Lab 5-8 Practical 2

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What is the cardiac cycle?

Cycle of contraction and relaxation of both atria and ventricles

What is systole?

Contraction of an atrium or ventricle; blood is pumped out

What is diastole?

Relaxation of an atrium or ventricle; blood fills the chamber

During atrial diastole, where does blood enter the atria from?

Veins

What percentage of ventricular filling is passive?

80%

What percentage of ventricular filling is due to atrial systole?

20%

What closes the AV valves during ventricular systole?

Rising ventricular pressure

When does ventricular systole begin?

Shortly after atrial systole

During passive ventricular filling, are AV valves open or closed?

Open

During passive ventricular filling, are semilunar valves open or closed?

Closed

During isovolumetric contraction, what is the status of both valve sets?

Both AV and semilunar valves are closed

During ventricular ejection, which valves are open?

Semilunar valves

During isovolumetric relaxation, which valves are open?

Neither; both sets are closed

What is end-diastolic volume (EDV)?

Ventricular volume at the end of diastole

What is end-systolic volume (ESV)?

Ventricular volume at the end of systole

What is stroke volume (SV) in terms of EDV and ESV?

SV = EDV − ESV

What produces the first heart sound (lub)?

Closure of AV valves

What produces the second heart sound (dub)?

Closure of semilunar valves

What instrument is used to auscultate heart sounds?

Stethoscope

What is a heart murmur?

An abnormal heart sound indicating a valve defect

What is a pulse?

Surge of arterial pressure as the heart ejects blood

What is heart rate measured in?

Beats per minute (bpm)

What is the slide’s normal resting heart-rate range?

60–100 bpm

What average resting heart-rate range does the slide give?

70–76 bpm

What is the average heartbeat duration listed?

0.8 seconds

How do you calculate heart rate from beat duration?

60 seconds ÷ seconds per beat

What is blood pressure?

Pressure exerted against arterial walls

What is systolic blood pressure?

Arterial pressure during ventricular systole

What is diastolic blood pressure?

Arterial pressure during ventricular diastole

What instrument measures blood pressure?

Sphygmomanometer

What units measure blood pressure?

mmHg

In what order is blood pressure written?

Systolic over diastolic

Where is the blood-pressure cuff placed?

Upper left arm

Where should the stethoscope be placed for blood-pressure measurement?

Over the brachial artery

How quickly should cuff pressure be released?

About 2 mmHg per second

How is pulse pressure calculated?

Systolic BP − diastolic BP

What is one complete cardiac cycle?

One heartbeat, including contraction and relaxation of both the atria and ventricles.

What does systole mean in the cardiac-cycle discussion?

Ventricular contraction.

What does diastole mean in the cardiac-cycle discussion?

Ventricular relaxation.

How do the atria and ventricles contract in a healthy heart?

The two atria contract together; as they relax, the two ventricles contract together.

What controls opening and closing of heart valves?

Pressure changes within the heart chambers.

What two kinds of events move blood through the heart?

Alternating chamber contraction and relaxation, and pressure-dependent valve opening and closing.

At 75 beats per minute, how long is one cardiac cycle?

About 0.8 second.

At 75 beats per minute, approximately how long does atrial contraction last?

0.1 second.

At 75 beats per minute, approximately how long does ventricular contraction last?

0.3 second.

At 75 beats per minute, approximately how long is the quiescent period?

0.4 second of total heart relaxation.

What is the quiescent period?

The part of the cardiac cycle when the heart is in total relaxation.

What opens the AV valves during passive ventricular filling?

Atrial pressure exceeding ventricular pressure.

During passive ventricular filling, what are the AV and semilunar valve states?

AV valves open; semilunar valves closed.

During passive ventricular filling, what are the atrial and ventricular states?

Both atria and ventricles are relaxed.

What is the function of atrial contraction during ventricular filling?

It completes ventricular filling.

During atrial contraction, what is the state of the ventricles?

Relaxed in ventricular diastole.

During atrial contraction, what are the AV and semilunar valve states?

AV valves open; semilunar valves closed.

What is end-diastolic volume (EDV)?

The maximum volume of blood in a ventricle at the end of ventricular filling.

When is end-diastolic volume reached?

At the end of ventricular diastole, after atrial contraction completes filling.

What begins the isovolumetric contraction phase?

Ventricular contraction raises ventricular pressure and closes the AV valves.

What is the status of all heart valves during isovolumetric contraction?

Both AV and semilunar valves are closed.

Why does ventricular volume stay constant during isovolumetric contraction?

All valves are closed, so no blood enters or leaves the ventricles.

What opens the semilunar valves during ventricular ejection?

Ventricular pressure rising above pressure in the great vessels leaving the heart.

What is the status of the heart valves during ventricular ejection?

AV valves closed; semilunar valves open.

What is stroke volume (SV)?

The amount of blood ejected from each ventricle during one heartbeat.

How do you calculate stroke volume from ventricular volumes?

SV = EDV − ESV.

What is end-systolic volume (ESV)?

The smallest ventricular blood volume, remaining at the end of ventricular systole.

What causes semilunar valves to close during isovolumetric relaxation?

Ventricles relax and their pressure falls below pressure in the great vessels.

What is the status of all valves during isovolumetric relaxation?

Both AV and semilunar valves are closed.

What causes the dicrotic notch on the aortic pressure tracing?

A brief pressure fluctuation when the aortic valve snaps shut.

What does the P wave represent relative to the cardiac cycle?

Electrical activity preceding atrial contraction.

What does the QRS complex precede in the cardiac cycle?

Ventricular contraction and the first heart sound.

What does the T wave occur near in the cardiac cycle?

Ventricular repolarization near the end of ventricular systole.

What produces the first heart sound (S1 or 'lub')?

Closure of the AV valves at the beginning of ventricular systole.

What produces the second heart sound (S2 or 'dup')?

Closure of the semilunar valves at the end of ventricular systole.

Which normal heart sound marks the beginning of ventricular systole?

S1 ('lub').

Which normal heart sound marks the end of ventricular systole?

S2 ('dup').

How are the two normal heart sounds commonly described?

A 'lub-dup' sequence.

What is a heart murmur?

An abnormal heart sound, often indicating a valvular problem.

What can cause a swishing regurgitation murmur?

Backward blood flow through a valve that does not close tightly.

What can cause a high-pitched screeching heart murmur?

Tortuous blood flow through a constricted or stenosed valve.

Where are aortic valve sounds best auscultated?

Second intercostal space at the right sternal margin.

Where are pulmonary valve sounds best auscultated?

Second intercostal space at the left sternal margin.

Where are mitral valve sounds best auscultated?

Fifth intercostal space near the heart apex, in line with the middle of the left clavicle.

Where are tricuspid valve sounds typically auscultated?

Right sternal margin at the fifth intercostal space; the location varies.

Which AV valve usually closes slightly before the other?

The mitral valve closes slightly before the tricuspid valve.

Which semilunar valve normally closes slightly before the other?

The aortic valve closes slightly before the pulmonary valve.

What can make the pulmonary valve closure slightly delayed?

Deep but gentle inhalation, which fills the right ventricle and delays pulmonary valve closure.

Why are valve sounds auscultated at specific thoracic sites rather than directly over each valve?

Sound transmission through blood and thoracic structures makes particular sites best for hearing each valve.

What is an arterial pulse?

Alternating pressure surges causing expansion and recoil of an artery with each left ventricular contraction and relaxation.

What is pulse pressure?

The difference between systolic and diastolic arterial blood pressures.

How do you calculate pulse pressure?

Pulse pressure = systolic pressure − diastolic pressure.

How does resting pulse rate generally relate to heart rate?

They normally equal one another in beats per minute.

What resting pulse rate does the textbook give as an average?

About 70–76 beats per minute.

Besides rate, what pulse characteristics can be assessed?

Rhythmic regularity and amplitude or tension.

How can a superficial arterial pulse be palpated?

Compress the artery over bone or firm tissue using the fingertips of the first two or three fingers.

Where is the superficial temporal pulse felt?

Anterior to the ear in the temple region.

Where is the facial artery pulse felt?

Just anterior to the masseter on the mandible, near the corner of the mouth.

Where is the common carotid pulse felt?

At the side of the neck.

Where is the brachial pulse felt?

In the cubital fossa where the brachial artery divides into radial and ulnar arteries.

Where is the radial pulse felt?

On the lateral side of the wrist above the thumb.

Where is the femoral pulse felt?

In the groin.

Where is the popliteal pulse felt?

At the back of the knee.