Physiology 18
The first heart sound ("lubb") is associated with
closing of the mitral valve.
The movement of _______________ into the cardiac muscle cell depolarizes the cardiac muscle cell.
sodium and calcium
When the cardiac muscle cell is at rest, the concentration of _____________ is greater on the outside of the cell.
sodium and calcium
During the cardiac cycle,
the QRS complex of the ECG precedes the increase in ventricular pressure.
Which of the following has the fastest rate of spontaneous depolarization? AV bundle branches the AV node the SA node Purkinje fibers
the SA node
Organisms that are poikilothermic _______.
have temperature fluctuations that coincide with the external temperature and lack internal homeostatic temperature regulatory mechanisms
Caffeine has effects on conducting cells and contractile cells that are similar to those of NE. What effect would drinking large amounts of caffeinated beverages have on the heart rate?
heart rate would increase
The sinoatrial node is located _______.
in the right atrial wall of the human heart
The effect of the sympathetic nervous system on the heart is to _______.
increase the heart rate and increase the force of contraction
David suffers from a prolapsed mitral valve. This condition would cause
increased effort by the left ventricle and regurgitation
Each of the following factors will increase cardiac output except increased parasympathetic stimulation. increased sympathetic stimulation. increased heart rate .increased venous return. increased parasympathetic stimulation.
increased parasympathetic stimulation.
Aortic valve stenosis is characterized by _______.
increased resistance to blood flow, thickening of the myocardium and narrowing of the aortic semilunar valve
In cardiac muscle, the fast depolarization phase of the action potential is the result of ________ membrane permeability to ________ ions.
increased; sodium
Modifiers that affect the force of contraction of the heart are _______.
inotropic
Calcium channel blockers block the movement of calcium _____
into the cell and decrease heart rate
The total refractory period of cardiac muscle _______.
is longer than the total refractory period for skeletal muscle
Cardiac muscle cells are __________.
mechanically, chemically, and electrically connected to one another
Heart rate is controlled by neurons of the cardiovascular center located in the
medulla oblongata.
Which structure provides a rapid-conduction path that tenses the papillary muscles before the ventricular myocardium contracts, preventing "slamming" of the right AV cusps?
moderator band
List the phases of the cardiac cycle
atrial systole, atrial diastole, ventricular systole, ventricular diastole
Acetylcholine slows the heart because it
opens potassium ion channels in SA node cells and causes the pacemaker potential to depolarize more slowly.
A ___________________ drug increases the force of contraction of the heart.
positive inotropic
The autorhythmicity of cardiac pacemaker cells is made possible by the reduced permeability of _______
potassium
The cardiac cell plasma membrane is most permeable to ______________________
potassium
Which ion(s) at least initially lowered the frog heart rate in the activity you just performed?
potassium and sodium
The repolarization of cardiac muscle is due to _______.
potassium exiting the cell
List the three stages of an action potential in a cardiac muscle cell.
rapid depolarization, plateau, and repolarization
If a patient's tricuspid valve was leaking during systole, what would happen?
regurgitation back into the right atrium
Which of the following would be greater? the end-diastolic volume when the heart rate is 60 beats/minute the end-diastolic volume when the heart rate is 150 beats/minute
the end-diastolic volume when the heart rate is 60 beats/minute
When vagus nerve stimulation was applied to the frog heart, _______.
the heart rate slowed and eventually stopped
Which part of the human body regulates temperature?
the hypothalamus
Which branch of the autonomic nervous system dominates after a large meal?
the parasympathetic branch
What part of your tracing illustrates vagal escape?
the part where the heart resumed beating
Which of the following is greater during left ventricular systole? the peak pressure in the ventricle the peak pressure in the aorta Neither is greater.
the peak pressure in the ventricle
Tetanic muscle contractions don't occur in a normal cardiac muscle because
the refractory period lasts until the muscle relaxes.
Which event does NOT happen during ventricular diastole?
Atrioventricular valves close because of the contracting ventricles.
Define autorhythmicity
Autorhythmicity is the ability of the heart to contract without neural or hormonal stimulation.
Which of the following statements most accurately defines what is happening during the second phase of ventricular systole of the cardiac cycle?
Blood is being ejected from the ventricles through open semilunar valves.
What effect would compressing the inferior vena cava just below the diaphragm have on cardiac function?
Sympathetic stimulation of the heart would increase.
In an ECG recording, which of the following coincides with ventricular repolarization?
T wave
Which structures collect blood from the myocardium, and into which heart chamber does this blood flow?
Coronary veins collect blood from the myocardium and carry it to the right atrium.
If the human heart were experiencing hyperthermia, what do you think would be the effect on the heart rate?
The heart rate would increase
If the connection between the vagus nerve and the heart is cut, which of these changes will occur?
The heart will beat faster.
If the cells of the SA node failed to function, how would the heart rate be affected?
The heart would beat slower because the AV node would be the pacemaker.
intrinsic heart rate?
During parasympathetic stimulation, acetylcholine released by parasympathetic neurons opens chemically gated potassium channels in the plasma membrane.
Muscarine is a poison found in poisonous mushrooms. Muscarine binds to acetylcholine receptors and mimics its action. Which of the following describes the effect of muscarine?
Like pilocarpine, it decreases the heart rate
List the important features of the ECG, and indicate what each represents
P wave (atrial depolarization), QRS complex (ventricular depolarization), T wave (ventricular repolarization
What statement is true regarding pressures and volumes in the cardiac ventricles?
The pressure is greater in the left ventricle, but the volumes are equal in the two chambers.
If there is a complete block between the SA node and the AV node, how would the ECG be affected
The rate of P waves will be faster than the rate of QRS complexes
The doublet that results with more frequent stimulation of the frog heart represents _______
an extrasystole and an extra contraction of the ventricles
What factor would decrease stroke volume?
an increase in afterload
In this activity, the right flow tube simulates the _______.
aorta
The ________ valve opens when left ventricular pressure exceeds aortic blood pressure.
aortic
In the non-exercising heart, which event of the cardiac cycle lasts the longest?
atrial diastole
The heart is innervated by ________ nerves.
both parasympathetic and sympathetic
Which of these would cause stroke volume to increase?
both when venous return is increased and when diastolic blood pressure is decreased
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
4, 3, 2, 5, 1
Compute Joe's stroke volume if his end-systolic volume (ESV) is 40 mL and his end-diastolic volume (EDV) is 125 mL.
85 mL
During ventricular systole, the
AV valves are closed.
What effect would an increase in venous return have on the stroke volume?
An increase in venous return would fill the ventricles with more blood, increasing sarcomere length, which would increase the stroke volume
Compare arteriosclerosis with atherosclerosis.
Arteriosclerosis is any thickening and toughening of arterial walls; atherosclerosis is a type of arteriosclerosis characterized by changes in the endothelial lining and the formation of fatty deposits (plaque) in the tunica media.
Define cardiac regurgitation
Cardiac regurgitation is the backflow of blood into the atria when the ventricles contract.
What is coronary ischemia?
Coronary ischemia is a condition in which the blood supply of the coronary arteries is reduced.
Given the description of Tran's varicose veins, what is the name of one of the affected vessels in his legs?
Great Saphenous Vein
What effect does potassium have on the resting membrane potential of the cardiac cell?
Increasing extracellular potassium causes the resting membrane potential to become more positive.
What structure carries the electrical signal from the septum of the heart through the ventricular myocardium?
Purkinje fibers
Abnormally slow depolarization of the ventricles would most change the shape of the ________ in an ECG tracing.
QRS complex
How would properly functioning valves prevent varicose veins?
Valves prevent backward flow of blood
Veins are more prone to inappropriate stretching and twisting than arteries, because
Veins have thinner walls than arteries
Why is ventricular fibrillation fatal?
Ventricular fibrillation is fatal because the ventricles quiver and do not pump blood to the systemic circulation.
Intercalated discs serve to transfer all of the following from cell to cell except action potentials .the force of contraction .small molecules .ionic currents. Z-lines.
Z-lines.
When the ventricles beat rapidly in succession, _______.
a compensatory pause followed
Excessive vagal stimulation of the heart will result in _______.
a decrease in heart rate and, eventually, a temporary cessation of the heartbeat
Research shows that in the absence of neural and hormonal influences, the SA node generates action potentials at a frequency of about 100 times per minute. However, the resting heart rate is about 70 beats per minute. What would the approximate heartrate be if the vagus nerve were severed?
about 100 beats per minute
Which of the following decreases the rate of depolarization in the heart?
acetylcholine
The sinoatrial node has receptors for _______.
acetylcholine, epinephrine and norepinephrine
An adrenergic drug that worked in opposition to epinephrine would _______.
be an antagonist and decrease heart rate
Beta blockers are used to treat high blood pressure (hypertension). Which receptors do you think are being blocked?
beta-adrenergic
Activation of which kind of receptor causes heart rate to increase
beta-one receptor
Activation of which kind of receptor causes heart rate to increase?
beta-one receptor
Stroke volume depends on all of the following except the pressure required to pump blood into the aorta. the contractility of the ventricle. end-systolic volume. cardiac output. end-diastolic volume.
cardiac output.
Ringer's solution contains which of the following?
cations, anions and electrolytes
Modifiers that affect heart rate are _______.
chronotropic
Drugs that block the beta-one adrenergic receptors will
decrease heart rate.
Drugs known as calcium channel blockers such as nifedipine can be used to
decrease the force of cardiac contraction.
Cardiac output can be increased by all of the following except increasing heart rate. decreasing end-systolic volume. increasing ejection fraction. increasing stroke volume. decreasing ejection fraction.
decreasing ejection fraction.
Arteriosclerosis can lead to all of the following except except hypertension. diabetes coronary artery disease. stroke.
diabetes
Delivering single shocks in succession to stimulate the frog heart _______.
did not increase the height of the ventricular systole wave
With respect to heart rate, which of the following worked in opposition to each other?
digitalis and atropine
With respect to heart rate, which of the following had the same effect?
digitalis and pilocarpine as well as atropine and epinephrine
For the frog heart, temperature and heart rate are _______.
directly proportional
The ________ lines the chambers of the heart, covers the heart valves, and is continuous with the endothelium.
endocardium
In cardiac muscle, calcium ions
enter the cell through slow voltage gated ion channels
The visceral pericardium is the same as the
epicardium.
Which of the following affect heart rate through the use of a cAMP (second messenger) system?
epinephrine and norepinephrine
When multiple stimuli were applied at 20 stimuli/sec, _______.
extra systoles were produced
Heat-releasing mechanisms include which of the following?
vasodilation and sweating
The phase in the cardiac cycle when the mitral valve is closed and the aortic valve is open is the
ventricular ejection of ventricular systole.
Skeletal muscle is capable of which of the following?
wave summation and fused tetanus
The mitral valve closing is associated with all of the following except at the same time at the tricuspid valve. when left ventricular pressure exceeds left atrial pressure.at the beginning of ventricular systole. when the right ventricle pressure exceeds the right atrial pressure. when the left atrial pressure exceeds the left ventricular pressure.
when the left atrial pressure exceeds the left ventricular pressure.