products.

true

Ventricular systole is caused by

ventricular depolarization

Asynchronous, haphazard, ventricular contractions are characteristic of interventricular septal defect coarctation of the aorta ventricular fibrillation Tetralogy of Fallot

ventricular fibrillation

When the ventricles relax

ventricular pressure drops

The T wave on an EKG is due to?

ventricular repolarization

The outer layer of the heart, called the epicardium, is also the

visceral layer of the pericardium