1.Gastrointestinal System

8/11/2019 1.Gastrointestinal System

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Gastrointestinal

system



• Oral cavity

• Tongue

• Esophagus

• Stomach

• Duodenum

• Jejunum• Ileum

• Colon

• Rectum• Anal canal

• Liver and pancreas



Oral cavity

• Begins in the Mouth , otherwise known as

the "Buccal Cavity“.

• Divided into vestibule, lips, cheeks, oral

cavity proper and teeth.

• Vestibule:- narrow space bounded

externally by the lips and the cheeks, and

internally by the teeth and gums.

• Parotid duct opens on the inner surface of

the cheek opposite the crown of the 2nd

molar tooth.



• Lips:- are fleshy folds lined externally byskin and internally by the mucous member.

• Cheeks:- are fleshy flaps, continuing in thefront with the lips, and the junction is

indicated my the nasolabial sulcus which

extend from the side of the nose to the

angle of the mouth.



• Oral cavity proper :- bounded

-anterolaterally by the teeth, the gum

and the alveolar arches of the jaws.

-Roof:- formed by hard and soft palate.

-Floor:- by tongue posteriorly andsublingual region anteriorly, below the

tongue.

• Posteriorly, the cavity communicates with

the pharynx.



• Gums (Gingivae):- are soft tissues which

envelop the alveolar processes of the

upper and lower jaws and surround the

neck of the teeth.



Tongue



• Tongue:- The tongue is a skeletal muscle(voluntary) on the floors of the mouths.

• Approximately 3inch long.• Muscles of tongue:- The eight muscles of the

human tongue are classified as either intrinsic orextrinsic .

• The four intrinsic muscles act to change theshape of the tongue, and are not attached to anybone.

• The four extrinsic muscles act to change the

position of the tongue, and are anchored to bone.



Shapea root

an apex

dorsum surfaceinferior surface

apex

root

body

Oral part

Pharyngeal part

terminal sulcus



The mucous membrane of the inferior

surface of the tongue:

Frenulum of tongueSublingual caruncle

Sublingual fold

Frenulum of tongue

Sublingual caruncle

Sublingual fold



• Extrinsic muscles:- originate from bone and

extend to the tongue and their main functionsare altering the tongue's position allowing for

protrusion, retraction, and side-to-side

movement.

-Genioglossus

-Hyoglossus

-Styloglossus

-Palatoglossus



• Intrinsic muscles:-The main function

of the intrinsicmuscles is toprovide shape.

-Superior longitudinal

-Inferior longitudinal

-Vertical

-Transverse



• Blood supply;- lingual artery, tonsillar and

pharyngeal artery.

• Lymphatic drainage:- tip of the tongue

drain into submental nodes, and right and

left halves of anterior 2/3rd drain into

submandibular nodes, and posterior 1/3rd

drain into Jugulo-omohyoid lymph node.



Never supply

• Anter ior 2/3rds of tongue

-General somatic afferent: lingual nerve

branch of V3 of the trigeminal nerve CN V

-Taste:- chorda tympani branch offacial nerve CN VII (carried to the tongue

by the lingual nerve).

• Poster ior 1/3rd of tongue

-General somatic afferent and taste:

Glossopharyngeal nerve CN IX.



• Motor:- All intrinsic and extrinsic muscles

of the tongue are supplied by the

hypoglossal nerve (CN XII), except for one

of the extrinsic muscles, Palatoglossus,which is innervated by CN X of the

pharyngeal plexus.



The Palate

Constitutes:the roof of the mouth

the floor of the nasal

cavity.Composition:

hard palate(2/3)

soft palate(1/3)

hard palate

soft palate



Teeth



The Teeth (Dentes)

Two sets of teeth in man: Deciduous (milk)

and permanent .

Basic shape:

Crown

Neck (cervix)

Root (or roots)



Structure:

EnamelDentine

Cement

Periodontalmembrane

Dentine

Enamel

Cement

Periodontalmembrane



Crown - exposed surface of tooth.

Neck - boundary between root

and crown.

Enamel - outer surface

Dentin – bone-like, but noncellularPulp cavity - follow with blood

vessels and nerves

Root canal - canal length of rootgingival sulcus - where gum andtooth meet.



Types and Numbers of Teeth

Dental succession

Deciduous (baby, milk) teeth - 20, replaced by

Permanent teeth - 32 teeth



The Salivary Glands

The major salivary glands• parotid gland

• submandibular gland

• sublingual gland



). The Parotid Gland

Parotid Glandpapilla



). The Submandibular Gland

Submandibular GlandSubmandibular duct

Sublingual

caruncle



Sublingual GlandSublingual duct

Sublingual

caruncle

Ⅲ). The Sublingual Gland

Sublingual fold

Name Shape Location Duct meatus



Name Shape Location Duct meatus

Parotid gland Three sided

pyramid

anterior and

inferior to the

external acousticmeatus, overlying

the ramus of

mandible.

Opposite of the

upper 2nd molar

tooth

Submandibular

gland

Lying superior to

the digastric

muscles.

Opens on the floor

of the mouth, at

the side of the

frenulum of the

tongue.

Sublingual gland Almond shape Lie anterior to the

submandibular

gland under the

tongue.

Opens directly into

the floor of the

mouth.



Pharynx

………go thro respiratory system..



Esophagus



• The esophagus is a narrow musculartube through which food passes from the

pharynx to the stomach.

• It is usually about 25 cm long.

• The esophagus is continuous with part ofthe pharynx at the level of the C6 vertebra.

• The abdominal part of the oesophagus isonly about 1.25cm.



• The esophagus passes through posterior

mediastinum in thorax and enters

abdomen through a hole in the diaphragmat the level of the tenth thoracic vertebrae

(T10).

• Nonkeratinized stratified squamousepithelium.

• Muscularis externa

- upper 3rd is compose of striated muscles

- middle 3rd mixed type

- lower 3rd smooth muscles.



Esophageal constrictions

• Normally, the esophagus has 4 constrictions atthe following levels.

• At the esophageal inlet, where the pharynx joinsthe esophagus, behind the cricoidcartilage,15 cm from the incisor teeth.

• Where it is crossed by the aortic arch, 25cm from the incisor teeth.

• Where it is crossed by the left bronchus,27.5 cm from the incisor teeth.

• Where it pierces the diaphragm, 37.5 cm fromthe incisor teeth).

• The distances from the incisor teeth areimportant.



Relation• Anterior:- trachea, right pulmonary artery, left

bronchus, pericardium with left atrium, thediaphragm

• Posterior :- vertebral column, right posteriorintercostal arteries, thoracic duct, azygos vein,thoracic aorta, right pleural recess anddiaphragm.

• To the left:- aorta, left subclavian artery,

thoracic duct, left lung and pleura, left recurrentlaryngeal nerve.

• To the right:- right lung and the pleura, azygosvein and the right vagus.



• Arterial supply:- cervical part by branch ofinferior thyroid artery, thoracic part by

esophageal branch of the aorta, andabdominal part by branches of left gastricartery.

• Venous drainage:- upper part drain intobrachiocephalic vein, middle part goes toazygos vein and lower part goes to leftgastric vein.

• The lower end is one of the sites forprotosystemic anastamosis.



• Lymphatic drainage:- cervical part drain into

deep cervical nodes, thoracic part to the

posterior mediastinal nodes and abdominal partto left gastric nodes.

• Nerve supply:-

- Parasympathetic, upper half by recurrentlaryngeal nerve and lower half by oesophageal

plexus. Nerves are sensor, motor and

secretomotor to the oesophagus.

- Sympathetic:- upper half by fibers of middlecervical ganglion and lower half by upper four

thoracic ganglia. Nerves are vasomotor.



Stomach



The Stomachesophagus

duodenum

Liver

Kidney

Transverse colon

spleen

Gallbladder

diaphragm Cardia

Pylorus



• Also known as gaster or venter, and is a

muscular bag, hollow, dilated part of the

digestion system.

• It is located between the esophagus and

the small intestine.

• It acts as a reservoir of food and helps indigestion of carbohydrates, proteins and

fats.



• Location:- it lies obliquely in the upper andleft part of the abdomen, occupying theepigastric, umbilical and lefthypochondriac region.

• Most of the stomach lies under cover ofthe left costal margin and the ribs.

• Shape and position:- when empty,stomach is J-shaped (vertical), whenpartially distended, it become pyriform.

• Size:- it is 25cm long, and mean capacityis one ounce (30ml) at birth, one litre atpuberty and 1.5 to 2litres or more in adults.



• External features:-

- two orifices or openings,

- two curvatures or borders, and

- two surfaces.

• Two orifices:- cardiac or i f ice is joined by lower

end of oesophagus and it lies behind the 7th costal cartilage 2.5cm from the junction with the

sternum, at the level of T11 vertebra.

- py lor ic o r i f ice opens into duodenum, it lies

to the right of the medial plane, at level of lower

border of L1 vertebra.



• Two curvatures:- lesser cu rvature isconcave and forms the right border of the

stomach and attached to lesser omentum.The most dependent part is the curvatureis marked by the angular notch or incisuraangularis.

- greater cu rvatu re is convex and formthe left border and attached to greateromentum, the gastrosplenic ligament and

the gastrophrenic ligament. At upper end itpresent cardiac notch which separates itform oesophagus.



) Two curvatures

pyloric antrum

pyloric canal

greater curvature

lesser curvature

angular incisure



• Two surfaces:- anterior or anterosuperior

surface faces forward and upward

-Posterior or posteroinferior surface

faces backward and downward.



• The stomach is divided into 2 parts:-

- Cardiac and

- Pylorus

..by the line drawn downwards and to the

left form the incisura angularis.



• Cardiac part is further divided into fundus

and body.

• The gastric glands distributed in the

fundus and body of the stomach,

containing all three types of secretory cells

i) mucous cells ii) the chief, peptic orzymogenic cells and iii) the parietal or

oxyntic cells

• Pyloric part is divided into pyloric antrum(7.5cm) and pyloric canal (2.5cm).



Four parts

fundus

body

pyloric part

pyloric antrum

pyloric canal

Angular incisure

cardiac part

cardiac incisure



Relations of the Stomach

• Peritoneal relations:- stomach is lined by the

peritoneum on both its surface. At lesser

curvature it forms lesser omentum and at greater

curvature it forms the greater omentum.

• Near the fundus the two layers meet to form

gastrosplenic ligament and near the cardiac end

the peritoneum on the posterior surface formsgastrophrenic ligament.



• Visceral relations:- the anterior surface of

the stomach is related to the liver, thediaphragm, and the anterior abdominalwall.

• The posterior surface is related to thestructures forming stomach bed. i)diaphragm, ii) the left suprarenal gland, iii)

left kidney, iv) pancreas, v) transversecolon, vi) splenic flexure of the colon, vii)splenic artery, sometime spleen.



Interior of Stomach

• Mucosa

• Submucosa

• Muscularis

• Serosa ……………………….



Musculature and Inner Surface

) The musculature of the stomach

Three layers of smooth muscle

outer longitudinal layer:

inner circular layer: uniform, pyloric

sphincter ---- a thickened muscular ring at

the pylorus

Internal to circular muscles: an incomplete

layer of oblique muscle.



longitudinal layer

circular layer

oblique layer(incomplete)

Pyloric sphincter



) The inner surface of the stomach

The mucosa : thick.

Gastric ulcers

neoplasms



Blood supply

Lymphatic drainage



Lymphatic drainage

• It can be divided into 4 territories:-

• Area a or pancreaticosplenic nodes

• Area b or left gastric nodes

• Area c or right gastroepiploic nodes

• Area d or pyloric nodes



Nerve supply

• The stomach is supplied by sympathetic andparasympathetic nerves.

• Sympathetic nerves are derived from T6 to T10segments of the spinal cord, via the greatersplanchnic nerves and coeliac and hepaticplexuses.

• Pathway for the pain sensations from thestomach.



• Parasympathetic nerves are derived from the vagus,through oesophagus plexus and gastric nerves.

• Anterior or left vagal fibres divides into i) gastricbranch for anterior surface of the fundus and bodyof stomach, ii) two pylorus branches

• Posterior or right vagal fibres divides into i) smaller

gastric branches for the posterior surface of thefundus, body and antrum, ii) larger, coeliacbranches for the coeliac plexus.

• It stimulates to increase the motility of the stomach

and secretion of the gastric juice rich in pepsin andHCL



Functions



Functions• Reservoir of food.

• Mixing of food with the gastric juice by peristalticmovement.

• Secrets gastric juice via gastric gland help indigestion of the food.

• Produce HCL which destroys many organismspresent in food and drinks.

• Protect the gastric mucosa from HCL byproducing mucus.

• Absorption of drugs, water, salt, alcohol etc.• Produce intrinsic factor which helps in the

absorption of Vitamin B12.

1.Gastrointestinal System

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