The Stomach (ST)
Narda G. Robinson in Interactive Medical Acupuncture Anatomy, 2016
Carotid body: Supplied by the carotid sinus nerve (CN IX). This cluster of chemoreceptors and supporting cells located at the carotid artery bifurcation monitors arterial oxygen and carbon dioxide levels. It senses changes in pH and temperature as well. In response to low blood oxygen levels, the chemoreceptors trigger an increase in the rate and depth of respiration, heart rate, and blood pressure. Feedback about blood chemistry travels to cardiorespiratory centers in the medulla oblongata (brainstem) through CN IX afferent branches. The medullary cardiorespiratory centers integrate carotid body messages with signals from aortic body chemoreceptors through vagal nerve afferents. Centers such as the rostral ventrolateral medulla (RVLM) coordinate changes in respiration and blood pressure as a result of the converging input from somatic and autonomic fibers.
Circulatory controls
Burt B. Hamrell in Cardiovascular Physiology, 2018
Less stretch of the carotid sinus leads to more sympathetic nerve activity—potentially confusing until you consider the following. All the cardiovascular control systems are operating all the time. They do not turn on when needed and then turn off. The carotid sinus wall is always stretched by arterial blood pressure and there are continuous carotid sinus nerve action potentials, the frequency of which increase with more stretch of the sinus and decrease with less stretch. Carotid sinus nerve action potentials act to inhibit the sympathetic nerve output from the medullary cardiovascular centers. When blood pressure falls and there is less stretch of the carotid sinus wall and less carotid sinus nerve action potentials to the medulla there is less suppression of the sympathetic nerve output and increased action potentials in the sympathetic nerves to the heart and blood vessels. The converse is true of the parasympathetic system. Basal carotid sinus nerve activity maintains activation of parasympathetic nerve cell bodies in the medulla and reduced carotid sinus nerve activity results in less activation and less parasympathetic nerve activity.
Control of breathing
Andrew M. Luks, Philip N. Ainslie, Justin S. Lawley, Robert C. Roach, Tatum S. Simonson in Ward, Milledge and West's High Altitude Medicine and Physiology, 2021
Extensive evidence indicates that hypoxia-inducible factors mediate adaptive responses to hypoxemia and are sensed by the carotid body (see Figure 9.3: reviewed in: Semenza and Prabhakar 2018). Kline et al. (2002) studied the importance of the hypoxia-inducible factor-1α (HIF-1α) in the changes in HVR with acclimatization. In this study, heterozygous transgenic mice, with one chromosome for HIF-1α knocked out (homozygous knock-out mice die in utero), were compared with wild-type mice. Whereas there was no difference in response to acute hypoxia, the effect of chronic hypoxia (three days at 0.4 atm) was different. The wild-type mice showed the expected increase in HVR, while the knock-out mice showed reduced HVR. They showed this result both in terms of , especially respiratory rate, and in carotid sinus nerve activity, indicating it was an effect in the carotid body as opposed to a purely central effect.
The carotid body and associated tumors: updated review with clinical/surgical significance
Published in British Journal of Neurosurgery, 2019
Nasir Butt, Woong Kee Baek, Stefan Lachkar, Joe Iwanaga, Asma Mian, Christa Blaak, Sameer Shah, Christoph Griessenauer, R. Shane Tubbs, Marios Loukas
However, this discovery has often been credited to his mentor Albrecht von Haller, who was known for his interest in the role of the nervous system on the physiology of the heart and blood vessels.2–4 For decades after its description, the function of the carotid body remained a mystery. According to Zappata and Larraín,5 its role as a sensory receptor for chemical changes in the blood was largely based on histological studies by de Castro in 1926.5 By establishing a histological description of the carotid body, de Castro was able to propose its role as a sensory organ, “tasting blood,” before his work was disrupted by the Spanish Civil War.6 At about the same time, the Heymans, a father and son team, were researching the physiological significance of these structures using cross-circulation experiments on dogs.6 These authors ran an experiment in which they severed the connection of the carotid sinus nerve. They then injected potassium cyanide into the carotid arteries and found that severe hyperventilation followed when the connection was intact. However, when the nerve connection to the carotid body was cut, there was no corresponding increase in respiration.6 For their role in discovering the function of the carotid body, the Heymans received the Nobel Prize in 1938.
Strong stimulation triggers full fusion exocytosis and very slow endocytosis of the small dense core granules in carotid glomus cells
Published in Journal of Neurogenetics, 2018
Amy Tse, Andy K. Lee, Noriko Takahashi, Alex Gong, Haruo Kasai, Frederick W. Tse
Our results show that with a large [Ca2+]i rise, exocytosis of glomus SDCGs can shift from the kiss-and-run mode to full fusion, resulting in a more complete release of transmitters. During a severe hypoxic challenge, the cytosolic [Ca2+] of glomus cells (averaged from the entire cell) increased to ∼1 to 1.6 μM (Buckler & Vaughan-Jones, 1994). Since the hypoxia-evoked [Ca2+]i rise is mediated via activation of VGCCs, it is conceivable that the Ca2+ entry via VGCCs generates a spatial Ca2+ gradient, such that the secretory granules near the vicinity of VGCCs are exposed to a local Ca2+ concentration which is higher than the cytosolic average. In chromaffin cells, the local Ca2+ near the VGCCs was estimated to be 10–100 μM (Garcia, Garcia-de-Diego, Gandia, Borges, & Garcia-Sancho, 2006). It is not clear whether secretory granules in glomus cells are tightly coupled to VGCCs. Nevertheless, it is conceivable that some glomus granules near the VGCCs may be exposed to [Ca2+] in the range of 10 μM and thus undergo full fusion for a more complete release of transmitters. This would result in a more robust stimulation of the carotid sinus nerve and the triggering of the respiratory and cardiovascular reflexes.
Does surgical technique influence the postoperative hemodynamic disturbances and neurological outcomes in carotid endarterectomy?
Published in Acta Chirurgica Belgica, 2019
Serkan Burç Deşer, Mustafa Kemal Demirag, Fersat Kolbakir
Carotid endarterectomy (CEA) is a safe and an effective surgical technique which has been used for the treatment of severe extracranial carotid artery stenosis to reduce the risk of stroke for symptomatic and asymptomatic patients under the age of 75 with ≥ 70% stenosis in line with NASCET criteria and with a 3% perioperative risk [1–7]. Surgical options comprise conventional (C-CEA) and eversion carotid endarterectomy (E-CEA) techniques. C-CEA performed through a longitudinal arteriotomy of the internal carotid artery (ICA) followed by primary closure, autologous vein or prosthetic patch angioplasty. Longitudinal arteriotomy minimizes disruption of the carotid sinus nerve fibers during C-CEA [6]. E-CEA which is obliquely transection of the internal carotid artery (ICA) at the carotid bifurcation was initially reported by DeBakey et al [8], later described by Etheredge [9] and improved E-CEA by Raithel [10]. Major stroke, mortality rate, postoperative cranial nerve injury, cerebral ischemia, postoperative blood pressure alterations and early thrombosis or restenosis are main complications of CEA [5,11]. Transaction of the carotid sinus nerve fibers during E-CEA may leads to loss of baroreceptor responses which lead to increase in peripheral vascular resistance, blood pressure and heart rate [12–14]. Consequently, increase in the sympathetic activity may lead to uncontrolled hypertension, heart failure, myocardial infarction and stroke [14]. E-CEA has found to be associated with the loss of the baroreceptor reflex and postoperative hypertension in previously published studies [15]. This study aimed to compare the postoperative hemodynamic changes, postoperative stroke rate and complications between E-CEA and C-CEA.
Related Knowledge Centers
- Baroreceptor
- Blood Pressure
- Carotid Body
- Carotid Sinus
- Common Carotid Artery
- Glossopharyngeal Nerve
- Internal Carotid Artery
- Partial Pressure
- Vagus Nerve
- Homeostasis