cardiac cycle

Question 1

overiview

Answer 1

• late diastole: both sets of chambers are relaxed and ventricles are filling passively
• atrial systole: atrial contraction forces a small amount of additional blood into ventricles
• isovolumic ventricular contractions: first phase of ventricular contraction pushes AV valves closed but does not create enough pressure to open semilunar valves
• ventricular ejection: as ventricular pressure rises and exceeds pressure in the arteries, the semilunar valves open and blood is ejected
• isovolumic ventricular relaxation: as ventricles relax, pressure falls, blood flows back into the cusps of semilunar valves and snaps them closed

Question 2

diastolic filling

Answer 2

• atrium and ventricle is relaxed
• blood enters down pressure gradient
• mitral valve is open, pulmonary valveis closed

Question 3

atrial contraction

Answer 3

• precedes ventricular systole
• adds less than 20 percent to ventricular filling at rest
• p wave represents atrial depolarization and immediately precedes contraction

Question 4

isovolumic contraction

Answer 4

• mitral valve closes, aortic is closed
• end diastolic volume
• QRS complex on ECG
• ventricular depolarization

Question 5

ventricular ejection

Answer 5

• rapid for the first 1/3 that accounts for 2/3 of the ejected volume
• reduced ejection phase during relaxation after peak aortic pressure

Question 6

diastole

Answer 6

• pressure falls but remains higher than atrial pressure
• mitral valve remains closed
• isovolumic relaxation
• immediately follows the T wave associated with ventricle repolarization

Question 7

dicrotic notch

Answer 7

• seen on arterial pressure waveform
• aortic valve closure and momentary retrograde flow of blood
• due to elastic recoil of the aorta

Question 8

rapid diastolic filling

Answer 8

-ventricular pressure falls below atrial
-mitral valve opens
-

Question 9

jugular and atrial pressure waveforms

Answer 9

-a wave: due to atrial contraction

C wave: results from displacement of mitral valve during isovolumic contraction of ventricle

V wave: due to atrial filling while the mitral valve is closed during ventricular systole and isovolumic relaxation

Question 10

heart sounds

Answer 10

S1: closure of AV

S2: closure of semilunar valves

S3: rapid ventricular filling: not normal inadults. caused by increased filling pressure. congestive heart failure or mitral valve regurgitation in children

S4: atrial contraction: not normal, associated with ventricular hypertrophy where ventricular compliance is decreased