ECG - Leads Intro

As the heart undergoes depolarization and repolarization, electrical currents spread throughout the body because the body acts as a volume conductor . The electrical currents generated by the heart are commonly measured by an array of electrodes placed on the body surface and the resulting tracing is called an electrocardiogram (ECG, or EKG). By convention, electrodes are placed on each arm and leg (standard and augmented limb leads), and six electrodes are placed at defined locations on the chest (precordial leads). These electrode leads are connected to a device that measures potential differences between selected electrodes to produce the characteristic ECG tracings.

Some of the ECG leads are bipolar leads (e.g., standard limb leads) that utilize a single positive and a single negative electrode between which electrical potentials are measured. Unipolar leads (augmented leads and chest leads) have a single positive recording electrode and utilize a combination of the other electrodes to serve as a composite negative electrode. Normally, when an ECG is recorded, all leads are recorded simultaneously, giving rise to what is called a 12-lead ECG.


CV Physiology | Electrocardiogram Leads

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Functional Magnetic Resonance Imaging (fMRI) And How It Works

The fMRI employs a magnetic field to collect information about the body. It is one of the most prominent methods in neuroscience for studying the structure of the brain, including differences in the structural characteristics of different people's brains.

It works with a system that produces images of the brain's functions that indicates whether the activity of neurons is increased or decreased in specific parts of the brain and under which conditions.


How Brain Activity Is Measured

PH measures the acidity or basicity of liquid solutions

The term is used in chemistry, biology, and agronomy. PH translates the values of the concentration of the hydrogen ion into numbers between 0 and 14.

  • Pure water corresponds to a pH of 7, which is neutral (neither acidic nor alkaline). 
  • A pH less than 7 is considered acidic.
  • A pH greater than 7 is considered basic or alkaline.



pH | Definition, Uses, & Facts

The human brain vs. the computer

When we contemplate which has more problem-solving power, the brain or the computer, we might think that the modern computer would come out on top. Indeed, computers have been built and programmed to beat human masters in complex games, such as chess.

However, humans still trump computers in many real-world tasks, such as identifying a particular pedestrian on a crowded city street. Computers are unable to beat humans at conceptualization and creativity.



Why Is the Human Brain So Efficient?