Cardiac Cycle

Question 1

What needs to be present for blood to flow from one area to another?

Answer 1

Pressure gradient

Question 2

What triggers atrial systole?

Answer 2

SA node (pacemaker of the heart)

Question 3

What is happening to the pressure in the atrial and the ventricular pressures during atrial systole?

Answer 3

Atrial pressure increases as the atria contract and the ventricles also increase in pressure (d/t flow of blood into them). *Note: Atrial pressure is slightly greater, so we have blood flowing into a lower pressure system (the ventricle)*

Question 4

• What is happening to aortic pressure during atrial systole?

Answer 4

• Decreasing (thru atrial contraction and EVEN INTO VENTRICULAR CONTRACTION)
  
  • Pressure is falling d/t peripheral run off
  • Also the aorta is not receiving any blood from the ventricles at this time (because the ventricles are still in diastole)

Question 5

• What happens almost immediately in ventricular systole?

Answer 5

• Closure of AV Valves
  
  • ​Ventricular pressure exceeds atrial pressure and forces the AV valves to close
  • PREVENTS RETROGRADE FLOW

Question 6

• What is happening to ventricular volume during early ventricular systole?
• What is happening to aortic pressure?
• What is happening to ventricular pressure?

Answer 6

• Volume is constant (Isovolumetric contraction)
• Aortic pressure still decreasing slightly
• Ventricular pressure increases dramatically

Question 7

• What ends the period of isovolumetric contraction?

Answer 7

• When ventricular pressure exceeds aortic pressure

Question 8

• What happens when isovolumetric contraction is over?

Answer 8

• Ventricular pressure exceeds aortic pressure
• Aortic valve opens
• Blood is ejected from ventricles
• Ventricular pressure follows aortic pressure for a brief time period
• Shortly after, aortic pressure starts to decrease as the rate of ejection slows down

Question 9

• What is one of the first things that occurs during ventricular diastole?

Answer 9

• Pressure in ventricle drops below arterial pressure
• Closure of semilunar valves
• AORTIC AND VENTRICULAR PRESSURES NOW RAPIDLY DIVERGE FROM ONE ANOTHER (B/C Peripheral run off is now controlling aortic pressure and ventricular filling is now controlling ventricular pressure)

Question 10

What is happening to ventricular, atrial and aortic pressures during early systole?

Answer 10

• Pressure in ventricles rising
• Atrial pressure is rising somewhat d/t increased venous return
• Aortic pressure is declining d/t peripheral run off

Question 11

What is the purpose of atrial systole?

Answer 11

• Top off ventricular volume

Question 12

• What is happening to the aortic pressure during atrial systole?

Answer 12

• Decreasing d/t peripheral run off

Question 13

• During isovolumetric contraction the pressure in the ventricle increases rapidly. There is also an increase in atrial pressure. Why?

Answer 13

• Isovolumetric contraction of the ventricles are causing bulging of AV valve, which leads to an increase in atrial pressure

Question 14

• During the ejection of blood ventricular pressure and aortic pressure increase together to _

Answer 14

Peak systolic pressure

Question 15

• What are the key events that are occurring during isovolumetric relaxation?

Answer 15

• AV Valves closed
• Semilunar valves closed
• Pressure in ventricles is dropping quickly
• Aortic pressure slowly decreasing (d/t peripheral run off-so not following ventricular pressure anymore)

Question 16

• What ends isovolumetric relaxation?

Answer 16

When ventricular pressure drops below atrial pressure

Question 17

• What is diastasis?

Answer 17

• Occurs as ventricular filling slows to a near stop
• At this time, ventricular pressure is essentially equal to ventricular pressure during late ventricular diastole

Question 18

• If we change heart rate, what component of blood pressure changes the most?

Answer 18

DIASTOLE (The heart, when HR is increased, will spend lest time in diastole)

Question 19

• What is occurring during the fourth heart sound (if you can even hear it)
• Where does this occur in relation to other heart sounds?

Answer 19

• Produced by atria contracting and ejecting blood into the already mostly-full ventricle
• Heard just before S1 (Closure of AV valves)

Question 20

• The jugular vein pressure wave follows which pressure wave most closely?

Answer 20

Atrial pressure wave

Question 21

• When does the a wave in jugular pressure occur?

Answer 21

• Atrial contraction

Question 22

• When does the c wave in jugular pressure occur?

Answer 22

• QRS during isovolumetric contraction period
• Matches the increase in atrial pressure as AV valves bulge back from isovolumetric ventricular contraction

Question 23

• When does the jugular v wave occur?

Answer 23

• Ventricular contraction
• Similar wave is occurring in the atrial pressure curve d/t venous return