Autonomic Regulation of the Cardiovascular System - Essay Example

?Autonomic Regulation of the Cardiovascular System Autonomic Regulation of the Cardiovascular System [Institute’s Autonomic Regulation of the cardiovascular system The autonomic nervous system is a component of the peripheral nervous system, which controls involuntary actions, such as digestion and breathing. Furthermore, this system holds a prominent role in controlling a variety of cardiovascular systems, which include the control of blood pressure and heart rate. Additionally, the autonomic nervous system is essential, because it delivers life-giving oxygen and a variety of other nutrients to the body (American Physiological Society, n.p, n.d). The different parts of the autonomic nervous system aim to control the cardiovascular system in a variety of different ways. Since the autonomic nervous system (ANS) is divided into sympathetic and parasympathetic nervous system, these two divisions perform different functions for the heart. The sympathetic nervous system functions unconsciously, without any thought given. In this case, the SNS will be responsible for increasing the heart rate or increasing heart output under certain circumstances, without any intervention on the part of the individual. The parasympathetic nervous system aims to relax the muscles generally, which means that it will slow down the heart rate, according to a variety of circumstances (Olivera, n.p, 2006). However, the different ways that the cardiovascular system is controlled, through effective autonomic regulation needs discussion. It involves the use of a range of different bodily muscles, arteries and receptors among others to monitor the cardiovascular system in a variety of different circumstances. While it has been stated above that the sympathetic and parasympathetic divisions of the autonomic nervous system (ANS) seek to control the flow of blood, the way for doing that is through blood volume and arterial pressure. This tends to be maintained by the stretch receptors in the heart and arteries. Nerve traffic is received from these receptors, which trigger the working of the divisions of the ANS. The ANS nerves adjust the heart rate accordingly, the arterial resistance, as well as the venous tone. The cardiac output, along with systemic vascular resistance (SVR) is monitored in such a way that the arterial pressure is controlled (Rhoades, Bell, pp.311, 1995). The autonomic nervous system is definitely connected to the brain and the spinal cord for the maintenance of its functions. The cardiovascular system will be controlled, through a proper process, which tends to involve the firing of postganglionic parasympathetic and sympathetic neurons. This firing occurs, because of the pre-ganglionic neurons present in the brain (for parasympathetic nervous system) and spinal cord (for both the divisions of the ANS). Particular neurons present in the cardiovascular system send a message to these neurons in the brain and the spinal cord, and along with a range of other environmental factors, the cardiovascular system adjusts according to the brain signals (Rhoades, Bell, pp.311-312, 1995). However, now since the paper has established the grounding of the working of the autonomic system to influence the cardiovascular system, it is essential to go into detail about the entire process. There cannot be an enough emphasis on the idea that the cardiovascular system requires the regulation of precise reflex actions, so that the blood supply, which contains oxygen that is necessary for any human body can be supplied to different body tissues, under different types of circumstances. This homeostatic process considers a variety of mechanical (barosensory) information about pressure in the arterial system, and chemical (chemosensory) information about the amount of oxygen and carbon-dioxide present in the blood. As stated above, the sympathetic and parasympathetic activity tends to be verified upon the information, provided by these sensors. The receptors present in the cardiovascular system (mentioned above) tend to include the mechanoreceptors (also called baro-receptors), which are present in the heart and major blood vessels. Additionally, the chemo-receptors are located in the different carotid bodies. These bodies are specialized organs, which are located at the division of the common carotid arteries. In fact, some chemosensory tissue is also present in the aorta. The baroreceptors are activated through the nerve endings, because of the deformation of the vessel walls, which are elastic, as these vessel walls expand and contract. The chemo-receptors are activated, when the oxygen and carbon-dioxide present in the blood puts oxygen. These systems are afferent and produce a message, which is transferred to the nucleus of the solitary tract through the vagus nerve. The information is then transmitted to the hypothalamus and the particular brainstem tegmental nuclei. When the information that occurs as a result of arterial pressure and blood gas is relayed, the activity of the specific visceral motor pathways, and of certain cardiac muscles and other specialized structure is also changed. A simple example will simplify the matter, and make it easier to understand. A rise in blood pressure will tend to activate the baro-receptors. This will inhibit the tonic activity of the sympathetic neurons that are located in the spinal cord. Simultaneously, this pressure will also result in a rise of the parasympathetic neurons present in the dorsal motor nucleus of the vagus, which will directly influence the heart rate. One should also understand that the chemo-receptors will have some influence, but not as much as baro-receptors in this particular circumstance. As a result of the preganglionic neurons adjusting, there is stimulation to the noradrenergic effects of postganglionic system. The cardiac musculature is decreased. When the cholinergic parasympathetic innervation of the heart decreases, the ventricular conduction system also slows down. When these sympathetic and parasympathetic activity occurs, which results in the decrease of the heart rate and the effectiveness of the artiral and ventricular mycordial contraction, the blood pressure is effectively reduced by the autonomic nervous system (Purves D, Augustine GJ, Fitzpatrick D, et al, n.p, 2001). However, in times of a drop in blood pressure, the autonomic nervous system will react in a different way. The blood pressure may drop, for example from blood loss. The parasympathetic activity will be decreased in such a circumstance, and the sympathetic activity will be increased. When the norepinephrine is released from the postganglionic neurons of the sympathetic division, this will result in the increasing the rat of cardiac peacemaker activity. It will also lead to a rise in cardiac contractility, and will make sure that there is an increase in the release of catecholamines, located in the adrenal medulla. These catecholamines tend to be aggravate the sympathetic effects, when there is an urgent/emergency situation. The norepinephrinem, which is released from the sympathetic ganglion cells also, has another function. It acts on the muscles of the arterioles, so that the tone of the peripheral muscles will rise. This will include areas of the skin, the subcutaneous tissues, as well as muscles. The norepinephrinem drives away the blood and oxygen from these areas and turns them into the direction of those organs, which urgently need oxygenated blood, which will include brain, kidneys and hearts, when a circumstance of blood loss occurs. If this action is not done, or the reflex sympathetic system fails to work, and does not raise the blood pressure, then the individual can experience a major breakdown in the function of the organs ((Purves D, Augustine GJ, Fitzpatrick D, et al, n.p, 2001). The autonomic regulation of the cardiovascular system has a driving response, as well as a conditioned response. The driving response can be best explained by an example. For instance, when a diver dives into the water, and his/her face is inside the water, the heart rate slows down (parasympathetic division) and the peripheral vasoconstriction also decreases (sympathetic division). The chemo-receptor also has a role, which reinforces the driving response, because the breath is held during the drive, thus decreasing the arterial pressure and pH level, and increasing the Pco2. The cardiac output is distributed to the organs, so that the brain activity does not stop. The heart-brain circuit makes use of the oxygenated blood, which is used by the skeletal muscles in normal circumstances. As soon as the driver comes out of water, and breathes into the air, the heart rate and cardiac output increase. Furthermore, it has been proved that the rise and fall in blood pressure have also been both classically and operant conditioned by humans, in response to certain circumstances. Hence, the autonomic regulation of the cardiovascular system is also conditioned. The fight-or-flight response and the relax-and-wellbeing response are one of the primary examples of this type of conditioning, under certain situations (Rhoades, Bell, pp. 317, 1995). In conclusion, the autonomic nervous system is organized in the way of a reflex arch, which includes a variety of organs and receptors playing part. It contains visceral receptors, the central nervous system, the effector organs and an efferent and afferent pathway. Information is received from the systemic baro-receptors, chemo-receptors, and cardiopulmonary low-pressure receptors and relayed to a variety of other receptors, and releasing certain information, which is necessary for the effective control of the cardiovascular system. Hence, it can be ascertained that the autonomic nervous system does effectively control the cardiovascular system, by having effects on the heart rate, myocardial contractility, atrioventricular velocity, and various other cardiac electrophysiological parameters. This will include the refractory periods, automaticity, ? brillation-de? brillation thresholds and various activities after potentials (Virtanen, pp.14, 2007). References American Physiological Society > Autonomic Regulation of Cardiovascular Function in Health and Disease. n.d. American Physiological Society > American Physiological Society. Retrieved July 12, 2012, from http://www.the-aps.org/mm/hp/Audiences/Public-Press/For-the-Press/releases/12/23.html Purves D, Augustine GJ, Fitzpatrick D. 2001. Autonomic Regulation of Cardiovascular Function - Neuroscience - NCBI Bookshelf. National Center for Biotechnology Information. Retrieved July 12, 2012, from http://www.ncbi.nlm.nih.gov/books/NBK Olvera, C. 2006. The Autonomic Nervous System: The Regulatory Structure of the Body - Yahoo! Voices - voices.yahoo.com. Yahoo! Voices - voices.yahoo.com. Retrieved July 12, 2012, from http://voices.yahoo.com/the-autonomic-nervous-system-regulatory-structure-32459.html Rhoades, R. A., & Bell, D. R. 1995. Medical Physiology: Principles for Clinical Medicine - Rodney A. Rhoades, David R. Bell - Google Books. Google Books. Retrieved July 12, 2012, from http://books.google.com.pk/books?id=1kGcFOKCUzkC&pg=PA311&dq=autonomic+regulation+of+the+cardiovascular+system&hl=en&sa=X&ei=e2X-T-vvEYjdsgb6-tzOBQ&ved=0CDMQ6AEwAQ#v=onepag Virtanen, R. 2001. Association Between Autonomic Regulation and Cardiovascular Risk Factors in Middle-Aged Subjects. National Public Health Institute. Retrieved July 12, 2012, from www.ktl.fi/attachments/suomi/julkaisut/j Read More