The Autonomic Nervous System Can Be Challenging To Un 636584

The Autonomic Nervous System Can Be Challenging To Understand Because

The Autonomic Nervous System (ANS) can be challenging to understand because it is connected to virtually every body function in opposite ways. We are going to explore the physiology of the ANS in this discussion by looking at specific examples of how it works. For your first discussion post, describe how the parasympathetic nervous system influences one function in your body. For example, the parasympathetic nervous system causes decreased blood pressure. If you chose this body function, you would describe the physiology behind the decreased blood pressure.

How does it happen? What occurs in the heart/blood vessels? Which scenarios or external factors would cause the parasympathetic nervous system to activate this response? For your reply post, discuss the sympathetic nervous system’s influence on the function your peer chose. For example, if your classmate discussed the parasympathetic influences the diameter of your pupil, you need to describe how the sympathetic nervous system affects the diameter of your pupil.

Your post and reply should each be at least one paragraph long (about 4-5 sentences minimum). Try to use a body function that is unique from other examples already posted by other students. There are hundreds of options!

Paper For Above instruction

The autonomic nervous system (ANS) plays a crucial role in regulating involuntary functions within the human body, functioning through a delicate balance between its two divisions: the parasympathetic and sympathetic nervous systems. This paper explores how the parasympathetic nervous system influences a specific body function, namely the regulation of heart rate and blood pressure, and how the sympathetic nervous system subsequently affects this function. Understanding these interactions highlights the complexity of the ANS and its vital role in maintaining homeostasis, particularly in response to various internal and external stimuli.

Parasympathetic Influence on Blood Pressure

The parasympathetic nervous system primarily acts to conserve energy and promote relaxation within the body. When activated, it exerts its effects predominantly through the vagus nerve (cranial nerve X), which innervates the heart. Specifically, parasympathetic stimulation releases the neurotransmitter acetylcholine (ACh) at the sinoatrial (SA) node of the heart, resulting in decreased heart rate through the activation of muscarinic receptors. A lowered heart rate reduces cardiac output, which is the amount of blood ejected by the heart per minute. Since blood pressure is a product of cardiac output and peripheral resistance, a decrease in cardiac output subsequently leads to lower blood pressure. This response is typically triggered in scenarios involving rest, relaxation, or the body's attempt to counteract stress or high blood pressure conditions (Guyton & Hall, 2016).

Physiology Behind Decreased Blood Pressure

The decrease in blood pressure during parasympathetic activation involves several physiological processes. When the vagus nerve stimulates the heart, it causes the nodes in the heart's conduction system to slow their pace, particularly affecting the SA node. As a result, the impulse frequency diminishes, leading to a deceleration of the heart rate (Bradycardia). Additionally, parasympathetic activation induces vasodilation of blood vessels, especially in the gastrointestinal and coronary circulation, further decreasing peripheral resistance. The combined effects of decreased cardiac output and vasodilation work synergistically to lower blood pressure, restoring it within normal ranges after instances of hypertension or sympathetic overactivity (Berntson et al., 2014).

External Factors Activating Parasympathetic Response

External factors that activate the parasympathetic nervous system include states of relaxation, such as during sleep, meditation, or deep breathing exercises. Additionally, consumption of a meal rich in carbohydrates or calories can stimulate parasympathetic activity as part of the "rest and digest" response. Psychologically, feelings of calmness, safety, or well-being also trigger parasympathetic activation, counteracting stress responses mediated by the sympathetic nervous system. This activation helps to restore physiological balance following sympathetic dominance during stressful situations like anxiety or physical exertion (Thayer & Lane, 2007).

Sympathetic Influence on Blood Pressure and Heart Rate

The sympathetic nervous system exerts opposing effects to the parasympathetic division, especially during stress or arousal. When activated, it releases norepinephrine onto adrenergic receptors in the heart, leading to increased heart rate (tachycardia) and enhanced contractility. This results in increased cardiac output, which elevates blood pressure to facilitate blood flow to vital organs and muscles. Furthermore, the sympathetic nervous system promotes vasoconstriction of peripheral arteries via alpha-adrenergic receptors, increasing peripheral resistance. These combined effects prepare the body to respond to acute stressors, such as physical activity or danger, by increasing blood flow and oxygen delivery (Levy et al., 2011).

Conclusion

The balance between the parasympathetic and sympathetic nervous systems is essential for maintaining cardiovascular stability. The parasympathetic system decreases heart rate and blood pressure during rest, while the sympathetic system increases these parameters during activity or stress, illustrating their opposing yet complementary roles. Disruption in this balance can lead to pathological conditions such as hypertension or cardiac arrhythmias. Understanding how these divisions of the ANS regulate critical functions like blood pressure underscores their importance in overall health and stress adaptation (Benarroch, 2013).

References

• Benarroch, E. E. (2013). Autonomic nervous system: Basic anatomy and clinical correlates. Continuing Education in Neurology, 19(2), 1-10.
• Brady, E. C., et al. (2014). The role of the vagus nerve in heart rate regulation. American Journal of Physiology-Heart and Circulatory Physiology, 306(9), H1284-H1292.
• Guyton, A. C., & Hall, J. E. (2016). Textbook of Medical Physiology (13th ed.). Elsevier.
• Levy, M., et al. (2011). Sympathetic nervous system activity and cardiovascular disease. American Journal of Hypertension, 24(1), 41-47.
• Thayer, J. F., & Lane, R. D. (2007). The role of vagal function in the risk for cardiovascular disease and mortality. Biological Psychology, 74(2), 224-242.