Digestive system

MOUTH

Mouth or Oral cavity is bounded by muscles and bones

Mouth is covered by

1.ANTERIORLY –By the lips

2.POSTERIORLY- It is continous with the oropharynx

3.LATERALLY – By the muscles of the cheeks.

4.SUPERIORLY- By the bony hard palate and muscular soft palate.

5.INFERIORLY –By the muscular tongue and the soft tissues of the floor of the mouth

The oral cavity is lined throught with mucus membrane ,consisting of stratified squamous epithelium containing small mucus –secreting glands.

The part of the mouth between the gums and the cheeks is the vestibule and the remainder of the is the oral cavity.

The palate forms the roof of the mouth and is divided into the anterior hard palate and the  posterior soft palate .

The vulva is a curved fold of muscle covered with a mucus membrane

Ø  It is the upper extended portion of thedigestive tract.

Ø  The anterior opening of the mouth is bounded by lips.

Ø  The cavity is dome shaped roof is called PALATE.

Ø  This form an arch with uvula hanging behind in the centre.

Ø  The pharyngeal tonsils present on either side of the cavity protects against the infection of the adjacent area.

Ø  In the mouth food is masticated with the help of teeths and it is also mixed with saliva called “BOLUS”.

TONGUE

Tongue is a voluntary muscular structure that occupies the floor of the mouth.

It is attached by its base to the hyoid bone .

1.INTRODUCTION  : It is a boneless muscle which is present in the mouth .

2. SITUAITION :Situaited at the base of the mouth .

3.STRUCTURE: 2/3^rd portion in front & 1/3^rd  portion in the postrrior part of oral cavity has taste buds & papillae on its surface.

It is a mobile organ with a tip of body and base.

4.BLOOD SUPPLY:

Ø  ARTERIAL BLOOD SUPPLY : Lingual artery branch of Carotid artery.

Ø  VENOUS DRAINAGE: Lingual vein into internal jugular vein .

                    NERVE SUPPLY

                               MOTOR NERVE SUPPLY – Hypoglossal nerve.

Ø                          SENSORY NERVE SUPPLY- Lingual nerve, glassopharyngeal nerve.

FUNCTIONS:

It helps for speech

It helps for Deglutition.

It helps to find the sense of  taste.

It helps for mastication.

                                                            TEETH

                       

                              

The teeth are embedded in the alveoli or sackets of the alveolar ridges of the mandible and the maxilla.

The babies are born with two sets , or dentitions, the temporary or deciduous teeth and the permanent teeth .

After birth the teeth of both dentitions are present , in immature form ,in the mandible and maxilla.

There are 20 temporary teeth, 10 in each jaw.

They begin to erupt when the child is about 6 months old, and should all be the present by 24 months.

The permanent teeth begin to replace the deciduous teeth in the 6^th year of the age and this dentition,consisting of 32 teeth, is usually complete by the 24^th year.

FUNCTIONS  OF THE TOOTH 

1.       The incisor and canine teeth are the cutting teeth and are used for biting off pieces of food.

2.       The premolar and molar teeth,with broad ,flat surfaces, are used for grinding or chewing food.

STRUCTURE OF THE TOOTH 

The shapes of the different teeth  vary,the structure is the same and consists of

1.the crown -  the part that protrudes from the gum.

2.the root – the part embedded in the bone,

3.the neck – the slightly narrowed region where the crown merges with the root.

 The centre of the tooth is the pulp cavity containing blood vessels ,lymph vessels,and nerves, and surrounding this is hard ivory-like substance called DENTINE.

Outside the dentine of the crown is a thin layer of very hard substance, name it has ENAMEL.

The root of the tooth,on the other hand, is covered with a substance resembling bone, called it has CEMENT ,which secures the tooth in its socket.

Blood vessels and nerves pass to the tooth through a small foramen at the apex of each root.

BLOOD SUPPLY

ARTERIAL BLOOD SUPPLY – Branches of the maxillary arteries.

VENOUS DRIANAGE-  Internal jugular veins.

NERVE SUPPLY

The nerve supply to the upper teeth is by branches of the MAXILLARY Nerves and to the lower teeth by branches of the MANDIBULAR Nerves.

These are both branches of the TRIGEMINAL NERVES(5^th cranial nerves)

                                

    SALIVARY GLANDS

1.INTRODUCTION:

            Salivary glands secrete saliva into the oral cavity.

2.SITUIATION :

            These are paired major salivery glands situated outside the mouth and their secretions reaches mouth through ducts.

            Minor Salivary glands are located in the mucous of the oral cavity.

3.MAJOR GLANDS :

            1.PAROTID GLANDS

            2.SUBMANDIBULAR GLANDS

            3. SUBLINGUAL GLANDS.

4. CONTENTS OF SALIVA :

            1.90% of water.

            2.10% of Salts and minerals.

5. FUNCTIONS OF SALIVA:

v  It maintains the Body temperature.

v  It regulates the pH level of the body.

v  It helps to swallow the food.

v  It Produces the Moisturization in the oral cavity.

PHARYNX

1.       INTRODUCTION :  it is a common passage for both air & food. It is a muscular tube lined by mucus membrane.

2.       SITUATION : situated at the base of the skull to the level of sixth cervical vertebra.

3.       MEASUREMENT :  about  12 cm

4.       STRUCTURE :

The pharynx is divided into three parts:

1.       Nasopharynx

2.       Oropharynx

3.       Laryngopharynx

NASOPHARYNX :

Ø  It lies behind the nose above the level of soft palate.

Ø  The lateral wall contains opening of pharygotympanic tube (auditory tube), which leads to the middle ear.

Ø  On the posterior wall is the pharyngeal tonsil.

Ø  It is well developed in children  & small or absent in adults.

Ø  An enlarged pharyngeal tonsil is called adenoids.

      OROPHARYNX :

Ø  It lies behind the mouth below the level of soft palate.

Ø  It contains the palatine tonsils on its lateral wall.

     LARYNGOPHARYNX :

Ø  It extends from the  oropharynx  & continue as esophagus below.

     MUSCLES OF PHARYNX :

The wall of pharynx is formed by mainly three pairs of constrictive muscles.

·         Superior constrictor

·         Middle constrictor

·         Inferior constrictor

5.       BLOOD SUPPLY :

ARTERIAL SUPPLY : branches of external carotid , facial & maxillary arteries.

VENOUS DRAINAGE : internal jugular and facial vein .

6.       NERVE SUPPLY :

Pharynx  is supplied by pharyngeal plexus of nerves formed by branch of vagus,  branch of glossopharyngeal nerve & branches of superior cervical sympathetic ganglion.

7.       APPLIED ANATOMY :

Ø  Pharyngitis – inflammation of pharynx

Ø  Tonsillitis : inflammation of tonsils.

8.       FUNCTIONS :

v  It act as passage for both air and food.

v  It play and important role in hearing.

v  The palatine tonsil & pharyngeal tonsil protects the body from microorganism.          
STOMACH

1.       INTRODUCTION : it is a hallow muscular organ in the digestive system.

2.       SITUATION : it is situated in the epigastric region and towards to the left hypochondriac region and expandable to the umbilical region in the abdominal cavity

3.       SHAPE : J shape

4.       MEASUREMENTS :

                Length : 25 cm

                Capacity :1.5 litre to 2 litre

5.       ORGANS ASSOCIATED WITH THE STOMACH

ANTERIORLY : left lobe of liver and abdominal wall.

POSTERIORLY : abdominal aorta ,pancreas ,spleen,left kidney and adrenal gland
SUPERIORLY : Diaphragm , oesophagus (food pipe) and lobe of the liver.

INFERIORLY : Transverse colon and small intestine.

6.       STRUCTURE 

PARTS OF THE STOMACH :

 FUNDUS , BODY AND PYLORIC ANTRUM

 FUNDUS – it is the upper part of the stomach

BODY – the body lies between the fundus and pyloric sphincter.

PYLORIC ANTRUM : it is the lower part of the stomach contain pyloric sphincter.

The pyloric sphincter operates the opening between stomach and duodenum.

Duodenum walls containing four layers outer peritoneal coat from the serous layer muscular coat has three layers of smooth muscle fibre .i.e .

1)      Outer longitudinal fibers

2)      Middle longitudinal fibres

3)      Inner oblique fibre

                     Submucous layer contain blood vessels, lymphatic and nerve plexus.

Mucus membrane containing many gastric gland

                                The gastric gland secret gastric juice .

 THERE ARE TWO OPENINGS

  Cardiac sphincter and pyloric Sphincter

THERE ARE TWO CURVATURES :

 GREATER CURVATURE : greater curvature is convex and forms the left border of the stomach.

It provides attachment of greater omentum for storage .

LESSER CURVATURE :

   The lesser curvature is concave and short and forms the right border of the stomach , it provides attachment for lesser omentum .

7.       BLOOD SUPPLY :

ARTERIAL SUPPLY : Gastric artery , it is a branch of celiac artery .

VENOUS DRIANAGE : Portal vein, spleenic vein .

8.       NERVE SUPPLY :

                Sympathetic nerve supply

                Para sympathetic nerve supply

9.       APPLIED ANATOMY

GASTRITIS :  inflammation of the stomach

Ulceration of the stomach

Carcinoma of stomach

10.   FUNCTIONS

·         Helps for storage of food upto 3-4 hours

·         It helps for mixing of food with the help of gastric juice

·         Production of hcl to kill the poisonous / harmfull substances of the food

·         It helps to secret the vitamin B₁₂

LIVER 

1.INTRODUCTION :

                     Liver is the Largest gland in digestive system of the  Body.

2.SITUTATION:

                      It is Situated in the upper part of the Abdominal cavity occupying the greater part of the right hypochondriac region, Part of the Epigastric region and extending into the left hypochondriac .

3.SURFACES: 

                     Upper and Anterior surfaces are smooth and curved to fit the under surface of     the    diaphragm.

                   POSTERIOR SURFACE is irregular in outline.

4.SHAPE:                 

                             WEDGE Shape.

5.WEIGHT  : 1.5 to 2.5 kg

6.PARTS OF THE LIVER : 

            Mainly are of 4 Lobes .

1. RIGHT LOBE    
2.  LEFT LOBE
3. CAUDATE LOBE        
4.  QUADRATE LOBE

                 * RIGHT LOBE: It is the Largest lobe of liver  and forms 5/6 the  of the liver .

                                                     It presents CAUDATE and  QUADRATE  lobes.

*CAUDATE LOBE : It is bounded on right side.

        It has 2 process

Ø  CAUDATE PROCESS

Ø      PAPILLARY PROCESS

*QUADRATE LOBE  : It lies on the interior surface , it is in rectangular shape.

                       *LEFT LOBE : Forms 1/6 th  of the liver . It is flattened from above downward.

                7. ORGANS ASSOCIATED WITH THE LIVER .

                          A) SUPERIORLY : Diaphragm & Anterior abdominal wall .

                          B) INFERIORLY  : Stomach, Bile ducts, Duodenum,Hepatic flexure of the colon, right kidney & adrenal gland.

                          C) POSTERIORLY : Oesophagus , IVC, Aorta,Gall bladder, Vertebral column & Diaphragm .

                          D) LATERALY: Lower ribs & Diaphragm .

           













   8.         8.  STRUCTURE:

             9.BLOOD SUPPLY

a.      Arterial supply :

b.       hepatic artery. 1. Right and left Coeliac artery.

             b.Venous Drainage :

                      Hepatic vein ,Inferior Venecava and Portal vein .

           10.LYMPHATIC DRAINAGE:

                                                Draining lymph to Abdominal & Thoracic nodes .

             11. NERVE SUPPLY :

                              A) SYMPATHETIC NERVE SUPPLY

                               B) PARA SYMPATHETIC NERVE SUPPLY.

             12.APPLIED ANATOMY

                         Hepatitis , Liver failure , Cirrohosis of liver. jaundice 

            14.FUNCTIONS.

                      1.Carbohydrate metabolism

                      2.protein metabolism :

                                 Deamination of amino acids.

                       3.Fat metabolism :

                               Desaturation of fat.

                        4.Breakdown of erythrocytes and defence against microbes.

                        5.Detoxification of drugs & noxious substances.

                        6.Metabolism of ethanol .

                        7.Inactivation of harmones

                         8.Synthesis of Vitamin

                          9.Production of heat.

                        10.Secretion of bile.

                         11.Storage of Vitamin.

PANCREASE

1.INTRODUCTION:

It Is a  Mixed Gland Which Is Present In The Digestive System .

2.SITUATION :

Pancrease Is Situated In The Epigastric And Left Hypochondriac  Regions Of The Abdominal Cavity.

3. SHAPE

LEAF SHAPE

4. MEASUREMENTS

LENGTH :12 to 15 c m

WEIGHT: 60 grams

COLOUR: Pale Gray

5.PARTS

Pancreased described into

1.HEAD

2.BODY

3.NARROW TAIL

§  Head lies in the curve of the duodenum.

§  Body lies in a narrow tail.

§  Tail lies in front of the left kidney and reaches the spleen.

§  The abdominal aorta and the inferior venecava lie behind the gland.

§  The pancrease is both an exocrine and endocrine gland.

THE EXOCRINE PANCREASE :-

v  It contains of a large number of lobules made up of the small alveoli, the walls of which consists of secretory cells.

v  Each lobule is drained by tiny duct and these unite to form the pancreatic duct .

v  Which extends the whole length of the gland and opens into the duodenum .

v  The duodenum the pancreatic duct joins  the common bile duct to form the hepato pancreatic ampulla.

v  The duodenal opening of the ampulla is controlled by the hepatopancreatic spincter of oddi .

THE ENDOCRINE GLAND.

Ø  Division of groups of the glands specialled cells called the “pancreatic islets of langherhans”.

Ø  The islets have no ducts so the hormones diffuse directly into the blood and more in the tail.

Ø  1 to 2 million islets cells are found in human pancrease.

Ø  Alpha cells secretes glucagon .

Ø  Beta cells secretes insulin harmone.

   7.BLOOD SUPPLY.

Arterial supply: pancreatic branches of spleenic artery.

Venous drainage: Splenic and portal veins.

8. NERVE SUPPLY

Symphatetic nerve supply

Parasympatetic nerve supply..

FUNCTIONS

1.EXOCRINE PART

Secretion of digestive enzymes and pancreatic juice and helps to digest the carbohydrates,proteins and fats.

2.ENDOCRINE PART

Islets of langerhans produces the Insulin.

Pancreatic juice helps to digestion of proteins, carbohydrates and fats.

     GALL BLADDER.

1.INTRODUCTION: It is a sac like structure as the reserviour of bile.

2.SITUIATION: It is located anteriorly under the liver and on its right abdominal surface.

3.SHAPE: PEAR Shape.

4.PARTS:

                FUNDUS

                BODY

                NECK.

5.MEASURMENTS

                LENGTH: 7-10 cm

                BREADTH:3 cm

                CAPACITY:30-50ml.

6 STRUCTURE:

7.BLOOD SUPPLY:

                ARTERIAL SUPPLY: Cystic artery a branch of right hepatic artery.

                VENOUS DRIANAGE: Portal vein.

8.NERVE SUPPLY:

                SYMPATHETIC NERVE SUPPLY.

                PARA SYMPATHETIC NERVE SUPPLY.

9.FUNCTIONS .

v  Gall bladder helps to store the bile.

v  It helps to absorption of water and inorganic salts.

v  It concentrates 10cc of liver bile into 1cc of gall bladder bile.

v  Gall bladder secretes mucus and excretes cholesterol.

10.APPLIED ANATOMY :

1.GALL STONES :

               Gall stones consist of deposits of the constitutes of bile,most commonly cholesterol.

2.ACUTE CHOLECYSTITIS:

               This is usually a complication of gallstones or an exacerbation of chronic cholecystitis, especially if there has been partial or intermittent obstruction of the cystic duct.

3.CHRONIC CHOLECYSTITIS:

               The onset is usually insidious ,sometimes following repeated acute attacks.

4.TUMOURS OF THE BILIARY TRACT:

               MALIGNANT TUMOURS

5.JAUNDICE

         

   SMALL INTESTINE

1.INTRODUCTION:-  It is continous with the stomach at the pyloric sphincter      and  leads into the large intestine at the ileocaecal valve.

2.SITUATION:-  It lies in the abdominal cavity surrounded by the large intestine 

.

3.SHAPE:- Tube like structure

4.MEASURMENT:-

LENGTH: Over 5meters  long

DUODENUM:25 c.m

JEJNUM :2 meters long

ILEUM: 3 meters long

    5.ORGANS ASSOCIATED WITH DUODENUM

ANTERIOR : Gall bladder, Quadrate lobe of liver.

POSTERIOR: Bile duct,Gastroduodenal artery,portal vein, IVC, Head of Pancrease.

SUPERIOR: Neck of Pancrease,Greater omentum, Head of Pancreas.

TO THE RIGHT : Right kidney,Ascending colon.

TO THE LEFT: Left Kidney,Descending colon.

INFERIOR: Right Ureter,Left Ureter,INFERIOR VENECAVA.

6. SECTIONS:

The Small intestine comprises 3 main sections continous with each other.

v  Duodenum is 25 cm long and Curves  around the head of the pancrease.

v  Jejnum is the middle section of the Small intestine and is about 2 meters long.

v  The ileum or terminal section is about 3 meters long and ends at  the ileocaecal valve, which controls the flow of material from the ileum to the caecum ,the first part of the large intestine , prevents Regurgitation.

7. STRUCTURE OF THE SMALL INTESTINE:

The walls of the Small intestine are composed of the four layers of tissue.

Ø  PERITONEUM

Ø  MUCOSA.

           PERITONEUM:

                                    A Double layer of Peritoneum called the mesentry attaches the jejnum and ileum to the posterior abdominal wall.

           MUCOSA:

The Surface area of the small intestine mucosa is greatly increased by permanent circular folds, Villi and Microvilli.

Ø  The villi are tiny finger-like projections of the mucosal layer into the intestinal lumen, about 0.5 to 1mm long.

Ø  Their walls Consist of columnar epithelial cells (or) enterocytis . with tiny microvilli on their free border.

Ø  Goblet cells that Secrete mucus are interpersed between the enterocytes.

Ø  These epithelial cells enclose a network of blood and lymph capillaries.

Ø  The lymph capillaries are called LACTEALS because absorbed fat gives the lymph a milky appearance.

Ø  The intestinal glands are simple tubular glands situated below the surface between the villi.

Ø  Lymph nodes are found in the mucosa at the irregular intervals throughout the length of the small intestine these are known as SOLITARY LYMPHATIC FOLLICLES. And about 20 or 30 larger nodes situated towards  the distal end of the ileum are called “Aggregated lymphatic follicles” (Peyers patches).

        7.BLOOD SUPPLY

        ARTERIAL SUPPLY: Superior mescentric artery.

        VENOUS DRIANAGE: Superior mescentric vein that joins to the portal vein.

        8.NERVE SUPPLY:

                                    SYMPHATHETIC NERVE SUPPLY.

                                    PARA SYMPHATETIC NERVE SUPPLY.

        9. INTESTINAL JUICE:

v  About 1500 ml of juice are secreted daily by the glands of the small intestine .

v  It consists of

v  Water

v  Mucus

v  Mineral salts

v  The PH of Intestinal juice is usually between 7.8 & 8.0

Function

Food from the stomach is allowed into the duodenum through the pylorus by a muscle called the pyloric sphincter.

.LARGE INTESTINE

1. INTRODUCTION :-

                         Large intestine is a “ARCH” like structure in the Digestive system .

2. SITUATION :-

                        It is situated beginning at the caecum in the right iliac fossa and terminating at the rectum and anal canal  deep in the pelvis. 

3. MEASURMENTS:-

                                    Length – 1.5 meters long.

                                    Lumen is about 6.5 cm in diameter.

4. PARTS:-

The colon is divided into

v   THE CAECUM:

v  ASCENDING COLON,

v  TRANSVERSE COLON,

v  DESCENDING COLON,

v   SIGMOID COLON ,

v  RECTUM AND ANAL CANAL.

                      THE CAECUM:- It is the first part of colon . it is a dilated parts and connecting to the ascending colon in superior region.

The vermiform appendix is present in this region ,usually about 8-9cm long and it contains more lymphoid tissue.

ASCENDING COLON,

                   This pass upwards from the caecum to the level of the liver where it curves actually to the left.

  TRANSVERSE COLON,

This is a loop of colon that extends across the abdominal cavitynin front of the duodenum and the stomach to the area of the spleen, curves to downwards.

DESCENDING  COLON :-

This passes down the left side of the Abdominal cavity then curves  the  midline.

After it enters the true pelvis it is known as the SIGMOID COLON.

SIGMOID COLON

It is S shaped curve in the pelvis that contains downwards to become the rectum .

THE RECTUM

It is a slightly dilated section of the colon about 13cm long.

It leads from the sigmoid colon and terminates in the anal canal.

THE ANAL CANAL

v  This is a short passage about 3.8cm long in the adults and leads from the rectum the extesior.

v  2 sphincter muscles control the anus: the internal sphincter consisting of smooth muscle is under the control of the autonomic nervous system.

v  The external sphincter formed by skeletal muscke is under voluntary control.

 

5. STRUCTURE:-

6. BLOOD SUPPLY:-

Arterial supply:

          Superior and Inferior mescentric artery branches of ileocolic artery.

VENOUS DRAINAGE:

   Ileocolic vein joins to portal vein .

7. LYMPH  DRIANAGE:-

Ileocolic group of lymph node.

8. NERVE SUPPLY:-

SYMPHATETIC NERVE SUPPLY:       

                                               

 Preganglionic fibres T10-L1 Segments of sigmoid colon.

PARA SYMPHATETIC NERVE SUPPLY:

                    From vagus nerve.

9. APPLIED ANATOMY:-

v Appendicitis: Inflammation of the vermiform appendix.

v Microbial diseases: Typhoid fever.

v Salmonella infection –Food poisioning,cholera dyscentry.

v Inflammatory diseases- crohns disease –inflammatory condition of the alimentary tract.

v Ulcerative colitis:

Chronic inflammatory disease of the mucosa of the rectum and colon, which  may ulcerate due to infection.

v  TUMOURS:      Rectum and colon.

v  HERNIAS: Protrusion of an organ (or) part of a organ through a weak point.

v  VOLVULOS: This occurs when a loop of bowel twists through 180^ cutting of its blood supply, causing gangrene and obstruction.

v  INTUSSUSCEPTION:  Length of intestine is invaginated into  itself if occurs most common in children.

v  INTESTINAL OBSTRUCTION: Constriction of the Intestine, Stenosis,pressure on the intestine from an outside.

10.             FUNCTIONS:-

1.Storage of matter.

2.Absorption of fluids and solutes.

3. Lubrication of Undigested matter to facilitate its passage.

4.Protection against bacterial invasion due to presence of numerous lymphatic follicles.

5.Synthesis of vitamin B from colonic flora.