Mid Diastole to Late Diastole

Our analysis of events in the left atrium and ventricle, and the aorta begins at the far left of Figure 14-25 with the events of mid-diastole to late diastole. The left atrium and ventricle are both relaxed, but atrial pressure is very slightly higher than ventricular pressure. Because of this pressure difference, the AV valve is open, and blood entering the atrium from the pulmonary veins continues on into the ventricle. To reem-phasize a point made earlier: All the valves of the heart offer very little resistance when they are open, and so only very small pressure differences across them are required to produce relatively large flows. Note that at this time—indeed, throughout all of diastole—the aortic valve is closed because the aortic pressure is higher than the ventricular pressure.

Vander et al.: Human Physiology: The Mechanism of Body Function, Eighth Edition

Circulation CHAPTER FOURTEEN

Circulation CHAPTER FOURTEEN

(a) Systole

Isovolumetric ventricular contraction

Ventricular ejection

Blood flows out of ventricle

Atrium relaxed

Atrium relaxed

Ventricle contracts Atrium I relaxed

AV valve:

Aortic and pulmonary valves:

Closed Closed

Ventricle contracts Atrium I relaxed

Ventricle contracts

Closed Open

(b) Diastole

Isovolumetric ventricular relaxation

Atrium relaxed

Ventricle relaxed

AV valve:

Aortic and pulmonary valves:

Atrium relaxed

Ventricle relaxed

Atrium relaxed

Ventricle relaxed

Ventricular filling

Blood flows into ventricle

Atrium relaxed

Ventricle relaxed

Atrial contraction

Atrial contraction

Closed

Open Closed

Open Closed

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Essentials of Human Physiology

Essentials of Human Physiology

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Responses

  • Cora
    What is the mid to late diastole?
    8 years ago
  • bernd
    What valves are open during mid to late systole?
    1 year ago
  • fausta
    What happens in midtolate diastole?
    1 month ago

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