How is the Digestive Process Controlled, Neurologicaly?

Digestive system is well controlled and maintained by autonomic nervous system. Autonomic Nervous System is the branch of Peripheral Nervous System. Different organs of the body are being controlled by the 12 different cranial nerves.

The vagus nerve is the longest of the cranial nerves, or nerves originating in the brain, and extends through the abdomen to control, organize the physical and chemical release and functions.

 The Enteric Nervous System- The Gut Brain.

The enteric nervous system is the collection of neurons in the gastrointestinal tract that constitutes t
he "brain of the gut" and can function independently of the central nervous system.

This system controls the motility, exocrine and endocrine secretions, and micro circulation of the gastrointestinal tract.

The enteric nervous system closely resembles the central nervous system. It contain some 100 million neurons.

In the enteric nervous system, the nerve-cell bodies are grouped into small ganglia that are connected by bundles of nerve processes forming two major plexuses, called the

1. Myenteric (or Auerbach's) plexus
2. The Submucous (or Meissner's) plexus.

The Myenteric Plexus: lies between the longitudinal and circular layers of muscles and extends the entire length of the gut. It primarily provides motor innervation to the two muscle layers and secretomotor innervation to the mucosa.
The Submucous Plexus:  located in the submucosa between the circular muscle layer and the muscularis mucosa, is the best developed in the small intestine, where it plays an important part in secretory control.

What is Peristalsis.

Movement of food through GI system:

The large hollow organs of the digestive system contain muscle that enables their walls to move. The movement of organ wall can propel food and liquid and also can mix contents within each organ.

What is Peristalsis?

The action of Peristalsis looks like an ocean wave moving through the muscle. The muscle of the organ produces a narrowing and then propels the narrowed portion slowly down the length of organ. These waves of narrowing push the food and fluid in front of them through each hollow organ.

•  The first major muscle movement occurs when food or liquid is swallowed. Although we are able to swallowing by choice, once we swallow begins it becomes involuntary and proceeds under the control of nerves.
• The esophagus is the organ into which the swallowed food is pushed. It connects the throat above with the stomach below. At the junction of the esophagus and stomach, there is ring like valve closing the passage between the two organs called as LOWER ESOPHAGUS SPHINCTER. However, as the food approaches the closed ring, the surrounding muscles relax and allow the food to pass.
• The food enters the stomach, which has three task to do.  

1.Storage. 

2.Mixing of food and digestive juices. 

3.Emptying the contents to the small intestine.

• Several factors affect emptying of the stomach, including the mature of food and degree of muscle action of the emptying stomach and the next organ to receive the stomach contents (the small intestine). As the food is digested in the small intestine and dissolved into the juices from the pancreas, liver and intestine, the contents of the intestine ate mixed and pushed forward to allow further digestion.
  
  
  • Finally, all of digested nutrients are absorbed through the intestinal walls. The waste products of this process include undigested parts of the food, known as fiber, and older cells that have beed shed from the mucosa. These materials are propelled into colon, where they remain usually for a day or two, until the feces are expelled by a bowel movement.

What is IBS (Irritable Bowel Syndrome)

What is IBS ( Irritable Bowel Syndrome):

Irritable Bowel Syndrome (IBS) is a functional disorder affecting the large intestine or colon isn't working properly, leading to chronic and recurrent abdominal discomfort or pain and bowel habit changes. Over the years IBS has been called different names, such as spastic colon and mucous colitis. Irritable Bowel Syndrome has not been shown to lead to other diseases.

Possible causes of IBS:

The cause of irritable bowel syndrome is unknown. Since IBS is a functional disorder, there is no infection, inflamation or structural change to be seen. People with IBS seem to have increased gut sensitivity may result from a problem in the interaction of the brain, the intestines and the autonomic nervous system. The most likely triggers of IBS symptoms are diet, emotional ** stress and hormonal changes. IBS may, in some cases, be the result of another disease.

Colon spasm (external)

 Normally muscles contract and relax in coordinated rhythm to move waste material through the colon. In IBS, this rhythm is interrupted by a sudden, involuntary contraction called a spasm.

Symptoms:

Normal bowel function varies from one person to the next, and most people have a bowel disturbance from time to time. People with IBS may experience chronic and recurrent abdominal discomfort or pain and bowel disturbances, such as diarrhea, constipation or alternating diarrhea and constipation. Other symptoms may include:

• Change in frequency of bowel movements

• Abdominal pain relieved by defection

• Bloating

• Excessive amount of gas

• Passage of mucous with a bowel movement

• Feeling that bowel is not completely empty

• Nausea

Symptoms management

• Evaluate your diet to see if there are foods that apear to trigger IBS symptoms

• Increase fiber intake as this soften stool and improve movement through the intestinal tract

• Examine the external factors such as home. work or financial burdens to identify stress

• Consult a doctor about medicines such as antispasmodics or analgesics

Why is Digestion Important?

As we all know Digestion is the process of converting large food particles into small food particle so that it can be absorb in blood stream. When we eat such things as bread, meat, fruits and vegetables, they are not in form that the body can use as nourishment. Our food must be change into small molecules to absorb in blood and carried to cells through out the body. We must have to digest our food to get energy and we need energy to do any work even to close our eyes.
        In short Digestion in as important as breathing because we need energy to breath and we got energy by digestion our food.

Large Intestine (Human Digestive System)

Large Intestine:

 The Large intestine extends from the end of the end of the small intestine to the anus. It is about 5 feet long. It's caliber is largest at the commencement at the cecum, and gradually diminshes as far as the rectum, where there is a dilatation of considerable size just above the anal canal.

Parts of Large Intestine:

Large intestine is divided into three parts:

• Cecum
• Colon
• Rectum

Small Intestine

Small Intestine:

 The small intestine is the site where most of the chemical and mechanical digestion is occured. The small intestine absorbs the digested food into the capillaries through villi. Most of the food is digested in Jejunum and Ileum.

The Functions of small intestine

1. The digestion of proteins.
2. Peptides are degraded into amino acids.
3. Lipids (fats) are degraded into fatty acids.
4. Carbohydrates are degraded into the simple sugar.

The three main sections of small intestine are:

• The Duodenum

• The Jejunum

• The Ileum

  The Duodenum:

  It starts from Stomach and ends on Jejunum ligament of Treiz. It is the first and shortest part of small intestine. The bile and pancreatic juice is mix with food in duodenum.
  
  

  The Jejunum:

  The jejunum is a part of small bowel , located between the Duodenum and Ileum. The internal surface of Jejunum, the mucous membrane, is covered in projection called villi,  which increase the surface area of tissues which absorbs the nutrients from the gut contents.
  
  

  The Ileum: 

  It is the last part of small intestine and it connects Jejunum to the large intestine. It absorbs the Vitamin B12 and bile salts. It also have villi on inner surface. The villi contain large number of capillaries.
  
  

Stomach

Stomach

The stomach is a muscular organ located on the left side of the upper abdomen. It starts from the end of esophagus and ends on duedenum. The food enters the stomach through a muscular valve called lower esophagus sphincter.
     The stomach secrets acid and enzymes that digest the food. Ridges of muscle tissue called rugger line the stomach. The stomach muscles contract periodically, churning food to help digestion. The food exits through another muscular valve known as pyloric sphincter. It is a flexible muscular sac. Capacity is 1.5 L .
Functions:

1. stores food.
2. Mixes gastric juice.
3. Secretes HCl, enzymes and substances.

Parts of Stomach: 
Followings are the part os stomach

• Cardia
• Fundus
• Body
• Antrum

Layers of Stomach:

•  Mucosa
• Submucosa
• Muscularis
• Serosa

Cell and their Secretions:

• Parietal cells: HCl
• Chief (peptic) Cells: Pepsinogen
• Mucous Neck Cells: Mucosa
• G Cells: Gastrin

The Three Phases of the Food Digestion Process.

The Three Phases of the Food Digestion Process.

Before we eat the food our mind start the work for the food Digestion and make ground for that. Then our mouth and stomach do our work and digestion end by ending the work of our intestines

1. Cephalic Phase:

    In the cephalic phase of digestion, the anticipation of food prepares the body for the digestion, absorption and use of energy in food.The feel of food in the mouth or thoughts related  to food send signals to the medulla oblongata via the vagus nerve to stimulate the release of stomach chemicals. Vagus nerve is the longest nerve originating in the brain, and extends through the abdomen.
   

2. Gastric Phase:

   The Gastric phase starts our stomach when food entered in the stomach by releasing the gastric juices. Which play a very vital role in digestion. This process helps to intake food and digestion.
   

3. Intestinal Phase: 

   The intestinal phase starts when food reach in duodenum (small intestine).