Electrical activity of cells, tissues and organs

Electrical Biosignals

 Electrical activity of cells, tissues and organs 

'' What is Electrical Activity? ''

Electrical activity or electrophysiology is the study of the electrical properties of biological cells, tissues and organs. It includes measurements of change in voltage or electric current on a far-ranging variety of scales from single ion channel proteins to entire organs like the heart.

Electrical Activity of Cells

One of the simplest physiological units is the cell. It has the power of maintaining itself alive given suitable surroundings. Animal and plant cells consist of many molecular structures that are electrically responsive. Glucose-induced electrical activities - Diabetes mellitus is a chronic metabolic disease which could either be insulin insufficient (type 1) or insulin resistant (type 2). The cause of Insulin insufficiency is generally considered to be a result of β-cell damage by autoimmunity. Glucose stimulated insulin secretion is associated with a complex electrical activity in the pancreatic islet β-cell, which is characterized by a slow membrane depolarization superimposed with bursts of action potentials. Closing adenosine triphosphate (ATP)-sensitive K+ channels (KATP) in response to glucose increase is generally considered the initial event that depolarizes the β-cell membrane and activates the voltage-dependent Ca2+ channels, leading to the increase in intracellular Ca2+ that triggers the release of insulin. The β-cells become electrically active in glucose concentrations known to produce insulin secretion. The type of electrical activity depends on glucose concentration.

 Electrical Activity of Organs 

Brain - an organ of soft nervous tissue contained in the skull of vertebrates, functioning as the coordinating centre of sensation, intellectual and nervous activity. The functions of the brain depend on the ability of neurons to transmit and to respond appropriately to electrochemical signals received from other cells. Neurotransmitters are chemicals that are released at synapses when an action potential activates them. They then attach themselves to receptor molecules on the membrane of the synapse's target cell, and thereby alter the electrical or chemical properties of the receptor molecules.

As a side effect of the electrochemical processes used by neurons for signaling, brain tissue generates electric fields when it is active. When large numbers of neurons show synchronized activity, the electric fields generated can be large enough to detect outside the skull, using Electroencephalography (EEG) or Magnetoencephalography (MEG). During an epileptic seizure, the brain's inhibitory control mechanisms fail to function and electrical activity rises to pathological levels, producing EEG traces that show large wave and spike patterns not seen in a healthy brain.

Heart - a hollow muscular organ that pumps blood through the circulatory system by rhythmic contraction and dilation. It constantly generates a sequence of electrical activity with every single heart beat. This can be recorded on a paper or displayed on a monitor by attaching special electrodes to a machine that can amplify and record an EKG or ECG (electrocardiogram). The electrical signal travels through the network of conducting cell "pathways," which stimulates your upper and lower chambers to contract. The signal is able to travel along these pathways by means of a complex reaction that allows each cell to activate one next to it, stimulating it to "pass along" the electrical signal in an orderly manner. As cell after cell rapidly transmits the electrical charge, the entire heart contracts in one coordinated motion, creating a heartbeat.

 Importance in Clinical Medicine 

An Electrolyte imbalance can be manifested in several ways. The symptoms will depend on which electrolyte is out of balance. An altered level of magnesium, sodium, potassium, or calcium may produce one or more symptoms like nervous system disorders, seizures or irregular heartbeat.

EEG is an electrophysiological monitoring method to record electrical activity of the brain. It measures voltage fluctuations resulting from ionic current within the neurons of the brain. In clinical contexts, EEG refers to the recording of the brain's spontaneous electrical activity over a period of time, as recorded from multiple electrodes placed on the scalp. With every good thing comes a bad. EEG causes low spatial resolution on the scalp, and unlike PET and MRS, it cannot identify specific locations in the brain at which various neurotransmitters, drugs, etc can be found.

The electrocardiogram (ECG or EKG) is a noninvasive test that is used to reflect underlying heart conditions by measuring the electrical activity of the heart. An EKG shows the heart’s electrical activity as line tracings on paper. The spikes and the dips are called waves. A natural electrical system causes the heart muscle to contract. This pumps blood through the heart to the lungs and the rest of the body. It is done to check the heart's electrical activity or find the cause of unexplained chest pain or pressure. This could be caused by a heart attack or an inflammation of the sac surrounding the heart. However, the EKG is a static picture and may not reflect severe underlying heart problems at a time when the patient is not having any symptoms.

Bioelectricity has many effects other than the hazards discussed here. Devices such as pacemakers and defibrillators have saved countless lives. The measurement of the electrical characteristics and electrical activity of the human body have proved essential in ECG, EEG and other techniques. The uses of electricity and electromagnetic effects in healthcare are immense and are only going to grow in the future.

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