M4: Cardiac Cycle

Question 1

contraction phases of the heart is known as…

Answer 1

systole

Question 2

Phases of the cardiac cycle

Answer 2

Phase 1: ATRIAL CONTRACTION
- active ventricular filling
Phase 2: Isovolumetric contraction
- venrticle begins contraction
Phase 3: VENTRICULAR EJECTION
Phase 4: ISOVOLUMETRIC RELAXATION
Phase 5: VENTRICULAR FILLING (passive)
- all chambers relaxed

Question 3

Valve status in each phase of cardiac cycle

Answer 3

Phase 1: ATRIAL CONTRACTION (systole)
- SL closed
- AV open
Phase 2: Isovolumetric contraction
- SL closed
- AV closed
Phase 3: VENTRICULAR EJECTION
- SL open
AV closed
Phase 4: ISOVOLUMETRIC RELAXATION
- SL closed
- AV closed
Phase 5: VENTRICULAR FILLING (passive)
- SL closed
- AV open

Question 4

dicrotic noth

Answer 4

Little increase in aortic pressure when period of isometric relaxation starts.
Causeed by sudden closure of SL valves

Question 5

relaxation phases of the heart are known as…

Answer 5

diastole

Question 6

what phase makes up 70% of ventricular filling and why?

Answer 6

passive ventricular filling
- most blood flows in
- active ventricular filling only pushes out %30

Question 7

why are there different pressure in the left vs right side of the heart?

Answer 7

L side pumping out to body, requires higher pressure than R side

Question 8

diastolic blood pressure

Answer 8

• 80 mm Hg
• when the ventricular pressure overcomes aortic pressure and open aortic SL valve (between period of isovolumetric contraction and period of ejection)

Question 9

systolic blood pressure

Answer 9

• 120 mm Hg
• peak of blood pressure in aorta and ventricles during period of ejection

Question 10

end-systolic volume

Answer 10

• 55mL (varies between people)
• volume of blood in L ventricle at the end of ventricular systole

Question 11

end-diastolic volume

Answer 11

• 125 mL (varies between people)
• volume of blood in L ventricle at the end of ventricular diastole

Question 12

stroke volume (SV)

Answer 12

EDV – ESV = SV
Volume of blood pumped out of the heart per beat

Question 13

what makes the “lubb-dubb” sound of the heart?

Answer 13

Sounds aren’t caused by valves closing, but the turbulent movement of the blood they displace in that process.

LUBB
- AV valves closing at beginning of ventricular systole

DUBB
- Sl valves closing at beginning of ventricular diastole