CV:The Cardiac Cycle
Phsl 6051 Feb. 15, 2008
Lisa Carney Anderson
ander350@umn.edu
612-625-5644
Reading Assignment
• Chapter 12: 373-378
Objectives
• Discuss pressure gradients that lead to the
operation of the heart valves
• Discuss the mechanical and electrical events
of the cardiac cycle during diastole and
systole using Figure 12-20
• Predict the point within the cardiac cycle
when one could hear a murmur for each
valve
Figure 12-7
Valves
Valve Operation
• Passive structures opening and closing
according to surrounding pressure
• EX- Tricuspid valve
Pressure RA > RV OPEN
Pressure RV > RA CLOSED
Cardiac Cycle
• Two major division of cardiac cycle
– Systole
– Diastole
• Four smaller divisions of cardiac cycle
–
–
–
–
Isovolumetric contraction
Ejection
Isovolumetric relaxation
Filling
Figure 12-19a
Systole
Fig 12-19b
Diastole
NEVER
•
•
•
•
NEVER Are all four valves open!
They can all be closed
Two open/Two closed
BUT! Never are they all four open!
Figure 12-20
Cardiac Cycle
Question
• Which of the four divisions of the cardiac
cycle begins with the first heart sound?
–
–
–
–
A.
B.
C.
D.
Ejection.
Filling.
Isovolumetric contraction.
Isovolumetric relaxation.
Valve defects
Fig 12-22
Question
• If the mitral valve is stenotic, when will you
hear the murmur?
– A. Diastole
– B. Systole
Fig 12-21
Ventricular vs. Arterial
Case study
• Roger Crockett, a 68-year-old man with a
40-pack-year smoking history and recent
complaints of angina (sub-sternal chest
pressure) upon exercising, goes to you, his
primary care provider.
• (Copyright ©2000 The McGraw-Hill Companies)
Critical thinking
• While listening to his heart with a stethoscope,
you notice a high-pitched, blowing, systolic
murmur, heard best directly under the left nipple.
A review of Roger's medical records shows no
prior history of a heart murmur. What is causing
this new murmur?
• Is the cause of the murmur in any way related to
his heart attack? Explain.
Questions?
Next Lecture Regulation of Cardiac
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