Cardiac Cycle

Question 1

What are the anatomical structures involved in cardiac pump function?

Answer 1

Ventricular walls

Heart valves

Chordae Tendinea

Papillary muscles

Pericardium

Sarcomeres

Question 2

Where will you find the lowest pressure in teh body?

Answer 2

Right atrium

(also known as central venous pressure)

Question 3

The atria have how many layers of muscle?

Answer 3

2 layers

each are perpendicular to one another

Question 4

The ventricles have how many layers?

Answer 4

3 layers

( 2 perpendicular, one diagonal)

Question 5

How does right ventricular ejection occur?

Answer 5

1. Shortening of the free wall
2. compression of the chamber (Bellows Action)

Question 6

How does left ventricular ejection occur?

Answer 6

1. Constriction of chamber
2. Shortening of Chamber
3. Traction on Right ventricular wall

Question 7

What occurs when you have ventricular pressure?

Answer 7

The AV valves close

Question 8

What occurs when you have high atrial pressure?

Answer 8

The AV valves open

Question 9

Since the valves are made of connective tissue, what type of opening do they do?

Answer 9

The valves passivly open when there is a pressure difference

Question 10

What the requirements for effective cardiac pumping (effective efficient ventricular pumping action)?

Answer 10

1. The contractions of individual cardiac muscle cells must occur at regular intervals and be synchronized.
2. The valves must open fully
3. The valves must not leak
4. The muscle contractions must be forceful
5. The ventricles must fill adequately during diastole

Question 11

what is the cardiac cycle?

Answer 11

The period of time from the beginning of one ventricular contraction to the beginning of the next

Question 12

What are the two phases that are part of the cardiac cycle?

Answer 12

1. Systole: contraction of the ventricle
   
   • closure of the A-V valves -> closure of the Semilunar valves
   • 1/3rd of the cycle
2. Diastole: the period of ventricular relaxation
   
   • closure of the semilunar valve -> closure of the A-V valve
   • 2/3rd of the cycle

Question 13

There are two phases of systole, what are they?

Answer 13

Isovolumic contraction

Ejection period

Question 14

There are two stages in diastole, what are they?

Answer 14

Isovolumic relaxation

Filling period

Question 15

What occurs during Isovolumic Contraction Period?

Answer 15

1. ventricles generate pressure (by slow contraction) without expulsion of blood volume (increase in pressure causes AV valves to close)
2. Bothe A-V valve and semilunar valves are closed (closed chamber)

This is also known as Ventricular Systole

Atria are relaxed

Question 16

What occurs during the ejection period?

Answer 16

1. the A-V valves are closed and semilunar valves have opened up (this is because the pressure in the ventricle is now higher than the pressure in the aorta/pulmonary trunk)
2. Rapid ejection: 70% of total ejection volume is expelled during the 1st 1/3 of the ejection period
3. Reduced Ejection: the remaining 30% of the ejected volume occurs during the last 2/3 of the ejection period.

Question 17

What occurs during Isovolumic relaxation?

Answer 17

1. The ventricular chamber volume remains constant but the chamber pressure drops
2. Both A-V and Semilunar Valves are closed

Ventricles are relaxed

Dicrotic Notch occurs during this phase

Question 18

What occurs during the filling period?

Answer 18

1. A-V valves are open and the semilunar valves are closed (rapid filling occurs and fills 2/3 of the ventricle)
2. Diastasis: (slow filling) the 2nd 1/3 of diastole contributes minimally to ventricular filling
3. Arterial Systole: (SA node excites and causes contraction of the atria = top off) the last 1/3 of diastole contribute about 15% to ventricular filing

This is also know as mid-to-late diastole

Heart Blood pressure is low as the blood enters atria and flows into ventricles

Question 19

After the atria contract and top off the ventricle what occurs?

Answer 19

Atria contract due to the SA node firing -> ventricles are topped off -> ventricles strecth but contraction does not occur because the AV node hold exicitation -> eventually the excitation is released -> ventricles begin to contract -> pressure increases -> AV valve closes -> now in ventricular systole

Question 20

What causes the semilunar valves to close?

Answer 20

When the arterials are filled with blood they stretch. When they recoil to propel the blood forward some of the blood goes back which causes the Semilunar valves to close

Question 21

What is the Dicrotic notch?

Answer 21

Brief rise in aorta pressure caused by backflow of blood rebounding off semilunar valves

Question 22

What are the normal audible sounds?

Answer 22

S1

S2

Question 23

What is S1?

Answer 23

1st heart sound that is heard during Isovolumic contraction. This is when the A-V valves close

Low Pitch, Loud and Long

Question 24

What is S2?

Answer 24

2nd heart sound. This is heard during Isovolumic Relaxation when the semilunar valves close

High Pitch, loud and short

Question 25

What is the sound that the regularly non-audible heart sound make?

Answer 25

A gallop sound

Question 26

What is the significance of hearing S3 and/or S4 in adults?

Answer 26

In adults they are associated with myocardial disease

Question 27

What are non-audible heart sounds?

Answer 27

S3 and S4

Question 28

What is S3?

Answer 28

The third heart sound. This is heard when there is a transition from rapid diastolic filling to diastasis. ## Footnote **Low pitch and faint**

Question 29

What is S4?

Answer 29

This is the 4th heart sound. This is heard during Atrial Systole. ## Footnote **Low pitch and faint**

Question 30

On a normal, there is a thing know as the S2 splitting. How can this be heard during clinical exam? What exactly is the S2 splitting?

Answer 30

S2 occurs from the closing of the aortic and pulmonic valves. There are times where there is a delay in the valve closure. This is normal. ## Footnote To hear during exam: Ask patient to inspire -\> increases thoracic cage volume and flattens the diaphragm **The decrease in thoracic pressure = increase in venous return (increase R. ventricle stoke volume) -\> this causes the _pulmonic valve to close later_ (since more blood needs to get through)** **More blood remaining stagnant in the lungs (due to increase capacity of the capillary bed when inspiring) = reduce blood return to the Left side of the heart (decrease in left stoke volume) -\> aortic valve closes faster**

Question 31

What causes heart Murmurs?

Answer 31

Turbulence

Question 32

The intensity (loudness) and frequency (pitch) of a heart murmur depends on what?

Answer 32

Depend on the velocity which is determined by pressure gradient across area of murmur production

Question 33

What are the three catagories of heart murmurs?

Answer 33

Systolic Diastolic Continous

Question 34

What are the two type of Systolic Murmurs?

Answer 34

Ejection (Mid-Systolic) Murmor Regurgitant Murmur

Question 35

Ejection (Mid-Systolic) Murmor

Answer 35

* Etiology: Forward FLow across stenotic semilunar valve(s) * Timing: starts after Isovolumiv contraction (delay from S1) with semilunar valve closure * Occurence: **Aortic and pulmonary valvular stenosis** * Quality: crescendo-decrescendo systolic

Question 36

Regurgitant Murmurs (Systolic)

Answer 36

* Etiology: Retrograde Flow from high to low pressure chamber * Timing: starts with S1 until end of Isovolumic Relaxation * Occurence: A**V valvular incompetence or Ventricular Septal Defect** * Quality: pansystolic or holosystolic murmur

Question 37

What are the two types of Diastolic Murmurs?

Answer 37

Diastolic Fillinf Murmurs (Rumbles) Regurgitant Murmurs

Question 38

Regurgitant Murmurs (Diastolic)

Answer 38

* Etiology: Retrograde flow across incompetent semilunar valve * Timing: Isovolumic relaxation at SL valves closure (S2) until S1 * Occurence: **Aortic or pulmonary Incompetence** * Quality: High Pitch, high frequency, blowing decrescendo

Question 39

Diastolic Filling Murmurs (Rumbles)

Answer 39

* Etiology: Forward flow across stenotic AV valve)s) * Timing: Starts after Isovolumic relaxation (delay from S2) with AV valve opening and end with AV valve vlosure * Occurence: **Mitral and tricupsid AV valvar stenosis** * Quality: Prominent during rapid diatolic filling and atrial systole. Low frequency rumbling

Question 40

What are the two type of Continous Murmurs?

Answer 40

Rapid Blood Flow through the heart High-to-low pressure shunts

Question 41

Rapid Blood FLow through the heart | (Continous Murmurs)

Answer 41

* Occurence * Mammary Souffle * Mid-late pregnancy to end of lactation * High cardiac output such as in anemia * High Speed flow, volume of blood increases up to 50%

Question 42

High to low pressure shunts | (Continous Murmurs)

Answer 42

Occurence: Congenital Cardiovascular Defect - shunt systemic circulation (aorta) to arterial pulmonary circulation Patent ductus arteriosus It has a waxing and wanning intensity

Question 43

What are the mechanical events of the cardiac cycle?

Answer 43

1. Late Diastole: both sets of chanmbers are relaxed and ventricles fill passively 2. Atrial sytole: atrial contraction forces a small amount of blood into ventricles 3. Isovolumic ventricular contraction: first phase of ventricular contraction pushes AV valves closed but does not create enough pressure to open semilunar valves 4. Ventricular ejection: pressure rises and exceed pressure in the arteries, the semilunar valves open and blood is ejected 5. Isovolumic ventricular relaxation: as ventricles relax, pressure in ventricles falls, blood flows back into cusps of semilunar valves and snaps them closed