Ch 20: Set 1
Joe's cardiac output at rest is 5 L/min. When he is exercising strenuously it is 20 L/min. What is Joe's cardiac reserve?
15 L/min
The normal rate of spontaneous depolarization of the AV node is...
40-60 per min
If the heart rate is 70 beats per minute and stroke volume is 70 ml, then CO is?
4900 mL/min
The apex of the heart is at approximately the level of the ______ intercostal space.
5th
Of the amount of blood entering the ventricles before they contract, about _____ comes in before atrial contraction.
70%
The heart rate of normal adult is
70-80 beats/min
What is located in the pericardial cavity?
A small amount of serous fluid
If the SA node is damaged, which part of the heart is most likely to take over as a pacemaker?
AV nodal cells
What occurs during a PR interval?
AV node conduction
Energy for contraction of myocardial cells comes primarily from...
Aerobic respiration in the mitochondria
Blood leaving the left ventricle goes through which valve?
Aortic semilunar
The coronary sulcus is a groove on the outside of the heart that marks the...
Atria and ventricles
Conduction of the cardiac impulse is slowed as it passes through the AV node. This allows time for the?
Atria to contract completely before the ventricles start to contract
What occurs during a P wave?
Atrial depolarization
The plateau phase of the cardiac contractile cell action potential is caused by?
Ca2+ inflow
The amount of blood ejected from the heart in one minute is called the?
Cardiac output
Which vessel is a branch of the left coronary artery?
Circumflex artery
All cardiac veins empty into the _______, which then empties into the _______.
Coronary sinus; right atrium
What would not increase cardiac output?
Decrease heart rate; no change in stroke volume
An electrocardiogram actually records...
Electrical changes that occur in the myocardial cells
The amount of blood in the ventricles just before they contract is the...
End diastolic volume
The visceral pericardium is also called the?
Epicardium
How does calcium work in cardiac muscle cells?
Extracellular Ca2+ diffuses into the cardiac muscle cells, binds to Ca2+ channels in the sarcoplasmic reticulum and causes Ca2+ release into the cytosol.
Which component of a myocardial cell allows it to electrically stimulate adjoining cells?
Gap junctions
Which of the following commonly decreases with age?
Heart rate
The Starling law of the heart says that the higher the end diastolic volume, the:
Higher the stroke volume
In response to exercise, the heart would be called upon to _____ the amount of blood pumped, and this would be initiated by signals from ______ fibers.
Increase; sympathetic
What would not increase stroke volume?
Increased arterial blood pressure
Which of the following would be an effect of cutting the vagus nerve?
Increased heart rate
What is the effect of norepinephrine on the heart?
Increases rate and strength of contraction
The apex of the heart points?
Inferiorly and laterally
Which structure is present in the cardiac muscle tissue but not skeletal muscle tissue?
Intercalated disks
The anterior and posterior interventricular sulci mark the position of which internal heart structure?
Interventricular septum
Which part of the cardiac cycle occurs between the time the AV valves close and the semilunar valves open?
Isovolumetric contraction
Phophodiesterase is the enzyme that degrades cAMP. A drug that inhibits phosphodiesterase would have what effect on the heart?
It would increase cardiac contractility by prolonging Ca2+ availability inside the cell.
Which ionic imbalance would decrease the strength of cardiac muscle contraction?
Low calcium
The heart is located in the...
Mediastinum, which is located in the thoracic cavity
Damage to which of the following parts of the brain would cause the body to have less control over cardiac activity?
Medulla oblongata
The Purkinje fibers are found in which layer of the heart wall?
Myocardium
Are arteries associated with atrioventricular valves?
NO
In an ECG taken from a person who has no SA node activity, which component will not appear?
P wave
In response to an elevation in blood pressure, the cardiac control center would attempt to restore homeostasis primarily through:
Parasympathetic stimuli to the SA node
An obstruction in the pulmonary trunk would prevent blood from?
Picking up oxygen in the lungs
If lines were drawn on a typical ECG recording showing where atrial and ventricular systole begin and end, then the ventricular systole would be seen as beginning during a ____ and ending during the next ____.
QRS complex; T wave
During isovolumetric relaxation of the cardiac cycle the atria and ventricles are?
Relaxed
What do skeletal muscle cells, cardiac autorhythmic cells and cardiac contractile cells have in common?
Repolarization is caused by K+ outflow
Where is the SA node?
Right atrium; medial to the opening of the superior vena cava
List the components of the cardiac conduction system in the correct sequence.
SA node, AV node, AV bundle, Purkinje fibers
Place the components of the heart in correct order of decreasing intrinsic rhythm.
SA node, AV node, Purkinje cells
Which type of tissue is found in the serous pericardium?
Simple squamous epithelium
Which of the following commonly increases with age?
Size of the left ventricle
List the order in which cardiac pacemaker potential is caused by cyclic changes in membrane potential.
Slow inflow of Na+ without K+ outflow; rapid Ca2+ inflow; rapid K+ outflow
The chordae tendineae prevent....
The atrioventricular valve cusps from prolapsing into the atria during ventricular systole
The apex of the heart is part of?
The left ventricle wall
The ANS is the main extrinsic control for cardiac activity, acting through both sympathetic and parasympathetic fibers innervating the heart. This control system is not symmetric--one part of the ANS has less control over the heart. Which of the following statements is NOT correct?
The parasympathetic division has significant control of contractility through its action on the ventricular myocardium.
Based on the information given below, which individual has the greatest tolerance for strenuous exercise? Assume they are similar in terms of size and muscular fitness.
The person with the highest cardiac reserve
The plateau phase of the cardiac myocardial cell potential prevents?
Titanic contractions, which would cease pumping action of the heart
The higher the _____, the greater the cardiac output.
Venous return
Damage to cells of the AV bundle would prevent the cardiac impulse from reaching the?
Ventricles
What occurs during the QRS complex?
Ventricular depolarization
The semilunar valves close at the beginning of?
Ventricular diastole
Pressure in the ventricles would be highest during?
Ventricular systole
The pericardial cavity is between the
Visceral pericardium and parietal pericardium
Which two layers of the heart are the most similar in tissue structure?
Visceral pericardium and parietal pericardium
A point where two arteries connect and combine their blood flow is called an:
anastamosis
Because of the distribution of the cardiac impulse by the conduction system, ventricular contraction begins...
at the apex of the heart and pushes blood toward the semilunar valves.
The 'skeleton' of the heart provides...
attachment for the heart valves and cardiac muscle
The aorta and pulmonary trunk extend from the heart at its...
base
The alternate contraction and relaxation of the atria and ventricles are referred to as the...
cardiac cycle
Increased input from the baroreceptors to the cardiac control center would cause which of the following to occur?
decreased sympathetic stimulation and increased parasympathetic stimulation
The cells of the heart's normal pacemaker spontaneously generate...
electrical signals about 70-80 times/min
During ventricular diastole, pressure in the ventricles...
eventually exceeds pressure in the arteries and the semilunar valves open
A needle being inserted into the heart would travel through the layers of the heart wall and coverings in which order, beginning on the outside?
fibrous pericardium, parietal pericardium, visceral pericardium, myocardium, endocardium
Intercalated discs include these structures:
gap junctions; desmosomes
The action of acetylcholine after binding to muscarinic receptors on the SA node is to?
open K+ channels, causing hyperpolarization and a decreased rate of spontaneous depolarization
The right ventricle of the heart acts as a pump for the...
pulmonary circulation
The function of pericardial fluid is to...
reduce friction between the pericardial membranes
With respect to the effect on cardiac output, the term preload refers to...
the amount of tension developed in the myocardium before it contracts.
An auricle is an extension of?
the atrial wall
The presence of arterial anastamoses in the heart reduces...
the chance of a MI by providing alternate sources of blood flow to the myocardium.
Cardiac output from the left ventricle is probably lower than the right ventricle if?
the person has pulmonary edema.
The effects on the SA node by the parasympathetic division of the ANS is called:
vagal tone
The coronary sinus is a ______ located in the _______.
vein; posterior antrioventricular sulcus
A blood clot in the circumflex artery would cause a MI in part of the...
walls of the left atrium and posterior left ventricle
