In-Class
Questions
Session 2 /

Heart Physiology I

M.A.S.T.E.R. Learning Program, UC Davis School of Medicine

Date Revised: 1/11/02

Revised by: Andrew Dao and Reza Danesh

Muscle length tension as related to understanding isometric contraction (optional):

  1. Draw the length tension curves for total, passive, and active force generated by isometric contraction. What determines maximum tension and why?

Electrophysiology of the Heart

  1. A). Draw and describe the phases of a pacemaker action potential. B). Diagram the effect of parasympathetic stimulation of these cells. The conductance of which ion(s) is/are being affected? C). Diagram the effect of sympathetic stimulation of these cells. The conductance of which ion(s) is/are being affected?
  1. A) Draw the ventricular and atrial action potentials. B) Describe each phase in terms of ion conductance. C) How do the two differ from each other and from an AP of skeletal muscle?
Cardiac Cycle & Cardiac Output
  1. A. Draw and label 2 cycles of the Cardiac Cycle.

B. Include the left ventricular pressure curve, the ventricular action potential and ECG.

  1. Add aortic pressure to the graph.
  2. Add left atrial pressure.
  3. Add volume axis and draw a left ventricular volume curve.
  1. Using the theory behind the law of Laplace, explain why a person with a dilated heart (due to congestive heart failure, for example) is more likely to suffer myocardial ischemia than a person with a nondilated heart?
  1. In a normal heart, what type of contraction is occurring in the left ventricular muscle before the aortic valve opens?

What type of contraction are we looking at after the aortic valve opens? (That is, in the left ventricle.)

What determines how much the ventricular muscle fibers will shorten?

Please note the below information was NOT covered in your syllabus this year. Skeletal muscle and reflexes will be covered in the Spring Quarter. However, it would be advisable for you to obtain an understanding of this material which is briefly presented below. An understanding of muscle contraction will help you better understand the cardiophysiology. Dr. Carlsen advises you to read the recommended textbook on the subject matter.
Skeletal Muscle
  1. Compare and contrast depolarization in a muscle fiber action potential versus muscle fiber shortening upon contraction in terms of the following:
  1. Fill in the chart below concerning types of muscle fibers:

TYPE I / TYPE Ila / TYPE IIB
Rate of Contraction
ATP production
# of mitochondria
Rate of fatigue
Fiber Size
Function:

8. What are three ways to increase the force of a muscle contraction?

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