Parasympathetic Nerves

Submitted by Thiruvelan on Tue, 11/22/2011
Parasympathetic Nerves

The digestive system is under supervision of the Autonomic Nervous System (ANS). The ANS supervise the automatic body process that is not under our conscious control. This means that when we consume food without our knowledge, our body digests it.

Parasympathetic Nervous System

The Autonomic Nervous Systems are the Sympathetic Nervous System (SNS) and the Parasympathetic Nervous System (PNS). The SNS is in-charge for the flight or fight response of our body system. When we are fearful (flight) or anger (fight), the SNS signals to increases, our heart rate and provides more energy to our body in preparation to face the situation. In order to provide this extra energy to the heart, lungs and muscle, it inhibits (slows or stops) digestion by diverting blood flow from the digestive tract.

On the other hand, the PNS is in-charge of the digestion. It stimulates salivary gland secretion and peristalsis contractions by increasing blood flow to the digestive tract. Thus, PNS increases the digestion and absorption of food.

Functions of Parasympathetic nervous system

Some of the functions of parasympathetic nervous systems are:

  • Stimulates the flow of saliva,
  • slow down heartbeat,
  • constricts bronchi,
  • stimulates peristalsis movement of the stomach,
  • stimulates stomach secretion,
  • stimulates liver to release bile acid,
  • Contract’s bladder

Parasympathetic nervous system (PNS) increases; digestion, intestinal motility, insulin activity, resistance to infection, rest and recuperation and endorphins ('feel good' hormone). In addition, it decreases; heart rate, blood pressure, and body temperature.

Vagus Nerves

The main nerves of the parasympathetic nervous system are the vagus nerves (tenth cranial nerves). PNS originates in the medulla oblongata; other parasympathetic neurons also extend from the brain and from the lower tip of the spinal cord.

Vagus nerves, which emerge from the back of the skull to the way through the abdomen, with numerous branching nerves linking the heart, lungs, voice-box, stomach, and ears. The vagus nerve carries information between the brain and the body; it collects information about what the body is doing, and governs a range of reflex responses.

The vagus nerve regulates the heartbeat, control muscle movement, manage breathing, and transport various chemicals throughout the body. It manages the digestive tract in working condition; contracting the stomach and intestinal muscles to help digest food, and send information about what is digesting and what are the nutrients get out of it.

Two types of Nerves help control the digestive system

Extrinsic (outside) are nerves from the brain (or spinal cord) to the digestive organ release two chemicals acetylcholine and adrenaline. Acetylcholine helps faster digestion by increasing the contraction of the digestive organs to squeeze with more forcefully and push the food through the digestive tract. It also stimulates the stomach and the pancreas to secrete more digestive-juice.

Adrenaline, on the other hand, has the opposite effect of acetylcholine. It relaxes the stomach muscle & intestine, also decreases the blood flow to these organs, which in-turn slow down or stop digestion.

The intrinsic (inside) nerves are embedding in the walls of the esophagus, stomach, small intestine, and colon. The intrinsic nerves are stimulated when the walls of the organs are stretch by the entry of food. They release chemical substances that speed up or delay the food movement and the secretion of juices by the digestive organs.

In co-ordination nerves, hormones, blood, and the organs of the digestive system carryout, the complex tasks of digestion and nutrient absorption from the foods we consume every day.