Chapter 20 - The Heart

Calculate cardiac output if the heart rate is 125 beats/minute, the end-diastolic volume is 130 ml, and the end-systolic volume is 40 ml.

11,250 ml / min

In an adult at rest, the end-diastolic volume is typically

130 mL.

The following are structural components of the conducting system of the heart. 1. Purkinje fibers 2. AV bundle 3. AV node 4. SA node 5. bundle branches The sequence in which excitation would move through this system is

4, 3, 2, 5, 1.

At rest, the end-systolic volume (ESV) is what percent of the end-diastolic volume (EDV)?

40%

The following is a list of vessels and structures that are associated with the heart. What is the correct order for the flow of blood entering from the systemic circulation?1. right atrium 2. left atrium 3. right ventricle 4. left ventricle 5. venae cavae 6. aorta 7. pulmonary trunk 8. pulmonary veins

5, 1, 3, 7, 8, 2, 4, 6

What is considered a "normal" cardiac output when resting? Please provide units.

5-7.5 L/min

Calculate the cardiac output of a patient with a heart rate of 100 beats/minute and a stroke volume of 75 ml.

7500 ml / min

What is the ligamentum arteriosum?

A remnant of the ductus arteriosus

During ventricular systole, the

AV valves are closed

How is heart rate controlled? Dual innervation controls the heart rate. Parasympathetic and sympathetic divisions of the ANS control heart rate. Heart rate is controlled through the cardiac plexus. All the listed answers are correct.

All the listed answers are correct.

Considering the left ventricle, why does isovolumetric ventricular contraction occur during ventricular systole?

Aortic pressure is higher than ventricular pressure and the ventricle must pressurize the blood to open the aortic valve

________ is to slow heart rate as ________ is to fast heart rate.

Bradycardia; tachycardia

T or F: Oxygenated blood flows through the right side of the heart.

F

________ is when the heart can't maintain adequate cardiac output.

Heart failure

Which of the following statements is correct concerning the cardiac cycle? The event of the cardiac cycle that completes ventricular filling is ventricular systole. At the beginning of the cardiac cycle, the atria are relaxed and the ventricles are contracting. The backflow of blood towards the ventricles causes the semilunar valves to open. In late ventricular diastole, all chambers are relaxed and filling to about seventy percent of their capacity. The first event of ventricular systole is ventricular ejection.

In late ventricular diastole, all chambers are relaxed and filling to about seventy percent of their capacity.

Name the ridged bundles of muscle found projecting inside the right atrium.

Pectinate muscles

What is the function of the coronary circulation?

Provide a blood supply to the heart

Identify the valve located at the exit of the right ventricle.

Pulmonary semilunar valve

Depolarization of the ventricles is represented on an electrocardiogram by the

QRS complex

Hypertension increases ________ causing stroke volume to ________.

afterload; decrease

When heart rate increases, the time spent in

all phases decreases but most of the decrease is during diastole.

The __________ valve prevents backward flow of blood into the left ventricle.

aortic

The ________ carry blood away from the heart.

arteries

The earlike extension of the atrium is the

auricle

The property of heart muscle to contract in the absence of neural or hormonal stimulation is called

automaticity

Which of the following would not increase heart rate? faster depolarization of the pacemaker potential increased sympathetic stimulation of SA node increased levels of epinephrine beta blocking drugs decreased parasympathetic stimulation of nodal fibers

beta blocking drugs

The ________ valve prevents backward flow into the left atrium.

bicuspid

With each ventricular systole,

blood pressure increases.

During the plateau phase of the cardiac action potential, which ion is entering the cardiac muscle cell?

calcium

The long plateau phase of the cardiac muscle action potential is due to1QQA

calcium channels remaining open.~A

Most of the middle layer in the heart wall is composed of

cardiac muscle cells

The term used to describe fluid collecting in the pericardial cavity that restricts the movement of the heart is known as

cardiac tamponade.

The coronary sinus drains the ________ into the ________.

cardiac veins; right atrium

The cusps (leaflets) of atrioventricular valves attach directly to

chordae tendineae

The first heart sound ("lubb") is associated with

closing of the atrioventricular valves.

The structures responsible for distributing excitation to the contractile cells are

conducting cells

The first blood vessels to branch from the aorta are the ________ arteries.

coronary

The term ________ refers to blockage in the coronary circulation.

coronary artery disease

If the force of ventricular contraction increases, what will happen to the end-systolic volume?

decrease

The P wave of the electrocardiogram is a signal from

depolarization of the atria

Which of the following would cause stroke volume to increase?

drugs that stimulate beta-1 receptors

The ________ is the volume of blood in a ventricle at the beginning of systole.

end-diastole volume

The ________ is the amount of blood in a ventricle after it has contracted and before it begins to refill.

end-systolic volume

The amount of blood remaining in the ventricle when the semilunar valve closes is the

end-systolic volume.

The visceral pericardium is the same as the

epicardium

The moderator band is found on both the right and left side of the heart. T or F

false

The structure that permits blood flow from the right atrium to the left atrium in the fetal circulation is the

foramen ovale

If the pacemaker cells in the SA node become more permeable to potassium ions, the`

heart rate will decrease and cells will hyperpolarize.

Which of the following factors does NOT occur during exercise? increased stroke volume increased preload increased afterload decreased afterload

increased afterload

The ________ is shared by the two ventricles.

interventricular septum

During the beginning of ventricular systole when the muscle is contracting but not enough pressure has built up to open the semilunar valves the heart is said to be in

isovolumetric contraction.

The AV node delay is beneficial because

it allows time for the atria to contract.

What happens to the electrical impulse when it reaches the AV node?

it gets delayed

Blood returning to the heart from the pulmonary circuit first enters the

left atrium

In mitral valve prolapse, the cusps of the mitral valve are pushed into the

left atrium.

Which chamber has the thickest wall?

left ventricle

An MI that affects the ________ side of the heart is more severe because it has to pump blood with ________ force.

left; more

The ________ side of the heart supplies blood to the systemic circuit, while the ________ side of the heart supplies blood to the pulmonary circuit. (Figure 20-1)

left; right

In the middle of the thoracic cavity is a region occupied by the heart, great vessels, thymus, esophagus, and trachea called the

mediastinum

Heart rate is controlled by neurons of the cardiovascular center located in the

medulla oblongata.

Gradual drifting of membrane potential toward threshold in autorhythmic cells is termed a

pacemaker potential.

Each of the following factors will increase cardiac output except increased parasympathetic stimulation. venous return. sympathetic stimulation. force of contraction. heart rate.

parasympathetic stimulation.

Contractions of the papillary muscles

prevent the atrioventricular valves from reversing into the atria.

Oxygen is added to blood as it flows through the ________ circuit.

pulmonary

Blood leaves the right ventricle by passing through the

pulmonary valve.

The right atrium receives blood from all of the following structures except the systemic circuit. coronary sinus. pulmonary veins. superior vena cava. inferior vena cava.

pulmonary veins.

Compared to the right ventricle, the left ventricle has all the following characteristics except is round in cross section. produces about four to six times more pressure when it contracts. works harder.has a thicker wall. pumps a greater volume.

pumps a greater volume.

The backward flow of blood from a ventricle to its atrium or from a outflow vessel to its ventricle is called

regurgitation.

Stroke volume depends on all of the following factors except the contractility of the ventricle. venous return of blood to the heart. respiratory rate. end diastolic volume. the pressure required to pump blood into the aorta.

respiratory rate.

Blood returning to the heart from the systemic circuit first enters the

right atrium.

Which chamber of the heart exits into the pulmonary trunk?

right ventricle

Which of the following are involved in the pulmonary circuit?

right ventricle, pulmonary trunk, left atrium

The pulmonary valve prevents backward flow into the

right ventricle.

The endocardium consists of this type of tissue.

simple squamous epithelium

The normal pacemaker of the heart is located in

sinoatrial node

Which ion's entry causes rapid depolarization? Which ion's entry causes the plateau? Which ion's exit causes repolarization?

sodium; calcium; potassium21`

The volume of blood ejected from each ventricle during a contraction is called the

stroke volume.

Cardiac output is increased by

sympathetic stimulation.

The phase in the cardiac cycle when the mitral valve is closed and the aortic valve is open is the

systolic ejection phase.

Tetanic muscle contractions don't occur in a normal cardiac muscle because

the refractory period lasts until the muscle relaxes.

Identify the right atrioventricular valve.

tricuspid valve

Beginning with the right atrium, what is the order of the valves through which blood will pass?

tricuspid valve, pulmonary valve, mitral valve, aortic valve

The ________ carry blood toward the heart.

veins

The amount of blood returning to the heart is the

venous return

Which factor directly influences preload?

venous return

The heart spends most of the cardiac cycle in which phase?

ventricular diastole

The T wave on an ECG tracing represents

ventricular repolarization