English dictionary definition of REFRACTORINESS along with additional meanings, example sentences, and different ways to say. Refractory period. Cellular Physiology Terminology. Normal resting membrane potential is -85mv to -95mv. Refractory period (physiology) In common sense, refractory period is the characteristic recovery time, a period of time that is associated with the motion of the image point on the left branch of the isocline (for more details, see also Reaction-diffusion and Parabolic partial differential equation ). Also found in: Dictionary, Thesaurus, Acronyms, Encyclopedia, Wikipedia . the state of being refractory. postrepolarization refractoriness refractoriness to stimuli that exists even after a fiber has completely repolarized; see also absolute refractory period. Chemotherapy-induced thrombocytopenia (CIT) is a common hematologic toxicity of myelosuppressive and ablative therapy. A phenomenon commonly seen with indirect acting stimuli is refractoriness [5–8]. By week 16, gender can be assessed on ultrasound. To date, its physiological mechanisms remain unclear, limiting the insights gained from findings of abnormal refractoriness in individuals with schizophrenia. A vector is a physical quantity which has both magnitude and direction in space. 2.2 Inclusion criteria and definition of DRE. The depolarization propagates through the myocardium similar to … Growing evidence suggests that impairment in RyR2 refractoriness is a unifying mechanism for various forms of inherited and acquired arrhythmias. 1. Recent evidence suggests that there may be two phases of SICI with maximum inhibition at ISI of 1 ms and 2.5 ms (Fisher et al. Platelet refractoriness can be simply defined as a post-transfusion platelet increment that is less than expected. The measurement of refractory periods (RPs) has been widely used to assess R, but conventional electrode and extrastimulus mapping techniques have not provided reliable maps of RPs. 1 Enormous advances in the understanding of AF pathophysiology have occurred over the past 20 years. The distal convoluted tubule is the nephron segment that lies immediately downstream of the macula densa. refraction: [ re-frak´shun ] the act or process of refracting; specifically, the determination of the refractive errors of the eye and their correction with glasses. Sensory neurons receive information via their receptors, which are part of the peripheral nervous system, and convert this information into electrical impulses.These impulses act as signals and are passed on to the central nervous system. Medical definition of Refractoriness : the insensitivity to further immediate stimulation that develops in irritable and especially nervous tissue as a … can be introduced depending on the study protocol. The model is based on a "free" firing rate, which exists in the absence of refractoriness. Reentry Model. The phenomenon of psychological refractoriness just discussed accounts for many of the underlying processes in faking. During a blood meal, a malaria-infected female Anopheles mosquito inoculates sporozoites into the human host .Sporozoites infect liver cells and mature into schizonts , which rupture and release merozoites . refractoriness definition in English dictionary, refractoriness meaning, synonyms, see also 'refractor',refractiveness',refraction',refractorily'. Vagal Maneuvers with Supraventricular Tachycardia. Intraventricular conduction delay are due to abnormalities in the specialized conduction system in the ventricles that transmit impulses arising from the SA node transmitted through the AV node to the ventricles. A preparation consisting of a papillary muscle and attached bundle of Purkinje fibers has been employed to study refractoriness of single cardiac fibers of the dog heart. Refractoriness was defined as less than 5% of the donor's platelets circulating in a transfused recipient at 20 hours after transfusion after 2 sequential transfusions. * P < 0.01 compared with high-lateral RA, RAA and PVs in baseline conditions. The refractory period lasts almost as long as the contraction. refractoriness: 1 n the trait of being unmanageable Synonyms: recalcitrance , recalcitrancy , unmanageableness Type of: intractability , intractableness the trait of being hard to influence or control Origin: L. Refractorius This entry appears with permission from the Dictionary of Cell and Molecular Biology (11 Mar 2008) Lexicographical Neighbors of Refractory PART THREE Coordinated Body Functions. Re-entry is the most common cause of supraventricular and ventricular arrhythmias that require treatment. Refractoriness synonyms, Refractoriness pronunciation, Refractoriness translation, English dictionary definition of Refractoriness 2. This condition is known as platelet refractoriness and is diagnosed by evaluating the corrected count increment following platelet transfusion. Definition. This function may be a better description of a spiking neuron's response than the peri-stimulus time histogram. 2002). ‘a pressor response’. Voltage is the measure of potential energy generated by separated charge. Definition of bradycardia and tachycardia. Stronger test stimuli can overcome this refractoriness resulting in greater inhibition. Tension developed. Physiology. Although short in length, the distal convoluted tubule plays a critical role in sodium, potassium, and divalent cation homeostasis. Vector - Symbolic representation of physical force. In the ECG below note the arrow pointing at a premature P wave in the ST-T segment. Iron deficiency is one of the most common nutritional problems of the human race. Start studying Physiology Exam 1. Abstract. For a short period after the passage of an impulse, the threshold for stimulation is raised, such that if a nerve is stimulated twice in quick succession, it may not respond to the second stimulus. In basketball, for example, the player taking the shot preprograms a single, relatively complex action that involves a move to begin a shot, a delay to withhold it, and then the actual shot—all done in rapid succession. Computer simulations have been used to study the mechanisms of postrepolarization refractoriness in cardiac cells under ischemic conditions at the cellular level. Absence of AV node physiology was defined as the failure to demonstrate dual AV node physiology (defined as above) during coronary sinus pacing up to the AV nodal block cycle length or by atrial extrastimulation until AV nodal refractoriness was reached. Recent evidence indicates that the breeding season of the Suffolk ewe ends because of loss of response to a day length that was previously inductive. hard or impossible to manage; stubbornly disobedient: a refractory child. Relative refractoriness is the period when the generation of a new action potential is possible, but only upon a suprathreshold stimulus. This period overlaps the final 1/3 of repolarization. An action potential is generated in the body of the neuron and propagated through its axon. What phase are L-type (I Ca-L) calcium channels active during non-pacemaker cardiac action potentials? This chapter deals mainly with defibrillation of non-perfusing rhythms postrepolarization refractoriness refractoriness to stimuli that exists even after a fiber has completely repolarized; see … It can be detected by the stimulation of nerves and muscles by paired electrical impulses. What does refractoriness mean? Creates slow, inward, long-lasting current important in vascular smooth muscle contraction. A refractory material or refractory is a material that is resistant to decomposition by heat, pressure, or chemical attack, and retains strength and form at high temperatures. The coupling interval (S2) is reduced by 10–20 ms to 200 ms or refractoriness. 2001) can lead to wavebreak and the initiation of multiple re-entrant spiral waves (Fenton et al. Abstract. What is the meaning of REFRACTORINESS? The ERP. Mosquito microbiota play critical roles in many mosquito biology processes, including nutrition, digestion, mating and sexual reproduction, development, immune response functions, and refractoriness to pathogens (Douas, 2011). Electrophysiology studies (EPS) are tests that help doctors understand the nature of abnormal heart rhythms ( arrhythmias ). As a result, the estimated value approaches the solution of the continuous problem, as the bin size goes to zero, at significantly higher speed of convergence. Producing an increase in blood pressure by stimulating constriction of the blood vessels. It is measured in volts or millivolts. Refractoriness refers to a diminished airway response to a given stimuli when a subsequent challenge is performed within a relatively short time frame (e.g. The term auditory refractoriness is typically only used to refer to EEG components or their generators, i.e., postsynaptic potentials. It is associated with serious health risks including abnormal mental and motor development in infancy, impaired work capacity, increased risk of premature delivery, and, in severe anemia, increased maternal and infant mortality. Search for: Neurophysiology. Refractoriness refers to a diminished airway response to a given stimuli when a subsequent challenge is performed within a relatively short time frame (e.g. By definition, the bronchoconstriction caused by allergic stimuli occurs through an indirect mechanism. Anatomy and Physiology I. Module 11: The Nervous System and Nervous Tissue. The … The inclusion criteria for the meta-analysis were as follows: 1. a focus on patients newly diagnosed with epilepsy who had never received antiepileptic drugs, 2. intractability, refractoriness, or drug-resistance of epilepsy as an outcome, and had the clear definition of … The physiological significance of this shortening of atrial refractoriness may be reflected in a heightened propensity for the reinduction of AF after conversion to sinus rhythm. Tachyphylaxis is the continued or repeated exposure to a drug that may lead to a weakened pharmacological response. Re-entry can also occur in the sinoatrial node and atrioventricular node. 1. For reentry to occur, certain conditions must be met that are related to the following: the presence of a unidirectional block within a conducting pathway. Despite their unproven effect on survival, their indisputable efficacy in relieving congestive symptoms makes them first line therapy for most patients. The myocardium is a smooth muscle which allows it to function autonomically. Voltage and current are two important factors to consider in the study of neurons. As the atrial ERP gradually lengthens to a baseline level, the propensity to reinduce AF diminishes, as does the duration of the reinduced AF episodes, possibly because of progressive lengthening of the atrial wavelength. The topic of cardioversion in the ICU, including its mechanism of action, is discussed elsewhere. See more. The accessory pathway is most commonly located in the posteroseptal region; however, other locations have been described. The quality of being refractory. The role of luminal Ca regulation in Ca signaling refractoriness and cardiac arrhythmogenesis Sándor Györke, 1,3 Andriy E. Belevych,1,3 Bin Liu, Igor V. Kubasov,4 Cynthia A. Carnes,2,3 and Przemysław B. Radwański2,3 1Department of Physiology and Cell Biology and 2College of Pharmacy, The Ohio State University, Columbus, OH Stimulus Novelty, and Not Neural Refractoriness, Explains the Repetition Suppression of Laser-Evoked Potentials October 2010 Journal of Neurophysiology 104(4):2116-24 Anatomy of the conduction system, including abnormal A-V connections. ‘Vascular pressor responses to hypoxia are increased in patients with obstructive sleep apnea.’. This presumed to be a consequence of diminished receptor sensitivity in response to consistent stimulation by a drug agonist, which produces a diminished pharmacological response in consequence. 2000; Watanabe et al. Shortening of tissue refractoriness (eg, by sympathetic stimulation) Lengthening of the conduction pathway (eg, by hypertrophy or abnormal conduction pathways) Slowing … Definition of platelet refractoriness. Phase 2. The ERP is defined as the time period during which cardiac cells remain inexcitable to a physiological stimulus following an action potential upstroke. Refractory definition, hard or impossible to manage; stubbornly disobedient: a refractory child. The answer, of course, is electricity. Definition of "refractoriness" at Define.com Simple Psychedelic Plain Text English Dictionary with Hyperlinks to The Free World Bank - A BIG Thinking Scientific Save the World High Level Concept on … Auditory refractoriness refers to the phenomenon that the amplitudes of certain electroencephalography (EEG) components are smaller for sounds that are preceded by shorter periods of silence. 1. Physiologic S3 and supine hypotension may be observed on cardiovascular exam. Anatomy and Physiology. This involves delivery of a train of eight impulses (A1) at a fixed cycle length, followed by a single premature impulse (A2). This behavior is reflected in measurements of the Effective Refractory Period (ERP) and Relative Refractory Period (RRP). : Human Physiology: The Mechanism of Body Function, Eighth Edition. FIGURE 14-23 All content on this website, including dictionary, thesaurus, literature, geography, and other reference data is for informational purposes only. 3 h). Electrophysiologic testing uses catheters inserted into the heart to find out where abnormal heartbeats are coming from. o normal impulse formation . The malaria parasite life cycle involves two hosts. The term permanent junctional reciprocating tachycardia (PJRT) describes an orthodromic atrioventricular reentry tachycardia using a usually concealed slowly conducting accessory pathway with decremental properties as the retrograde limb. 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