Sympathetic and Parasympathetic Nervous System

The sympathetic nervous system is a subsystem of the autonomic nervous system that regulates autonomic functions. The sympathetic nervous system helps the body prepare for stressful activities by slowing down bodily processes that aren’t as necessary in an emergency, such as digestion.

These are the processes that occur without conscious thoughts and are not under direct conscious control.

The Sympathetic nervous system also combines with the parasympathetic nervous system to maintain homeostasis, which is defined as the balance of internal physiological systems that all living creatures require.

The sympathetic nervous system is responsible for triggering actions that need quick reactions by increasing heart rate, Dilating the pupils, Secretion of sweat glands, Dilating the muscles, Relaxation of the bladder etc.

The Sympathetic Nervous System can maintain homeostasis in the body by sweating to cool down or by controlling heart rate. The Sympathetic Nervous System activates organs, as opposed to the parasympathetic nervous system, which slows physiological processes.

When you’re relaxed, the parasympathetic branch stimulates digestion and the urinary system, but the Sympathetic Nervous System slows them down because these functions aren’t needed during times of high stress.

The parasympathetic branch is, in essence, is the adversary of the sympathetic branch. In addition, Sympathetic Nervous System neurons have shorter axons than those of the parasympathetic nervous system, so they react more faster; in fact, responses can often happen before a person is aware of them.

Functions of Sympathetic Nervous System

Fight-or-flight Response

In threatening conditions, the Sympathetic Nervous System’s principal job is to trigger the fight-or-flight reaction. 

The Sympathetic Nervous System would respond by causing the eyes to dilate and the heart to beat faster in this condition. These autonomic reactions to a potentially dangerous circumstances are thus critical for survival. In terms of evolution, the Sympathetic Nervous System would have been used to fight or escape prey, as well as to seek for food and survival.

More modern-day stressors, such as financial difficulties, work-related stress, or anything that causes significant anxiety for individuals, can also trigger the Sympathetic Nervous System.

The amygdala (a region of the brain involved with fear and emotions) will send a distress signal to the hypothalamus when a stressful or anxiety-provoking scenario develops (a command structure of the brain associated with maintaining homeostasis).

The Sympathetic Nervous System subsequently sends impulses to the adrenal glands, which eventually release adrenaline into the bloodstream.

This will trigger the physiological changes required to prepare for fight-or-flight situations.

The Sympathetic Nervous System’s responses result in increased awareness and readiness for fight or flight. Fundamentally, the fight-or-flight response is mediated by impulses transmitted to the adrenal glands through the Sympathetic Nervous System.

Both short-term and long-term stress reactions are facilitated by the adrenal glands.

Once the threat has passed, the parasympathetic nervous system takes control and restores normal bodily functions.

Regulating Body Temperature

The Sympathetic Nervous System can regulate the body temperature of organisms through the usage of fat reserves in the body to achieve homeostasis. It makes use of these reserves by increasing heat generation and altering blood flow to the skin. It can also trigger sweat glands to allow the body to cool down, as well as fatty acid release to start long-term reactions to prolonged cold.

Cardiovascular Effects

The Sympathetic Nervous System has the potential to affect the cardiovascular system. When exercising (when the heart rate has to rise), changing posture (e.g., from a sitting to a standing position), and transitioning from sleep to being awake, this comes into play.

These changes via the Sympathetic Nervous System are required, especially while shifting postures, as else dizziness and fainting can occur.

Parasympathetic nervous system

The parasympathetic nervous system (PNS) is one of the autonomic nervous system’s two functionally different and continuously functioning divisions. The sympathetic nervous system, on the other hand, is in opposition to it (Sympathetic Nervous System). In calm “rest and digest” situations, the parasympathetic nervous system takes over, whereas the sympathetic nervous system controls the fight or flight reaction in stressful situations. The PNS’ primary job is to store energy for later use and to control body activities such as digestion and urination.

Functions of Parasympathetic nervous system

The parasympathetic nervous system has the following functions:

Salivation The parasympathetic nervous system increases the production of saliva, which includes enzymes that help in the digestion of meals, as part of its rest-and-digest function.

Lacrimation: it is the process of making tears. Tears lubricate our eyes and protect their fragile tissues.

Urination The Parasympathetic Nervous System squeezes the bladder, allowing urine to flow out

Digestion: increases the production of saliva, which helps digestion. It also causes peristalsis, or the movement of the stomach and intestines, which helps the body breakdown fats by producing bile.

Defecation: Defecation occurs when the Parasympathetic Nervous System constricts the intestine’s sphincters and forces digested food particles down the digestive system, allowing a person to have a bowel movement

Difference between Parasympathetic and Sympathetic Nervous System

Importance of Parasympathetic System

Both the sympathetic and parasympathetic nervous systems are essential for our survival and wellness. However, in order for our bodies to live as long as possible with maximum health and function, there must be a balance between the two. Your body will be in fight or flight mode much too often and for far too long if there is a miscommunication between your brain and the impulses that stimulate sympathetic reactions, which can have detrimental consequences on your general health.

When your spinal cord and nerves are functioning properly, you may achieve a healthy balance between the two elements of your autonomic nervous system.

Conclusion

Once the threat has gone, the sympathetic nervous system does not de-stress the body. The parasympathetic nervous system, which is part of the autonomic nervous system, helps the body relax. This mechanism promotes the body to rest and digest in order to reverse the fight-or-flight response. As the body returns to homeostasis, or equilibrium, blood pressure, breathing rate, and hormone flow all return to normal.

The sympathetic and parasympathetic nerve systems cooperate to maintain this baseline and regular biological functions.