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Tuesday, February 24, 2009


There are three additional organs take part in digestion of the food are the liver, the gallbladder, and the pancreas.
The liver is located in the right upper quadrant or RUQ of the abdomen. The liver creates an yellowish-brown colored or greenish, thick fluid named bile. Bile contains a fatty substance i.e. cholesterol, bile acids, and many bile pigments. The pigment named bilirubin is manufactured from the breakdown of hemoglobin in the liver. Bile combines with bilirubin in the liver and then passes into the duodenum. This material is also excreted out from the body with feces.

The bile is manufacturing continuously in the liver travels down to the gallbladder via hepatic duct and cystic duct. Gallbladder is a pear-shaped sac like structure, which is under the liver. Gallbladder collects the bile and stored inside. The bile gets concentrated in the gallbladder. The bile forced to out to the duodenum via common bile duct and pancreatic duct. The duodenum or the first part of the small intestine receives a mixture of bile and pancreatic juice.

Emulsification is an effect of bile on fats in the duodenum, by which bile breaks large fat globules and then the enzymes from the pancreas can digest the fats. So fat digestion is the important function of the bile. Without bile fat materials from the food will remain undigested. The liver apart from producing bile, which also participates many important functions in human body.

The liver maintains the amount of blood sugars also called glucose normal in the body by removing excess of sugars from the bloodstream and stores it in the form of starch (glycogen) in the liver cells. In the situation of very low blood sugars in the blood, which is a danger condition to the body, the glycogens or the starch are converted again to the glucose by the liver. This process is called glycogenesis.

Another important function of the liver is also to convert fats and proteins in the body into glucose and uses it when the body needs it. This process is called gluconeogenesis.
The liver also produces the important blood proteins essential for blood clotting. Bilirubin is produced by the liver destruction of old erythrocytes. The liver also removes the poison materials from the blood through a process called detoxification.

The another important function of the liver is formation of urea. The liver receives amino acids from the blood and it removes ammonia and which is converted into urea, and removed by kidney and excreted out with urine.

The liver helps in the digestion of fats via bile.

The liver also helps in controlling body temperature. It stores hematrin necessary for the formation of RBCs. It forms RBC in the fetal life. It is a storehouse for many chemicals enzymes, and substances life vitamins etc.

Hepatic Portal System:

The blood vessels that bring to the liver from the intestines. This system of blood vessels is called hepatic portal system.

Digested foods pass into the portal vein directly after being absorbed into the bloodstream from the small intestine, thus giving the liver first chance at using the nutrients.

Functions of the pancreas:

The pancreas is an gland, which works both as an endocrine and also as an exocrine organ. As an exocrine, the pancreas produces pancreatic juices filled with enzymes called amylase and lipase to digest the food. These pass into the duodenum through the pancreatic duct.

As an endocrine gland, the pancreas secretes insulin into the bloodstream. Insulin is a hormone essential to help release sugar from the blood, which acts as a carrier to bring glucose into cells of the body to be used for energy.
In the next lesson we will see about GI system more..ok
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The food enters into the mouth after crossing the oral cavity first comes across the organs one by one:
1. pharynx,
2. esophagus
3. stomach
4. duodenum
5. jejunum
6. ileum
7. cecum
8. ascending colon
9. transverse colon
10. descending colon
11. sigmoid colon
12. rectum
13. anus

The another three organs related to this tract are liver, gallbladder, and pancreas.

We will see about each organ and its functions one be one.


This is of about 5-inch long, lined with mucus, and a muscular tube. The air from the nasal cavity to the trachea or windpipe and the food from the mouth to the esophagus are passing towards pharynx.

When we swallow food i.e. deglutition occurs, the epiglottis, a tissue flap covers the windpipe or trachea. This prevents the food cannot enter and stay inside windpipe.

Eso- means inward, phag/o means swallowing. Esophagus is tube of about 10-inch extending from the pharynx to the stomach. The food after enters from the pharynx to the esophagus propels it toward the stomach through a rhythmic contractions of the esophageal muscle called peristalsis, which means constriction. Peri- means surrounding –stalsis means constriction. The food propelled to the stomach next to the esophagus by a muscle contraction happens rhythmically. In this stage food becomes the bolus or semisolid mass.


Esophagus propels the food to the stomach. The stomach is composed of fundus, the upper portion of the stomach, and the body or the middle portion, and the pylorus or the lower portion. Sphincters are the muscle rings in the stomach those control the opening into and from the stomach.

There are two rings named cardiac sphincter and pyloric sphincter. The cardiac sphincter relaxes and then contracts so the food moves from the esophagus to the stomach, the pyloric sphincter allows the food to enter the stomach after some digestion there. Rugae are the folds lining the stomach in the mucus membrane or mucosa. These rugae contain glands that produce enzymes important for digestion called hydrochloric acid.

The food after enters into the stomach prepared for further digestion and absorption into the bloodstream mechanically and chemically. This will happen after about 1 to 4 hours depending upon the amount of food eaten and the type of food eaten.


Now the food is ready to enter the first part of the small intestine. The food travels about 20 feet from the pylorus to the first part of the small intestine, called duodenum. Small intestine has three parts. Now the food enters first to the duodenum for the pylorus sphincter. Duodenum is of about 1 foot in length. At this time bile from the liver and gallbladder and pancreatic juice from the pancreas also enter into the stomach along with partially digested food. Before passes to the second part of the small intestine, the food gets more digested by the bile and the enzymes from the liver and gallbladder and pancreas inside the first part of the small intestine.

The food then passes into the second part of the small intestine, called jejunum. This is of about 8 feet long. Villi are the microscopic projections lining the walls of the small intestine. These are of millions in number and are tiny in structure. Villi have capillaries of microscopic blood vessels, they absorb the digested nutrients into the bloodstream and lymph vessels.

The undigested food then passes into the third part of the small intestine, called ileum. This is of about 11 feet long. Ileum attaches to the first part of the large intestine or colon.


From the ileum to the anus large intestine extends. Large intestine divided into four parts, such as cecum, colon, sigmoid colon, and rectum. A pouch on the right side that attaches to the ileum by the ileocecal valve, called cecum. The appendix hangs from the cecum. The appendix has no clear function in the body. It will be a problem only when it get infected or inflamed.

Large intestine is of 5 feet long, which has three divisions, they are ascending colon, transverse colon, and descending colon. The ascending colon extends from the cecum to the under surface of the liver, where it turns to the left to become transverse colon, this area is of a hepatic flexure as there the liver is near to it. The transverse colon passages horizontally to the left towards the spleen, and turns downward into the descending colon. At the distal end of the descending colon there in S-shaped (sigma) named sigmoid colon. The descending colon extends to the rectum. The rectum opens out into anus, the undigested waste material collected in the large intestine excreted out form the body.

The undigested food is stored until it is excreted out. This absorbs most of the water within it. These solid waste materials are called feces or stools.

In the next lesson we will learn about FUNCTIONS OF THE LIVER, GALLBLADDER, AND PANCREAS..ok
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ORAL CAVITY:  Anatomy and physiology of GI tract starts from mouth. Mouth is also called oral cavity. Oral cavity consists of
1. Lips
2. Teeth
3. Tongue
4. Hard palate
5. Soft palate
6. Cheeks
7. Uvula
8. Tonsils
9. Gums

CHEEKS AND LIPS:  The cheeks form the walls of the oval-shaped oral cavity, and the lips surround the opening to the cavity.

HARD PALATE:  The hard palate forms the anterior portion of the roof of the mouth. Rugae are irregular ridges in the mucous membrane covering the anterior portion of the hard palate.

SOFT PALATE:  The soft palate is posterior to the hard palate, which is muscular in structure. Uvula is a small and soft tissue hanging from the soft palate. Uvula means little grape. Uvula is helping in producing sounds and speech.

TONGUE:  In the oral cavity tongue extends across the floor of the oral cavity. It attaches in the mouth by muscles to the lower jaw. Tongue moves food around when chewing and swallowing. Chewing action is called mastication, and swallowing action is called deglutition. There are numerous small areas raised on the tongue. They are called papillae, these contain taste buds. Taste buds are sensitive to the chemical materials of food. These buds differentiate various tastes of food as they move across the mouth on the tongue.


The part of the throat near the mouth called oropharynx has mucous membranes. These mucous membranes have depressions on it, and they contain masses of lymphatic tissue called tonsils. These tonsils produces cells called lymphocytes, which protects our body from the invasion of micro-organisms. These lymphocytes are white blood cells. These cells have the ability to fight against diseases.

GUMS:  These are fleshy tissues inside the oral cavity. These tissues surround the teeth sockets. These tissues are called gums.

TEETH:  Teeth are the important part in the oral cavity. Teeth are of many types. By drawing a median line we can divide upper and lower teeth into four arches. Each arch contains eight teeth. Normal adult whether male or female has 32 permanent teeth.

Teeth are of eight types based on their anatomy structure, such as
1. central incisor
2. lateral incisor
3. cuspid or canine
4. first premolar
5. second premolar
6. first molar
7. second molar
8. third molar or wisdom teeth.

The central incisor, the lateral incisor, and the cuspid or canine are nearest teeth to the lips (labi/o means lip). The first premolar, the second premolar, and the first molar are adjacent to cheek surfaces or buccal surfaces (bucc/o means cheek).

The buccal surfaces and lips form the facial surface (faci/o), tongue surface (lingu/o) is against the facial surface and mesial surface and distal surfaces are near and farthest areas to the medial surface. There is also an surface called occlusal surface (occlus/o means to close).

TEETH ANATOMY:  Each teeth consists above the gum a surface called crown and root below the gum within the bony socket of each tooth. Enamel is a layer protects each tooth, this is the outermost layer of the crown, which is hard and dense white substance. This is the hardest substance in the body. Another yellow color substance beneath the enamel extending throughout the crown named dentin. This is composed of bony tissue softer than enamel. This dentin is covered and protected by cementum. Cementum is surrounded by a membrane called periodontal membrane, which holds the tooth in place within the teeth socket. Underneath the dentin is a soft and delicate tissue fills the center of the tooth called pulp. The blood vessels, ending of the nerves, lymph vessels, connective tissues are within this pulp. This canal like structure is called root canal.

SALIVARY GLANDS:  There are three pairs of salivary glands in the oral cavity. Saliva is produced by these glands. Saliva contains enzymes important for digestion of the food. On each side of the mouth three types of salivary glands called parotid, submandibular gland, and sublingual gland. These glands have narrow ducts that carry the saliva into the oral cavity. These salivary glands are exocrine glands as they have ducts.

In the next lesson, we will learn about GASTROINTESTINAL SYSTEM ANATOMY AND FUNCTION..Okay
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DIGESTIVE SYSTEM:  INTRODUCTION TO THE DIGESTIVE SYSTEM: Digestive system is also called gastrointestinal system or alimentary canal. Digestive tract starts from the mouth and ends at the anus. Food enters into the body through the mouth and then enters into the intestines, after the food material absorbed, and the waste material excreted out from the anus.

Travel track of food materials:

Food travel starts first from mouth to pharynx to esophagus to stomach to duodenum where gallbladder, liver, and pancreas take part in the travel of the food then to jejunum to ileum to cecum to ascending colon to transverse colon to descending colon to sigmoid colon to rectum to anus.

What happens to the food as travels when enters into the GI (gastrointestinal tract)?

The food enters the body as a complex food material, we chewed the food, the saliva mixed with the food. The complex food material broken down into simpler material. The food material chemically and mechanically broken down. These processes happen as the food travels from the mouth to the intestines.

The complex food materials broken into simpler amino acids. The complex glucose or sugar material in the food broken into simpler sugars, and also the large triglycerides made up of fat molecules are broken down into glycerol and simpler fatty acids. This process is called catabolism.

The food now digested and the digested food must be absorbed in the bloodstream in this stage. This process is happened when the food in the small intestine absorbed by the walls of it.

These energy particles in the food such as catabolized nutrients in the blood such as amino acids, glucose, triglycerides, and glycerol and burnt in the presence of oxygen and energy stored in the food is released.

Body cells in this stage use the simple amino acids to build again large proteins. This process is called anabolism. These large proteins take important place in growth and development of the body. The rest of the fatty acids and glycerol absorbed by the small intestine entered now into the lymphatic vessels, not into the bloodstream. Lymph vessels and blood vessels join together in the chest area of the body and the fat materials digested enter into the blood.

The solid waste materials in this stage eliminated from the body as these materials cannot be absorbed by the blood. These materials now entering into the large intestine. This solid waste is called feces. The feces is then excreted out from the body through the anus, a small opening.

In the next lesson we will see about ANATOMY AND PHYSIOLOGY OF THE GASTROINTESTINAL SYSTEM..okay

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Often Used Medical Terms

ACHONDROPLASIA: It is an inherited disorder in which the bones of the arms and legs fail to grow to normal size owing to a defect in both cartilage and bone. It results in a type of dwarfism characterized by short limbs, a normal-sized head and body, and normal intelligence.

LAPAROSCOPY:  Laparoscopy or peritoneoscopy is a virtual examination of the peritoneal cavity (abdomen) with the use of a laparoscope. The laparoscope is inserted through an incision in the abdomen near the navel, and gas is infused into the peritoneal cavity. This procedure is used to examine the organs in the abdomen for evidence of disease or to perform surgical procedures such as biopsies and tying off of the uterine (fallopian) tubes.

ARTERIOLE:  The relationship between an artery, arterioles, capillaries (tiniest of blood vessels), a venule.

ADENOIDS:  The adenoids-aden/o means gland –oid means like, these resembling like glands, but they are not exocrine or endocrine glands, but these are lymphatic tissues in the part of the throat near the nose and nasal passages. Enlargement of this tissue may cause blockage of the airway from the nose to the throat, and adenoidectomy may be advised.

In the next lesson we will see about GASTROINTESTINAL SYSTEM..okay..
Come on...