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The sympathetic nervous system's primary process is to stimulate the body's fight or flight response. It is, however, constantly active at a basic level to maintain homeostasis. [4] The sympathetic nervous system is described as being antagonistic to the parasympathetic nervous system. The latter stimulates the body to "feed and breed" and to ...
Structure. The cardiac plexus is divided into a superficial part, which lies in the concavity of the aortic arch, and a deep part, between the aortic arch and the trachea. The two parts are, however, closely connected. The sympathetic component of the cardiac plexus comes from cardiac nerves, which originate from the sympathetic trunk.
Parasympathetic innervation of the heart is partially controlled by the vagus nerve and is shared by the thoracic ganglia. Vagal and spinal ganglionic nerves mediate the lowering of the heart rate. The right vagus branch innervates the sinoatrial node. In healthy people, parasympathetic tone from these sources is well-matched to sympathetic tone.
At rest, heart rate is between 60 and 100 beats per minute. This is a result of the activity of two sets of nerves, one acting to slow down action potential production (these are parasympathetic nerves) and the other acting to speed up action potential production (sympathetic nerves). [18] Modulation of heart rate by ANS is carried by two types ...
The parasympathetic system is responsible for stimulation of "rest-and-digest" or "feed-and-breed" [4] activities that occur when the body is at rest, especially after eating, including sexual arousal, salivation, lacrimation (tears), urination, digestion, and defecation. Its action is described as being complementary to that of the sympathetic ...
Accelerator nerve. Accelerator nerves are cardiopulmonary splanchnic nerves that allow the sympathetic nervous system's stimulation of the heart. They originate from the ganglion cells of the superior, middle, and inferior cervical ganglion of the sympathetic trunk. [ 1] The accelerator nerves increase the heart rate.
Cardiopulmonary nerves are splanchnic nerves that are postsynaptic and sympathetic. They originate in cervical and upper thoracic ganglia and innervate the thoracic cavity. All major sympathetic cardiopulmonary nerves arise from the stellate ganglia and the caudal halves of the cervical sympathetic trunks below the level of the cricoid cartilage.
Rate dependence of the action potential is a fundamental property of cardiac cells and alterations can lead to severe cardiac diseases including cardiac arrhythmia and sometimes sudden death. [3] Action potential activity within the heart can be recorded to produce an electrocardiogram (ECG). This is a series of upward and downward spikes ...