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GASTROINTESTINAL
SYSTEM(GIT)
Part 1: Anatomy and Physiology of the
Digestive system.
Part 2 : Functions of the Digestive system.
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Anatomy Of Digestive System
The organ of the digestive system can be
separated into two groups.
1.Alimentary canal. (‫)القناة الهضمية‬
2.Accessory digestive organ.)‫(أعضاء هضمية ملحقة‬
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‫تجويف الفم‬
‫الغدد اللعابية‬
‫اللسان‬
‫البلعوم‬
‫المرئ‬
‫الكبد‬
‫المرارة‬
‫األمعاء الغليظة‬
‫األمعاء الدقيقة‬
‫القولون الصاعد‬
‫المستقيم‬
‫‪4‬‬
‫قناة الشرج‬
‫فتحة الشرج‬
Alimentary Canal (GIT)

Mouth)‫(الفـــم‬
Pharynx )‫(البلعوم‬
Esophagus )‫(المرئ‬
Stomach )‫(المعدة‬
Small Intestine )‫(األمعاء الدقيقة‬
Large Intestine )‫(األمعاء الغليظة‬

FUNCTIONS OF DIGESTIVE SYSTEM Ingestion )‫(بلع‬
•
Propulsion )‫(دفع‬
•
Digestion )‫(هضم‬
•
Absorption )‫(امتصاص‬
•
Defecation )‫(إخراج‬





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Mouth
Mouth (Oral Cavity)
Lips
Hard Palate
Soft Palate
Tongue
Uvula
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‫السقف األملس‬
‫السقف العظمي‬
‫البلعوم األنفي‬
‫تجويف القم‬
‫اللوزة السقفية‬
‫الشفتان‬
‫اللوزة اللسانية‬
‫البلعوم الفمي‬
‫الزائدة اللسانية‬
‫اللسان‬
‫البلعوم المزماري‬
‫المرئ‬
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‫القصبة الهوائية‬
Activities in mouth
After food is placed in the mouth mechanical
digestion begins . )‫(هضم ميكانيكي‬
Food is physically broken down in small
particles by chewing (mastication), which is
a voluntary process. )‫ إرادية‬:‫(المضغ‬
Saliva contains salivary amylase which helps
in the digestion of starch in mouth.
)‫ النشا‬- ‫(أنزيم األمليز اللعابي‬
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Salivary Glands
The product of the salivary glands, Saliva is a
mixture of mucus & serous fluids.
)‫(خليط سائل ومخاط‬
Mucus helps to moisten the food & to bind food
to form a bolus. )‫(ترطيب الطعام‬
It also contain,
An enzyme salivary amylase for digestion of
starch. ) ‫النشويات‬
‫(أنزيم األمليز‬
Lysozyme and antibodies (IgA) that inhibit
bacteria, therefore it has protective function.
))‫(أنزيم محلل وأجسام مضادة لقتل البكتيريا (وظيفة مناعية‬
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Pharynx
PHARYNX
OROPHARYNX
LARYNGOPHARYNX
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Ingestion
Swallowing )‫(البلع‬
It’s a complicated process requires the
coordinated activities of; tongue, soft
palate, pharynx & esophagus.
Phases:
1. Buccal phase )‫(مرحلة خموية‬
2. Pharyngeal phase )‫(مرحلة بلعومية‬
3. Esophageal phase )‫(مرحلة مريئية‬
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‫منقبضة‬
‫‪12‬‬
‫منبسطة‬
‫معرة المرئ العلوية منقبضة‬
‫ّ‬
ESOPHAGUS
Layers of esophagus & GI tract
Inside to outside the layers are;
 Mucosa
 Submucosa
 Muscularis Externa
 Serosa
 Activities in the esophagus( ‫(نشاطات المرئ‬
In the esophagus the food is simply propelled down by
peristaltic waves to the stomach. )‫(دفع الطعام بواسطة التملجات‬
As the food reaches the lower end the cardio-esophageal
sphincter relaxes to open & the food enters the stomach.
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Nervous Control Of GIT

Submucosal Nerve Plexus

Myenteric Nerve Plexus
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Stomach
C shaped organ present on the left side of
the abdomen.
PARTS:
 Fundus
 Body
 Greater Curvature
 Lesser curvature
 Pylorus
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Stomach
Stomach act as temporary “storage tank” for food as well as a site for
food break down.)‫ (مستودع تخزين‬also churn & mix the food, physically
breaking it down to smaller fragments.)‫(تقطيع وخلط‬
Chemical breakdown of protein begins in the stomach.
)‫(تكسير البروتينات يبدأ في المعدة‬
The gastric mucosa )‫(غشاء المعدة‬is lined by simple columnar epithelium
secreting large amount of mucus )‫ (إفراز المادة المخاط‬.
There are gastric glands which secrete the solution called
GASTRIC JUICE. )‫(عصارة المعدة‬
The gastric gland contains two important type of
cells;)‫(خاليا المعدة‬
1.
Chief cells. Producing protein digesting enzymes,
PEPSINOGENS.)‫(خاليا أساسية‬
2.
Parietal cells. Produces Hydrochloric acid
(HCL).)‫ حامض الهيدروكلوريك‬: ‫(خاليا جدارية‬
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Functions of Hcl
-it activates the enzyme, pepsinogen to pepsin causing
protein digestion.
-It also acts as a bactericidal for the micro organism
present in food. )‫نشط‬
‫(تحويل أنزيم غير نشط‬
HCl secretion is controlled by neural & hormonal factors.
Neural factor includes;
‫(إفراز الحامض تحت تحكم عصبي وهرموني النظر والتفكير ورائحة الطعام هذه عوامل‬
)‫عصبية‬
•
Sight of food.
•
Thinking of food.
•
Smell of food.
All these reflexly stimulate parasympathetic nervous
system to increase gastric juice & HCl secretion.
( Gastrin (‫)عوامل هرمونية للتحكم في إفراز عصارة المعدة‬
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Hormonal control of Hcl
(‫)عوامل هرمونية للتحكم في إفراز عصارة المعدة‬
-Gastrin is a hormone secreted by the G cells of the
stomach, increases gastric juice & HCl secretion.
-Histamine also increases HCl secretion.
-Secretin, is a hormone secreted by duodenal cells
inhibit gastric juice secretion.
-Gastric Inhibitory Peptide (GIP) a hormone also
decreases gastric juice secretion.
‫) يزيد من إفراز عصارة المعدة‬G ‫(هرمون القاسترين يفرز بواسطة خاليا‬
.‫وحامض الهيدروكلوريك‬
.‫هيستامين يزيد إفراز المعدة‬
‫سكرتين يقلل عصارة المعدة كذلك ببتيد المعدة المثبط‬
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In the stomach after the action of HCl &
churning movement semi fluid chyme is
formed. )‫ سائل الكيموس‬، ‫(حركة خلط‬
Once the food has been well mixed peristaltic
wave will start, pyloric valve open & throws
3ml or less chyme into duodenum. ‫(موجات‬
)‫تمعجية‬
Once the duodenum get filled “(Entrogastric
reflex) occurs which will stop further gastric
emptying. )‫ تفريغ المعدة‬، ‫(منعكس معوي معدي‬
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‫البواب = ‪Pylous‬‬
‫ّ‬
‫ص ّمام = ‪Valve‬‬
‫صمام البواب فاتح جزئيا‬
‫صمام البواب مغلق‬
‫البواب‪.‬‬
‫موجات تمعجية في الجزء السفلي من المعدة لخلط وتحريك الكيموس ودخوله صمام ّ‬
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Small Intestine
Small intestine is a muscular tube extending from pyloric sphincter to the
iliocecal valve.
The length is about 2 to 4 meter in living person.
Sub divisions (parts) of small intestine:
Duodenum
2.
Jejunum
3.
Ileum
Pyloric sphincter of stomach controls the entry of food in the small
intestine.)‫مصرة المعدة‬
(
ّ
Chemical digestion of food start seriously starts here by various digestive
enzymes produced by intestinal cells more importantly by pancreas
discharged into duodenum by pancreatic ducts.Blie (formed by the
liver) also enters the duodenum through bile duct in the same area.
)‫ البنكرياس والصفراء يبدأ في اإلثني عشر‬،‫(الهضم بواسطة إنزيمات هاضمة من األمعاء الدقيقة‬
1.
Nearly all food absorption takes place in small intestine. )‫(امتصاص المواد الغذائية‬
Its wall has structure that increase the surface area for absorption like
intestinal villi and micro villi (tiny projections from the mucosal
cell)
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)‫نتوأت في خاليا غشاء المعدة‬
‫( تزاد مساحة سطح االمتصاص بواسطة‬
As the food reaches small intestine
carbohydrate & protein digestion have been
started.
It takes 3-6 hrs. journey of the food to reach
the large intestine by that time all food
digestion has been completed.
‫ ساعات في األمعاء الدقيقة حتى‬6 ‫ إلى‬4 ‫(يأخذ هضم الطعام حوالي‬
.)‫إلى األمعاء الغليظة القولون‬
The important enzymes helping in the digestion
are,
• Pancreatic enzymes )‫(أنزيمات البنكرياس‬
• Intestinal enzymes.)‫(أنزيمات األمعاء الدقيقة‬
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Absorption
After the action of gastric juice,pancreatic juice,
bile & different intestinal enzyme the food get
digested and then absorption of all the
digested material & water occurs all along the
entire length of the small intestine.
Most substances are absorbed & enter the
capillary bed in the villus to be transported in
blood to liver.
Lipids or fats are absorbed by capillaries as well
as lacteals and carried to liver by both blood
& lymphatic fluids.
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The Large Intestine (‫األمعاء الغليظة )القولون‬
Larger in diameter
1.5 m long
Extends from iliocecal valve to the anus.
Major function is absorption of water )‫(امتصاص الماء‬
.
Subdivisions:
 Cecum
 Appendix
 Colon
 Rectum & Anal Canal
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What is finally delivered to the large intestine contains
some undigested food & few nutrients.
In the colon the remaining water is absorbed and the
bacteria present there metabolizes some remaining
nutrients producing gas (flatus).
The bacteria also synthesizes vitamins like vit.K & some
B vitamins.
Feces, the more or less solid product is delivered to the
rectum contain undigested food, mucus, millions of
bacteria and very little water.
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Defecation
The process of giving out the feces is
known as Defecation.
As the feces reaches the rectum the slow-moving but powerful contraction of
large intestine known as Mass
movement occur to push the rectal
contents outside.
Defecation reflex is spinal reflex it can be
controlled voluntarily.
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Accessory Digestive Organ
)‫(أعضاء هاضمة ملحقة‬
Salivary Glands )‫(الغدد اللعابية‬
There are three pairs of salivary gland.
 Parotid Gland
 Submandibular Gland
 Sublingual Gland
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Liver and Gall bladder (‫)الكبد وكيس الصفراء‬
Liver is the largest gland in the body.
Functions:
 Metabolic functions )‫(استقالب‬
 Secretion of bile )‫(تكوين وإفراز‬
 Detoxification )‫(إزالة السموم‬
 Synthesis of plasma protein )‫(إنتاج بروتينات البالزما‬
 Storage of blood & Vitamins )‫(تخزين الدم والفيتامينات‬
Gall bladder )‫(كيس الصفراء المرارة‬
The gall bladder stores & concentrates the bile secreted by the
liver. )‫(تخزين وتركيز الصفراء‬
While the food is in duodenum it discharge its contents there
for emulsification of fat.
‫ تكسير الدهون إلى جزيئات صغيرة ليسهل هضمها وامتصاصها‬:‫استحالب‬

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Have a break
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Role of pancreas
)‫(دور البنكرياس‬
Pancreas secrets a juice rich in;
:‫البنكرياس يفرز أنزيمات‬
• Pancreatic amylase )‫(أمليز البنكرياس‬
• Trpsin )‫(تربسين‬
• Chymotrypsin )‫(كيموتربسين‬
• Carboxypeptidase )‫(ببتيد الكاربون‬
• Pancreatic lipase )‫(بنكرياس ليبيز‬
• Nucleases )‫(أنزيم (نووي) نيوكلييز‬
• Bicarbonate & water )‫(ما وبيكربونات‬
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Regulation of pancreatic secretion
)‫(تنظيم إفراز عصارة البنكرياس‬
The release of pancreatic juice is stimulated by
vagus stimulation & hormones like secretin &
cholecystokinin (CCK).
.‫يحفز بواسطة العصب الحائر وهرمونات السكرتين وهرمون الصفراوية‬
(CCK)
Hence pancreatic juice helps in digestion of
Protein & Lipids.
.‫عصارة البنكرياس تساعد هضم البروتين والدهون‬
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‫تنظيم إفراز‬
‫عصارة البنكرياس‪:‬‬
‫تحفيز العصب الحائر‬
‫يؤدي لتحرير‬
‫عصارة البنكرياس‬
‫‪ .1‬دخول الكيموس في اإلثنى‬
‫عشر يؤدي إلفراز‬
‫هرمون السكرتين و ‪CCK‬‬
‫من الخاليا المخاطية في‬
‫اإلثنى عشر‪.‬‬
‫‪ .2‬دخول هرمون السكرتين‬
‫و ‪ cck‬في الدم‪.‬‬
‫‪39‬‬
‫‪ .3‬هرمون ‪ CCK‬يحفز إفراز عصارة بنكرياس غنية باألنزيمات هرمون السكرتين يفرز‬
‫عصارة غنية بالبيكربونات‪.‬‬
Role of Liver & Gall bladder
‫دور الكبد والصفراوية‬
Liver is a central organ for metabolism of
carbohydrate, protein & lipids.
Metabolic functions of liver include; ‫(وظائف‬
)‫استقالبية‬
Carbohydrate metabolism & regulating blood
glucose level.
Cholesterol metabolism
Synthesis of plasma proteins.
Synthesis of vitamin.)‫(تصنيع‬
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Cont..
Secretion of bile is one of the important function of
liver.
Bile is a yellow-to-green watery solution containing
bile salt, bile pigment (chiefly bilirubin)
cholesterol phospholipids & electrolytes.
Its function is to emulsify large fat globules into
smaller ones. It is stored in gall bladder and the
release is controlled by neural & hormonal
factors.
Secretin & cholecystokinin causes gall bladder
contraction & release of bile.
Fatty food reaching the duodenum also increases
bile secretion.
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Jaundice
)‫اليرقان (الصفار‬
Increase in the concentration of bilirubin
in blood lead to yellowish discoloration of
sclera as well as the skin is known as
jaundice.)‫(زيادة تركيز البيلروبين‬
The causes are; )‫(األسباب‬
• Increase hemolysis . ‫(تكسير كريات الدم‬
)‫الحمراء‬
• Inflammation of liver (Hepatitis)( ‫التهاب‬
‫)الكبد‬
• Blockage of biliary tree. )‫(انسداد قناة الصفراوية‬
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CARBOHYDRATE
Starch
Mouth
Salivary Amylase
Oligosaccharides
Small Intestine
Pancreatic Amylase
Maltose
Small Intestine
Lactase, Maltase Sucrase
Glucose
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Proteins
Proteins
Stomach
Pepsin
Large Polypeptides
Small Intestine
Small Intestine
Trypsin, Chymotrypsin
Carboxypeptidase
Small Polypeptides
Amino peptidase
carboxypeptidase
Aminoacid
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LIPIDS
Unemulsified lipids
Small Intestine
Emulsified by bile salt
From liver
Small Intestine
Pancreatic Lipase
Monoglycerides
And Fatty acids
Glycerol and
Fatty acids
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GASTROINTESTINAL
MOVEMENTS
Peristalsis )‫(تمعجية‬
It’s a involuntary
process involve
alternating waves of
contraction &
relaxation squeeze
the food along the
tract.
)‫حركات غير إرادية متعاقبة (مترادفة‬
‫لدفع الطعام‬

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SEGMENTATION CONTRACTION
‫انقباض تقسيمي متعاقب لخلط الطعام‬

Single segment of
the intestine
alternately contract
& relax thus the
food is mixed
rather propelled
along the tract.
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