GASTROINTESTINAL SYSTEM ANATOMY AND FUNCTIONS-LESSON 57
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.
PHARYNX:
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.
ESOPHAGUS:
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.
STOMACH:
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.
SMALL INTESTINE OR SMALL BOWEL:
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.
LARGE INTESTINE OR LARGE BOWEL:
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.
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.
PHARYNX:
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.
ESOPHAGUS:
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.
STOMACH:
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.
SMALL INTESTINE OR SMALL BOWEL:
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.
LARGE INTESTINE OR LARGE BOWEL:
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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