Chapter 18 The Heart Flashcards
heart muscle is deprived of oxygen
ischemia
death of heart muscle cells
infarction
a condition of rapid and irregular or out of phase contraction of ventricular heart muscle cells
fibrillation
an abnormal pacemaker
ectopic focus
total heart relaxation
quiescent period
The myocardium receives its blood supply from the coronary arteries
true
cardiac muscle has more mitochondria and depends less on a continual supply of oxygen than does skeletal muscle
False; depends more on a continual supply of oxygen (I think)
anastomoses among coronary arterial branches provide collateral routes for blood delivery to the heart muscle
true
if blood volume decreased dramatically due to massive bleeding, the autonomic nervous system will attempt to maintain cardiac output by increasing the heart rate
true
tissues damaged by myocardial infarction are replaced by fibrous connective tissue
true
the left side of the heart pumps the same volume as the right
true
when released in large quantities, thyroxine causes a sustained increased heart rate
true
arterial blood supply to heart muscle is continuous whether the heart is in systole or diastole
false; coronary arteries not arterial
auricles slightly increase blood volume in the ventricles
true
the lub sounds of the heart are valuable in diagnosis because they provide information about the function of the heart’s pulmonary and aortic semilunar valves
false; provide information about the function of the heart’s mitral and tricuspid valves
autonomic regulation of heart rate is via two reflex centers found in the pons
false; found in the medulla
the papillary muscles contract after the other ventricular muscles so that they can take up the slack on the chordae tendineae before the full force of ventricular contractions sends blood against the AV valve flaps
false; ??
an ECG provides direct information about valve function
false; electrical activity
as pressure in the aorta and pulmonary trunk were switched, oxygen rich blood would be pumped from the left ventricle to the lungs
true
heart tissue is supplied with nutrients primarily by diffusion from the heart chambers through the myocardium
false; primarily by coronary arteries through to the myocardium???
normal heart sounds are caused by which of the following events?
closure of the heart valves
during the isovolumetric relaxation phase of the cardiac cycle, ______.
atrioventricular, aortic, and pulmonary valves are closed
hemorrhage with a large loss of blood causes ______.
a lowering of blood pressure due to change in cardiac output
the left ventricular wall of the heart is thicker than the right wall in order to _______.
pump blood with greater pressure
which chambers of the heart contain oxygenated blood?
left atrium and ventricle
if the SA node is not functioning, an ECG will show __________.
no P waves with a HR between 40-60
The receiving chambers of the heart include the ________.
right and left atria
the condition where fluid compresses the heart and limits its ability to contract is called _______.
cardiac tamponade
the term for pain associated with deficient blood delivery to the heart that may be caused by the transient spasm of coronary arteries is _______.
angina pectoris
to auscultate the aortic semilunar valve, you would place your stethoscope in the ______.
second intercostal space to the right of the sternum
the source of blood carried to capillaries in the myocardium would be the ______.
coronary arteries
the fact that the left ventricle to the heart is thicker than the right ventricle reveals that it _______.
pumps blood against a greater resistance
the parietal pericardium _________.
lines the internal surface of the fibrous pericardium
which of the following is not an age-related change affecting the heart?
thinning of the valve flaps
if cardiac muscle is deprived of its normal blood supply, damage would primarily result from _______.
decreased delivery of oxygen
if the length of the absolute refractory period in cardiac muscle cells was the same as it is for skeletal muscle cells, ________.
tetanic contractions might occur, which would stop the heart’s pumping action
norepinephrine acts on the heart by _______.
causing threshold to be reached more quickly
if the vagal nerves to the heart were cut, the result would be that _________.
the heart rate would increase by about 25 beats per minute
the foramen ovale ________.
connected the two atria in the fetal heart
Which vessel(s) of the heart receive(s) blood from the right ventricle?
the pulmonary trunk
which of the following receives blood during ventricular systole?
both aorta and pulmonary trunk
which of the following is not part of the intrinsic conduction system of the heart?
atrioventricular valve
the AV valves are closed __________.
when the ventricles are in systole
Pectinate muscles are found in the ________.
atria only
select the correct statement about the heart valves.
the mitral valve separates the right atrium from the right ventricle
select the correct statement about the function of myocardial cells
the entire heart contracts as a unit or it does not contract at all.
select the correct statement about the structure of the heart wall.
the myocardium is the layer of the heart that actually contracts
compared to skeletal muscle, cardiac muscle ________.
has gap junctions that allow it to act as a functional syncytium
during the period of ventricular filling, ________.
blood flows passively from the atria through the AV valves into the ventricles
the second heart sound is heard during which phase of the cardiac cycle?
isovolumetric relaxation
which is most responsible for the synchronized contraction of cardiac muscle tissue?
gap junctions
select the correct statement about cardiac output
a slow heart rate increases end diastole volume, stroke volume, and force of contraction
which is not a vessel that brings blood directly into the right atrium
pulmonary vein
isovolumetric contraction _________.
refers to the short period during ventricular systole when the ventricles are completely closed chambers
given an end diastolic of 120ml/beat and an end systolic volume of 50ml/beat, the stroke volume would be ________.
70ml/beat
if the mitral valve is unable to close properly, _________.
blood could flow back into the left atrium
during exercise, which of the following would occur on an ECG compared to an individual at rest?
the time from one R to the R of the next heartbeat would
which coronary artery is most responsible for supplying blood to the myocardial tissue of the left atrium?
circumflex artery
what is the expected heart rate when a heart is removed from a living body?
100 beats/ minute
while auscultating heart sounds during a checkup, Andy’s doctor hears a high-pitched sound during ventricular contraction. Which type of valve could cause this?
stenotic aortic semilunar valve
exercise results in skeletal muscles compressing veins which encourages blood to return to the heart. In this scenario, which of the following is correct?
preload increases
the “pacemaker potential” of pacemaker cells is produced by the opening of _______ at the end of an action potential.
slow Na+ channels
The plateau phase of an action potential in cardiac muscle cells is due to the ________.
influx of Ca2+ through slow Ca2+ channels
The Frank-Starling Law states that, if other factors are constant, a _________.
higher end diastolic volume will produce a higher stroke volume.
define systole and diastole. Which heart chambers are usually referenced when these terms are used?
systole- contraction of muscle; diastole- relaxation of muscle; ventricles
define the terms end diastolic volume and end systolic volume and relate them to the calculation of stroke volume.
EDV is the amount of blood that collects in a ventricle during diastole. ESV is the volume of blood remaining in a ventricle after its contracted. SV= EDV - ESV
What is the difference between the auricles and the atria?
auricles are flap like appendages attached to the atria that increase the atrial volume. The atria are receiving chambers for blood returning to the heart from pulmonary and systemic circulation.
The heart is called a double pump because there are two functionally separate circulations. Trace the pathway of each of these circulations and include the following information: heart, chambers involved, major blood vessels involved, and general areas through which the blood flows. Begin with the right atrium.
o RIGHT ATRIUM to VENTRICLE to PULMONARY VEINS (pulmonary circuit pump);
o LEFT ATRIUM to LEFT VENTRICLE to AORTA to BODY TISSUES to VENAE CAVAE (systemic circuit pump)
What two important functions does the cardiac conduction system preform?
o INITIATE IMPULSES (pacemaker)
o DISTRIBUTE IMPULSES so that it depolarizes and contracts in an orderly, sequential manner
Why is oxygen so much more critical to the heart muscle than to skeletal muscles?
o Cardiac muscle is highly dependent on oxygen and relies almost exclusively on aerobic respiration
o It cannot tolerate a lack of oxygen due to an inadequate amount of blood
o When anaerobic respiration is forced, lactic acid and rising H+ levels impair heart function
Explain the role of pacemaker cells in cardiac tissue.
set pace for contractions of heart
What is the functional importance of the intercalated discs of cardiac muscle? What is the functional importance of the fibrous skeleton of the heart?
o Contain anchoring desmosomes that prevent cell separation
o Gap junction which allow ions to travel from cell to cell, transmitting current across the entire heart
o The fibrous skeleton acts as a tendon, an insertion and insulator, giving the cardiac cells something to pull or exert their force on and isolating atrial from ventricular contractions
list the 3 vessels that bring oxygen-poor blood to the right atrium. Which regions of the body do they serve?
superior vena cava- superior to diaphragm
inferior vena cava- inferior to diaphragm
coronary sinus- collects blood draining from myocardium
List and define the three most important factors that affect stroke volume
o PRELOAD- the degree to which heart muscle cells are stretched before they contract
o CONTRACTILITY- a contractile strength achieved at a give muscle length
o AFTERLOAD- pressure that must be overcome from the ventricles to eject blood
A 14-year-old girl undergoing a physical examination prior to being admitted to summer camp was found to have a loud heart diastolic murmur at the second intercostal space to the left side of the sternum. Explain the reason for the loud heart murmur associated with this girl’s condition.
The heart murmur is due to incomplete closing of the pulmonary valve.
A man enters the hospital complaining of chest pain. His history includes smoking, a stressful job, a diet heavy in saturated fats, lack of exercise, and high blood pressure. Although he is not suffering from a heart attack, his doctor explains to him that a heart attack is quite possible. What did the chest pain indicate? Why is this man a prime candidate for a heart attack?
His symptoms indicate angina pectoris, possibly due to either atherosclerosis or stress induced spasms of the coronary arteries. If the arteries are occluded, the heart muscle could be deprived of blood, and therefore oxygen. A heart attack could occur if the coronary vessels experience further occlusion.
An older woman complains of shortness of breath and intermittent fainting spells. Her doctor runs various tests and finds that the AV node is not functioning properly. What is the suggested treatment?
The suggested treatment is surgery to implant an artificial pacemaker.
A patient takes a nitroglycerin tablet sublingually for chest pain. Nitroglycerin acts directly on smooth muscle, producing relaxation and vessel dilation. How would this relieve chest pain?
Angina pectoris is thoracic pain caused by a fleeting deficiency in blood delivery to the myocardium, with resulting in decreased oxygen being delivered to the cells. Because nitroglycerin acts as a vasodilator, blood flow is increased,promoting the delivery of oxygen to the cells.
A patient was admitted to the hospital with chest pains. On admission, his pulse was 110 and blood pressure was 96/64. According to his history, his normal pulse rate is usually between 80 and 88 and his blood pressure runs from 120/70 to 130/80. Explain why these changes in BP and HR occur.
Increased heart rate without maintaining his normal blood pressure is suggestive of reduced stroke volume. Both a drop in blood volume and a weakened heart could cause this, but the chest pains suggest heart damage. Failure of compensating mechanisms to maintain blood pressure suggest a serious decline incardiac output
A 55-year-old male was admitted to the hospital with heart failure. He complains of increasing shortness of breath on exertion and needing to sleep on three pillows at night. On physical assessment, the nurse determines that his ankles and feet are very swollen. Which of these symptoms reflect left-sided heart failure and which reflect right-sided heart failure?
Because the heart is a double pump, each side can initially fail independently of the other. If the left side fails,pulmonary congestion occurs. The right side of the heart continues to propel blood to the lungs, but the left side does not adequately eject the returning blood into the systemic circulation. Thus, blood vessels in the lungs become engorged with blood, pressure within them increases, and fluid leaks from the circulation into the lung tissue, causing pulmonary edema. Shortness of breath and difficulty breathing in a prone position may occur.
If the right side of the heart fails, peripheral congestion occurs. Blood stagnates within body organs, and pooled fluids in the tissue spaces impair the ability of body cells to obtain adequate nutrients and oxygen and to rid themselves ofwastes. Edema is most noticeable in the extremities (feet, ankles, and fingers)
Asystole is the total absence of ventricular electrical activity. Explain why defibrillation would not be effective in this situation.
Defibrillation is accomplished by electrically shocking the heart, which interrupts its chaotic twitching by depolarizing the entire myocardium. In this case, the ventricles are at a total standstill and defibrillation would not be effective.
A patient is prescribed a calcium channel blocker to prevent angina (chest pain), by decreasing the demand for oxygen. Explain why.
By preventing the influx of calcium ions into myocardial and vascular smooth muscle cells, calcium channel blockers inhibit the intracellular release of additional stores of calcium ions. A drug that inhibits the release of intracellular calcium ions decreases the force of myocardial contractility, thereby decreasing the oxygen demand.
A doppler ultrasound was performed on an infant who had symptoms of breathlessness and it was found that he had a patent ductus arteriosus. Discuss the location and function of the ductus arteriosus in the fetus and relate it to the reason for the infant’s breathlessness.
The ductus arteriosus is a shunt between the pulmonary trunk and the aorta in the fetus, which normally closes at birth. Breathlessness is due to the mixing of deoxygenated blood and oxygenated blood because the connection between the aorta and the pulmonary trunk remains slightly open.
