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COM: Cardiopulm (Final) COPY > Lecture 3&6: Cardiac Cycle & Heart Sounds I & II > Flashcards

Lecture 3&6: Cardiac Cycle & Heart Sounds I & II Flashcards

1
Q

Define systole

A

The contraction of the heart

  • Can be devided into atral systole (atrial contraction) or ventricular systole (ventricular contraction)
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2
Q

Define diastole

A

The relaxation of the heart

  • Commonly referred to as ventricular diastole but the atria do relax too -> atrial diastole is covered up by ventriular systole
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3
Q

T/F: Unlike skeletal muscle, cardiac muscle can generate its own action potential

A

True

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4
Q

What are the general roles of the SA and AV nodes of the heart?

A

Spontaneously depolarize and generate the AP that causes the cardiac muscle too contract

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5
Q

Under normal conditions, the _______ node of the heart is faster to reach threshold thna the _______ node, and therefore it serves as the pacemaker.

A

SA; AV

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6
Q

When do we refer to a heart rhythm as sinus rhythm?

A

When the SA node is the pacemaker of the heart then the regular heart rhythm is considered sinus rhythm -> SA node driving the heart

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7
Q

What kind of change in heart rate would we see if the AV node was driving the heart instead of the SA node?

A

The heart rate would decrease because the AV node s slower than the SA node -> you woud expect a HR in the 40’s if the AV node was driving the heart

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8
Q

After the SA node generates the AP, 2 things hapen at about the same time, what are they?

A

1) The AP depolarizes the atria using the gap junctions between the cardiac muscle cells
2) The AP travels to the AV node via an internodal pathway

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9
Q

Why does the electrical conduction through the atria travel via gap junctions and through the ventricles travel via the internodal pathway?

A

The walls of the atria are so thin that the gap junctions are suitable. However, the walls of the ventricles are way to thick for gap junctions to be sufficient

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10
Q

What is the internodal pathway?

A

Modified cardiac muscle cells that are modified for conduction and dont have contractile properties. This enables the depolarization to go from the SA node to the AV node quickly

  • Once the AP gets to the AV node its like a road block. The AV node has the slowest conduction and delays the contraction of the ventricles momentarily which is needed for the heart to function properly
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11
Q

Once the AV node transmits the AP to the ventricles, specialized cardiac muscle (the bundle branches and prikinje fibers) transmit the AP to the ventricles, depolarizing what parts of the ventricles in what order?

A

The septum then the free walls of both ventricles starting from the apex back up

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12
Q

The AV node receives the depolarization from the SA node via what pathway?

A

Internodal pathway

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13
Q

Since the atria depolarize first, they contract first - this ____________ (increases/decreases) the pressure in the atria

A

Increases

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14
Q

What happens to the pressure in the atria and ventricles during atrial systole?

A
  • The atrial pressure increases as the atria contract

- The ventricular pressure increases as blood is pushed from the atria into the ventricles

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15
Q

When does ventricular systole occur?

A

After the atria contract and begin to relax, the ventricles start to contract

  • Remember: the pause while the AV node was slow gave the atria time to do their job before the ventricles start to contract
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16
Q

During ventricular systole, what contracts first and why?

A

Because the septum was depolarized first, it also contracts first

An area of the heart that depolarizes first will also contract first

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17
Q

What happens during ventricular systole after the septum contracts?

A

The walls of the ventricles contract next, squeexing the blood into the chambers

  • Contraction starts at the appex and travels up toward the atria just as conduction does
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18
Q

During ventricular systole, what happens to the pressure in the ventricles when they contract?

A

The pressure increases

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19
Q

When is the pressure in the ventricles the highest?

A

During systole -> peak pressure on graph is systolic pressure

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20
Q

Why does the atrial pressure increase during ventricular systole?

A

Blood is coming back to the heart through the veins, this blood cant get into the ventricles so it accumulates in the atria and there is an increase in the pressure

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21
Q

Why does atrial pressure increase slightly then drop back down when the ventricles contract?

A

Right where ventricular pressure exceeds atrial pressure, the mitral valve closes -> the atrial pressure then increases a little because the valve bulges back into the atria decreasing the volume of the atria slightly

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22
Q

What happens during ventricular diastole?

A

The relaxation of the ventricles begins, causing a decrease in the ventricular pressure

The initial slight decrease in ventricular pressure on the graph is still ventricular systole bc the ventricle is still in contraction there is just blood leaving the heart which causes the pressure to go down slightly

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23
Q

What happens during atrial systole?

A

The pressure in the atria exceed that in the ventricle and forces the blood in the atria to move into the ventricle

  • Ventricular volume increases but only slightly due to the ventricles -> the majority of the blood that fills the ventricles is due to gravity
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24
Q

Why does aortic pressure stay quite a bit above the atrial and ventricular pressures?

A

Due to smooth muscle in the aorta

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25
Q

During ventricular systole, the ventricles contract, increasing the pressure in the ventricles, then what happens?

A

Almost immediately, the ventricular pressure exceeds the atrial pressure, causing the AV valves to close, preventing blood from flowing back into the atria

26
Q

Describe the isovolumetric contraction of the ventricle?

A

The stage of ventricular systole when the ventricular volume remains constant, while the pressure increases drastically

27
Q

Arterial blood pressure is measured at 118/68; while the pulmonary arterial pressure is 26/14. What is the minimum pressure in the left ventricle when the aortic valve opens?

A

68

28
Q

Arterial blood pressure is measured at 118/68; while the pulmonary arterial pressure is 26/14. What is the minimum pressure in the right ventricle when the pulmonic valve opens?

A

14

29
Q

Arterial blood pressure is measured at 118/68; while the pulmonary arterial pressure is 26/14. What is the minimum pressure in the left ventricle at the peak of systole?

A

118

30
Q

During ventricular systole, the ventricular pressure must exceed ____________ pressure on each side to open the valve

A

Diastolic

31
Q

What is normal aortic and pulmonary arterial pressures?

A

Normal aortic pressure = 120/70

Normal pulmonary artery pressure = 25/15

32
Q

During ventricular diastole, when do the aortic and pulmonary valves close?

A

When the pressure in the ventricle drops below the arterial pressure

33
Q

During ventricular diastole, why does the blood “backflow” into the aorta when the aortic valve closes?

A

When the valve closes, the force driving the blood forward (the pressure in the ventricle) is “cut-off” from the blood and gravity is free to pull the blood back down

34
Q

What is isovolumetric relaxation of the ventricles?

A

A period during ventricular diastole when no blood enters or leaves the ventricles while it is relaxing (both the AV and aortic valves are closed

35
Q

What occurs during ventricular diastole?

A

When the atrial pressure exceeds ventricular pressure, the AV valves will open, and blood will move from the atria to the ventricles (atria are NOT contracting at this point)

36
Q

What pressure does the L and R ventricle have to be at for the blood to enter from the atria?

A

The ventricular pressure must be lower thna all other pressures during diastole for blood to move from high pressure to low pressure

37
Q

The closing of the aortic valve produces the __________________ in the aortic pressure wave

A

Dicrotic notch

  • indicator that there is some back force; this is the 2nd heart sound
  • Happens during ventricular diastole
38
Q

During ventricular diastole, because the ventricular pressure and volume are both very low when the AV valves open, blood flows into the ventricles. Why does the aortic pressure continue to drop?

A

The blood is leaving the aorta and flowing into the smaller vessels in the periphery.

39
Q

During ventricular diastole, the aortic pressure continues to drop as the ventricles begin filling. This occurs bc the blood is leaving the aorta and flowing into the smaller vessels in the periphery. What is this called?

A

Peripheral run-off

40
Q

During ventricular diastole, the aortic pressure continues to drop as the ventricles begin filling. This occurs bc the blood is leaving the aorta and flowing into the smaller vessels in the periphery. This is called peripheral run-off. What is this determined by?

A

The resistance to blood flow

41
Q

What ECG wave occurs when Na+ influx is occuring in atrial myocytes?

A

P wave

42
Q

What happens to ventricular and arterial pressures during atrial contraction?

A

Both increase -> ventricular pressure is increasing bc blood is flowing in and atrial pressure increases bc its contracting

43
Q

During the PR interval, the atria are contracting. Where is the depolarization?

A

The AV node

44
Q

Most of the ventricular contraction occurs during what segment on the ECG?

A

ST segment

45
Q

Ventricular and aortic ressure begin to fall prior to ______ wave - sothe ventricle is still contracting but pressure is falling due to the ejection of the blood

A

T wave

46
Q

When on the ECG does isovolumetric relaxation occur?

A

During the end of the T wave

47
Q

The AV valves open and ventricular filling resumes at or after the end of the ______ wave

A

T

48
Q

Jugular is a representation of what is happening where?

A

In the atria

49
Q

What is the a wave of the jugular pressure wave?

A

The pressure wave created by the atrial contraction. Since there is no valve between the atria and great veins, the pressure is reflected backwards

50
Q

What is the c wave of the jugular pressure wave?

A

The pressure wave created by the period of isovolumetric contraction in the ventricles - there is bulging of the wall back into the atria

  • Isovolumetric contraction is preventing blood in the jugular from getting into the atria so the pressure in the jugular increases
51
Q

What is the v wave on the jugular pressure wave?

A

The pressure wave created as blood returns back to the heart but cant enter the ventricle

  • The valves are open and allow for blood to flow in
52
Q

What is responsible for the first heart sound?

A

AV valve closure

  • As the AV valve closes the blood that is returning to the heart hits the closed valves as it tries to enter the ventricle. That impact creates vibration in the cardiac tissue that can be heard as the first heart sound
53
Q

What is responsible for the second heart sound?

A

Aortic and pulmonary valves closing

  • It is pproduced when the blood in the aorta/pulmonary artery backflows and bounces off the closed valves
54
Q

What is responsible for the third heart sound?

A

Rapid filling of the ventricles

  • This sound is normal in children, but may or may not be heard in normal adults!
55
Q

What is responsible for the fourth heart sound?

A

During atrial contraction when atria are topping off the ventricles

56
Q

The ________ heart sound may be heard during atrial contraction. It is the result of that last little bit of blood being squeezed into the ventricle.

A

Fourth heart sound

  • It is normal in children but not generally heard in normal adults
57
Q

Murmurs are indicative of what type of problem?

A

Valvular problem

58
Q

What are the 2 conditions that result in a murmur being heard?

A
  • Blood is moving in a direction it shouldn’t be moving

- Blood is having a hard time moving in the direction it should be moving in

59
Q

A systolic murmur is heard between what heart sounds?

A

The first and second heart sounds

60
Q

During what part of the cardiac cycle is an inconsistency or regurgitation of an AV valve heard?

A

Systole

61
Q

What causes a diastolic murmur?

A
  • Blood is moving back into the aorta or pulmonary artery caused by regurgitation (aortic regurgitation)

Or

  • Blood is having a hard time moving in the direction it should be moving in -> cant get into the ventricle due to stenosis
62
Q

What causes a systolic murmur?

A
  • Blood is moving back into the atria caused by regurgitation (mitral regurgitation)

Or

  • Blood is hhaving a hard time moving in the direction it should be moving in -> in this case the blood cant get into the aorta/pulmonary artery due to stenosis

COM: Cardiopulm (Final) COPY (20 decks)

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