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.