GASTROINTESTINAL SYSTEM(GIT). 2 Part 1: Anatomy and Physiology of the Digestive system. Part 2 :...

GASTROINTESTINAL SYSTEM(GIT)

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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. ( الهضمية (القناة2.Accessory digestive organ.( هضمية أعضاء

(ملحقة

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اللعابية الغدد

الفم تجويف

اللسان

البلعوم

المرئ

الكبد

المرارة

الدقيقة األمعاء

الشرج فتحة

الشرج قناة

المستقيم

الصاعد القولون

الغليظة األمعاء

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Alimentary Canal (GIT) Mouth (الفـــم) Pharynx (البلعوم) Esophagus (المرئ) Stomach (المعدة) Small Intestine ( الدقيقة (األمعاء Large Intestine( الغليظة (األمعاء

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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األملس السقف

األنفي البلعوم

السقفية اللوزة

اللسانية اللوزة

الفمي البلعوم

المزماري البلعوم

المرئ

العظمي السقف

القم تجويف

الشفتان

اللسانية الزائدة

اللسان

الهوائية القصبة

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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 - اللعابي األمليز (أنزيم

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Salivary Glands

The product of the salivary glands, Saliva is a mixture of mucus & serous fluids.

( ومخاط سائل (خليطMucus helps to moisten the food & to bind

food to form a bolus.( الطعام (ترطيبIt also contain, An enzyme salivary amylase for digestion of

starch. ( النشويات األمليز ( أنزيمLysozyme and antibodies (IgA) that inhibit

bacteria, therefore it has protective function.(( مناعية ( وظيفة البكتيريا لقتل مضادة وأجسام محلل (أنزيم

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Pharynx

PHARYNX

OROPHARYNX LARYNGOPHARYNX

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IngestionSwallowing(البلع) It’s a complicated process requires the

coordinated activities of; tongue, soft palate, pharynx & esophagus.

Phases:1. Buccal phase( خموية (مرحلة2. Pharyngeal phase( بلعومية (مرحلة3. Esophageal phase( مريئية (مرحلة

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منقبضة منبسطةمنقبضة العلوية المرئ ة �معر

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ESOPHAGUSLayers of esophagus & GI tractInside to outside the layers are; Mucosa Submucosa Muscularis Externa Serosa Activities in the esophagus( ( المرئ نشاطات

In the esophagus the food is simply propelled down by peristaltic waves to the stomach.( بواسطة الطعام دفع (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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StomachStomach act as temporary “storage tank” for food as well as a

site for food break down. ( تخزين also churn & mix(مستودعthe food, physically breaking it down to smaller fragments.( وخلط (تقطيع

Chemical breakdown of protein begins in the stomach.( المعدة في يبدأ البروتينات (تكسير

The gastric mucosa ( المعدة is lined by simple columnar(غشاءepithelium secreting large amount of mucus ( المادة إفراز. (المخاط

There are gastric glands which secrete the solution called GASTRIC JUICE. ( المعدة (عصارة

The gastric gland contains two important type of cells;( المعدة (خاليا

Chief cells. Producing protein digesting enzymes, PEPSINOGENS.( أساسية (خاليا

Parietal cells. Produces Hydrochloric acid (HCL).( الهيدروكلوريك : حامض جدارية (خاليا

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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 نشط غير أنزيم (تحويل

HCl secretion is controlled by neural & hormonal factors.

Neural factor includes;والتفكير ) النظر وهرموني عصبي تحكم تحت الحامض إفراز

عصبية عوامل هذه الطعام (ورائحة• Sight of food.• Thinking of food.• Smell of food.

All these reflexly stimulate parasympathetic nervous system to increase gastric juice & HCl secretion.

( Gastrin ( المعدة عصارة إفراز في للتحكم هرمونية (عوامل

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Hormonal control of Hcl

( المعدة عصارة إفراز في للتحكم هرمونية (عوامل-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.المعدة ( عصارة إفراز من يفرز ) G يزيد القاسترين هرمون

خاليا بواسطةالهيدروكلوريك .وحامض

المعدة إفراز يزيد .هيستامينالمثبط المعدة ببتيد كذلك المعدة عصارة يقلل سكرتين

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In the stomach after the action of HCl & churning movement semi fluid chyme is formed.( الكيموس سائل ، خلط (حركة

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. ( المعدة تفريغ ، معدي معوي (منعكس

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Pylousالبو~اب =

Valveصم~ام =

مغلق البواب صمام � جزئيا فاتح البواب صمام

. البو�اب صمام ودخوله الكيموس وتحريك لخلط المعدة من السفلي الجزء في تمعجية موجات

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Small IntestineSmall 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:1. Duodenum2. Jejunum3. IleumPyloric sphincter of stomach controls the entry of food in the small intestine.

( المعدة ة (مصر~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.اإلثني ) في يبدأ والصفراء البنكرياس الدقيقة، األمعاء من هاضمة إنزيمات بواسطة الهضم

(عشر

Nearly all food absorption takes place in small intestine. ( الغذائية المواد (امتصاصIts wall has structure that increase the surface area for absorption like

intestinal villi and micro villi (tiny projections from the mucosal cell)المعدة ) غشاء خاليا في نتوأت بواسطة االمتصاص سطح مساحة (تزاد

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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.

( حوالي الطعام هضم األمعاء 6إلى 4يأخذ في ساعاتالقولون الغليظة األمعاء إلى حتى .(الدقيقة

The important enzymes helping in the digestion are,

• Pancreatic enzymes( البنكرياس (أنزيمات• Intestinal enzymes.( الدقيقة األمعاء (أنزيمات

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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 (القولون) األمعاءالغليظة

Larger in diameter1.5 m longExtends from iliocecal valve to the anus.Major function is absorption of water

( الماء . (امتصاصSubdivisions: 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( ملحقة( هاضمة أعضاء

Salivary Glands ( اللعابية (الغددThere are three pairs of salivary gland.

Parotid Gland Submandibular Gland Sublingual Gland

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Liver and Gall bladder ( وكيس الكبد(الصفراء

Liver is the largest gland in the body.Functions: Metabolic functions (استقالب) Secretion of bile ( وإفراز (تكوين Detoxification( السموم (إزالة Synthesis of plasma protein ( البالزما بروتينات (إنتاج Storage of blood & Vitamins( والفيتامينات الدم (تخزين

Gall bladder ( المرارة الصفراء (كيسThe gall bladder stores & concentrates the bile

secreted by the liver.( الصفراء وتركيز (تخزينWhile the food is in duodenum it discharge its contents

there for emulsification of fat.هضمها: ليسهل صغيرة جزيئات إلى الدهون تكسير استحالب

وامتصاصها

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Have a break

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Role of pancreas( البنكرياس (دور

Pancreas secrets a juice rich in;أنزيمات يفرز :البنكرياس

• Pancreatic amylase( البنكرياس (أمليز• Trpsin (تربسين)• Chymotrypsin (كيموتربسين) • Carboxypeptidase( الكاربون (ببتيد• Pancreatic lipase( ليبيز (بنكرياس• Nucleases( ( نيوكلييز ( نووي (أنزيم• Bicarbonate & water( وبيكربونات (ما

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Regulation of pancreatic secretion( البنكرياس( عصارة إفراز تنظيم

The release of pancreatic juice is stimulated by vagus stimulation & hormones like secretin & cholecystokinin (CCK).

السكرتين وهرمونات الحائر العصب بواسطة يحفزالصفراوية (CCK) .وهرمون

Hence pancreatic juice helps in digestion ofProtein & Lipids.

والدهون البروتين هضم تساعد البنكرياس .عصارة

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إفراز تنظيم: البنكرياس عصارة

الحائر العصب تحفيزلتحرير يؤديالبنكرياس عصارة

اإلثنى. 1 في الكيموس دخولإلفراز يؤدي عشر

و السكرتين CCKهرمونفي المخاطية الخاليا من

. عشر اإلثنى

السكرتين. 2 هرمون دخول.cck و الدم في

يفرز CCKهرمون. 3 السكرتين هرمون باألنزيمات غنية بنكرياس عصارة إفراز يحفز. بالبيكربونات غنية عصارة

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Role of Liver & Gall bladder

والصفراوية الكبد دورLiver is a central organ for metabolism of

carbohydrate, protein & lipids.Metabolic functions of liver include;

( استقالبية وظائف )

Carbohydrate metabolism & regulating blood glucose level.

Cholesterol metabolismSynthesis 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( الصفار ( اليرقان

Increase in the concentration of bilirubin in blood lead to yellowish discoloration of sclera as well as the skin is known as jaundice.( البيلروبين تركيز (زيادة

The causes are;(األسباب) • Increase hemolysis . ( الدم كريات تكسير

(الحمراء• Inflammation of liver (Hepatitis)( الكبد (التهاب• Blockage of biliary tree.( الصفراوية قناة (انسداد

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Mouth

Small Intestine

Small Intestine

CARBOHYDRATE

Starch

Oligosaccharides

Maltose

Glucose

Lactase, Maltase Sucrase

Pancreatic Amylase

Salivary Amylase

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Stomach

Small Intestine

Small Intestine

Proteins

Proteins

Large Polypeptides

Small Polypeptides

Aminoacid

Amino peptidase carboxypeptidase

Trypsin, ChymotrypsinCarboxypeptidase

Pepsin

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Small Intestine

Small Intestine

LIPIDS

Unemulsified lipids

MonoglyceridesAnd Fatty acids

Glycerol andFatty acids

Pancreatic Lipase

Emulsified by bile saltFrom liver

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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.( مترادفة ( متعاقبة إرادية غير حركات

الطعام لدفع

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SEGMENTATION CONTRACTIONالطعام لخلط متعاقب تقسيمي انقباض

Single segment of the intestine alternately contract & relax thus the food is mixed rather propelled along the tract.

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