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Related Concept Videos

Disturbances in Heart Rhythm01:29

Disturbances in Heart Rhythm

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Arrhythmia or dysrhythmia refers to an abnormal heart rhythm caused by a defect in the heart's conduction system. It can cause the heart to beat irregularly, too quickly, or too slowly, leading to symptoms like chest pain, shortness of breath, and fainting. Factors such as stress, caffeine, alcohol, nicotine, cocaine, certain drugs, congenital defects, diseases, and electrolyte abnormalities can trigger arrhythmias.
Arrhythmias are categorized by their speed, rhythm, and origin. A slow heart...
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Pulse rhythm01:30

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Pulse rhythm refers to the pattern of pulsations within specific intervals, offering valuable insights into the regularity or irregularity of the heart's beats as observed through the pattern of pulsation within specific intervals. A regular pulse exhibits a consistent heart rate with uniform waveforms and pulsation force, variations of which can be classified as normal, weak, or bounding.
Conversely, an irregular pulse pattern is termed dysrhythmia, stemming from disruptions in cardiac...
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ECG Interpretation of Rhythms01:24

ECG Interpretation of Rhythms

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An electrocardiogram (ECG)graphically represents the heart's electrical activity on ECG paper or a monitor.
Components of the Electrocardiogram
The primary components of a normal ECG waveform in Normal sinus rhythm(NSR) include the P wave, PR interval, QRS complex, ST segment, T wave, and occasionally a U wave.
ECG waveforms are divided by vertical and horizontal lines at standard intervals.
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Circadian Rhythms and Gene Regulation02:19

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The biological clock is involved in many aspects of regulating complex physiology in all animals. It was in 1935 when German zoologists, Hans Kalmus and Erwin Bünning, discovered the existence of circadian rhythm in Drosophila melanogaster. However, the internal molecular mechanisms behind the circadian clock remained a mystery until 1984, when Jeffrey C. Hall, Michael Rosbash, and Michael W. Young discovered the expression of the Per gene oscillating over a 24-hour cycle. In subsequent...
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Electrophysiology of Normal Cardiac Rhythm01:19

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The normal cardiac rhythm is a synchronized electrical activity that facilitates the regular and coordinated contraction of the heart muscle. This process is essential for efficient blood circulation throughout the body. The fundamental elements involved in establishing and maintaining this rhythm include the unique electrical properties of cardiac muscle cells, the sinoatrial (SA) node's pacemaker function, the specialized conducting system, and the ionic mechanisms underlying each phase...
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Anatomy of the Heart01:27

Anatomy of the Heart

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The human heart is made up of three layers of tissue that are surrounded by the pericardium, a membrane that protects and confines the heart. The outermost layer, closest to the pericardium, is the epicardium. The pericardial cavity separates the pericardium from the epicardium. Beneath the epicardium is the myocardium, the middle layer, and the endocardium, the innermost layer. There are four chambers of the heart: the right atrium, the right ventricle, the left atrium, and the left ventricle.
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Related Experiment Video

Updated: Feb 4, 2026

Advanced Cardiac Rhythm Management by Applying Optogenetic Multi-Site Photostimulation in Murine Hearts
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Advanced Cardiac Rhythm Management by Applying Optogenetic Multi-Site Photostimulation in Murine Hearts

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Limulus and heart rhythm.

Sodikdjon A Kodirov1,2,3,4,5, Dimitrios Psyrakis6, Johannes Brachmann7,5

  • 1Department of General Physiology, Saint Petersburg University, Saint Petersburg, Russia.

Journal of Experimental Zoology. Part A, Ecological and Integrative Physiology
|September 26, 2018
PubMed
Summary

Comparative heart physiology reveals that invertebrate hearts share fundamental similarities with mammalian hearts, beating spontaneously and regulated by nerves. Even neurogenic hearts like the horseshoe crab

Keywords:
Cardiac ganglioninvertebratemammalmyogenic rhythmneuronregulatory nerves

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Area of Science:

  • Comparative physiology
  • Cardiovascular research
  • Invertebrate biology

Background:

  • The study of heart function in the animal kingdom (Animalia) is crucial for understanding organismal development.
  • Heart rate is a vital physiological parameter, with significant interest in comparative heart physiology.
  • Classic studies on Limulus polyphemus and mollusks have driven research in this field.

Purpose of the Study:

  • To explore the comparative physiology of hearts and their functions across Animalia.
  • To investigate the regulation of cardiac rhythm in invertebrates and compare it to mammals.
  • To examine the myogenic and neurogenic nature of cardiac rhythm in different species.

Main Methods:

  • Review of extensive studies on invertebrate cardiac rhythm regulation.
  • Analysis of physiological parameters, specifically heart rate.
  • Comparison of cardiac mechanisms between invertebrates and vertebrates.

Main Results:

  • Invertebrate heart physiology is fundamentally comparable to that of mammals.
  • Invertebrate hearts exhibit spontaneous beating and are regulated by excitatory or inhibitory nerves.
  • While most invertebrates and vertebrates have myogenic hearts, some, like Limulus polyphemus, exhibit a neurogenic cardiac rhythm.

Conclusions:

  • The basic principles of heart physiology are conserved across a wide range of animals, including invertebrates and mammals.
  • Myogenic heart activity, the capacity for cardiomyocytes to contract without neural input, is a precursor even in species with neurogenic rhythms.
  • Embryonic stages of species like Limulus polyphemus demonstrate a myogenic heart rhythm, highlighting the fundamental nature of this mechanism.