Pharmacy Clinic
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Digestive System
The digestive system is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. Inside this tube is a lining called the
mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce juices to help digest food.
The Alimentary canal is a muscular tube about 9 meters long, which passes through out the body to carry on a special function:
The gastrointestinal tract includes the esophagus, stomach, liver, gall bladder, pancreas, small intestine, large intestine, appendix, rectum, and
anus.
Structure of the wall of digestive tract:
I- Mucous membrane , or mucosa:
It is the surface of epithelium with small amount of smooth muscles, in some rejoins it develops projections in order to increase the surface of
absorption, it also contain glands which secrete digestive enzymes that helps in the digestion process.
II- Sub mucousa:
Contains blood vessels, lymphatic tissues and nerves. Its vessels serve to nourish the surrounding tissues and to carry away absorbed materials.
III- Muscular layers:
This layer contains muscle fibers that control the contraction and dilation of the vessels.
IV Serous layer or Serosa:
It is the outer most layer and has the job of serous fluid secretion in order to keep the outer layer moist, and lubricate to make the organs within
the abdominal cavity slide freely against one another.
Function of the digestive system:
The main function of the digestive system begins when food inters the mouth that is the first station.
In the mouth food is mixed with the saliva and is pushed to the esophagus. After food inters the mouth, mastication (chewing) breaks up large
food particles into small one and mix it with the secretions of the salivary gland, after this, digested food pass through the esophagus by aid of the
tongue into the stomach in order to start the process of digestion.
In the stomach, food is stored, mixed with acid, mucus, and pepsin. In order to understand the digestion in the stomach , we have to study the
anatomy of it.
Stomach
Anatomy of the Stomach:
The organ of main interest is stomach, a temporary "storage tank", where the chemical breakdown of proteins begins. In stomach the food
converted into a creamy paste called chyme. The stomach is about 25 cm long in an adult, but its diameter and volume depend on how much food it
contains. Its volume is about 50 ml, but stomach can hold about 4 litres.
The top part of the stomach is close to the heart, hence its name - cardia, or cardiac region. This part is attached to esophagus. Fundus is part of
the stomach hidden away behind the diaphragm, and lies superolatteraly to cardia. The body is the middle portion of the stomach, which continues
into lower part, called pylorus. Pylorus is shaped like a funnel, and through the pyloric sphincter continues into duodenum.
The convex surface of the stomach is its curvatura major (greater curvature), and the concave surface is curvatura minor (lesser curvature).
Extending from these curvatures are two mesenteries: lesser omentum connects the lesser curvature to the liver, and greater omentum runs from
the greater curvature and covers the coils of the small intestine
The stomach contain many different glands that secrete gastric acids, mucus, and also hydrochloric acid. Also stomach has a very rich blood and
lymphatic supply.
Gastric Secretion:
Gastric glands secrete about 2500 ml of gastric juice daily. Hydrochloric acid secreted by the glands in the body of the stomach kills many ingested
bacteria, aids protein digestion, provide appropriate pH for pepsin to start protein digestion, and stimulate the flow of bile and pancreatic juice. The
concentration of hydrochloric acid is enough to damage tissues, but gastric mucosa does not affected by this acid in normal conditions.
Gastric mucosa also secretes bicarbonate. This bicarbonate with the mucous form a layer on the mucosal cells and protect it from damage by gastric
juice.
Pepsinogen Secretion:
It is the precursor of pepsin in the gastric juice
Hydrochloric acid Secretion:
Pareital cells secrete this type of acid when these cells stimulated. H-K ATPase synthesized in the pareital cells , this enzyme by concentration
gradient carrry H+ into the stomach and the primary source of H+ is the ionization of water and exchanged with K+.
Cl- is also actively transported into the gastric juice. For each H+ secreted and OH remain in the cell and neutralized by the dissociation of carbonic
acid buffer system and the formed HCO3- from this dissociation exchanged by Cl- by HCO3- -Cl- exchange mechanism in the membrane.
NOTE: carbonic anhydrase is an enzyme located in the gastric cells that catalyses the formation of carbonic acid ( H2CO3)
Acid secretion is stimulated by Histamine via H2 receptors, by Acetylcholine via M1 muscarinic receptor, and by gastric via gastrin receptors in the
membrane of the parietal cells.
H2 receptors increase intracellular cGMP , where as M1 muscarinic receptors and gastrin receptors increase intracellular Ca++ concentration so
contraction takes place potentiating acid release.
When food inter the stomach, the organ relaxes, after this relaxation , peristaltic movement mix food and push it to the duodenum. This passage
controlled by the pyloric sphincter which has limited function in the gastric emptying.
Food in the stomach accelerate the release of gastric secretion at the presence of food in the mouth.
The rate of stomach emptying into the duodenum depends on the type of food ingested. Food rich with CHO leaves the stomach in few hours.
Protein rich food leaves more slowly, and emptying is the slowest after a meal containing fat.
NOTE: Acetylcholine receptors are of two types:
1) nicotinic receptors
2) muscarinic receptors:
-M1
-M2
Gastro - Intestinal (GI) Tract, or alimentary canal is a long hollow muscular tube, situated in the ventral body cavity. It is opened to the external
environment at both ends. The main role of GI tract is to digest the food and absorb it through its lining into the blood. The nutrients are then
carried into the rest of the body.
The main organs of the GI tract are: mouth, pharynx, esophagus, stomach, small intestine and large intestine, which lead to the terminal opening,
anus.
Teeth, tongue, gallbladder, salivary glands, liver and pancreas are accessory organs of GI tract, and some of them produce saliva, bile and enzymes
to help the digestive processes.
Small intestine is further divided into three parts: duodenum, jejunum and ileum.
Similarly, the large intestine is divided into several parts. The first portion of large intestine is caecum, which has appendix, a blind-ended sac, as an
extension. The next part is colon, which is anatomically divided into ascending, transverse, descending and sigmoid segments, all of which are
histologically similar. The terminal portion of large intestine is rectum, which ends with anus.
After passage of food from the stomach through the pyloric sphincter to the duodenum which is the first part of small intestine.
Digestion which is begin in the mouth and the stomach is completed in the small intestine in the mucosal cells.
The small intestine is presented with 9 L of fluids, 2L from dietary sources and 7L from GIT secretion.
Small Intestine
Anatomy of the small intestine:
The small intestine is where more than 99% of digestion takes place. It is a long (about 20 feet) muscular tube. Small intestine having 3 parts: the
duodenum (nearest the stomach), the jejunum (the middle part), and the ileum (the end part).
The small intestine has a very specialized lining called the mucosa. This lining has very specialized cells that break food down into molecules that
can then be taken up into the intestinal blood. From here, all the blood goes to the liver where some molecules are reprocessed and then sent out
to the rest of the body (fat, for example).
The liver also removes the toxins that we take in so that they can't get to the rest of the body.
Almost all of what we eat is taken up into the blood and used by the body. However, some parts of food can't be digested (primarily plant fiber).
By the time food reaches the end of the small intestine, it has been thoroughly digested. Many nutrients are taken up by a particular part of the
small intestine. For example, iron and calcium are taken up in the duodenum and vitamin B12 in the ileum. This is why when surgeons remove a
part of the bowel in an operation that a specific vitamin or mineral deficiency can result.
The small intestine is a tubular organ that extends from the pyloric sphincter to the beginning of the large intestine, it fills much of the abdominal
cavity.
Parts of the Small Intestine:
1- duodenum:
about 25 cm long, 5cm in diameter, it follows C- shaped path
2- Jejunum and ileum:
260 cm length
All these are suspended by a double layer called mesentry (this supporting tissue contains the blood vessels, nerves, and lymphatic vessels that
supply the intestinal wall.
Structure of the small intestinal wall:
Mostly the intestinal Villi which are located in the duodenum and at the proximal part of jejunum.
1- mucus secretion: from the goblet cells through out the mucosa of small intestine.
At the bases of villi secrete great amount of watery fluid, reabsorb it rapidly which provide a vehicle for moving digestive products into the villi.
2- Fluid secretion: Small intestine has a neutral pH of 6.5-7.5 and has embedded enzymes that act to digest food molecules just before
absorption takes place, these enzymes include :
Peptidase split peptides into aminoacids
Sucrase, maltase, lactase split double sugars, maltose, sucrose, and maltose into simple sugars, glucose, fructose, galactose.
Intestinal lipase split fats into fatty acids and glycerol.
Absorption in the Small Intestine:
Due to the presence of villi, small intestine is the most absorptive area of the alimentary canal.
CHO digestion begins in the mouth and completed in small intestine and absorbed by villi.
Proteins also digested by pepsin and completed in the small intestine
All absorption done by the active transport or facilitated diffusion.
Fats also digested by enzymes from intestinal mucosa and pancreas, the resulting fatty acid and glycerol and so absorbed by the presence of villi.
Also the absorption of electrolytes, vitamins, and fluids is the responsibility of small intestine.
At the end of the ileum, Cecum of the large intestine join by a sphincter muscle called the ileocecal valve. It separate large intestine from small
intestine.
When peristalsis in the ileum is increased, it force some of the contents of the small intestine into the cecum.
Large Intestine:
(1.5 meter long)
So called because its diameter is greater than small intestine. Large intestine goes upward in the right side and down ward in the left side to the
pelvis. It reabsorbs water and electrolytes remained in the alimentary canal and store feces until defecation occurs.
Large Intestine Consists of:
1- Cecum; the beginning of the large intestine
2- Projection from Cecum called vermiform appendix which has no digestive function, it has lymphatic tissues that can serve to resist infections.
3- Colon: - Ascending colon
- Transverse colon ( the movable part and the longest one)
- Descending colon (making the S-shaped curve
- Sigmoid colon
The large intestine has no small intestinal functions, only has goblet cells which secrete mucus to protect the intestinal wall from erosions and helps
to control pH of the large intestinal contents.
Movement of the large intestine produce mass movement and colon constrict vigorously, forcing its contents to move toward the rectum, then
defecation happens by holding a deep breath and contracting the abdominal wall muscles.
There are also two solid digestive organs, the liver and the pancreas, which produce juices that reach the intestine through small tubes. In addition,
parts of other organ systems (for instance, nerves and blood) play a major role in the digestive system.
Peptic Ulcer Disease
Introduction:
PUD is a heterogeneous group of disorders involving the upper gastrointestinal tract, it is resulted from an imbalance between a defensive forces
and aggressive forces.
Ulcers are holes in the mucosa that develop when portions are actually digested away. They have long been associated with stress, genetic factors,
and smoking and have generally been treated by acid-suppressive therapy and lifestyle changes.
mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce juices to help digest food.
The Alimentary canal is a muscular tube about 9 meters long, which passes through out the body to carry on a special function:
The gastrointestinal tract includes the esophagus, stomach, liver, gall bladder, pancreas, small intestine, large intestine, appendix, rectum, and
anus.
Structure of the wall of digestive tract:
I- Mucous membrane , or mucosa:
It is the surface of epithelium with small amount of smooth muscles, in some rejoins it develops projections in order to increase the surface of
absorption, it also contain glands which secrete digestive enzymes that helps in the digestion process.
II- Sub mucousa:
Contains blood vessels, lymphatic tissues and nerves. Its vessels serve to nourish the surrounding tissues and to carry away absorbed materials.
III- Muscular layers:
This layer contains muscle fibers that control the contraction and dilation of the vessels.
IV Serous layer or Serosa:
It is the outer most layer and has the job of serous fluid secretion in order to keep the outer layer moist, and lubricate to make the organs within
the abdominal cavity slide freely against one another.
Function of the digestive system:
The main function of the digestive system begins when food inters the mouth that is the first station.
In the mouth food is mixed with the saliva and is pushed to the esophagus. After food inters the mouth, mastication (chewing) breaks up large
food particles into small one and mix it with the secretions of the salivary gland, after this, digested food pass through the esophagus by aid of the
tongue into the stomach in order to start the process of digestion.
In the stomach, food is stored, mixed with acid, mucus, and pepsin. In order to understand the digestion in the stomach , we have to study the
anatomy of it.
Stomach
Anatomy of the Stomach:
The organ of main interest is stomach, a temporary "storage tank", where the chemical breakdown of proteins begins. In stomach the food
converted into a creamy paste called chyme. The stomach is about 25 cm long in an adult, but its diameter and volume depend on how much food it
contains. Its volume is about 50 ml, but stomach can hold about 4 litres.
The top part of the stomach is close to the heart, hence its name - cardia, or cardiac region. This part is attached to esophagus. Fundus is part of
the stomach hidden away behind the diaphragm, and lies superolatteraly to cardia. The body is the middle portion of the stomach, which continues
into lower part, called pylorus. Pylorus is shaped like a funnel, and through the pyloric sphincter continues into duodenum.
The convex surface of the stomach is its curvatura major (greater curvature), and the concave surface is curvatura minor (lesser curvature).
Extending from these curvatures are two mesenteries: lesser omentum connects the lesser curvature to the liver, and greater omentum runs from
the greater curvature and covers the coils of the small intestine
The stomach contain many different glands that secrete gastric acids, mucus, and also hydrochloric acid. Also stomach has a very rich blood and
lymphatic supply.
Gastric Secretion:
Gastric glands secrete about 2500 ml of gastric juice daily. Hydrochloric acid secreted by the glands in the body of the stomach kills many ingested
bacteria, aids protein digestion, provide appropriate pH for pepsin to start protein digestion, and stimulate the flow of bile and pancreatic juice. The
concentration of hydrochloric acid is enough to damage tissues, but gastric mucosa does not affected by this acid in normal conditions.
Gastric mucosa also secretes bicarbonate. This bicarbonate with the mucous form a layer on the mucosal cells and protect it from damage by gastric
juice.
Pepsinogen Secretion:
It is the precursor of pepsin in the gastric juice
Hydrochloric acid Secretion:
Pareital cells secrete this type of acid when these cells stimulated. H-K ATPase synthesized in the pareital cells , this enzyme by concentration
gradient carrry H+ into the stomach and the primary source of H+ is the ionization of water and exchanged with K+.
Cl- is also actively transported into the gastric juice. For each H+ secreted and OH remain in the cell and neutralized by the dissociation of carbonic
acid buffer system and the formed HCO3- from this dissociation exchanged by Cl- by HCO3- -Cl- exchange mechanism in the membrane.
NOTE: carbonic anhydrase is an enzyme located in the gastric cells that catalyses the formation of carbonic acid ( H2CO3)
Acid secretion is stimulated by Histamine via H2 receptors, by Acetylcholine via M1 muscarinic receptor, and by gastric via gastrin receptors in the
membrane of the parietal cells.
H2 receptors increase intracellular cGMP , where as M1 muscarinic receptors and gastrin receptors increase intracellular Ca++ concentration so
contraction takes place potentiating acid release.
When food inter the stomach, the organ relaxes, after this relaxation , peristaltic movement mix food and push it to the duodenum. This passage
controlled by the pyloric sphincter which has limited function in the gastric emptying.
Food in the stomach accelerate the release of gastric secretion at the presence of food in the mouth.
The rate of stomach emptying into the duodenum depends on the type of food ingested. Food rich with CHO leaves the stomach in few hours.
Protein rich food leaves more slowly, and emptying is the slowest after a meal containing fat.
NOTE: Acetylcholine receptors are of two types:
1) nicotinic receptors
2) muscarinic receptors:
-M1
-M2
Gastro - Intestinal (GI) Tract, or alimentary canal is a long hollow muscular tube, situated in the ventral body cavity. It is opened to the external
environment at both ends. The main role of GI tract is to digest the food and absorb it through its lining into the blood. The nutrients are then
carried into the rest of the body.
The main organs of the GI tract are: mouth, pharynx, esophagus, stomach, small intestine and large intestine, which lead to the terminal opening,
anus.
Teeth, tongue, gallbladder, salivary glands, liver and pancreas are accessory organs of GI tract, and some of them produce saliva, bile and enzymes
to help the digestive processes.
Small intestine is further divided into three parts: duodenum, jejunum and ileum.
Similarly, the large intestine is divided into several parts. The first portion of large intestine is caecum, which has appendix, a blind-ended sac, as an
extension. The next part is colon, which is anatomically divided into ascending, transverse, descending and sigmoid segments, all of which are
histologically similar. The terminal portion of large intestine is rectum, which ends with anus.
After passage of food from the stomach through the pyloric sphincter to the duodenum which is the first part of small intestine.
Digestion which is begin in the mouth and the stomach is completed in the small intestine in the mucosal cells.
The small intestine is presented with 9 L of fluids, 2L from dietary sources and 7L from GIT secretion.
Small Intestine
Anatomy of the small intestine:
The small intestine is where more than 99% of digestion takes place. It is a long (about 20 feet) muscular tube. Small intestine having 3 parts: the
duodenum (nearest the stomach), the jejunum (the middle part), and the ileum (the end part).
The small intestine has a very specialized lining called the mucosa. This lining has very specialized cells that break food down into molecules that
can then be taken up into the intestinal blood. From here, all the blood goes to the liver where some molecules are reprocessed and then sent out
to the rest of the body (fat, for example).
The liver also removes the toxins that we take in so that they can't get to the rest of the body.
Almost all of what we eat is taken up into the blood and used by the body. However, some parts of food can't be digested (primarily plant fiber).
By the time food reaches the end of the small intestine, it has been thoroughly digested. Many nutrients are taken up by a particular part of the
small intestine. For example, iron and calcium are taken up in the duodenum and vitamin B12 in the ileum. This is why when surgeons remove a
part of the bowel in an operation that a specific vitamin or mineral deficiency can result.
The small intestine is a tubular organ that extends from the pyloric sphincter to the beginning of the large intestine, it fills much of the abdominal
cavity.
Parts of the Small Intestine:
1- duodenum:
about 25 cm long, 5cm in diameter, it follows C- shaped path
2- Jejunum and ileum:
260 cm length
All these are suspended by a double layer called mesentry (this supporting tissue contains the blood vessels, nerves, and lymphatic vessels that
supply the intestinal wall.
Structure of the small intestinal wall:
Mostly the intestinal Villi which are located in the duodenum and at the proximal part of jejunum.
1- mucus secretion: from the goblet cells through out the mucosa of small intestine.
At the bases of villi secrete great amount of watery fluid, reabsorb it rapidly which provide a vehicle for moving digestive products into the villi.
2- Fluid secretion: Small intestine has a neutral pH of 6.5-7.5 and has embedded enzymes that act to digest food molecules just before
absorption takes place, these enzymes include :
Peptidase split peptides into aminoacids
Sucrase, maltase, lactase split double sugars, maltose, sucrose, and maltose into simple sugars, glucose, fructose, galactose.
Intestinal lipase split fats into fatty acids and glycerol.
Absorption in the Small Intestine:
Due to the presence of villi, small intestine is the most absorptive area of the alimentary canal.
CHO digestion begins in the mouth and completed in small intestine and absorbed by villi.
Proteins also digested by pepsin and completed in the small intestine
All absorption done by the active transport or facilitated diffusion.
Fats also digested by enzymes from intestinal mucosa and pancreas, the resulting fatty acid and glycerol and so absorbed by the presence of villi.
Also the absorption of electrolytes, vitamins, and fluids is the responsibility of small intestine.
At the end of the ileum, Cecum of the large intestine join by a sphincter muscle called the ileocecal valve. It separate large intestine from small
intestine.
When peristalsis in the ileum is increased, it force some of the contents of the small intestine into the cecum.
Large Intestine:
(1.5 meter long)
So called because its diameter is greater than small intestine. Large intestine goes upward in the right side and down ward in the left side to the
pelvis. It reabsorbs water and electrolytes remained in the alimentary canal and store feces until defecation occurs.
Large Intestine Consists of:
1- Cecum; the beginning of the large intestine
2- Projection from Cecum called vermiform appendix which has no digestive function, it has lymphatic tissues that can serve to resist infections.
3- Colon: - Ascending colon
- Transverse colon ( the movable part and the longest one)
- Descending colon (making the S-shaped curve
- Sigmoid colon
The large intestine has no small intestinal functions, only has goblet cells which secrete mucus to protect the intestinal wall from erosions and helps
to control pH of the large intestinal contents.
Movement of the large intestine produce mass movement and colon constrict vigorously, forcing its contents to move toward the rectum, then
defecation happens by holding a deep breath and contracting the abdominal wall muscles.
There are also two solid digestive organs, the liver and the pancreas, which produce juices that reach the intestine through small tubes. In addition,
parts of other organ systems (for instance, nerves and blood) play a major role in the digestive system.
Peptic Ulcer Disease
Introduction:
PUD is a heterogeneous group of disorders involving the upper gastrointestinal tract, it is resulted from an imbalance between a defensive forces
and aggressive forces.
Ulcers are holes in the mucosa that develop when portions are actually digested away. They have long been associated with stress, genetic factors,
and smoking and have generally been treated by acid-suppressive therapy and lifestyle changes.
