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October, 2006
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Myocardium: The muscle tissue of the Heart. It is composed of striated, involuntary muscle cells (Myocytes, Cardiac) connected to form the contractile pump to generate blood flow.

What is an Electrochemical Gradient?

JoVE 10699

Adenosine triphosphate, or ATP, is considered the primary energy source in cells. However, energy can also be stored in the electrochemical gradient of an ion across the plasma membrane, which is determined by two factors: its chemical and electrical gradients.

The chemical gradient relies on differences in the abundance of a substance on the outside versus the inside of a cell and flows from areas of high to low ion concentration. In contrast, the electrical gradient revolves around an ion’s electrical charge and the overall charges of the intracellular and extracellular environments. The electrical gradient of a positively-charged ion flows from positive to negative regions, while the reverse is true for negatively-charged ions. It is the combined action of these electrical and chemical factors that determine the ultimate direction of an electrochemical gradient. When an ion moves along this path, down its electrochemical gradient, energy is freed that can then power diverse biological processes.

 Core: Biology

Levels of Organization

JoVE 10648

Biological organization is the classification of biological structures, ranging from atoms at the bottom of the hierarchy to the Earth’s biosphere. Each level of the hierarchy represents an increase in complexity that builds upon the previous level.

The most basic levels include atoms, molecules, and biomolecules. Atoms, the smallest unit of ordinary matter, are composed of a nucleus and electrons. Molecules comprise two or more atoms held together by chemical bonds, most commonly covalent, ionic, or metallic bonds. Biomolecules are molecules found in living organisms, including proteins, nucleic acids, lipids, and carbohydrates. Biomolecules are often polymers—large molecules that are created from smaller, repeating units. For instance, proteins are composed of amino acids, and nucleic acids are composed of nucleotides. Biomolecules can be endogenous or exogenous. Endogenous means that the biomolecule is produced inside a living organism. Biomolecules can also be consumed; for example, a cow gets carbohydrates from digesting grass (exogenous), but the grass must produce the carbohydrates through photosynthesis (endogenous). The next hierarchical level comprises subcellular structures called organelles. Organelles are made up of biomolecules and compartmentalize eukaryotic cells. Organelle means “little organ” as

 Core: Biology

Compound Administration IV

JoVE 10214

Source: Kay Stewart, RVT, RLATG, CMAR; Valerie A. Schroeder, RVT, RLATG. University of Notre Dame, IN

There are many commonly used routes for compound administration in laboratory mice and rats. Protocols may, however, require the use of the less commonly used routes: intracardiac, footpad, and retro-orbital injections. Specialized…

 Lab Animal Research

Electrical Safety Precautions and Basic Equipment

JoVE 10114

Source: Ali Bazzi, Department of Electrical Engineering, University of Connecticut, Storrs, CT.

Electric machines and power electronics experiments involve electrical currents, voltages, power, and energy quantities that should be handled with extreme diligence and care. These may include three-phase AC voltage (208 V, 230 V, or 480 V), up …

 Electrical Engineering

Induced Pluripotency

JoVE 5333

Induced pluripotent stem cells (iPSCs) are somatic cells that have been genetically reprogrammed to form undifferentiated stem cells. Like embryonic stem cells, iPSCs can be grown in culture conditions that promote differentiation into different cell types. Thus, iPSCs may provide a potentially unlimited source of any human cell type, which is a major breakthrough in the field of regenerative…

 Developmental Biology

Construction of Defined Human Engineered Cardiac Tissues to Study Mechanisms of Cardiac Cell Therapy

1Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, 2The Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, 3Stem Cell & Regenerative Medicine Consortium, LKS Faculty of Medicine, University of Hong Kong

JoVE 53447

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