Lesson 20.3 Class Activity Study Notes

Lesson 20.3 Class Activity Notes

1. Cardiac Cycle Images

  • Task: For each image, determine the phase of the heart cycle.

  • **Phases: **

    • Atrial Diastole (AD): Relaxation of the atria; blood fills atria.

    • Atrial Systole (AS): Contraction of the atria; blood pushed into ventricles.

    • Ventricular Diastole (VD): Relaxation of the ventricles; blood fills ventricles.

    • Ventricular Systole (VS): Contraction of the ventricles; blood is ejected to the body.

  • Possible Labels for Images:

    • Image 1: VD/AD

    • Image 2: AS/VD

    • Image 3: AD/VD

    • Image 4: AD/VS

2. Waveforms Matching

  • Task: Match each waveform with its corresponding physiological event.

  • Matching Results:

    • P wave: B. Atrial depolarization (contraction)

    • QRS complex: C. Ventricular depolarization (contraction)

    • T wave: A. Ventricular repolarization (relaxation)

3. Blood Flow Scenarios

  • Task: Categorize the following statements into the correct scenarios based on pressure differences in the heart.

  • Scenarios:

    • Atrial pressure > Ventricular pressure

    • Blood flows into the ventricle

    • AV valves open

    • Ventricular pressure > Aortic pressure

    • Blood is ejected into the aorta

    • Semilunar valves open

4. Isovolumetric Phases Explanation

  • Question: Why is there no blood entering or exiting the ventricles during isovolumetric phases?

  • Answer: All valves are closed during both isovolumetric systole and isovolumetric diastole.

    • In isovolumetric systole, the ventricles contract with closed valves, preventing blood flow.

    • In isovolumetric diastole, the ventricles are relaxed with closed valves, maintaining blood volume.

5. Heart Sounds Matching

  • Task: Match each heart sound with the corresponding event.

  • Matching Results:

    • S1: D. AV valves closing

    • S2: E. Semilunar valves closing

    • S3: A. Blood flowing into ventricles

    • S4: B. Atrial contraction

    • Heart murmur: C. Regurgitation through valves

Summary

  • The heart cycle consists of distinct phases characterized by the activity of the atria and ventricles, defined by pressure changes and valve functionality. Understanding the flow of blood during these phases is crucial for grasping cardiac physiology and the heart sounds that accompany them.