The Nervous System and the Heart
Parasympathetic nervous system , division of the nervous system that primarily modulates visceral organs such as glands. The parasympathetic system is one of two antagonistic sets of nerves of the autonomic nervous system ; the other set comprises the sympathetic nervous system.
While providing important control of many tissues , the parasympathetic system is not crucial for the maintenance of life—unlike the sympathetic system, which activates the so-called fight-or-flight response. The nerve fibres of the parasympathetic nervous system are the cranial nerves , primarily the vagus nerve , and the lumbar spinal nerves. When stimulated, these nerves increase digestive secretions and reduce the heartbeat. The parasympathetic nervous system is organized in a manner similar to the sympathetic nervous system.
Its motor component consists of preganglionic and postganglionic neurons. The preganglionic neurons are located in specific cell groups also called nuclei in the brainstem or in the lateral horns of the spinal cord at sacral levels. Preganglionic axons emerging from the brainstem project to parasympathetic ganglia that are located in the head or near the heart , are embedded in the end organ itself e. Both pre- and postganglionic neurons secrete acetylcholine as a neurotransmitter , but, like sympathetic ganglion cells, they also contain other neuroactive chemical agents that function as cotransmitters.
Examples of secretory glands that are under parasympathetic control include the lacrimal gland , which supplies tears to the cornea of the eye ; the salivary glands , which produce saliva ; and the nasal mucous glands, which secrete mucus throughout the nasal air passages. You are using an outdated browser. Please upgrade your browser to improve your experience and security. Parasympathetic nervous system. Article Media. Info Print Cite. Submit Feedback. Thank you for your feedback.
Heart Nerve Anatomy
As a modern alternative, this book offers a scientific approach to the state-of-the-art knowledge about the complex relationship between these two organs. It does not deal with every aspect of the interrelationship between the heart and the nervous system, looking at these complex interactions mainly from the viewpoint of the heart and stressing the importance of knowledge in this domain for understanding cardiac function, physiology and disease.
However, the heart—brain relationship in stroke, an important topic to the neurologist, is not discussed. Chapter 1 describes the efferent and afferent nerve supply of the heart. It relies on studies in the pig, but also in humans. The authors of this chapter emphasize the importance of the intrinsic intracardiac neurones in the effective control of cardiac performance.
Gross and Microscopic Anatomy
Chapter 2 is written by the editor and concentrates on nervous circuitry controlling cardiac activity as part of emotional expression. First, a historical account of the neurobiology of emotion is given, briefly discussing the circuit of Papez and the limbic system. There is then a review of lesions, stimulation studies and neuroimaging in humans, concluding that different neuronal networks mediate specific emotions.
The role of the amygdala in fear and anger responses is stressed. An exhaustive review of fundamental research in the field of nervous circuitry for emotions and regulation of heart activity concludes that cardiovascular activity is regulated by a hierarchical system, in which the hypothalamus is functioning at the highest level of command.
Chapter 3 is devoted to the circadian organization of the autonomic nervous system. It describes the connections between the suprachiasmatic nucleus and the hypothalamus. The complex role of the neurotransmitters GABA and vasopressin is described nicely and the influence of the suprachiasmatic nucleus on the circadian rhythm of corticosterone secretion is also dealt with.
- Tom and Bella Series 1?
- The Bachelor (Vintage Classics);
- A prima (Portuguese Edition).
- parasympathetic nervous system | Definition & Function | Britannica.
Finally, some arguments are advanced for a direct influence of the suprachiasmatic nucleus on the autonomic nervous system, not limited to its influence on the pineal and the adrenal glands. Dysfunction of the brain may underlie cardiac disease. Chapter 4 discusses the cardiovascular effects of neuropathological conditions in experimental animals. The studies suggest that the insular cortex plays a role in the tonic regulation of autonomic responses; moreover, they show a right-hemispheric dominance for sympathetic effects.
The infralimbic cortex can also generate cardiovascular changes, mainly by inhibition of autonomic tone. The amygdala plays a major role in the integration of autonomic responses to emotional stimuli.
Chapter 5 reviews the clinical aspects of human neuropathology and cardiovascular regulation. The methods for assessing cardiovascular autonomic function are briefly described.
Then, different cardiovascular complications are discussed, e. ECG changes and cardiac arrhythmias in cerebral lesions, autonomic dysfunction in Parkinson's disease, multiple system atrophy, multiple sclerosis, migraine and peripheral neuropathies. Chapter 6 attempts to give a recent view on the hypothalamopituitary—adrenal system, stress and the heart. It is most likely that the hormones involved corticosteroids, CRH and melanocortins play a modulatory role in stress, both in the brain and at the heart level.
The cardiac nociceptive system is dealt with in Chapter 7. Angina pectoris pain is described as a visceral pain involving intrinsic cardiac neurones, mediastinal ganglia, the spinal cord and brain areas. The role of lactate, bradykinin, potassium, substance P and serotonin is reviewed. Only adenosine is released in substantial quantity during myocardial ischaemia and is able to excite cardiac nerves and provoke anginal chest pain.
Silent myocardial ischaemia and syndrome X are considered manifestations of an alteration of the cardiac nociceptive system. Chapter 8 is illuminating.
It stresses the differential representations of deep and superficial pain, as already hypothesized by Sir Thomas Lewis in Significant activation of upper cervical cord neurones occurs after noxious stimulation of the heart. The role of the nucleus of the solitary tract in central deep pain conduction remains controversial.
Chapter 9 is very short, discussing the neurophysiology of heart pain. Alas, it does not integrate the anatomical data from the previous chapter and gives a rather superficial survey of the subject.
- Fight or Flight: The Sympathetic Nervous System | Live Science!
- Venous Return?
- Happy Ever After: Number 4 in series (Bride Quartet);
- The Autonomic Nervous System and Heart Failure | Circulation Research.
- Comparative Anatomy and Histology: A Mouse and Human Atlas (Expert Consult).
He concludes that in patients with coronary heart disease, the central structures activated in angina pectoris, but not in silent ischemia, constitute the pathways involved in the perception of heart pain; consequently, the thalamus may have a central role in the perception of pain from the heart. Chapter 11 focuses on the central renin—angiotensin system in the regulation of body fluid and cardiovascular homeostasis. Synthesis of angiotensin II has indeed been demonstrated clearly in the brain.
The Autonomic Nervous System of the Heart | SpringerLink
The renin—angiotensin system produces pressor responses through activation of peripheral and central angiotensin II receptors. Furthermore, angiotensin II exerts tonic inhibitory control over baroreceptor reflex activity. The central renin—angiotensin system contributes to the development and maintenance of arterial hypertension in the spontaneously hypertensive rat. Chapter 12 reviews the role of mediators of inflammation in patients with coronary artery disease. It concludes that, besides the classical risk factors influencing atherogenesis, both a systemic and a local inflammatory response to either a systemic infection or an autoimmune reaction may induce atherosclerosis.
Reduction of the inflammatory response could lead to plaque stabilization. There is convincing evidence that depression and cardiovascular disease are linked in both ways.