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Physiology of the Heart

Practice exam questions, exam 2
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The cardiovascular system is essentially a transport system. What does it transport besides blood?
substrates for energy production, immunocompetent cells, heat
The left ventricle is a part of the _______ circulation.
systemic
The fibers of the median layer of cardiac muscle run in which direction?
diagonally
What is true of diastole?
an increased heart rate shortens diastole more than systole
What causes the valves of the heart to open and close, allowing the blood to pass from chamber to chamber ?
changes in pressure between the chambers
What is isovolumetric contraction?
contraction of the ventricle with increased pressure, but without change in volume
What is enddiastolic volume
the maximum volume of the entire cycle
What is stroke volume?
difference between enddiastolic volume and endsystolic volume
What generates the initial action potential in a healthy heart?
SA node
The term inotropic refers to what type of effect?
change in force of contraction
What is the correct order of receipt of action potentials in the heart?
SA node, AV node, bundle branches, Purkinje fibers
If the SA node fails, the AV node takes over heart rate determination. How do the rates of these two node compare?
AV node is slower
What is the purpose of the AV node on depolarization?
frequency filter
In regards to the heart, what does the parasympathetic nervous system not innervate?
left and right ventricles
What is the term for a change in speed of conduction?
dromotropic
The SA node is also known as what?
the pacemaker of the heart
Increased contractility results in what /
increased stroke volume
An electrocardiogram is a measure of what?
electrical events in the heart
When a lead is placed on each arm and the left leg, what is created?
Einthoven triangle
What is meant by Lead II?
the area between electrodes 1 and 3
What is the signal difference between the Goldberger method versus the Einthoven method?
Goldberger is stronger
How is the placement of electrode different in Wilson's method?
it uses electrodes on the chest
What does the QRS interval measure?
ventricular depolarization
What paper speed gives a better idea of random rhythmic events?
low speed
What is the major difference between a vectorcardiogram and an electrocardiogram?
vectorcardiogram shows all 3 leads, while ECG shows just one
What grades of heart murmurs are defined by the 'palpable thrill'?
5 and 6
How are murmurs generated?
turbulent blood flow
what is the main limitation of the vectorcardiogram?
cannot determine the duration of time when the heart is either completely repolarized or depolarized
What is a compensator pause?
time between ventricular extrasystole and supraventricular extrasystole
What is the major difference between fibrillation and flutter?
fibrillation is faster
What is a myocardial infarction?
blockage of the coronary arteries
What is the minimum cardia output?
minimum amount of blood the tissues need to maintain their metabolism
What are heart sounds?
sounds created by movement of blood and vibrations of the muscles and valves
What creates a machinery murmur?
combination of stenotic and insufficient valves; PDA
What is the largest loop in a vectorcardiogram?
R wave
What is a characteristic of a ventricular pacemaker?
no P waves
What is a nomotropic disturbance that is physiological (normal) in dogs?
sinus arrhythmia
What is a characteristic of 2nd degree AV block?
dropped beats
What can create the appearance of atrial fibrillation in a normal dog?
electrical interference
Moderate damage to the heart can cause what other actions by the body ?
kidneys to retain fluid
Maximum cardiac output is limited by what factor?
stroke volume and heart rate
Sinus bradycardia is an issue with what?
SA node establishing a rate that is too low
What can cause an interruption of signal between the AV node and the Bundle of His?
extreme vagal tone, infection, ischemia
A stenotic aortic valve would create a murmur during what event?
systole
What is a signal on an EKG of supraventricular extrasystole?
negative P wave
Ventricular extrasystole is characterized by what EKG event?
inverted T wave
What is a decrease or stoppage in the rate of conduction of the impulse through the AV node and Bundle of His?
AV block
How may heart failure manifest itself?
overloading the heart through increased cardiac output
What grade of heart murmur has a loud murmur without a palpable thrill?
4
On an ECG what event indicates the presence of a myocardial infarction?
deep Q wave
What event occurs during 3rd degree AV block?
atria and ventricles beat at different rates
What characterizes an incompetent murmur?
valvular insufficiency
Which is not a type of heart failure?
low pressure
What is a sign of a shifting pacemaker?
altered P wave or PQ segment
What happens after initial heart failure?
edema, overstretching of the heart muscle, ventricular dialation
When the right heart fails, edema or fluid buildup occurs where?
abdomen
Arterio-venous shunts and low resistance to blood flow cause what type of heart failure?
high output
How do ventricular septal defects cause heart failure?
thickening of the left ventricle
What type of vessels normally regulate blood flow?
arterioles
What is caused by a metabolic vitamin B deficiency?
loss of arteriolar tone
What happens in extreme cases of ventricular hypertrophy?
inability to eject enough blood