Vagotonia is the state of the autonomic nervous system in which there is increased parasympathetic input through the vagus nerve, or the equilibrium between the sympathetic and parasympathetic is biased towards the latter. [1] [2] The opposite phenomenon has been referred to as sympatheticotonia. [2]
Increased parasympathetic outflow prominently affects the heart, reducing the heart rate or, in extreme cases, completely halting heart beats. This is a common cause of fainting. [3]
The parasympathetic nervous system is dominant in situations of rest and relaxation, it has an activating effect on digestive organs and a relieving one on the heart. Endurance training increases vagotonia. For example, a low heart rate may be observed with sportsmen. [4]
The autonomic nervous system (ANS), sometimes called the visceral nervous system and formerly the vegetative nervous system, is a division of the nervous system that operates internal organs, smooth muscle and glands. The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions, such as the heart rate, its force of contraction, digestion, respiratory rate, pupillary response, urination, and sexual arousal. The fight-or-flight response, also known as the acute stress response, is set into action by the autonomic nervous system.
Exercise or workout is physical activity that enhances or maintains fitness and overall health. which is performed for various reasons, including weight loss or maintenance, to aid growth and improve strength, develop muscles and the cardiovascular system, prevent injuries, hone athletic skills, improve health, or simply for enjoyment. Many people choose to exercise outdoors where they can congregate in groups, socialize, and improve well-being as well as mental health.
The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system.
The sympathetic nervous system is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes considered an independent system.
Heart rate is the frequency of the heartbeat measured by the number of contractions of the heart per minute. The heart rate varies according to the body's physical needs, including the need to absorb oxygen and excrete carbon dioxide. It is also modulated by numerous factors, including genetics, physical fitness, stress or psychological status, diet, drugs, hormonal status, environment, and disease/illness, as well as the interaction between these factors. It is usually equal or close to the pulse rate measured at any peripheral point.
The diving reflex, also known as the diving response and mammalian diving reflex, is a set of physiological responses to immersion that overrides the basic homeostatic reflexes, and is found in all air-breathing vertebrates studied to date. It optimizes respiration by preferentially distributing oxygen stores to the heart and brain, enabling submersion for an extended time.
Vasodilation, also known as vasorelaxation, is the widening of blood vessels. It results from relaxation of smooth muscle cells within the vessel walls, in particular in the large veins, large arteries, and smaller arterioles. Blood vessel walls are composed of endothelial tissue and a basal membrane lining the lumen of the vessel, concentric smooth muscle layers on top of endothelial tissue, and an adventitia over the smooth muscle layers. Relaxation of the smooth muscle layer allows the blood vessel to dilate, as it is held in a semi-constricted state by sympathetic nervous system activity. Vasodilation is the opposite of vasoconstriction, which is the narrowing of blood vessels.
The cardiovascular centre is a part of the human brain which regulates heart rate through the nervous and endocrine systems. It is considered one of the vital centres of the medulla oblongata.
The baroreflex or baroreceptor reflex is one of the body's homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels. The baroreflex provides a rapid negative feedback loop in which an elevated blood pressure causes the heart rate to decrease. Decreased blood pressure decreases baroreflex activation and causes heart rate to increase and to restore blood pressure levels. Their function is to sense pressure changes by responding to change in the tension of the arterial wall. The baroreflex can begin to act in less than the duration of a cardiac cycle and thus baroreflex adjustments are key factors in dealing with postural hypotension, the tendency for blood pressure to decrease on standing due to gravity.
Postural orthostatic tachycardia syndrome (POTS) is a condition characterized by an abnormally large increase in heart rate upon sitting up or standing. POTS is a disorder of the autonomic nervous system that can lead to a variety of symptoms, including lightheadedness, brain fog, blurred vision, weakness, fatigue, headaches, heart palpitations, exercise intolerance, nausea, diminished concentration, tremulousness (shaking), syncope (fainting), coldness or pain in the extremities, numbness or tingling in the extremities, chest pain, and shortness of breath. Other conditions associated with POTS include myalgic encephalomyelitis/chronic fatigue syndrome, migraine headaches, Ehlers–Danlos syndrome, asthma, autoimmune disease, vasovagal syncope, and mast cell activation syndrome. POTS symptoms may be treated with lifestyle changes such as increasing fluid, electrolyte, and salt intake, wearing compression stockings, gentle and slow postural changes, avoiding prolonged bedrest, medication, and physical therapy.
Heart rate variability (HRV) is the physiological phenomenon of variation in the time interval between heartbeats. It is measured by the variation in the beat-to-beat interval.
Heart rate turbulence (HRT) is a baroreflex-mediated adjustment of heart rate which acts as a counter-mechanism to premature ventricular contraction (PVC). It consists of a brief speed-up in heart rate, followed by a slow decrease back to the baseline rate. PVCs can occur naturally in most otherwise-healthy adults, so measuring the characteristics of a given person's HRT can offer a non-invasive way to evaluate certain aspects of their cardiac or autonomic function without applying artificial external stimuli.
Endurance training is the act of exercising to increase endurance. The term endurance training generally refers to training the aerobic system as opposed to the anaerobic system. The need for endurance in sports is often predicated as the need of cardiovascular and simple muscular endurance, but the issue of endurance is far more complex. Endurance can be divided into two categories including: general endurance and specific endurance. Endurance in sport is closely tied to the execution of skill and technique. A well conditioned athlete can be defined as, the athlete who executes his or her technique consistently and effectively with the least effort. Key for measuring endurance are heart rate, power in cycling and pace in running.
The pacemaker current is an electric current in the heart that flows through the HCN channel or pacemaker channel. Such channels are important parts of the electrical conduction system of the heart and form a component of the natural pacemaker.
Athletic heart syndrome (AHS) is a non-pathological condition commonly seen in sports medicine in which the human heart is enlarged, and the resting heart rate is lower than normal.
The Bainbridge reflex is a cardiovascular reflex causing an increase in heart rate in response to increased stretching of the wall of the right atrium and/or the inferior vena cava as a result of increased venous filling. It is detected by stretch receptors in the wall of the right atrium, the afferent limb is via the vagus nerve, it is regulated by a center in the medulla oblongata of the brain, and the efferent limb involves reduced vagal activity and increased sympathetic nervous system outflow.
Vagal tone is activity of the vagus nerve and a fundamental component of the parasympathetic branch of the autonomic nervous system. This branch of the nervous system is not under conscious control and is largely responsible for the regulation of several body compartments at rest. Vagal activity results in various effects, including: heart rate reduction, vasodilation/constriction of vessels, glandular activity in the heart, lungs, and digestive tract, liver, immune system regulation as well as control of gastrointestinal sensitivity, motility and inflammation.
Neurocardiology is the study of the neurophysiological, neurological and neuroanatomical aspects of cardiology, including especially the neurological origins of cardiac disorders. The effects of stress on the heart are studied in terms of the heart's interactions with both the peripheral nervous system and the central nervous system.
George Edward Billman is an American physiologist and professor at Ohio State University. After receiving a Ph.D from the University of Kentucky in 1980, Billman began his professional career at the University of Oklahoma. In 1984, he joined the Ohio State staff, where he became an associate professor in 1990 and a full professor in 1996.
Autonomic drugs are substances that can either inhibit or enhance the functions of the parasympathetic and sympathetic nervous systems. This type of drug can be used to treat a wide range of diseases an disorders, including glaucoma, asthma, and disorders of the urinary, gastrointestinal and circulatory systems.