Electrical activity of cells, tissues and organs

''' Electrical Biosignals
'''

'' What is Electrical Activity? ''

Electrical activity 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.

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 Electrical Activity of Cells 

One of the simplest physiological units is the cell. It has the power of maintaining itself alive given suitable surroundings. The endocrine pancreas consists of clusters of cells called islets of Langerhans. Most of the cells in an islet are insulin-secreting β-cells. Electrical impulses or action potentials are generated in bursts when the bath or blood glucose level is in the stimulatory range. Insulin insufficiency is generally a result of β-cell damage by autoimmunity. 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, which triggers the release of insulin. However, glucose is unable to extract insulin release if electrical activity and the accompnying Ca2+ influx are prevented. Thus beta-cell electrical activity is a key element in the series of steps culminating in glucose-induced insulin secretion.

 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. 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. 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).

Heart - a hollow muscular organ that pumps blood through the circulatory system by rhythmic contraction and dilation. 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, which can be recorded by attaching special electrodes to a machine that can amplify and record an electrocardiogram.

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 Importance in Clinical Medicine 

EEG is an electrophysiological monitoring method to record electrical activity of the brain over a period of time. 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. It has also been shown to be useful for locating tumors. 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 as line tracings on paper. 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.

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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.

 Sources: 

https://en.wikipedia.org/wiki/Electrophysiology

http://oxforddictionaries.com/definition/english/electrophysiology

http://www.thefreedictionary.com/cell

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https://en.wikipedia.org/wiki/Biosignal

http://www.nature.com/ncomms/2014/140715/ncomms5420/full/ncomms5420.html

https://en.wikipedia.org/wiki/Krebs–Henseleit_solution

https://en.wikipedia.org/wiki/Brain

http://www.slideshare.net/mdshahidulislam/islet-society-meeting-2015-sydney

https://en.wikipedia.org/wiki/Heart#Electrical_conduction

https://courses.kcumb.edu/physio/ecg%20primer/ecgnormal.htm

http://www.medicinenet.com/electrocardiogram_ecg_or_ekg/article.htm

https://en.wikipedia.org/wiki/Electroencephalography#Disadvantages

http://www.medicinenet.com/electrocardiogram_ecg_or_ekg/page3.htm

http://www.dreamstime.com/stock-photo-electrical-signals-image836350

http://www.uni-em.com/products/ecg-machines/cardiomin-2k/