Heart

Contr addresss in the heart atomic number 18 controlled via a well-regulated galvanizing augury cascade that originates in pacemaker horse barn in the sinoatrial (SA) node and is walked via internodal atrial pathways to the atrioventrical (AV) node, the bundle of His, the Purkinje system, and to all part of the ventricle.Most cardiac cells have an action potential that includes a fast depolarization, an initial rapid repolarization, a plateau, and a slow repolarization process to return to resting potential. These changes argon delimitate by sequential energizing and inactivation of Na+, Ca2+, and K+ channels.Pacemaker cells have a passably different sequence of events. aft(prenominal) repolarization to the resting potential, there is a slow depolarization that occurs due to a channel that foundation buoy pass both Na+ and K+. As this funny present-day(prenominal) continues to change the cell, Ca2+ channels are activated to rapidly depolarize the cell. The hyperpolarization phase is again rule by K+ current.Spread of the electrical signal from cell to cell is via gap junctions. The rate of gap is dependent on anatomical reference features, but in any case can be altered (to a certain extent) via queasy input.

The electrocardiogram (ECG) is an algebraic sum of the electrical activity in the heart. The normal ECG includes well-defined waves and segments, including the P wave (atrial depolarization), the QRS mazy (ventricular depolarization), and the T wave (ventricular hyperpolarization). Various arrhythmias can be detect in irregular ECG recordings.Because of the plowshare of bean deed to cardiac muscle c ontraction, heart waver is sensitive to ion! ic composition of the blood. Most serious are increases in [K+] that can produce severe cardiac abnormalities, including palsy of the atria and ventricular arrhythmias.If you loss to get a full essay, locate it on our website: OrderEssay.net

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