Sympathetic and Parasympathetic Systems

Introduction

The autonomic nervous system (ANS) plays a critical function in homeostasis maintenance. Additionally, the system regulates blood pressure, contraction of the urinary bladder, body temperature, vision, and gastrointestinal response to nutrients. ANS is divided into two functional divisions known as sympathetic and parasympathetic systems that provide some input to specific tissues, thereby inhibiting or enhancing tissue activities (McCorry, 2007). Sympathetic and parasympathetic nervous systems perform opposing functions in tissue in that when one is increasing the other one is decreasing in a fast, precise, and controlled manner. Each system exercises dominance during certain conditions—for instance, sympathetic functions in emergencies such as fight or flight and physical activities (McCorry, 2007). The overall effect of this system is to prepare the body for an expected physical activity. Therefore, blood flow that is rich in nutrients and oxygen increases and targets specific skeletal muscles. The parasympathetic system, on the other hand, is predominant when the body is at rest. Therefore, it stores and conserves energy and regulates an individual’s basic functions, including digestion. This essay will discuss parasympathetic and sympathetic nerve terminals and ganglia and their sensory receptors, and the physiological factors in the heart muscles and smooth muscles.

Sympathetic Nerve Terminals

The functional units for the system are preganglionic and postganglionic neurons. The former originates from cell bodies located in the lumbar and thoracic regions of the spinal cord and the axons that go all the way to cell bodies of postganglionic neurons clustered in the ganglia (McCorry, 2007). The sympathetic nervous system is active when the body is responding to a threat. They activate divergent actions on different organs to achieve a common purpose. The respiratory, skeletal, and cardiovascular systems are activated together. The body starts sweating to keep off excess heat that is generated during fight and freight response. Besides, there is a shut down in the digestive system since blood delivers oxygen to the muscles. The responses are controlled by the sympathetic system that is controlled by the central nervous system. The CNS activates different structures to coordinate systemic change, increasing heartbeat and breathing rate.

Additionally, the actions of smooth muscles in the digestive system decrease due to the integrated response. The sympathetic nervous system had different effects on the heart. For instance, it controls heartbeat by stimulating the sinoatrial node situated in the posterior wall of the right atrium and maintains a rhythm of 60 to 100 heartbeats per minute Gordan et al., 2015). Additionally, it increases the heart’s contractility by enabling the organ to produce the required force during contraction. Lastly, it enhances the conduction of electric signals in the heart.

Parasympathetic Nervous System

The system is responsible for regulating body functions in an unconscious state, such as digestion, defecation, digestion, and urination. The preganglionic neurons that make up the system are situated at the homologous nucleus of cranial nerves. The nerves control smooth muscles because they can contract involuntarily Gordan et al., 2015). The targets of the fibers are terminal ganglia that are located in the target organs. Additionally, it decreases the rate of the heartbeat when the body is at rest. It also acts on smooth muscles to aid swallowing, and after that, it stimulated smooth muscles in the stomach so that food can be ingested Gordan et al., 2015). Besides, intestinal secretions are produced through the parasympathetic system’s action to facilitate the absorption of nutrients. Endocrine and exocrine secretions in the pancreas are produced so that food can be chemically broken down. Insulin is produced from the islets of the pancreas to ensure that nutrients are stored in the body.

References

Gordan, R., Gwathmey, J. K., & Xie, L. H. (2015). Autonomic and endocrine control of cardiovascular function. World Journal of Cardiology, 7(4), 204.

McCorry, L. K. (2007). Physiology of the autonomic nervous system. American Journal of Pharmaceutical Education, 71(4).

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