Biological Sciences
Autonomic Nervous System
The autonomic nervous system is a division of the peripheral nervous system that regulates involuntary bodily functions, such as heart rate, digestion, and respiratory rate. It consists of two main branches: the sympathetic nervous system, which prepares the body for action, and the parasympathetic nervous system, which helps the body rest and digest. These two branches work in opposition to maintain homeostasis in the body.
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10 Key excerpts on "Autonomic Nervous System"
eBook - PDF- Orhan E. Arslan(Author)
- 2014(Publication Date)
- CRC Press(Publisher)
197 9 Autonomic Nervous System (ANS) The Autonomic Nervous System (ANS) regulates visceral motor, glandular secretion, contraction of the vessels and reflex activities, transmission of visceral sensations, as well as emotional behavior. It consists of neurons that are located in the central nervous system (CNS) but also extend in the peripheral nervous system (PNS) (Figures 9.1 and 9.2). It is not a fully autonomous entity, as the name may imply, but rather, an interdependent system that functions under mas-sive input from the cerebral cortex and subcortical centers. The ability to voluntarily control the autonomic functions paved the way for biofeedback conditioning in which heart rate, body temperature, and blood pressure can be changed. This voluntary control is exemplified in the regulatory influ-ences of the premotor cortex, cingulate gyrus, and hippocam-pal gyrus on the visceral motor nuclei of the cranial nerves and the intermediolateral columns of the thoracic and sacral spinal segments through relay neurons within the thalamus and brainstem reticular neurons. Through diverse connec-tions with functionally diverse neurons at all levels of the CNS, the ANS maintains a stable homeostasis (internal sta-bility), which is essential for normal physiological functions. The ANS consists of peripheral efferent and afferent fibers and central neurons in the spinal cord, brainstem, diencepha-lon, and brain that are closely associated with the somatic nervous system. The ANS is divisible into sympathetic and parasympathetic components. The afferent component trans-mits visceral pain and organic visceral sensations (e.g., hun-ger, malaise, nausea, libido, bladder, and rectal fullness). For the most part, visceral pain fibers initially accompany the sympathetic postganglionic and then the sympathetic pregan-glionic fibers. As briefly outlined, the efferent component inner-vates the smooth muscles, glandular tissue, and sweat glands.
eBook - ePub- Ruud M. Buijs, Dick F. Swaab(Authors)
- 2013(Publication Date)
- Elsevier(Publisher)
Chapter 1The Autonomic Nervous System
a balancing act
Ruud M. Buijs* , Department of Cell Biology and Physiology, Institute for Biomedical Research, Universidad Nacional Autónoma de México, Mexico City, Mexico ,* Correspondence to: Ruud M. Buijs, Department of Cell Biology and Physiology, Institute for Biomedical Research, Universidad Nacional Autónoma de México, Av. Universidad 3000, Mexico City, DF, 04510, Mexico. E-mail: [email protected]Abstract
The overarching theme of the present chapter is the importance of the interaction between brain and body in order to maintain homeostasis – an interaction, rather than a mere top-down or reflex regulation, as signals from the organs may influence the functioning of the brain. For example, the reflex regulation of blood pressure and heart rate is not only subject to modulation by ascending information from the body, but also by descending information from several areas in hypothalamus and cortex. The central nervous system (CNS) has the capacity to control its output via the Autonomic Nervous System (ANS) using an amazing differentiation. For example, not only do the biological clock and prefrontal cortex contain neurons which influence the parasympathetic or sympathetic motor neurons, they also contain different neurons that project to diverse body compartments. In the end this leads to integrated responses whereby visceral sensory information reaches higher centers in the CNS via vagal or spinal sensory pathways, causing a reaction which takes into account factors such as the time of day, the season, the reproductive status, mood. Based on all this information, the brain sets the balance of the different parts of the ANS, causing its output to change its emphasis according to the situation. A disturbed balance, either as a result of behavior or of disease of any of the organs, may lead to pathology affecting the functioning of the entire individual.
- Andrew Kuntzman, Gerard J. Tortora(Authors)
- 2015(Publication Date)
- Wiley(Publisher)
The Autonomic Nervous System (ANS) acts without our conscious thought. It regulates contraction of cardiac muscle and smooth muscle, and glandular secretion in our bodies. The derivation is auto- self and -nomic law; in other words, the ANS was originally believed to be self-governing. The medulla oblongata and hypothalamus of the brain are now known to be the main integrative centers for the ANS. The ANS is divided into the sympathetic and parasympathetic divi- sions. The sympathetic division is very important when we are under stressful situations such as a medical emergency. It allows us to react quickly and gives us a surge of energy to deal with emergency situations. The sympa- thetic division mediates what is often called the fight-or-flight reaction. The parasympathetic division is known as the rest-and-digest division since its main functions are to heal and to aid digestion. The two divisions work in conjunction so when one division is turned on the other division is normally turned down. This is why, when we are under stress for a long time, we may develop high blood pressure. Every night, sleep forces a person into the parasympa- thetic state, and therefore we are able to repair tissues and to maintain homeostasis of the body. A goal for manual therapists may be to facilitate a patient’s movement toward the parasympathetic state so that his body may better heal itself and decrease stress.
eBook - PDF- Gerard J. Tortora, Bryan H. Derrickson(Authors)
- 2016(Publication Date)
- Wiley(Publisher)
526 CHAPTER 15 As you learned in Chapter 12, the motor (efferent) division of the peripheral nervous system (PNS) is divided into a somatic nervous system (SNS) and Autonomic Nervous System (ANS). The ANS usually operates without conscious control. However, centers in the hypothalamus and brainstem do regulate ANS reflexes. In this chapter, we compare structural and functional features of the somatic and Autonomic Nervous Systems. Then we discuss the anatomy of the motor portion of the ANS and compare the organization and actions of its two major parts, the sympathetic and parasympathetic divisions. Q Did you ever wonder how some blood pressure medications exert their effects through the Autonomic Nervous System ? The Autonomic Nervous System The Autonomic Nervous System and Homeostasis The Autonomic Nervous System contributes to homeostasis by conveying motor output from the central nervous system to smooth muscle, cardiac muscle, and glands for appropriate responses to integrated sensory information. 15.1 Comparison of Somatic and Autonomic Nervous Systems 527 damaged. The heart continues to beat when it is removed for trans- plantation into another person, smooth muscle in the lining of the gastrointestinal tract contracts rhythmically on its own, and glands produce some secretions in the absence of ANS control. The ANS usually operates without conscious control. For example, you probably cannot voluntarily slow down your heart rate; instead, your heart rate is subconsciously regulated. For this reason, some auto- nomic responses are the basis for polygraph (“lie detector”) tests. How- ever, practitioners of yoga or other techniques of meditation may learn how to regulate at least some of their autonomic activities through long practice. Biofeedback, in which monitoring devices display information about a body function such as heart rate or blood pressure, enhances the ability to learn such conscious control.
eBook - PDF- Gerard J. Tortora, Bryan H. Derrickson(Authors)
- 2020(Publication Date)
- Wiley(Publisher)
These tissues are often referred to as visceral effectors because they are usually associated with the viscera (internal organs) of the body. The term autonomic is derived from the words auto- = self and -nomic = law because the ANS was once thought to be self-governing. The Autonomic Nervous System consists of autonomic motor neurons that regulate visceral activities by either increas- ing (exciting) or decreasing (inhibiting) ongoing activities in their effector tissues (cardiac muscle, smooth muscle, and glands). Changes in the diameter of the pupils, dilation and con- striction of blood vessels, and adjustment of the rate and force of the heartbeat are examples of autonomic motor responses. Unlike skeletal muscle, tissues innervated by the ANS often function to some extent even if their nerve supply is damaged. The heart continues to beat when it is removed for transplan- tation into another person, smooth muscle in the lining of the digestive canal contracts rhythmically on its own, and glands produce some secretions in the absence of ANS control. The ANS usually operates without conscious control. For example, you probably cannot voluntarily slow down your heart rate; instead, your heart rate is subconsciously regulated. For this reason, some autonomic responses are the basis for polygraph (“lie detector”) tests. However, practitioners of yoga or other techniques of meditation may learn how to regulate at least some of their autonomic activities through long practice. Biofeedback, in which monitoring devices display information about a body function such as heart rate or blood pressure, enhances the abil- ity to learn such conscious control. (For more on biofeedback, see the Medical Terminology section at the end of the chapter).
eBook - ePubThe Theory of Endobiogeny
Volume 1: Global Systems Thinking and Biological Modeling for Clinical Medicine
- Kamyar M. Hedayat, Jean-Claude Lapraz(Authors)
- 2019(Publication Date)
- Academic Press(Publisher)
Chapter 3The Autonomic Nervous System
Abstract
The chapter introduces the Autonomic Nervous System (ANS) according to the theory of Endobiogeny. The ANS is key to the regulation of the terrain because it affects every level of function. The ANS has two branches: parasympathetic and sympathetic, which has two subbranches: alpha- and beta-sympathetic. The ANS is a sequential system that ensures proper sequencing of all activities. Thus, in the theory of Endobiogeny, all sequential activities can be characterized as para-, alpha- or beta-like, based on its function in preparation, calibration, and resolution, even if the ANS is not technically involved. This notion is applied to various physiologic activities from thought to adaptation to digestion. Many disorders characterized as psychosomatic or inorganic are related to dysfunctions of sequencing.Keywords
Autonomic Nervous System; Alpha-sympathetic; Beta-sympathetic; Central nervous system; Endobiogeny; Endocrine system; Integrative physiology; Parasympathetic; Peripheral nervous systemIntroduction
As postulated by the theory of Endobiogeny, the endocrine system is considered to be the manager of the terrain. According to this theory, the Autonomic Nervous System (ANS) regulates this manager of the terrain: the endocrine system. Thus, a study of the ANS precedes a study of the endocrine system. When the ANS is contextualized within its role in global functioning of all branches of the nervous system, the logic of its relationship to the endocrine system becomes more apparent. In Miller’s theory of living systems (Chapter 1 ), all living systems are characterized as having two general types of activities: energy-matter transformation and information processing (Fig. 3.1 ).1 Energy matter is transformed directly by the endocrine system and associated digestive and emunctory glands (cf. The Theory of Endobiogeny, Volume 3, Chapter 9). Information processing is managed by the various branches of the nervous system. The autonomic branch of the nervous system (ANS) links these two activities and all the organs implicated. The ANS remains permanently in close physical, physiologic and teleological proximity to them. In other words, the purpose of the ANS is to allow all other systems to serve their intrinsic purpose more efficiently
eBook - PDF- Charles M Tipton(Author)
- 2003(Publication Date)
- Elsevier Science(Publisher)
chaipier 5 THE Autonomic Nervous System Charles M. Tipton I T is a daunting task to present in a cohesive chapter a historical perspective on the functions of the Autonomic Nervous System during exercise by normal and phys-ically trained subjects. The multiplicity of systems regulated by the autonomic ner-vous system is summarized as follows by Hamill {76, p. 12): The Autonomic Nervous System (ANS) is structurally and functionally positioned to in-terface between the internal and external milieu, coordinating bodily functions to in-sure normal homeostasis (cardiovascular control, thermal regulation, gastrointestinal motility, urinary and bowel excretory functions, reproduction, and normal metaboUc and endocrine physiology), and adaptive responses to stress (fight or flight response). Coupled with the limitations on space, this restricts the scope of the chapter to the roles of the sympathetic and parasympathetic nervous systems in characterizing the cardiorespiratory responses to exercise. The approach here will be to focus on se-lected ideas and the people contributing to their development, with a primary em-phasis on dynamic exercise results from healthy populations. In general, animal findings will be incorporated when the experimental approach would be inappropri-ate for human investigations. Like other authors, I regret not being able to include many of the studies conducted by my contemporaries. HISTORICAL OVERVIEW OF THE Autonomic Nervous System The historical record of the structure and function of the Autonomic Nervous System began with the description by Galen of Pergamon (ca. 129-200) of the vagosympa-188 The Autonomic Nervous System 189 thetic trunk, the appearance of the rami communicans, and the existence of three separate gangUonic swelUngs/' Galen beUeved that nerves'' were hollow tubes and conducted animal spirits that went from one organ to another in a coordinated man-ner which was called sympathy'' (112, 160).
- Gerard J. Tortora, Bryan H. Derrickson(Authors)
- 2017(Publication Date)
- Wiley(Publisher)
Two examples of perceived visceral sensations are pain sensations from damaged viscera and angina pecto- ris (chest pain) from inadequate blood flow to the heart. Signals from the somatic senses and special senses, acting via the limbic system, also in- fluence responses of autonomic motor neurons. Seeing a bike about to hit you, hearing squealing brakes of a nearby car, or being grabbed by an attacker would all increase the rate and force of your heartbeat. The ANS consists of two main division (branches): the sympa- thetic nervous system and the parasympathetic nervous system. Most organs receive nerves from both of these divisions, an arrange- ment known as dual innervation. In general, one division stimulates the organ to increase its activity (excitation), and the other division decreases the organ’s activity (inhibition). For example, neurons of the sympathetic nervous system increase heart rate, and neurons of the parasympathetic nervous system slow it down. The sympathetic nerv- ous system promotes the fight-or-flight response, which prepares the body for emergency situations. By contrast, the parasympathetic nerv- ous system enhances rest-and-digest activities, which conserve and restore body energy during times of rest or digesting a meal. Although both the sympathetic and parasympathetic divisions are concerned with maintaining health, they do so in dramatically different ways. The ANS is also comprised of a third division known as the enteric nervous system (ENS). The ENS consists of millions of neurons in plexuses that extend most of the length of the gastrointestinal tract. Its operation is involuntary. Although the neurons of the ENS can function autonomously, they can also be regulated by the other divi- sions of the ANS. The ENS contains sensory neurons, interneurons, and motor neurons. Enteric sensory neurons monitor chemical changes within the GI tract as well as the stretching of its walls.
- Norman Calvey, Norton Williams(Authors)
- 2009(Publication Date)
- Wiley-Blackwell(Publisher)
13 Drugs and the Autonomic Nervous System Anatomy and physiology of the Autonomic Nervous System The Autonomic Nervous System consists of all efferent fi-bres which leave the CNS, apart from those which inner-vate skeletal muscles. Consequently, the system is widely distributed throughout the body. In all cases, the auto-nomic outflow from the brain stem and spinal cord makes synaptic connections with peripheral neurons, and these synapses normally occur in autonomic ganglia. The post-ganglionic fibres that originate from ganglion cells are usu-ally unmyelinated, and are responsible for the innervation of effector organs. The activity of the Autonomic Nervous System is in-voluntary and cannot be influenced by individual will or volition. Nevertheless, cellular function in many organs is influenced by autonomic activity, including contraction of smooth muscle in the heart and the uterus, secretion in the salivary, mucous and sweat glands, and endocrine secretion by the adrenal medulla. Afferent fibres from visceral structures are usually car-ried to the CNS by major autonomic nerves, such as the vagus and splanchnic nerves or the pelvic plexus. These pathways are concerned with the mediation of visceral sensation and the regulation of vasomotor and respira-tory reflexes. In addition, specialized afferent autonomic fibres arise from the baroreceptors and chemoreceptors in the carotid sinus and the aortic arch, and play an impor-tant part in the reflex control of heart rate, blood pressure and respiratory activity. Autonomic afferent fibres from blood vessels, which are concerned with the transmission of painful impulses, are usually carried by somatic nerves. Reflex activity in the Autonomic Nervous System may occur at a spinal level, and can be demonstrated in hu-mans after spinal cord transection. Vital functions such as respiration and the control of blood pressure are locally mediated via nuclei in the medulla oblongata.
- Liana Bolis, Julio Licinio, Stefano Govoni(Authors)
- 2002(Publication Date)
- CRC Press(Publisher)
425 13 The Function of the Autonomic Nervous System in Hypertension Guido Grassi and Giuseppe Mancia University of Milan-Bicocca and San Gerardo Hospital, Monza (Milan), Italy Time-honored studies of classic physiology have shown that autonomic neural factors play a fundamental role in the homeostatic control of the cardiovascular system by regulating organ perfusion and systemic blood pressure levels through changes in cardiac output and peripheral vascular resistance. Given the evidence that increased cardiac output and elevated peripheral vascular resis-tance represent the basic hemodynamic abnormalities of the hypertensive state, the hypothesis has been made that a dysfunction of the autonomic circulatory control might be the mechanism leading to the blood pressure elevation. Count-less studies have tested this hypothesis, providing convincing evidence that an imbalance in the autonomic modulation of the cardiovascular function with re-sultant sympathetic activation and parasympathetic inhibition does occur at the very beginning as well as at the later stages of the hypertensive state, thus con-tributing, in association with other etiological factors, to the development, main-tenance, and progression of the disease. The goal of this chapter is to examine the main autonomic alterations char-acterizing essential hypertension and to review the mechanisms through which these neurogenic derangements take place. The pivotal role of the autonomic dysfunction in the development of the metabolic, emorrheologic, and structural changes of the heart and arterial vessels observed in chronic hypertension as well as in the genesis of the hypertension-related cardiovascular risk will be finally highlighted. I. AUTONOMIC DYSFUNCTION IN EARLIER PHASES OF HYPERTENSION The early stages of hypertension are characterized by hyperkinetic circulation, i.e., increased cardiac output coupled with a resting tachycardia.
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