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StomachGastric Secretions, Motility, Digestion and Vomiting
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The extrinsic nerve supply to the stomach is from the sympathetic (via the coeliac plexus) and the parasympathetic (via the vagus) nervous systems. Sympathetic innervation inhibits motility, whereas parasympathetic activity stimulates motility.
Composition of Resting Pressure
Published in Han C. Kuijpers, Colorectal Physiology: Fecal Incontinence, 2019
Internal anal sphincter (IAS) smooth muscle cells generate electrical slow waves resulting in a rhythmic mechanical activity with a frequency of about 20 cpm and an amplitude of 5 to 10 mmHg.1,6,7 When electrical slow waves disappear the rhythmic pressure oscillation ceases and anal pressure decreases.1 Rhythmic contractions can be observed in muscle strips excised from the IAS; this spontaneous mechanical activity is myogenic in origin since it is not affected by nerve blocking agents.8 The extrinsic sympathetic innervation seems to have an important excitatory effect on the tonic activity. High spinal anesthesia, blocking the sympathetic outflow from the thoracolumbar region, causes a 50% drop in sphincter pressure.9 Efferent stimulation of the hypogastric nerve near to the inferior mesenteric artery induces contraction of the IAS.10 The parasympathetic innervation of the IAS comes from the sacral outflow via the pelvic plexuses. Its importance is not yet determined. The intrinsic enteric nervous system is responsible for IAS relaxation.8,11
General plastic
Published in Tor Wo Chiu, Stone’s Plastic Surgery Facts, 2018
Sympathetic innervation of sweat glands can be re-established and the resultant sweating activity tends to parallel the recipient site (e.g. emotion vs. temperature) rather than the donor site.
Cardiac arrhythmias six months following traumatic spinal cord injury
Published in The Journal of Spinal Cord Medicine, 2022
Shane J.T. Balthazaar, Morten Sengeløv, Kim Bartholdy, Lasse Malmqvist, Martin Ballegaard, Birgitte Hansen, Jesper Hastrup Svendsen, Anders Kruse, Karen-Lise Welling, Andrei V. Krassioukov, Fin Biering-Sørensen, Tor Biering-Sørensen
In conclusion, it is important for clinicians to note that many individuals with cervical SCI experience arrhythmias such as bradycardia, SA node arrest, SVT, and more rarely cardiac arrest, within the first month after SCI. As previously observed, no arrhythmias were seen in participants with thoracic SCI, with the exception of SA node arrests and limited bradycardia. However, it is worth noting by Month 6 there were no significant differences in the arrhythmogenic occurrences between cervical and thoracic groups that were initially revealed in the first month after SCI. A large and more in-depth study may provide insight about how the heart adapts to diminished sympathetic innervation and the characteristics of cardiovascular instability for each injury level resulting from an acute traumatic SCI.
Quantitative Evaluation of Pupil Responses in Patients with Prolactinomas Being Treated with Dopamine Agonists
Published in Neuro-Ophthalmology, 2022
Sedat Ava, Leyla Hazar, Mine Karahan, Seyfettin Erdem, Mehmet Emin Dursun, Zafer Pekkolay, Uğur Keklikçi
Normally, pupil responses are controlled by the autonomic nervous system. In the function of the PNS, acetylcholine as a neurotransmitter causes miosis in the pupil by stimulating the muscarinic receptors in the circular muscles of the iris, while in the function of the SNS, mydriasis occurs in the pupil when noradrenaline as a neurotransmitter stimulates the α-adrenergic receptors in the radial muscles of the iris.16 Sympathetic innervation is provided by the ipsilateral hypothalamus, while parasympathetic innervation is provided by the Edinger–Westphal nucleus located in the upper midbrain.17 Pupil responses normally reflect a balance between the SNS and PNS (between noradrenaline and acetylcholine) in the autonomic nervous system. In static pupillary function tests, PDs in dark environments show SNS function, whereas PDs in light environments show PNS function. Conversely, while the dilatation status (velocity and amplitude) of the pupil in dynamic tests indicates SNS function, the contraction status of the pupil (velocity and amplitude) indicates PNS function.
Emerging therapeutic targets for cardiac hypertrophy
Published in Expert Opinion on Therapeutic Targets, 2022
Alexander J. Winkle, Drew M. Nassal, Rebecca Shaheen, Evelyn Thomas, Shivangi Mohta, Daniel Gratz, Seth H. Weinberg, Thomas J. Hund
As with biomechanical stimuli, the heart has a myriad of signaling pathways for increasing heart rate and/or contractility in response to acute, physiological neurohumoral stimuli without changing structure. Neurohumoral stimulation includes sympathetic innervation, and many hormonal factors, such as those in the renin-angiotensin-aldosterone system (RAAS), vasopressin, and atrial natriuretic peptide (ANP). Sympathetic innervation is able to regulate heart rate and contractility [15] and can activate pathways such as those initiated by β-adrenergic receptors to further regulate inotropy [16]. RAAS is a homeostatic regulator that impacts many vital systems, but is especially important in the heart where angiotensin II regulates contractility, as well as arterial tension (a major contributor to afterload) [17]. In the event that a stimulus is not resolved (chronic time course) and/or is of a specific pathological nature, the heart must engage additional systems to increase cardiac output. Increasing heart rate is an important component of the response to acute stress but is not sustainable or sufficient in the case of chronic/pathological stress. Without further recourse, hypertrophy may be viewed as the heart’s attempt to increase stroke volume (and thereby output), by either increasing ventricular chamber volume and/or the fraction of blood volume ejected with each contraction.