Exam1Lec7CardiacCycle

Question 1

In phase b are valves open or closed and what happens to pressure?

Answer 1

Valves are closed and pressure develops durong myocardial contraction

Question 2

What to the two gray bars (b and d) represent?

Answer 2

They represent isobolumic contraction phases where we see no change in volume. All the valves are closed so no blood is moving in and out the heart and the heart itself is contracting/relaxing.

Question 3

When ventricular chamber pressure exceeds the aortic blood pressure what happens to the valves?

Answer 3

They open
Pressure upstream> pressure downstream-valves opens

pressure upstream< pressure down vlaves closes

Question 4

Blood moves according to what?

Answer 4

Pressure gradient

Question 5

What are the 7 phases of the cardiac cycle?

Answer 5

1. Atrial systole
2. Ventricular isvolumetric contraction
3. Rapid ventricular ejection
4. Slow ventricular ejection
5. Ventricular isovolumetric relaxation
6. Ventricular filling
7. Diastasis

Question 6

Phase 1: Atrial Systole

Answer 6

1. P-wave: atrial depolarization begins and triggers atrial contraction
2. A-wave: developes atrial pressure
3. Blood moves from atrial chamber and further fills the ventricles
4. AV valves are open but once they close, this causes that 1st heart sound. ENDS PHASE 1.

Question 7

Phase 2: Isovolumetric contraction

Answer 7

1. QRS wave: Ventricular dep precedes and triggers rapid venttricular contration
2. Contraction causes a rapid rise in developed ventricular pressure
3. With both input (A-V) and output (aortic) valves clides, no blood moves
4. Aortic valve opens: ending phase 2

Question 8

Phase 3: Rapid ejection

Answer 8

1. With ventricular pressure greater than the aortic pressure, the aortic valve opens and blood is rapidly ejected from the ventricle into the aorta producing a rise in systolic aortic pressure.
2. Ventricular contraction is transmitted mechanically to the atria producing the “c” wave in atrial pressure
3. T-wave: ventricular repolarization initiates ventricular relaxation

Question 9

Phase 4: Reduced ejection

Answer 9

1. Ventricular relaxation causes a decr in ventricular pressure.
2. Ventricle slowly empties
3. Continuous return of venous blood beings atrial filling and incr arterial pressure
4. Aortic valve closes: causes 2nd heart sound ending phase 4

Question 10

Phase 5: Isovolumic relaxation

Answer 10

1. Ventricular relaxation (and the empty ventricular chamber) causes a rapid drop in ventricular pressure.
2. Both input (A-V) and output (aortic) valves are closes, no ventricular blood moves
3. AV valve open: ending phase 5

Question 11

Phase 6: Ventricular filling (rapid flow)

Answer 11

1. Ventricular pressure is below atrial pressure, so with the opening of the A-V valve, atrial blood rapidly flows into the ventricle.
2. 3rd Heart sound is caused by the rapid turbulant flow (not due to any valves)

Question 12

Phase 7: Diastasis

Answer 12

1. AV valve is open, and venous blood is slowly filling both the atrial and ventricular chambers.
2. Decr , slow ventricular filling
3. Aortic pressure slowly declines as aortic blood is distributed to peripheral tissues
4. Atrial contraction (systole) ends Phase 7

Question 13

The heart mechanically operates within the limits of ____ relations established. by the ____ and ____ properties of the myocardial tissue.

Answer 13

pressure-volume, passive, active

Question 14

Equation for stroke volume

Answer 14

EDV-ESV=Stroke volume