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Related Concept Videos

The Cardiac Cycle01:13

The Cardiac Cycle

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The heart beats rhythmically in a sequence called the cardiac cycle—a rapid coordination of contraction (systole) and relaxation (diastole).
The Process
Electrical signals—sent from the sinoatrial (SA) node in the right atrial wall to the atrioventricular (AV) node between the right atrium and right ventricle—cause both atria to simultaneously contract. When the signal reaches the AV node, it pauses for approximately a tenth of a second, allowing the atria to contract and...
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Cardiac Cycle01:29

Cardiac Cycle

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The cardiac cycle refers to the sequence of events that occur in the heart from the beginning of one heartbeat to the next. It's characterized by alternating periods of contraction (systole) and relaxation (diastole) of the heart muscles.
During the cardiac cycle, blood flow through the heart is regulated entirely by changing pressure gradients. This sequence of events begins with the heart in a state of total relaxation, known as mid-to-late diastole, during which blood passively flows from...
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Physiology of the Heart: The Cardiac Cycle01:18

Physiology of the Heart: The Cardiac Cycle

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The cardiac cycle describes the events from one heartbeat to the next. It includes three main phases: diastole, atrial systole, and ventricular systole, all driven by changes in chamber pressures and the function of heart valves.
Diastole: The Relaxation Phase
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Correlation between ECG and Cardiac Cycle01:25

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The electrical signals recorded on an electrocardiogram (ECG) occur before the mechanical processes of contraction and relaxation during the cardiac cycle.
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...
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Mechanism of Cardiac Arrhythmias01:28

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Arrhythmias are irregular heart rhythms occurring when the heart's electrical impulses become abnormal. These disturbances can lead to various symptoms, depending on their severity and the underlying cause. Some common factors contributing to arrhythmias include hypoxia, ischemia, electrolyte imbalances, excessive catecholamine exposure, drug toxicity, and muscle overstretching. Arrhythmias can be classified into two main types based on the rate and site of origin of abnormal heart rhythms.
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Animal Mitochondrial Genetics02:59

Animal Mitochondrial Genetics

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Among all the organelles in an animal cell, only mitochondria have their own independent genomes. Animal mitochondrial DNA is a double-stranded, closed-circular molecule with around 20,000 base pairs. Mitochondrial DNA is unique in that one of its two strands, the heavy, or H, -strand is guanine rich, whereas the complementary strand is cytosine rich and called the light, or L, -strand. Compared to nuclear DNA, mitochondrial DNA has a very low percentage of non-coding regions and is marked by...
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Related Experiment Video

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Displacement Analysis of Myocardial Mechanical Deformation DIAMOND Reveals Segmental Heterogeneity of Cardiac Function in Embryonic Zebrafish
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Mitochondrial Deformation During the Cardiac Mechanical Cycle.

E A Rog-Zielinska1, E T O'Toole2, A Hoenger2

  • 1Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg, Bad Krozingen, and Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Anatomical Record (Hoboken, N.J. : 2007)
|October 11, 2018
PubMed
Summary

Mechanical forces deform mitochondria within cardiac cells. This study provides ultrastructural evidence of mitochondrial deformation and interactions, offering insights into cardiac cell mechanosensing and signaling.

Keywords:
electron tomographyheartmechanosensitivitymitochondriasarcoplasmic reticulum

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Area of Science:

  • Cardiovascular Biology
  • Cellular Ultrastructure
  • Biophysics

Background:

  • Cardiomyocytes undergo constant cyclic deformation.
  • The impact of this deformation on intracellular organelles, particularly mitochondria, is not fully understood.
  • Understanding these effects is crucial for comprehending cardiomyocyte responses to mechanical changes.

Purpose of the Study:

  • To provide three-dimensional ultrastructural evidence of mechanically induced mitochondrial deformation in rabbit ventricular cardiomyocytes.
  • To investigate mitochondrial interactions with other cellular components under varying mechanical conditions.

Main Methods:

  • Three-dimensional ultrastructural analysis using electron microscopy.
  • Examination of cardiomyocytes across a range of sarcomere lengths (stretch, slack, contracture).

Main Results:

  • Demonstrated mechanically induced mitochondrial deformation in cardiomyocytes.
  • Observed interactions between mitochondria and with microtubules, sarcoplasmic reticulum, and T-tubules.
  • Provided ultrastructural evidence across different mechanical states.

Conclusions:

  • Mechanically induced mitochondrial deformation occurs in cardiomyocytes.
  • Mitochondria interact with various intracellular structures, suggesting a role in mechanosensing.
  • These findings offer a structural basis for interpreting mechanically regulated signaling in cardiac cells.