Neuromuscular Physiology
Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan in Strength and Conditioning in Sports, 2023
Fundamentally, the nervous system is a network of nerve cells and its supporting connective tissue. The nervous system can be evaluated in two basic ways: based on its anatomical characteristics or based on functional characteristics. Anatomically, there are two parts: the central nervous system (CNS), consisting of the brain and spinal cord, and the peripheral nervous system (PNS) consisting of 43 pairs of peripheral nerves (12 cranial and 31 spinal). The function of the CNS is either autonomic or somatic. The autonomic nervous system is responsible for involuntary actions involved in “housekeeping” and homeostasis maintenance, such as peristalsis and regulation of heart rate and blood pressure. The somatic system innervates skin, muscles, joints and provides the CNS with environmental information. The primary function of the somatic nervous system is working in an integrative fashion with the muscular system, thus forming the neuromuscular system. The neuromuscular nervous system’s primary function is in producing voluntary movement and reflex arcs.
The Blood Vessel, Brain, and Immune System Connections
Mark C Houston in The Truth About Heart Disease, 2023
You have heard about the “flight or fight reaction” or the “rest and relax reaction”. These opposing reactions are related to the three distinct and major parts of the autonomic nervous system (ANS), called the “sympathetic nervous system” (SNS), the “parasympathetic nervous system” (PNS), and the “enteric nervous system” (ENS) (related to our gut) (Figure 14.1). The SNS and PNS systems oppose each other to give us a balance that is important to regulate the brain and entire nervous system with the arteries, heart, endocrine system, gut, and immune system. This internal communication is very important. If any of the SNS, PNS, or ENS predominates, it can lead to many cardiovascular problems and diseases. The autonomic nervous system is a component of the peripheral nervous system that regulates involuntary processes of our physiology and daily functions, including heart rate, blood pressure, respiration, digestion, and sexual arousal (Table 14.1).
Anatomy and Physiology of the Autonomic Nervous System
Kenneth J. Broadley in Autonomic Pharmacology, 2017
The autonomic nervous system controls the internal involuntary functions of the body. These are the functions concerned with the maintenance of a constant internal environment, that is, homeostasis. The major activities and systems under the control of the autonomic nervous system include digestion, the cardiovascular system (such as the blood pressure), blood chemistry, breathing and body temperature. Control of these functions is below the level of consciousness, hence the term involuntary nervous system. The major cellular structures that are innervated by the autonomic nervous system are smooth muscle, cardiac muscle, glandular tissue and adipocytes (fat cells). Thus, the digestion of food occurs by the secretion of digestive enzymes from the intestinal glands of the intestinal mucosa and rhythmic contraction and relaxation of circular and longitudinal smooth muscle arranged in the intestinal wall propels the chyme along and chums it up to aid digestion. We are unaware of this process and have little conscious control over it. The autonomic nervous system modulates this digestive activity by either speeding or attenuating.
The Contribution of Atypical Sensory Processing to Executive Dysfunctions, Anxiety and Quality of Life of Children with ADHD
Published in Occupational Therapy in Mental Health, 2023
Batya Engel-Yeger, Maayan Mevorach Shimoni
Our daily environments provide us with an ongoing sensory information. The enormous information from all sensory systems is integrated, processed and modulated in the central nervous system (CNS). While most people show normal sensory processing, about 5–15% show atypical sensory processing (ASP) (Engel-Yeger, 2010; Román‐Oyola & Reynolds, 2013), expressed in hyper or hypo sensitivity to sensory input. ASP results from an imbalance between excitation and inhibition of sensory input in the CNS. According to Dunn’s model (Dunn, 1999), the interaction between the neurological threshold to sensory input (that ranges from low to high) and the individual’s behavioral strategy to deal with this threshold (passive or active) yields four sensory processing patterns: (1) sensory seekers – individuals with hyposensitivity who actively seek for activities and environments with intense sensory input (such as extreme sport; spicy food; parties), to cope with their high threshold. (2) low registration – individuals with hyposensitivity who apply a passive strategy (do not actively seek for intense sensations), and thus miss information or seem withdrawn. (3) sensory avoiders – individuals with hypersensitivity who actively limit their exposure to stimuli or activities to avoid the uncomfortable sensations (for example, wear long sleeves in the summer) (4) sensory sensitive individuals who use a passive strategy – although they experience discomfort with sensations, they do not actively eliminate their exposure to the disturbing stimuli.
Body fat and muscle in relation to heart rate variability in young-to-middle age men: a cross sectional study
Published in Annals of Human Biology, 2023
Selma Cvijetic, Jelena Macan, Dario Boschiero, Jasminka Z. Ilich
The autonomic nervous system (ANS) regulates a number of physiological processes and its actions are largely involuntary. It is functionally divided into the sympathetic nervous system (SNS) and parasympathetic nervous system (PNS), acting opposingly to complement each other (Svorc 2018). The SNS and PNS release neurotransmitters that bind to the appropriate receptors on the cells, resulting in different biological effects (McCorry 2007). Both SNS and PNS regulate heart rate variability (HRV – the variance in time between heart beats), sending opposing signals for faster or slower beats, respectively (Svorc 2018). Therefore, HRV is commonly used as an indicator of ANS activity with sympathetic and parasympathetic activity modifying the heart rate intervals at distinct frequencies and in opposing manners (Tokić 2016; Shaffer and Ginsberg 2017). The HRV refers to the heart’s capability to react to various physiological and environmental influences, with lower HRV generally indicating a poorer autonomic function and reduced capacity of the body to deal with different stressors (Tracey 2007; Shaffer and Ginsberg 2017; Kim et al. 2018).
Communication between the gut microbiota and peripheral nervous system in health and chronic disease
Published in Gut Microbes, 2022
Tyler M. Cook, Virginie Mansuy-Aubert
Neuronal transmission allows for nearly instantaneous processing of sensory input or generation of motor output. This rapid signaling of peripheral neurons in the gut is critical for homeostatic mechanisms such as GI motility, secretion, and even immune response modulation.39 The peripheral nervous system (PNS) consists of vagal and spinal sensory (afferent) neurons, autonomic motor (efferent) neurons, and enteric neurons (Figure 2). Afferent neurons send information from the periphery to the brain or spinal cord, while efferent neurons project out from the central nervous system (CNS) to peripheral organs. Classifying by anatomical distribution, the twelve cranial nerves project from the brain/brainstem and spinal nerves from the spinal cord. The autonomic system is divided into sympathetic, parasympathetic, and enteric nervous systems (ENS).