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Related Concept Videos

Conduction System of the Heart01:20

Conduction System of the Heart

The cardiac conduction system produces and transmits electrical impulses that prompt myocardial contraction, ensuring efficient heart function. This intricate system ensures that the heart beats in a coordinated and efficient manner, beginning with the atria and then the ventricles. The conduction system optimizes cardiac output by maintaining this precise sequence, which is crucial for adequate blood circulation.
This system relies on the unique properties of nodal and Purkinje cells:...
Conduction System of the Heart01:19

Conduction System of the Heart

Autorhythmicity is a term that refers to the heart's inherent ability to generate electrical signals and instigate muscle contractions. This self-regulating conduction system within the heart consists of two key components: the pacemaker cells and specialized conducting cells.
The pacemaker cells are located in two primary nodes: the sinoatrial (SA) node and the atrioventricular (AV) node. The SA node pacemaker cells can autonomously depolarize, triggering an action potential that leads to the...
Anatomy of the Heart01:27

Anatomy of the Heart

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.
Anatomy of the Heart01:20

Anatomy of the Heart

The heart is a hollow, muscular organ approximately the size of a fist, consisting of four chambers. It is enclosed in the pericardium, a fibrous sac with two layers: the visceral and parietal pericardium, separated by a fluid-filled space containing serous fluid to reduce friction.
The heart has three layers: the innermost endocardium, the muscular myocardium, and the outer epicardium, all working together for optimal cardiac function.
Chambers of the Heart
The heart is made up of four...
Heart Valves01:16

Heart Valves

The human heart is a complex organ with an intricate system of valves that regulate blood flow. There are two main types of valves: atrioventricular (AV) valves and semilunar valves.
The AV valves prevent the backflow of blood from the ventricles to the atria during ventricular contraction. These valves function with the assistance of the chordae tendineae and papillary muscles. When the ventricles are relaxed, the chordae tendineae are slack, allowing blood to flow from the atria into the...
Specialized Characteristics of Cardiac Muscles01:27

Specialized Characteristics of Cardiac Muscles

The primary role of cardiac muscles is to propel blood throughout the cardiovascular system. The cardiac muscle cells, or cardiomyocytes, exhibit specialized characteristics that allow them to perform this function.
Cardiac muscle cells are smaller than skeletal muscles, averaging 10–20 mm in diameter and 50–100 mm in length. However, they have large energy demands for continuous contraction and relaxation. This energy is almost exclusively derived from aerobic metabolism of energy reserves in...

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Related Experiment Video

Updated: Jun 4, 2026

Biaxial Mechanical Characterizations of Atrioventricular Heart Valves
11:00

Biaxial Mechanical Characterizations of Atrioventricular Heart Valves

Published on: April 9, 2019

Multiple mitral leaflet contractile systems in the beating heart.

Julia C Swanson1, Gaurav Krishnamurthy, Akinobu Itoh

  • 1Department of Cardiothoracic Surgery, Stanford University School of Medicine, USA.

Journal of Biomechanics
|February 5, 2011
PubMed
Summary
This summary is machine-generated.

The anterior mitral leaflet has two distinct contractile systems. One involves beta-dependent pathways, while another operates independently of beta-blockade, suggesting multiple mechanisms aid mitral valve closure.

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Layer Microdissection of Tricuspid Valve Leaflets for Biaxial Mechanical Characterization and Microstructural Quantification
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Layer Microdissection of Tricuspid Valve Leaflets for Biaxial Mechanical Characterization and Microstructural Quantification

Published on: February 10, 2022

Related Experiment Videos

Last Updated: Jun 4, 2026

Biaxial Mechanical Characterizations of Atrioventricular Heart Valves
11:00

Biaxial Mechanical Characterizations of Atrioventricular Heart Valves

Published on: April 9, 2019

Layer Microdissection of Tricuspid Valve Leaflets for Biaxial Mechanical Characterization and Microstructural Quantification
07:34

Layer Microdissection of Tricuspid Valve Leaflets for Biaxial Mechanical Characterization and Microstructural Quantification

Published on: February 10, 2022

Area of Science:

  • Cardiovascular Physiology
  • Cardiac Mechanics
  • Biomedical Engineering

Background:

  • Mitral valve closure is crucial for cardiac function.
  • Anterior leaflet (AL) contraction may enhance closure.
  • Beta-blockade abolishes AL annular myocyte contraction.

Purpose of the Study:

  • To investigate if AL contractile events share a common pathway.
  • To determine if multiple AL contractile mechanisms exist.

Main Methods:

  • Implanted radiopaque markers in sheep to track AL motion.
  • Used 4-D videofluoroscopy for marker coordinate acquisition.
  • Applied inverse finite element analysis to calculate AL stiffness.

Main Results:

  • Beta-blockade (βB) abolished annular AL stiffening.
  • Sub-threshold rapid pacing (STIM) during βB increased stiffness in all AL regions.
  • STIM increased AL stiffness by 35% during isovolumic contraction and relaxation.

Conclusions:

  • At least two contractile systems exist in the AL.
  • One system involves beta-dependent pathways (annular cardiac myocytes).
  • A second, beta-independent system likely involves valvular interstitial cells or smooth muscle cells.