Chapter 18 mastering A & P
Which portion of the electrocardiogram represents the time during which the ventricles are in systole?
The Q-T interval is the period from the beginning of ventricular depolarization through ventricular repolarization, during which the ventricles are in systole
What separates the parietal and visceral pericardium?
The pericardial cavity separates the parietal and visceral pericardium. This cavity contains serous fluid that lubricates the visceral and parietal membranes
Which chamber receives blood from the superior and inferior vena cavae?
The right atrium receives unoxygenated blood from the systemic circuit.
The heart is actually (one, two, or three) pumps?
2; Yes, the right side of the heart pumps to/from the lungs (pulmonary circuit) and the left side of the heart pumps to/from the rest of the body (the systemic circuit).
Select the correct statement about the function of myocardial cells. A) Cardiac muscle cells are innervated by sympathetic, parasympathetic, and somatic nerve fibers so that the nervous system can increase heart rate. B)The entire heart contracts as a unit or it does not contract at all. C)The refractory period in skeletal muscle is much longer than that in cardiac muscle. D)The influx of potassium ions from extracellular sources is the initiating event in cardiac muscle contraction.
B) The entire heart contracts as a unit or it does not contract at all
Which statement regarding cardiac muscle structure is accurate? A) Cardiac cells possess fewer mitochondria than other types of muscle cells. B) Cardiac cells are long, cylindrical, and multinucleate. C) Myofibrils of cardiac muscle tissue vary in diameter and branch extensively. D) Cardiac muscle cells are independent of one another both structurally and functionally.
C) Myofibrils of cardiac muscle tissue vary in diameter and branch extensively. The myofibrils of cardiac muscle have various diameters; they also branch in order to maintain connections, via intercalated discs, with other muscle cells.
atrioventricular valves
between atria and ventricles
How would a decrease in blood volume affect both stroke volume and cardiac output?
decreased stroke volume and no change in cardiac output Yes, a decreased blood volume would decrease the end diastolic volume, thus lowering the stroke volume. Although this would initially lead to a decrease in the cardiac output, heart rate would increase because of increased activity of the sympathetic nervous system in an effort to maintain cardiac output.
In what direction does blood flow through the heart?
from a region of high pressure to a region of low pressure
How would an increase in the sympathetic nervous system increase stroke volume?
increased contractility A increase in sympathetic nervous system activity would increase contractility (by increasing available calcium), thus increasing stroke volume. Contractility causes an increase in stroke volume by decreasing end systolic volume; it does not change end diastolic volume.
The structure that prevents backflow of blood into the left atrium is the
mitral (bicuspid) valve
Which layer of the heart wall contracts and is composed primarily of cardiac muscle tissue?
myocardium is composed of cardiac muscle and a dense network of connective tissue.
Into which chamber of the heart do the superior vena cava, inferior vena cava, and coronary sinus return deoxygenated blood?
right atrium
What prefix means ventricle of heart
ventricle
Tachycardia
Abnormally rapid heartbeat
The vessel that carries oxygen-rich blood to tissues is the
Aorta
Which best describe the isovolumetric contraction phase of the cardiac cycle?
As ventricular systole starts, the AV valves are closed and the semilunar valves are closed. Because the ventricles are contracting and both valves are closed, pressure increases rapidly leading to ejection. This closed pressure system is important for the ventricles to be able to generate enough pressure to open the semilunar valves and eject blood from the heart.
The ____________ carries oxygen-poor venous blood of the coronary circulation into the right atrium
Coronary Sinus
Isovolumetric relaxation is characterized by which of the following?
During isovolumetric relaxation, all valves into and out of the ventricles remain closed. This prevents blood from flowing backward through the heart.
True or False: The moderator band is found on both the right and left side of the heart.
False The moderator band is a cord like structure found in the right ventricle. It contains portions of the cardiac conduction system that help convey the electrical message for the ventricles to contract. It works as a shortcut within the cardiac conduction system.
wWhat muscle is particularly associated with anchoring the right and left atrioventricular valves?
Papillary muscles contract to tense the right and left atrioventricular valves via the chordae tendineae just before ventricular systole.
What prefix means atrium.
atri
The prefix means electricity.
electro
What is the main function of heart valves?
prevent the backward flow of blood
Which of the following descriptions does not describe atrioventricular (AV) valves? - open based on pressure changes in the atria versus the ventricle -anchored inferiorly by specialized connective tissue - flap-like -formed from pocket-like cups
-AV valves are flap-like because they have one free edge.
By what mechanism would an increase in venous return increase stroke volume?
increased end diastolic volume Yes, an increase in venous return increases the end diastolic volume. The fibers are stretched more, resulting in an increase in the force of contraction (preload, or the Frank-Starling Mechanism).
What is a branch of the right coronary artery?
The posterior interventricular artery is a branch of the right coronary artery, although an anastomosis with the circumflex artery meets with it near its origin.
Isovolumetric relaxation and ventricular filling (two phases of the cardiac cycle) take place during __________.
Ventricular Diastole. Isovolumetric relaxation and ventricular filling occur during ventricular diastole when the ventricles are not actively contracting and ejecting blood.
At what point in the cardiac cycle does the semilunar valve open?
When pressure in the ventricle exceeds pressure in the aorta, the semilunar valve opens. This allows blood to be ejected from the ventricle
Name the ridged bundles of muscle found projecting inside the right atrium.
Pectinate muscle are located inside the right and left ventricles. They form large mountainous structures that attach to the chordae tendineae
What is equivalent to the ventricular volume during isovolumetric relaxation?
End systolic volume (ESV) Isovolumetric relaxation occurs at the beginning of ventricular diastole when the ventricular volume is at its minimum value−the end systolic volume (ESV). Because no volume changes occur during isovolumetric relaxation, ventricular volume remains at this value throughout the phase.
Which of the following would increase heart rate? A) decreased activity of the sympathetic nervous system B)acetylcholine C)increased activity of the parasympathetic nervous system D)epinephrine and norepinephrine
Epinephrine and norepinephrine Yes, secreted by the adrenal medulla as a result of sympathetic stimulation, these hormones act as part of the sympathetic response, increasing heart rate.
True or false: The base of the heart is located at the bottom of the heart.
False
Describe the pressures in the atria and ventricles that would cause the opening of the AV valves.
Higher pressure in the atria than in the ventricles forces the AV valves to open and blood moves into the ventricles
Identfiy the valve located at the exit of the right ventricle.
The pulmonary valve is the semilunar valve found between the right ventricle and the pulmonary trunk. Deoxygenated blood travels through the pulmonary valve as it exits the right side of the heart on its way to the lungs.
Which heart chamber pumps unoxygenated blood out the pulmonary trunk?
The right ventricle pumps unoxygenated blood out the pulmonary trunk to the lungs.
During the ventricular ejection phase of the cardiac cycle, which of the following is true? A)The atria are in systole. B)The AV valves are open. C)The ventricles are in diastole. D)The semilunar valves are open.
The semilunar valves are open During ventricular ejection, blood flows from the ventricles into the arteries. To do so, the blood must pass through the semilunar valves, which must be open during this phase.
True or false: The first branch off the arch of the aorta is the brachiocephalic artery in both the sheep and the human.
True
Which chamber of the heart sends oxygenated blood directly to the systemic circuit via the aorta?
left ventricle
interatrial septum
partition between the right and left atria
Which vessels return oxygenated blood to the left atrium?
pulmonary veins transport oxygen-enriched blood from the lungs to the left atrium.
The right tricuspid valve prevents backflow of blood from the right ventricle into the __________.
right atrium
The capillaries receiving blood flow from the left side of the heart are the
systemic capillaries
Consider the following characteristics of the cells found in muscle tissue. Which feature is shared by both cardiac muscle and skeletal muscle? A) striations B) triads C) intercalated discs D) branched cells
Striations Since both cardiac and skeletal muscles possess arrangements of motor proteins in regularly arrayed sarcomeres, they both display the banding known as striations.
Which of the following is true during ventricular systole? A) The AV valves are closed. B) The ventricles are empty. C)The ventricles are relaxed. d)The atria are in systole.
The AV valves are closed. At the beginning of ventricular systole, the one-way AV valves are forced shut. The AV valves remain shut throughout ventricular systole. This prevents blood from flowing back into the atria when the ventricles contract.
What heart chamber pushes blood through the aortic semilunar valve?
The aortic valve is located between the left ventricle and the aorta. The left ventricle pumps oxygenated blood out of the heart through the aortic valve to the body.
Which chamber pumps oxygenated blood out the aorta to the systemic circuit?
The left ventricle pumps oxygenated blood out the aorta to the entire body (systemic circuit).
Name the irregular ridges of muscle lining the ventricles.
Trabeculae carneae are the small elevated ridges of muscle arranged in a web type fashion found in both the right and left ventricles.
Identify the right atrioventricular valve.
Tricuspid valve The tricuspid valve is the atrioventricular valve located on the right side of the heart. It separates the right atrium from the right ventricle.
What causes the aortic semilunar valve to close?
greater pressure in the aorta than in the left ventricle Backflow of blood in the aorta (towards the left ventricle) closes the aortic semilunar valve.
Which of the following would increase cardiac output to the greatest extent? A) decreased heart rate and decreased stroke volume B) increased heart rate and decreased stroke volume C) increased heart rate and increased stroke volume D)decreased heart rate and increased stroke volume
increased heart rate and increased stroke volume Yes, cardiac output = heart rate x stroke volume.
electrocardiogram
A test that records the electrical activity of the heart
Identify the ear like flaps that are attached to the top chambers of the heart.
Auricles
What fibrous structure functions to anchor the atrioventricular valves in a closed position?
Chordae tendineae are the fibrous cords that attach the atrioventricular valves to papillary muscles. They help anchor the atrioventricular valves in a closed position during ventricular contraction.
Failure in a particular structure of the heart tends to cause a backup of blood in the lungs, known as pulmonary congestive heart failure. Failure of which structure of the heart would lead to such a backup?
Failure in the left ventricle can cause increased blood hydrostatic pressure in the lungs, causing fluid buildup in the alveoli.
True or False: Arterial blood supply to heart muscle is continuous whether the heart is in systole or diastole.
False
True or False: Oxygenated blood flows through the right side of the heart.
False Oxygenated blood returning from the lungs is received by the left atrium, then to the left ventricle before being pumped out to the body. This pathway of blood flow is known as the systemic circulation.
Why are gap junctions a vital part of the intercellular connection of cardiac muscles?
Gap junctions are a form of electrical synapse that allow action potentials to spread to connected cells. This property allows the signal to spread efficiently through the heart.
What is the period during the cardiac cycle when the valves leading to and from the ventricles are completely closed and blood volume in the ventricles remains constant as the walls contract?
Isovolumetric contraction phase The prefix -iso means "equal," so during any isovolumetric stage the volume does not change.
Put the phases of the cardiac cycle in the correct order, starting after ventricular filling.
Isovolumetric contraction, ventricular ejection, isovolumetric relaxation the ventricles must contract and eject blood before they relax and fill again.
Which of the following is correct about the filling of the ventricles? -The majority of ventricular filling is caused by contraction of the atria. -Most blood flows passively into the ventricles through open AV valves.
Most blood flows passively into the ventricles through open AV valves
Blood on the right never mixes with blood on the left, once the heart is fully developed.
Once fetal modifications (i.e. foramen ovale, ductus arteriosus) close following delivery of the infant, blood on the right side of the heart should not mix with blood on the left side of the heart.
Increased pressure in the ventricles would close what valve(s)?
The AV valves
Which of the following is equivalent to the ventricular volume during isovolumetric contraction? A) the minimum ventricular volume (MVV) B) the stroke volume (SV) C) The end diastolic volume (EDV) D) the end systolic volume (ESV)
The End Diastolic Volume Isovolumetric contraction occurs at the beginning of ventricular systole when the ventricular volume is at its maximum value−the end diastolic volume (EDV). Because no volume changes occur during isovolumetric contraction, ventricular volume remains at this value throughout the phase.
Name the inner lining of the heart.
The endocardium is the smooth, slick lining of the chambers of the heart. Endocardium is a continuation of endothelium that lines blood vessels. Both endocardium and endothelium are composed of simple squamous epithelial tissue, which minimizes friction between the wall of the chamber/vessel and the blood.
Which of the following is the innermost layer of the heart?
The endocardium lines the inside of the heart. Its surface is composed of simple squamous epithelium.
Which heart chamber receives blood from the pulmonary veins?
The left atrium receives oxygenated blood from the pulmonary veins.
Identify the most muscular chamber.
The left ventricle is responsible for pumping blood out to the body. This requires a lot of force. The left ventricle is the most muscular in order to pump the blood with adequate force.
A blockage in which of these vessels would most likely cause a myocardial infarction in the lateral right side of the heart?
The right marginal artery branches from the right coronary artery to nourish the lateral areas of the right ventricle. A blockage in this vessel could damage this area.
When the atria contract, which of the following is true? A) The semilunar valves are open. B) The ventricles are in diastole. C) The AV valves are closed. D) The atria are in diastole.
The ventricles are in diastole Atrial contraction fills each of the ventricles to their maximum capacity−the end diastolic volume (EDV). This occurs towards the end of ventricular diastole while the ventricles are still relaxed.
Most of the increase in left ventricular volume takes place during what phase of the cardiac cycle?
Ventricular filling the AV valves remain open, which allows blood to flow from the atria into the ventricles. The passive flow of blood during this phase (before atrial contraction) accounts for roughly 80 percent of the increase in ventricular volume.
At what point during the cardiac cycle does the AV valve close?
When ventricular pressure becomes greater than atrial pressure When ventricular pressure rises above atrial pressure, the AV valve closes. This prevents blood from flowing backward through the heart
Atrial pressure is greater than ventricular pressure during which phase of the cardiac cycle?
arterial contraction
At what point in the cardiac cycle does the AV valve open?
when atrial pressure becomes greater than ventricular pressure Blood flows through the heart in one direction (atria-ventricles-large arteries) and from high to low pressure. When pressure in the atrium becomes greater than ventricular pressure, the AV valve opens; and blood flows from the atrium into the ventricle.
At what point in the cardiac cycle does the semilunar valve close?
when pressure in the ventricle becomes less than aortic pressure When pressure in the ventricle drops below aortic pressure, the semilunar valve shuts. This prevents blood from flowing backward through the heart.
Which chamber of the heart exits into the pulmonary trunk?
Right ventricle
Calculate the cardiac output if heart rate (HR) is 90 beats per minute, stroke volume (SV) is 110 ml/beat, end diastolic volume (EDV) is 140 ml, and end systolic volume (ESV) is 30 ml.
9.9L/min Cardiac output is the product of heart rate times stroke volume. Cardiac output increases to meet increased metabolic demand, often by increasing both heart rate and stroke volume at the same time. This occurs, for example, during maximal exercise, when cardiac output may increase to four or five times the resting level
What is the ligamentum arteriosum?
A remnant of the ductus arteriosus; The ligamentum arteriosum is a remnant of the ductus arteriosus. The ductus arteriosus is a fetal shunt that connects the pulmonary trunk to the aorta.
Which of these pathways shows stimulation in the correct order? A) subendocardial conducting network, interventricular septum, AV bundle, AV node B) AV bundle, subendocardial conducting network, interventricular septum, SA node C)SA node, interventricular septum, AV node, papillary muscles D)AV node, AV bundle, interventricular septum, subendocardial conducting network
AV node, AV bundle, interventricular septum, subendocardial conducting network The signal comes from the SA node
Blood enters the left and right coronary arteries directly from which vessel or chamber?
Aorta
An increase in sympathetic stimulation of the heart would increase stroke volume by increasing __________.
Contractibility Increased sympathetic activity increases heart contractility. This causes cardiac fibers to contract more forcefully at all levels of preload. Regardless of end diastolic volume, this mechanism increases stroke volume by reducing end systolic volume.
List the blood flow from the Coronary Sinus to the Capillaries of the Lungs
Coronary Sinus > Right Atrium > Tricuspid Valve > Right ventricle > Pulmonary Semilunar Valve > Pulmonary Trunk > Pulmonary arteries > Capillaries of Lungs
These activities change heart rate by changing the balance of parasympathetic and sympathetic stimulation of the heart. Sort each of the activities according to whether it decreases or increases heart rate. Standing up laying down Digesting a meal Fright or anger Exercise
Decreases Heart Rate: Lying down, Digesting a meal Increases Heart Rate: Standing up, Fright or Anger, Exercise The balance between parasympathetic and sympathetic stimulation to the heart controls heart rate. Increased parasympathetic activity decreases heart rate, and sympathetic activity increases heart rate.
Predict the changes in heart rate, stroke volume, and cardiac output for each of the following conditions by filling out the table below. Drag the appropriate labels to their respective targets.
Increased sympathetic activity: Increase HR, SV, CO Increase Preload: No change in HR, increase SV and CO Increased exercise: Increase HR, SV, CO Increase contractility: No change in HR, increase SV and CO
The ___________ carries oxygen-poor venous blood from below the diaphragm from the areas of the lower body and extremities into the right atrium.
Inferior Vena Cava
What is the function of the coronary circulation?
Provide a blood supply to the heart; Correct. The coronary circulation provides oxygenated blood to the heart through coronary arteries. Coronary veins return the deoxygenated from the heart to the coronary sinus on the posterior surface of the heart. The coronary sinus empties the deoxygenated blood directly into the right atrium where it joins deoxygenated from the body.
What part of the intrinsic conduction system stimulates the atrioventricular (AV) node to conduct impulses to the atrioventricular bundle?
Sinoatrial (SA) node The sinoatrial node, by spontaneously depolarizing faster than the atrioventricular node, initiates heart contraction.
The _________ carries oxygen-poor venous blood from above the diaphragm from areas of the upper body and extremities into the right atrium.
Superior Vena Cava
Identify the valve found between the left atrium and left ventricle.
The atrioventricular valve on the left is the bicuspid valve. The mitral valve is also called the mitral valve.
Most of the decrease in ventricular volume takes place during which phase of the cardiac cycle?
Ventricular Ejection As the ventricles contract, blood is forced through the semilunar valves and out into the arteries, resulting in a reduction in ventricular blood volume. At the end of this phase, ventricular volume is at a minimum−the "end-systolic volume" (ESV).
Ventricular pressure is greater than aortic pressure during which phase of the cardiac cycle?
Ventricular ejection While pressure in the ventricle is greater than pressure in the aorta, the semilunar valve remains open. This allows blood to be ejected from the ventricle.
The structure that is located anatomically between the aorta and the left ventricle is the
aortic semilunar valve
What prefix means heart or heart action.
cardi
