query: cardiac cells have the ability to generate an electrical impulse which is called

pos: Cardiac pacemaker Cardiac pacemaker The contraction of cardiac muscle (heart muscle) in all animals is initiated by electrical impulses known as action potentials. The rate at which these impulses fire controls the rate of cardiac contraction, that is, the heart rate. The cells that create these rhythmic impulses, setting the pace for blood pumping, are called pacemaker cells, and they directly control the heart rate. They make up the cardiac pacemaker, that is, the natural pacemaker of the heart. In most humans, the concentration of pacemaker cells in the sinoatrial (SA) node is the natural pacemaker, and the resultant rhythm is a

pos: Cardiac pacemaker sinus rhythm. Sometimes an ectopic pacemaker sets the pace, if the SA node is damaged or if the electrical conduction system of the heart has problems. Cardiac arrhythmias can cause heart block, in which the contractions lose any useful rhythm. In humans, and occasionally in animals, a mechanical device called an artificial pacemaker (or simply "pacemaker") may be used after damage to the body's intrinsic conduction system to produce these impulses synthetically. One percent of the cardiomyocytes in the myocardium possess the ability to generate electrical impulses (or action potentials) spontaneously. <br>A specialized portion of the heart, called the sinoatrial

pos: Cardiac pacemaker controls the rate of contraction for the entire heart muscle because its cells have the quickest rate of spontaneous depolarization, thus they initiate action potentials the quickest. The action potential generated by the SA node passes down the electrical conduction system of the heart, and depolarizes the other potential pacemaker cells (AV node) to initiate action potentials before these other cells have had a chance to generate their own spontaneous action potential, thus they contract and propagate electrical impulses to the pace set by the cells of the SA node. This is the normal conduction of electrical activity in the

pos: Cardiac pacemaker ventricles, within the atrial septum. If the AV node also fails, Purkinje fibers are occasionally capable of acting as the default or "escape" pacemaker. The reason Purkinje cells do not normally control the heart rate is that they generate action potentials at a lower frequency than the AV or SA nodes. Cardiac pacemaker The contraction of cardiac muscle (heart muscle) in all animals is initiated by electrical impulses known as action potentials. The rate at which these impulses fire controls the rate of cardiac contraction, that is, the heart rate. The cells that create these rhythmic impulses, setting the pace

pos: Cardiac pacemaker Cardiac pacemaker The contraction of cardiac muscle (heart muscle) in all animals is initiated by electrical impulses known as action potentials. The rate at which these impulses fire controls the rate of cardiac contraction, that is, the heart rate. The cells that create these rhythmic impulses, setting the pace for blood pumping, are called pacemaker cells, and they directly control the heart rate. They make up the cardiac pacemaker, that is, the natural pacemaker of the heart. In most humans, the concentration of pacemaker cells in the sinoatrial (SA) node is the natural pacemaker, and the resultant rhythm is a

pos: Neural oscillation would oscillate in synchrony to form a single representation of the tree. This phenomenon is best seen in local field potentials which reflect the synchronous activity of local groups of neurons, but has also been shown in EEG and MEG recordings providing increasing evidence for a close relation between synchronous oscillatory activity and a variety of cognitive functions such as perceptual grouping. Cells in the sinoatrial node, located in the right atrium of the heart, spontaneously depolarize approximately 100 times per minute. Although all of the heart's cells have the ability to generate action potentials that trigger cardiac contraction, the

pos: Cardiology the mechanical and the electrical parts. The electrical part of the heart is centered on the periodic contraction (squeezing) of the muscle cells that is caused by the cardiac pacemaker located in the sinoatrial node. The study of the electrical aspects is a sub-field of electrophysiology called cardiac electrophysiology and is epitomized with the electrocardiogram (ECG/EKG). The action potentials generated in the pacemaker propagate throughout the heart in a specific pattern. The system that carries this potential is called the electrical conduction system. Dysfunction of the electrical system manifests in many ways and may include Wolff–Parkinson–White syndrome, ventricular fibrillation, and

pos: Catecholaminergic polymorphic ventricular tachycardia calcium exchanger, causing an electrical current known as a delayed afterdepolarisation. Afterdepolarisations, if large enough, can trigger additional action potentials, premature ventricular contractions, or sustained arrhythmias. CPVT can be caused by mutations in several genes, all of which are responsible for regulating the concentrations of calcium within cardiac muscle cells. The most commonly identified genetic mutation in CPVT is a mutation in the RYR2 gene that encodes the cardiac ryanodine receptor, responsible for releasing calcium from the sarcoplasmic reticulum. Mutations associated with CPVT have also been identified in the CASQ2 gene which encodes calsequestrin, a protein that binds calcium within

pos: Neurotransmitter the dopamine system. The addictive opiate drugs exert their effects primarily as functional analogs of opioid peptides, which, in turn, regulate dopamine levels. Neurons form elaborate networks through which nerve impulses—action potentials—travel. Each neuron has as many as 15,000 connections with neighboring neurons. Neurons do not touch each other (except in the case of an electrical synapse through a gap junction); instead, neurons interact at contact points called synapses: a junction within two nerve cells, consisting of a miniature gap within which impulses are carried by a neurotransmitter. A neuron transports its information by way of a nerve impulse called

pos: Cardiac action potential Cardiac action potential The cardiac action potential is a brief change in voltage (membrane potential) across the cell membrane of heart cells. This is caused by the movement of charged atoms (called ions) between the inside and outside of the cell, through proteins called ion channels. The cardiac action potential differs from action potentials found in other types of electrically excitable cells, such as nerves. Action potentials also vary within the heart; this is due to the presence of different ion channels in different cells (see below). Unlike the action potential in skeletal muscle cells, the cardiac action potential is

pos: T-type calcium channel is its ability to generate potentials that allow for rhythmic bursts of action potentials in cardiac cells of the sinoatrial node of the heart and in the thalamus of the brain. Because the T-type channels are voltage dependent, hyperpolarization of the cell past its inactivation voltage will close the channels throughout the SA node, and allow for another depolarizing event to occur. The voltage dependency of the T-type channel contributes to the rhythmic beating of the heart. Voltage-gated calcium channels are made up of several subunits. The α subunit is the primary subunit that forms the transmembrane pore of the

neg: Cardiac action potential This is known as the electrical conduction system of the heart, see figure 4. Other than the SAN, the AVN and purkinje fibres also have pacemaker activity and can therefore spontaneously generate an action potential. However, these cells usually do not depolarize spontaneously, simply because, action potential production in the SAN is faster. This means that before the AVN or purkinje fibres reach the threshold potential for an action potential, they are depolarized by the oncoming impulse from the SAN This is called "overdrive suppression". Pacemaker activity of these cells is vital, as it means that if the SAN were

neg: Cardiac physiology capable of generating its own electrical impulse followed by contraction. When two independently beating embryonic cardiac muscle cells are placed together, the cell with the higher inherent rate sets the pace, and the impulse spreads from the faster to the slower cell to trigger a contraction. As more cells are joined together, the fastest cell continues to assume control of the rate. A fully developed adult heart maintains the capability of generating its own electrical impulse, triggered by the fastest cells, as part of the cardiac conduction system. The components of the cardiac conduction system include the atrial and ventricular

neg: Cardiac excitation-contraction coupling a neurotransmitter called acetylcholine (ACh) which binds to specific receptor (M2 muscarinic receptor) on the sarcolemma of both SAN cells and ventricular cells. This again activates a G-protein. However this G-protein works by inhibiting, the cAMP pathway, therefore, preventing the sympathetic nervous system from increasing heart rate. As well as this, in the SAN, the G-protein activates specific potassium channel, that opposes action potential initiation (see SAN for more details), thus slowing heart rate. Cardiac excitation-contraction coupling Cardiac excitation-contraction coupling (Cardiac EC coupling) describes the series of events, from the production of an electrical impulse (action potential) to the contraction

neg: Heart pump blood through the heart and into the major arteries. The pacemaker cells make up 1% of cells and form the conduction system of the heart. They are generally much smaller than the contractile cells and have few myofibrils which gives them limited contractibility. Their function is similar in many respects to neurons. Cardiac muscle tissue has autorhythmicity, the unique ability to initiate a cardiac action potential at a fixed rate – spreading the impulse rapidly from cell to cell to trigger the contraction of the entire heart. There are specific proteins expressed in cardiac muscle cells. These are mostly

neg: Cardiac physiology of the pathway, as the impulse reaches the atrioventricular septum, the connective tissue of the cardiac skeleton prevents the impulse from spreading into the myocardial cells in the ventricles except at the atrioventricular node. The electrical event, the wave of depolarization, is the trigger for muscular contraction. The wave of depolarization begins in the right atrium, and the impulse spreads across the superior portions of both atria and then down through the contractile cells. The contractile cells then begin contraction from the superior to the inferior portions of the atria, efficiently pumping blood into the ventricles. The atrioventricular (AV) node

neg: Pulseless electrical activity Pulseless electrical activity Pulseless electrical activity (PEA), also known as electromechanical dissociation, refers to cardiac arrest in which the electrocardiogram shows a heart rhythm that should produce a pulse, but does not. Pulseless electrical activity is found initially in about 55% of people in cardiac arrest. Under normal circumstances, electrical activation of muscle cells precedes mechanical contraction of the heart (known as "electromechanical coupling"). In PEA, there is electrical activity, but the heart either does not contract or there are other reasons this results in an insufficient cardiac output to generate a pulse and supply blood to the organs. While

neg: Vagal tone associated with a diminished and more variable heart rate. On the opposite, during graded orthostatic tilt, vagal tone withdrawal is physiological and described as an indirect indicator of cardiovascular fitness. Heart rate is largely controlled by the heart's internal pacemaker activity. Considering a healthy heart, the main pacemaker is a collection of cells on the border of the atria and vena cava called the sinoatrial node. Heart cells exhibit automaticity which is the ability to generate electrical activity independent of external stimulation. As a result, the cells of the node spontaneously generate electrical activity that is subsequently conducted throughout the

neg: Cardiac physiology rapid depolarization, followed by a plateau phase and then repolarization. This phenomenon accounts for the long refractory periods required for the cardiac muscle cells to pump blood effectively before they are capable of firing for a second time. These cardiac myocytes normally do not initiate their own electrical potential, although they are capable of doing so, but rather wait for an impulse to reach them. Contractile cells demonstrate a much more stable resting phase than conductive cells at approximately −80 mV for cells in the atria and −90 mV for cells in the ventricles. Despite this initial difference, the other

neg: Sinoatrial node the discovery in a makeshift laboratory set up in a picturesque farmhouse in Kent, England, called Mann's Place. Their discovery was published in 1907. Sinoatrial node The sinoatrial node (SA node), also known as sinus node, is a group of cells located in the wall of the right atrium of the heart. These cells have the ability to spontaneously produce an electrical impulse (action potential; see below for more details), that travels through the heart via the electrical conduction system (see figure 1) causing it to contract. In a healthy heart, the SA node continuously produces action potential, setting the

neg: Parasympathetic nervous system a healthy heart, the main pacemaker is a collection of cells on the border of the atria and vena cava called the sinoatrial node. Heart cells exhibit automaticity which is the ability to generate electrical activity independent of external stimulation. As a result, the cells of the node spontaneously generate electrical activity that is subsequently conducted throughout the heart, resulting in a regular heart rate. In absence of any external stimuli, sinoatrial pacing contributes to maintain the heart rate in the range of 60-100 beats per minute (bpm). At the same time, the two branches of the autonomic nervous system

neg: Cardiac physiology toward the atrioventricular septum and the base of the heart. The Purkinje fibers have a fast inherent conduction rate, and the electrical impulse reaches all of the ventricular muscle cells in about 75 ms. Since the electrical stimulus begins at the apex, the contraction also begins at the apex and travels toward the base of the heart, similar to squeezing a tube of toothpaste from the bottom. This allows the blood to be pumped out of the ventricles and into the aorta and pulmonary trunk. The total time elapsed from the initiation of the impulse in the SA node until

neg: Cardiac muscle cell and are responsible for several functions. First, they are responsible for being able to spontaneously generate and send out electrical impulses. They also must be able to receive and respond to electrical impulses from the brain. Lastly, they must be able to transfer electrical impulses from cell to cell. All of these cells are connected by cellular bridges. Porous junctions called intercalated discs form junctions between the cells. They permit sodium, potassium and calcium to easily diffuse from cell to cell. This makes it easier for depolarization and repolarization in the myocardium. Because of these junctions and bridges the heart

neg: Cardiac pacemaker out of the cell and pumping (exchanging) potassium into the cell. Restoring these ion concentrations is vital because it enables the cell to reset itself and enables it to repeat the process of spontaneous depolarization leading to activation of an action potential. If the SA node does not function, or the impulse generated in the SA node is blocked before it travels down the electrical conduction system, a group of cells further down the heart will become its pacemaker. This center is typically represented by cells inside the atrioventricular node (AV node), which is an area between the atria and

neg: Purkinje fibers the nucleus causes Purkinje fibers to appear, on a slide, lighter and larger than their neighbors, arranged along the longitudinal direction (parallel to the cardiac vector). They are often binucleated cells. Heart rate is governed by many influences from the autonomic nervous system. The Purkinje fibres do not have any known role in setting heart rate unless the SA node is compromised. They are influenced by electrical discharge from the sinoatrial node. During the ventricular contraction portion of the cardiac cycle, the Purkinje fibres carry the contraction impulse from both the left and right bundle branch to the myocardium of

neg: Sinoatrial node Sinoatrial node The sinoatrial node (SA node), also known as sinus node, is a group of cells located in the wall of the right atrium of the heart. These cells have the ability to spontaneously produce an electrical impulse (action potential; see below for more details), that travels through the heart via the electrical conduction system (see figure 1) causing it to contract. In a healthy heart, the SA node continuously produces action potential, setting the rhythm of the heart and so is known as the heart's natural pacemaker. The rate of action potential production (and therefore the heart rate)

neg: Myocardial infarction complications phenomenon may cause rapid heart rates (ventricular tachycardia and even ventricular fibrillation), and ischemia in the electrical conduction system of the heart may cause a complete heart block (when the impulse from the sinoatrial node, the normal cardiac pacemaker, does not reach the heart chambers). As a reaction to the damage of the heart muscle, inflammatory cells are attracted. The inflammation may reach out and affect the heart sac. This is called pericarditis. In Dressler's syndrome, this occurs several weeks after the initial event. If pericarditis were to persist, pleural effusion may also occur which could in turn lead to

neg: Electrochemical cell cell is discharged, the concentration of the reactants decreases and the cell potential also decreases. Electrochemical cell An electrochemical cell is a device capable of either generating electrical energy from chemical reactions or using electrical energy to cause chemical reactions. The electrochemical cells which generate an electric current are called voltaic cells or galvanic cells and the other ones are called electrolytic cells which are used to drive chemical reactions like electrolysis. A common example of a galvanic cell is a standard 1.5 volt cell meant for consumer use. A "battery" consists of one or more cells, connected either in

neg: Cardiac contractility modulation which delivers an electrical signal with the intention to result in cardiac contraction, the Cardiac contractility modulation treatment applies the NES, adjusted to and synchronized with the electrical action in the cardiac cycle. In Cardiac contractility modulation therapy, electrical stimulation is applied to the cardiac muscle during the absolute refractory period. In this phase of the cardiac cycle, electrical signals cannot trigger new cardiac muscle contractions, hence this type of stimulation is known as a non-excitatory stimulation. However, the electrical signals increase the influx of calcium ions into the cardiac muscle cells (cardiomyocytes). In contrast to other electrical stimulation treatments

neg: Electrochemical cell Electrochemical cell An electrochemical cell is a device capable of either generating electrical energy from chemical reactions or using electrical energy to cause chemical reactions. The electrochemical cells which generate an electric current are called voltaic cells or galvanic cells and the other ones are called electrolytic cells which are used to drive chemical reactions like electrolysis. A common example of a galvanic cell is a standard 1.5 volt cell meant for consumer use. A "battery" consists of one or more cells, connected either in parallel, series or series-and-parallel pattern.<r: A cell is a device which can convert chemical energy

neg: Cardiac physiology is a second cluster of specialized myocardial conductive cells, located in the inferior portion of the right atrium within the atrioventricular septum. The septum prevents the impulse from spreading directly to the ventricles without passing through the AV node. There is a critical pause before the AV node depolarizes and transmits the impulse to the atrioventricular bundle. This delay in transmission is partially attributable to the small diameter of the cells of the node, which slow the impulse. Also, conduction between nodal cells is less efficient than between conducting cells. These factors mean that it takes the impulse approximately 100

neg: Lactation or back, or warming the breast with a cloth or shower. This is the mechanism by which milk is transported from the breast alveoli to the nipple. Suckling by the baby innervates slowly-adapting and rapidly-adapting mechanoreceptors that are densely packed around the areolar region. The electrical impulse follows the spinothalamic tract, which begins by innervation of fourth intercostal nerves. The electrical impulse then ascends the posterolateral tract for one or two vertebral levels and synapses with second-order neurons, called tract cells, in the posterior dorsal horn. The tract cells then decussate via the anterior white commissure to the anterolateral corner

neg: Heart arrhythmia needs, this manifests as a lower blood pressure and may cause lightheadedness or dizziness, or syncope (fainting). Some types of arrhythmia result in cardiac arrest, or sudden death. Medical assessment of the abnormality using an electrocardiogram is one way to diagnose and assess the risk of any given arrhythmia. Each heart beat originates as an electrical impulse from a small area of tissue in the right atrium of the heart called the sinus node or Sino-atrial node or SA node. The impulse initially causes both atria to contract, then activates the atrioventricular (or AV) node, which is normally the only

neg: Cardiac physiology needed to pump the blood through the systemic circulation. Atria facilitate circulation primarily by allowing uninterrupted venous flow to the heart, preventing the inertia of interrupted venous flow that would otherwise occur at each ventricular systole. Cardiac muscle tissue has autorhythmicity, the unique ability to initiate a cardiac action potential at a fixed rate – spreading the impulse rapidly from cell to cell to trigger the contraction of the entire heart. This autorhythmicity is still modulated by the endocrine and nervous systems. There are two types of cardiac muscle cell: cardiomyocytes which have the ability to contract easily, and modified

neg: Premature junctional contraction junctional contractions will appear as a normally shaped ventricular complex or QRS complex, not preceded by any atrial complex or P wave or preceded by an abnormal P wave with a shorter PR interval. Rarely, the abnormal P wave can follow the QRS. Premature junctional contraction Premature junctional contractions (PJCs), also called atrioventricular junctional premature complexes or junctional extrasystole, are premature cardiac electrical impulses originating from the atrioventricular node of the heart or "junction". This area is not the normal but only a secondary source of cardiac electrical impulse formation. These premature beats can be found occasionally in healthy people

neg: Cardiac muscle the walls of a house contain electrical wires and plumbing, cardiac muscle also contains specialised cells for conducting electrical signals rapidly (the cardiac conduction system), and blood vessels to bring nutrients to the muscle cells and take away waste products (the coronary arteries, veins and capillary network). Cardiac muscle cells or cardiomyocytes are the contracting cells which allow the heart to pump. Each cardiomyocyte needs to contract in coordination with its neighbouring cells to efficiently pump blood from the heart, and if this coordination breaks down then – despite individual cells contracting – the heart may not pump at all,

neg: Electrical conduction system of the heart the SA node's pacemaker activity. In order to maximize efficiency of contractions and cardiac output, the conduction system of the heart has: An electrocardiogram is a recording of the electrical activity of the heart. Under normal conditions, electrical activity is spontaneously generated by the SA node, the cardiac pacemaker. This electrical impulse is propagated throughout the right atrium, and through Bachmann's bundle to the left atrium, stimulating the myocardium of the atria to contract. The conduction of the electrical impulses throughout the atria is seen on the ECG as the P wave. As the electrical activity is spreading throughout the

neg: Muscle fatigue Muscle fatigue Muscle fatigue is the decline in ability of a muscle to generate force. It can be a result of vigorous exercise but abnormal fatigue may be caused by barriers to or interference with the different stages of muscle contraction. There are two main causes of muscle fatigue: the limitations of a nerve’s ability to generate a sustained signal (neural fatigue) and the reduced ability of the muscle fiber to contract (metabolic fatigue). Muscle cells work by detecting a flow of electrical impulses from the brain which signals them to contract through the release of calcium by the sarcoplasmic

neg: Muscle fatigue remain, and conduction velocities of the nervous system decreasing over time. Muscle fatigue Muscle fatigue is the decline in ability of a muscle to generate force. It can be a result of vigorous exercise but abnormal fatigue may be caused by barriers to or interference with the different stages of muscle contraction. There are two main causes of muscle fatigue: the limitations of a nerve’s ability to generate a sustained signal (neural fatigue) and the reduced ability of the muscle fiber to contract (metabolic fatigue). Muscle cells work by detecting a flow of electrical impulses from the brain which signals

neg: Atrial tachycardia Atrial tachycardia Atrial tachycardia is a type of heart rhythm problem in which the heart's electrical impulse comes from an ectopic pacemaker (that is, an abnormally located cardiac pacemaker) in the upper chambers (atria) of the heart, rather than from the sinoatrial node, the normal origin of the heart's electrical activity. Atrial tachycardias can exhibit very regular (consistent) heart rates ranging typically from 140 to 220 beats per minute. As with any other form of tachycardia (rapid heart beat), the underlying mechanism can be either the rapid discharge of an abnormal focus, the presence of a ring of cardiac tissue

neg: ANO5 to describe initial weakness in distal muscles. Credit: Genome Decoration Page/NCBI ANO5 Anoctamin 5 (ANO5) is a protein that in humans is encoded by the ANO5 gene. The ANO5 gene provides instructions for making a protein called anoctamin-5. While the specific function of this protein is not well understood, it belongs to a family of proteins, called anoctamins, that act as chloride channels. Chloride channels, which transport negatively charged chlorine atoms (chloride ions) in and out of cells, play a key role in a cell's ability to generate and transmit electrical signals. Most anoctamin proteins function as chloride channels that

neg: ANO5 ANO5 Anoctamin 5 (ANO5) is a protein that in humans is encoded by the ANO5 gene. The ANO5 gene provides instructions for making a protein called anoctamin-5. While the specific function of this protein is not well understood, it belongs to a family of proteins, called anoctamins, that act as chloride channels. Chloride channels, which transport negatively charged chlorine atoms (chloride ions) in and out of cells, play a key role in a cell's ability to generate and transmit electrical signals. Most anoctamin proteins function as chloride channels that are turned on (activated) in the presence of positively charged calcium

neg: Premature junctional contraction Premature junctional contraction Premature junctional contractions (PJCs), also called atrioventricular junctional premature complexes or junctional extrasystole, are premature cardiac electrical impulses originating from the atrioventricular node of the heart or "junction". This area is not the normal but only a secondary source of cardiac electrical impulse formation. These premature beats can be found occasionally in healthy people and more commonly in some pathologic conditions, typically in the case of drug cardiotoxicity, electrolyte imbalance, mitral valve surgery, and cold water immersion. If more than two such beats are seen, then the condition is termed junctional rhythm. On the surface ECG, premature

neg: Galvanic corrosion Galvanic corrosion Galvanic corrosion (also called bimetallic corrosion) is an electrochemical process in which one metal corrodes preferentially when it is in electrical contact with another, in the presence of an electrolyte. A similar galvanic reaction is exploited in primary cells to generate a useful electrical voltage to power portable devices. Dissimilar metals and alloys have different electrode potentials, and when two or more come into contact in an electrolyte, one metal acts as anode and the other as cathode. If the electrolyte contains only metal ions that are not easily reduced (such as Na, Ca, K, Mg, or Zn),

neg: Cardiac arrest often reverse a cardiac arrest, but without such intervention, death is all but certain. In certain cases, cardiac arrest is an anticipated outcome of a serious illness where death is expected. Sudden cardiac arrest (SCA) and sudden cardiac death (SCD) occur when the heart abruptly begins to beat in an abnormal or irregular rhythm (arrhythmia). Without organized electrical activity in the heart muscle, there is no consistent contraction of the ventricles, which results in the heart's inability to generate an adequate cardiac output (forward pumping of blood from heart to rest of the body). There are many different types of

neg: Beta-catenin matrix components, such as type I collagen and fibronectin. Aberrant activation of the Wnt pathway has been implicated in pathological processes such as fibrosis and cancer. In cardiac muscle development, beta-catenin performs a biphasic role. Initially, the activation of Wnt/beta-catenin is essential for committing mesenchymal cells to a cardiac lineage; however, in later stages of development, the downregulation of beta-catenin is required. In cardiac muscle, beta-catenin forms a complex with N-cadherin at adherens junctions within intercalated disc structures, which are responsible for electrical and mechanical coupling of adjacent cardiac cells. Studies in a model of adult rat ventricular cardiomyocytes have

neg: C2C12 of muscle wasting. C2C12 cells demonstrate rapid development and maturation into functional skeletal muscle cells or cardiac muscle cells, having the ability to contract and generate force. The rate of muscle formation from C2C12 cells can be controlled by the introduction of loss-of-functions genes vital for the fusion of myoblasts and myogenesis. Under necrotic conditions, such as tumor necrosis factor alpha (TNF-α), direct protein loss, particularly myosin heavy chain protein, in C2C12 skeletal muscle cells has been shown. C2C12 cells were used to elucidate inactivated X chromosome (Xi) replication during early S-phase of the cell cycle and is regulated epigenetically.

neg: Organ-on-a-chip lung-on-a-chip can more exactly reproduce the mechanical properties of a living human lung, its physiological responses will be quicker and more accurate than a Transwell culture system. Nevertheless, published studies admit that responses of a lung-on-a-chip don’t yet fully reproduce the responses of native alveolar epithelial cells. Past efforts to replicate in vivo cardiac tissue environments have proven to be challenging due to difficulties when mimicking contractility and electrophysiological responses. Such features would greatly increase the accuracy of in vitro experiments. Microfluidics has already contributed to in vitro experiments on cardiomyocytes, which generate the electrical impulses that control the heart

neg: Neural stem cell into neurons, astrocytes, and oligodendrocytes. There are two basic types of stem cell: adult stem cells, which are limited in their ability to differentiate, and embryonic stem cells (ESCs), which are pluripotent. ESCs are not limited to a particular cell fate; rather they have the capability to differentiate into any cell type. Neural stem cells are more specialized than ESCs because they generate only neural cells (neurons or glial cells). During embryonic development of vertebrates, NSCs of the central nervous system (CNS) are called radial glial cells (RGCs), and reside in a transient zone called the ventricular zone (VZ). Neurons

neg: Lymphopoiesis the majority (85–90%) of the NK cells have a high cytolytic capacity (the ability to lyse cells). A smaller subset (10–15%) called NK 'CD56 bright' is chiefly responsible for cytokine production and has enhanced survival. Traveling to lymph nodes the 'CD56 bright' NK cells differentiate again into mature NK cells which express killer cell immunoglobulin-like receptors (KIR), natural cytotoxicity receptors (NCR), and critical adhesion molecules. (Medical Immunology, p. 122) "Dendritic cell" is usually abbreviated DC or DCs. The process by which CLP cells may differentiate to generate dendritic cells of lymphoid lineage is not yet well defined. DCs are highly

neg: Cardiac physiology pathways consist of three bands (anterior, middle, and posterior) that lead directly from the SA node to the next node in the conduction system, the atrioventricular node. The impulse takes approximately 50 ms (milliseconds) to travel between these two nodes. The relative importance of this pathway has been debated since the impulse would reach the atrioventricular node simply following the cell-by-cell pathway through the contractile cells of the myocardium in the atria. In addition, there is a specialized pathway called Bachmann's bundle or the interatrial band that conducts the impulse directly from the right atrium to the left atrium. Regardless

neg: Bathmotropic Bathmotropic While bathmotropic, as used herein, has been defined as pertaining to modification of the "excitability" of the heart, it can also refer to modification of the "irritability" of heart muscle, and the two terms are frequently used interchangeably. The term "bathmotropic" is derived from the Ancient Greek word "βαθμός" ("bathmós"), meaning "step" or "threshold". In 1897 Engelmann introduced four Greek terms to describe key physiological properties of the heart: inotropy, the ability to contract; chronotropy, the ability to initiate an electrical impulse; dromotropy, the ability to conduct an electrical impulse; and bathmotropy, the ability to respond to direct mechanical

neg: Cardiac pacemaker in adult humans is about 70 beats per minute. Because the sinoatrial node is responsible for the rest of the heart's electrical activity, it is sometimes called the "primary pacemaker". If the SA node does not function properly and is unable to control the heart rate, a group of cells further down the heart will become the ectopic pacemaker of the heart. These cells form the Atrioventricular node (or AV node), which is an area between the left atrium and the right ventricle within the atrial septum, will take over the pacemaker responsibility. The cells of the AV node normally

neg: Muscle formed from the somatic lateral plate mesoderm. Myoblasts follow chemical signals to the appropriate locations, where they fuse into elongate skeletal muscle cells. The three types of muscle (skeletal, cardiac and smooth) have significant differences. However, all three use the movement of actin against myosin to create contraction. In skeletal muscle, contraction is stimulated by electrical impulses transmitted by the nerves, the motoneurons (motor nerves) in particular. Cardiac and smooth muscle contractions are stimulated by internal pacemaker cells which regularly contract, and propagate contractions to other muscle cells they are in contact with. All skeletal muscle and many smooth muscle

neg: Systole (binding) sites on F-actin filamentous proteins to be exposed, which causes muscle contraction to occur. The cardiac action potential spreads distally (or outwardly) to the small branches of the Purkinje tree via the flux of cations through gap junctions that connect the sarcoplasms of adjacent myocytes. The electrical activity of ventricular systole is coordinated by the atrioventricular node, which is a discrete collection of cells that receives electrical stimulation from the left and right atria and can provide an intrinsic (albeit slower) heart pacemaker activity. The cardiac action potential is propagated down electrical pathways through the bundle of His to

neg: Apex beat Apex beat The apex beat (lat. ictus cordis), also called the apical impulse, is the pulse felt at the point of maximum impulse (PMI), which is the point on the precordium farthest outwards (laterally) and downwards (inferiorly) from the sternum at which the cardiac impulse can be felt. The cardiac impulse is the vibration resulting from the heart rotating, moving forward and striking against the chest wall during systole. The PMI is not the apex of the heart but is on the precordium not far from it. The normal apex beat can be palpated in the precordium "left 5th intercostal

neg: Wound healing organ-specific lineages, had never been seriously challenged. Since then, the notion of adult stem cells having cellular "plasticity" or the ability to differentiate into non-lineage cells has emerged as an alternative explanation. To be more specific, hematopoietic progenitor cells (that give rise to mature cells in the blood) may have the ability "de-differentiate" back into hematopoietic stem cells and/or "transdifferentiate" into non-lineage cells, such as fibroblasts. Multipotent adult stem cells have the capacity to be self-renewing and give rise to different cell types. Stem cells give rise to progenitor cells, which are cells that are not self-renewing, but can generate

neg: Cardiac action potential action potential (see phase 2, below) and is a fundamental step in cardiac excitation-contraction coupling. There are important physiological differences between the cells that spontaneously generate the action potential (pacemaker cells; e.g. SAN) and those that simply conduct it (non-pacemaker cells; e.g. ventricular myocytes). The specific differences in the types of ion channels expressed and mechanisms by which they are activated results in differences in the configuration of the action potential waveform, as shown in figure 2. The standard model used to understand the cardiac action potential is that of the ventricular myocyte. Outlined below are the five phases of

neg: Weakness Weakness Weakness or asthenia is a symptom of a number of different conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, including muscular dystrophy and inflammatory myopathy. It occurs in neuromuscular junction disorders, such as myasthenia gravis. Muscle cells work by detecting a flow of electrical impulses from the brain, which signals them to contract through the release of calcium by the sarcoplasmic reticulum. Fatigue (reduced ability to generate force) may occur due to the nerve, or

neg: Cardiac contractility modulation cardiac muscle cells. Additionally, it was observed that therapeutically useful effects on the cardiac muscle were achieved if the electrical signals were applied not only to single cells but to large areas using larger leads, as used in conventional cardiac pacemakers. The contractility of both a healthy heart and a damaged heart could be increased through application of appropriate signals during the absolute refractory period of the cardiac muscle cells. An implantable Cardiac contractility modulation device was received by a patient for the first time in 2001. The first study on the therapeutic effects of in humans was presented in

neg: Macrophage to isolate, and after purification, only approximately 5 million cells can be obtained from one mouse. Macrophages can express paracrine functions within organs that are specific to the function of that organ. In the testis for example, macrophages have been shown to be able to interact with Leydig cells by secreting 25-hydroxycholesterol, an oxysterol that can be converted to testosterone by neighbouring Leydig cells. Also, testicular macrophages may participate in creating an immune privileged environment in the testis, and in mediating infertility during inflammation of the testis. Cardiac resident macrophages participate in electrical conduction via gap junction communication with cardiac

neg: Muscle weakness if there were no lactic acid to remove the chloride ions. Ultimately, it is uncertain if lactic acid reduces fatigue through increased intracellular calcium or increases fatigue through reduced sensitivity of contractile proteins to Ca. Muscle cells work by detecting a flow of electrical impulses from the brain which signals them to contract through the release of calcium by the sarcoplasmic reticulum. Fatigue (reduced ability to generate force) may occur due to the nerve, or within the muscle cells themselves. New research from scientists at Columbia University suggests that muscle fatigue is caused by calcium leaking out of the muscle

neg: Cardiac cycle and thereby to eject blood from the ventricles into the arteries and the cardiac circulatory system; and they provide a system of intricately-timed and persistent signaling that controls the rhythmic beating of the heart muscle cells, especially the complex impulse-generation and muscle contractions in the atrial chambers. The rhythmic sequence (or sinus rhythm) of this signaling across the heart is coordinated by two groups of specialized cells, the sinoatrial (SA) node, which is situated in the upper wall of the right atrium, and the atrioventricular (AV) node located in the lower wall of the right heart between the atrium and

neg: Interstitial cell of Cajal increases ICC activity through this channel. ANO1-knockout mice fail to produce slow waves and ANO1 channel inhibitors in humans block slow wave production. Many types of smooth muscle tissues have now been shown to contain ICC, but with few exceptions the function of these cells is not known and is currently an area of active research. These cells are derived from mesoderm. ICC serve as electrical pacemakers and generate spontaneous electrical slow waves in the gastrointestinal (GI) tract. Electrical slow waves spread from ICC to smooth muscle cells and the resulting depolarization initiates calcium ion entry and contraction. Slow waves

neg: Cardiac excitation-contraction coupling Cardiac excitation-contraction coupling Cardiac excitation-contraction coupling (Cardiac EC coupling) describes the series of events, from the production of an electrical impulse (action potential) to the contraction of muscles in the heart. This process is of vital importance as it allows for the heart to beat in a controlled manner, without the need for conscious input. EC coupling results in the sequential contraction of the heart muscles that allows blood to be pumped, first to the lungs (pulmonary circulation) and then around the rest of the body (systemic circulation) at a rate between 60 and 100 beats every minute, when the

neg: Heart block contract. In SA node suppression, on the other hand, the SA node doesn't generate an electrical impulse because it is reset by the electrical impulse that enters the SA node. There are three basic types of AV nodal block: Infra-Hisian block is that of the distal conduction system. Types of infra-Hisian block include: Of these types of infra-Hisian block, Mobitz II heart block is considered most important because of the possible progression to complete heart block. Heart block Heart block is a disorder in the heart's rhythm due to a fault in the natural pacemaker. This is caused by an

neg: Briard into an electrical signal that travels to the brain. When the photoreceptor cells deteriorate, vision is lost because the animal has no way to generate an image from the light reaching the retina. Puppies are usually blind before one year of age. For the first time ever, animals (Briards) that were born blind gained the ability to see after undergoing gene therapy, according to research from the University of Florida, Cornell University and the University of Pennsylvania. UF researchers had established that the apparently harmless adeno-associated virus can carry healthy copies of a gene into the cells of the retina,

neg: Cardiac contractility modulation the electrical non-excitatory state of the cardiac muscle cells (the absolute refractory period) cause an increase in myocyte calcium in the cytosol during systole. This increases the muscle contraction strength. Additionally, within minutes, cell metabolism and gene expression, which are typically abnormal in heart failure, improve towards their normal state. This beneficial effect occurs initially only in the area adjacent to the electrodes, but with time also spreads to remote areas of the cardiac muscle. Cardiac contractility modulation therefore restores the structure and function of damaged cells back towards their normal state. In some cases, disease-related changes in the ventricular

neg: Atrial tachycardia label subsets). The codification of the terms "first detected", "paroxysmal", "persistent", and "permanent" in the classification of atrial fibrillation should be compared for reference. Atrial tachycardia Atrial tachycardia is a type of heart rhythm problem in which the heart's electrical impulse comes from an ectopic pacemaker (that is, an abnormally located cardiac pacemaker) in the upper chambers (atria) of the heart, rather than from the sinoatrial node, the normal origin of the heart's electrical activity. Atrial tachycardias can exhibit very regular (consistent) heart rates ranging typically from 140 to 220 beats per minute. As with any other form of tachycardia

neg: Alkali metal cell to generate an action potential—a "spike" of electrical discharge. The ability of cells to produce electrical discharge is critical for body functions such as neurotransmission, muscle contraction, and heart function. Disruption of this balance may thus be fatal: for example, ingestion of large amounts of potassium compounds can lead to hyperkalemia strongly influencing the cardiovascular system. Potassium chloride is used in the United States for lethal injection executions. Due to their similar atomic radii, rubidium and caesium in the body mimic potassium and are taken up similarly. Rubidium has no known biological role, but may help stimulate metabolism, and,

neg: Cardiac cycle ventricle. The sinoatrial node, often known as the "cardiac pacemaker", is the point of origin for producing a wave of electrical impulses that stimulates atrial contraction by creating an action potential across myocardium cells. Impulses of the wave are delayed upon reaching the AV node, which acts as a gate to slow and to coordinate the electrical current before it is conducted below the atria and through the circuits known as the bundle of His and the Purkinje fibers—all which stimulate contractions of both ventricles. The programmed delay at the AV node also provides time for blood volume to flow

neg: Ectopic beat Ectopic beat Ectopic beat (or cardiac ectopy) is a disturbance of the cardiac rhythm frequently related to the electrical conduction system of the heart, in which beats arise from fibers or group of fibers outside the region in the heart muscle ordinarily responsible for impulse formation ("i.e.", the sinoatrial node). An ectopic beat can be further classified as either a premature ventricular contraction, or a premature atrial contraction. Some patients describe this experience as a 'flip' or a 'jolt' in the chest, or a 'heart hiccups', while others report dropped or missed beats. Ectopic beats are more common during periods

neg: Ventricular fibrillation is affected. Automaticity is a measure of the propensity of a fiber to initiate an impulse spontaneously. The product of a hypoxic myocardium can be hyperirritable myocardial cells. These may then act as pacemakers. The ventricles are then being stimulated by more than one pacemaker. Scar and dying tissue is inexcitable, but around these areas usually lies a penumbra of hypoxic tissue that is excitable. Ventricular excitability may generate re-entry ventricular arrhythmia. Most myocardial cells with an associated increased propensity to arrhythmia development have an associated loss of membrane potential. That is, the maximum diastolic potential is less negative and

neg: Potassium in biology inwardly rectifying channels, from prokaryotes and eukaryotes. The cell membrane potential created by potassium and sodium ions allows the cell to generate an action potential—a "spike" of electrical discharge. The ability of cells to produce electrical discharge is critical for body functions such as neurotransmission, muscle contraction, and heart function. The U.S. Institute of Medicine (IOM) sets Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs), or Adequate Intakes (AIs) for when there is not sufficient information to set EARs and RDAs. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes. The current AI for

neg: Guillain–Barré syndrome syndrome is caused by an immune attack on the nerve cells of the peripheral nervous system and their support structures. The nerve cells have their body (the soma) in the spinal cord and a long projection (the axon) that carries electrical nerve impulses to the neuromuscular junction where the impulse is transferred to the muscle. Axons are wrapped in a sheath of Schwann cells that contain myelin. Between Schwann cells are gaps (nodes of Ranvier) where the axon is exposed. Different types of Guillain–Barré syndrome feature different types of immune attack. The demyelinating variant (AIDP, see below) features damage to

neg: Neuroimmune system cells to endothelial tissue, thereby increasing the permeability of immune cells across capillaries. Neuroimmune interactions also occur when pathogens, allergens, or toxins invade an organism. The vagus nerve connects to the gut and airways and elicits nerve impulses to the brainstem in response to the detection of toxins and pathogens. This electrical impulse that travels down from the brain stem travels to mucosal cells and stimulates the secretion of mucus; this impulse can also cause ejection of the toxin by muscle contractions that cause vomiting or diarrhea. The neuroimmune system is involved in reflexes associated with parasitic invasions of hosts.

neg: Neuroimmune system systems. Instances of cytokine binding to neural receptors have been documented between the cytokine releasing immune cell IL-1 β and the neural receptor IL-1R. This binding results in an electrical impulse that creates the sensation of pain. Growing evidence suggests that auto-immune T-cells are involved in neurogenesis. Studies have shown that during times of adaptive immune system response, hippocampal neurogenesis is increased, and conversely that auto-immune T-cells and microglia are important for neurogenesis (and so memory and learning) in healthy adults. The neuroimmune system uses complementary processes of both sensory neurons and immune cells to detect and respond to noxious

neg: SCAR-Fc progressively, infected individual will experience abnormalities in left ventricular systolic and diastolic function, as well as electrical conduction defects manifesting as cardiac dysrhythmias. As a result, ejection fraction decreases substantially. The cytolytic destruction of heart cells can lead to dilated cardiomyopathy if not treated appropriately. The role of the immune system in response to the presence of a virus has both beneficial and detrimental effects on the cardiac system. The arrival of natural killer cells (NK cells) at the site of infection limits viral proliferation in myocytes. Conversely, while certain cytokines released from immune cells have protective effects, others such

neg: Calciseptine the breakdown of the protein by proteases. Calciseptine has been shown to block L-type calcium channels, thus inhibiting smooth muscle contraction and cardiac function. Voltage-dependent calcium channels are important for generating electrical signals in excitable cells like neurons and cardiac or smooth muscle cells. N-type Ca channels are found in neuronal cells, and play an important role in the coupling of nerve excitation and neurotransmitter secretion. L-type calcium channels are present in cardiac and smooth muscle cells, coupling excitation to muscle contraction. Other types of voltage-activated Ca-channels include T-type and P-type channels. Because the presence of calcium in the cytosol

neg: Julio Moizeszowicz (1938), that "it is possible to act chemically on the psychic apparatus." Today it is known that every neuron propagates its information through an action potential (electrical signal) and iits synapses are governed by neurotransmitters. The flow of information is transmitted inside neurons from dendrites in the body of the neuron, and from there, to the axon. To continue the propagation of impulses within neurons, the electrical impulse is converted into chemicals. This release of neurotransmitters in the synaptic gap (stored in vesicles) allows the intervention of psychotropic drugs. These neurotransmitters are "captured" by cell surface receptors, which generate an

neg: Cardiac physiology His and Purkinje fibres are specialised cardiomyocytes that function in the conduction system. Cardiomyocytes, are considerably shorter and have smaller diameters than skeletal myocytes. Cardiac muscle (like skeletal muscle) is characterized by striations – the stripes of dark and light bands resulting from the organised arrangement of myofilaments and myofibrils in the sarcomere along the length of the cell. T (transverse) tubules are deep invaginations from the sarcolemma (cell membrane) that penetrate the cell, allowing the electrical impulses to reach the interior. In cardiac muscle the T-tubules are only found at the Z-lines. When an action potential causes cells to

neg: Adult stem cell appears to represent a remnant of the stem cells of the embryonic neural crest. Similar cells have been found in the gastrointestinal tract, sciatic nerve, cardiac outflow tract and spinal and sympathetic ganglia. These cells can generate neurons, Schwann cells, myofibroblast, chondrocytes and melanocytes. Multipotent stem cells with a claimed equivalency to embryonic stem cells have been derived from spermatogonial progenitor cells found in the testicles of laboratory mice by scientists in Germany and the United States, and, a year later, researchers from Germany and the United Kingdom confirmed the same capability using cells from the testicles of humans. The

neg: Sarcoplasmic reticulum is triggered differently in different muscles. In cardiac and smooth muscle an electrical impulse (action potential) triggers calcium ions to enter the cell through an L-type calcium channel located in the cell membrane (smooth muscle) or T-tubule membrane (cardiac muscle). These calcium ions bind to and activate the RyR, producing a larger increase in intracellular calcium. In skeletal muscle, however, the L-type calcium channel is bound to the RyR. Therefore activation of the L-type calcium channel, via an action potential, activates the RyR directly, causing calcium release (see calcium sparks for more details). Also, caffeine (found in coffee) can bind

neg: Axon system Schwann cells form the myelin sheath of a myelinated axon. In the central nervous system oligodendrocytes form the insulating myelin. Along myelinated nerve fibers, gaps in the myelin sheath known as nodes of Ranvier occur at evenly spaced intervals. The myelination enables an especially rapid mode of electrical impulse propagation called saltatory conduction. The myelinated axons from the cortical neurons form the bulk of the neural tissue called white matter in the brain. The myelin gives the white appearance to the tissue in contrast to the grey matter of the cerebral cortex which contains the neuronal cell bodies. A

neg: Heart 8 around the two ventricles and proceeding toward the apex. This complex swirling pattern allows the heart to pump blood more effectively. There are two types of cells in cardiac muscle: muscle cells which have the ability to contract easily, and pacemaker cells of the conducting system. The muscle cells make up the bulk (99%) of cells in the atria and ventricles. These contractile cells are connected by intercalated discs which allow a rapid response to impulses of action potential from the pacemaker cells. The intercalated discs allow the cells to act as a syncytium and enable the contractions that

neg: Heart arrhythmia muscle cell firing off an impulse on its own. All of the cells in the heart have the ability to initiate an action potential; however, only some of these cells are designed to routinely trigger heart beats. These cells are found in the conduction system of the heart and include the SA node, AV node, Bundle of His and Purkinje fibers. The sinoatrial node is a single specialized location in the atrium that has a higher automaticity (a faster pacemaker) than the rest of the heart and, therefore, is usually responsible for setting the heart rate and initiating each heart

neg: Bundle of His Bundle of His The bundle of His or His bundle is a collection of heart muscle cells specialized for electrical conduction. As part of the electrical conduction system of the heart, it transmits the electrical impulses from the AV node (located between the atria and the ventricles) to the point of the apex of the fascicular branches via the bundle branches. The fascicular branches then lead to the Purkinje fibers, which provide electrical conduction to the ventricles, causing the cardiac muscle of the ventricles to contract at a paced interval. The bundle of His is an important part of the

neg: HBI-3000 hypotension and thrombembolic events. Most anti-arrhythmic medications exert their effects by decreasing the permeability of potassium ion channels (IKr) in heart cells. These potassium channel blockers delay ventricular repolarization and prolong action potential duration (APD; the prolongation of the electrical stimulus within heart cells). These changes can lower heart rate, eliminate atrial fibrillation, and ultimately sudden cardiac death. Ventricular myocytes are heart muscle cells found in the lower chambers of the heart. Heart rate is dependent on the movement of an electrical stimulus through the individual heart cells. This is mediated by the opening of ion channels on cell surfaces.

neg: Sinoatrial arrest an electrocardiogram (ECG) as a brief period of irregular length with no electrical activity before either the sinoatrial node resumes normal pacing, or another pacemaker begins pacing. If a pacemaker other than the sinoatrial node is pacing the heart, this condition is known as an escape rhythm. If no other pacemaker begins pacing during an episode of sinus arrest it becomes a cardiac arrest. This condition is sometimes confused with sinoatrial block, a condition in which the pacing impulse is generated, but fails to conduct through the myocardium. Differential diagnosis of the two conditions is possible by examining the exact

neg: Cardiac physiology is capable of generating its own impulse, the rate progressively slows from the SA node to the Purkinje fibers. Without the SA node, the AV node would generate a heart rate of 40–60 beats per minute. If the AV node were blocked, the atrioventricular bundle would fire at a rate of approximately 30–40 impulses per minute. The bundle branches would have an inherent rate of 20–30 impulses per minute, and the Purkinje fibers would fire at 15–20 impulses per minute. While a few exceptionally trained aerobic athletes demonstrate resting heart rates in the range of 30–40 beats per minute (the

neg: Neuronal lineage marker cells, progenitors and mature CNS cells have been applied to the study of NSCs. Other non-immunological methods have been used to identify populations of cells from normal and tumorigenic CNS tissues, which demonstrate some of the in vitro properties of stem cells, including high aldehyde dehydrogenase (ALDH) enzyme activity. ALDH cells from embryonic rat and mouse CNS have been isolated and shown to have the ability to generate neurospheres, neurons, astrocytes and oligodendrocytes in vitro, as well as neurons in vivo when transplanted into the adult mouse cerebral cortex. Once a stem cell divides asymmetrically, the more mature progenitor is

neg: Cardiac cycle split into pulmonary circulation—during which the right ventricle pumps oxygen-depleted blood to the lungs through the pulmonary trunk and arteries; or the systemic circulation—in which the left ventricle pumps/ejects newly oxygenated blood throughout the body via the aorta and all other arteries. In a healthy heart all activities and rests during each individual cardiac cycle, or heartbeat, are initiated and orchestrated by signals of the heart's electrical conduction system, which is the "wiring" of the heart that carries electrical impulses throughout the body of cardiomyocytes, the specialized muscle cells of the heart. These impulses ultimately stimulate heart muscle to contract

neg: Short QT syndrome the dispersion of repolarisation, occurs because the action potential shortening seen in this condition occurs to a greater extent in some layers of the heart wall than in others. This means that at certain points in the cardiac cycle, some layers of the heart wall will have fully repolarised, and are therefore ready to contract again, while other regions are only partially repolarised and therefore are still within their refractory period and not yet able to be re-excited. If a triggering impulse arrives at this critical point in the cardiac cycle, the wavefront of electrical activation will conduct in some

neg: Chimeric antigen receptor which the immune system is activated and releases an increased number of inflammatory cytokines. The clinical manifestations of this syndrome include high fever, fatigue, myalgia, nausea, tachycardia, capillary leakages, cardiac dysfunction, hepatic failure, and renal impairment. The neurological toxicity associated with CAR-T cells have clinical manifestations that include delirium, the partial loss of the ability to speak a coherent language while still having the ability to interpret language (expressive aphasia), lowered alertness (obtundation), and seizures. During some clinical trials deaths caused by neurotoxicity have occurred. The main cause of death from neurotoxicity is cerebral edema. In a study carried out

neg: Cardiac muscle cell Cardiac muscle cell Cardiac muscle cells or cardiomyocytes (also known as myocardiocytes or cardiac myocytes) are the muscle cells (myocytes) that make up the cardiac muscle (heart muscle). Each myocardial cell contains myofibrils, which are specialized organelles consisting of long chains of sarcomeres, the fundamental contractile units of muscle cells. Cardiomyocytes show striations similar to those on skeletal muscle cells. Unlike multinucleated skeletal cells, the majority of cardiomyocytes contain only one nucleus, although they may have as many as four. Cardiomyocytes have a high mitochondrial density, which allows them to produce adenosine triphosphate (ATP) quickly, making them highly resistant to

neg: Myocardial contractility Myocardial contractility Myocardial contractility represents the innate ability of the heart muscle (cardiac muscle or myocardium) to contract. The ability to produce changes in force during contraction result from incremental degrees of binding between different types of tissue, that is, between filaments of myosin (thick) and actin (thin) tissue. The degree of binding depends upon the concentration of calcium ions in the cell. Within an in vivo intact heart, the action/response of the sympathetic nervous system is driven by precisely timed releases of a catecholamine, which process determines the concentration of calcium ions in the cytosol of cardiac muscle cells.

neg: Carnitine-acylcarnitine translocase deficiency broken down and processed. As a result, these fatty acids are not converted into energy, which can lead to characteristic signs and symptoms of this disorder, such as weakness, hypoglycemia, and an irregular heartbeat. Free long-chain fatty acids or those that are joined with carnitine can affect the electrical properties of cardiac cells causing an irregular heart beat (arrhythmia, which can lead to cardiac arrest). Fatty acids may also build up in tissues and can damage the heart, liver, and muscles, and cause more serious complications. This condition has an autosomal recessive inheritance pattern, which means the defective gene is

neg: Otto Loewi physiological responses could be caused by applying an electrical impulse, which suggested that electrical transmission may be the only mode of endogenous signaling. In the early 20th century the controversy of whether cells used chemical or electrical transmission divided even the most prominent scientists. Loewi's famous experiment, published in 1921, largely answered this question. According to Loewi, the idea for his key experiment came to him in his sleep, causing him to go directly to the laboratory in the middle of the night. He dissected out of frogs two beating hearts: one with the vagus nerve which controls heart rate

neg: X-linked agammaglobulinemia X-linked agammaglobulinemia X-linked agammaglobulinemia (XLA) is a rare genetic disorder discovered in 1952 that affects the body's ability to fight infection. As the form of agammaglobulinemia that is X-linked, it is much more common in males. In people with XLA, the white blood cell formation process does not generate mature B cells, which manifests as a complete or near-complete lack of proteins called gamma globulins, including antibodies, in their bloodstream. B cells are part of the immune system and normally manufacture antibodies (also called immunoglobulins), which defend the body from infections by sustaining a humoral immunity response. Patients with untreated

neg: Action potential neurons, which are ubiquitous in the neocortex. These are thought to have a role in spike-timing-dependent plasticity. A neuron's ability to generate and propagate an action potential changes during development. How much the membrane potential of a neuron changes as the result of a current impulse is a function of the membrane input resistance. As a cell grows, more channels are added to the membrane, causing a decrease in input resistance. A mature neuron also undergoes shorter changes in membrane potential in response to synaptic currents. Neurons from a ferret lateral geniculate nucleus have a longer time constant and larger

neg: Amniotic stem cells gap junctions with each other, an indicator for cardiac-like cells. However, these results may be due to the specific features of the NRVM or fusion of the cells rather than the amniotic stem cell’s own potential to differentiate into cardiac cells. In general, these types of techniques are considered to be potentially significant but further investigations are required. Another area of interest is the use of these cells for improvement of cardiac tissue following a myocardial infarction. Several strategies have been tested in rats including the injection of dissociated amniotic stem cells into the infarct region, which yielded conflicting results