The document summarizes the anatomy and physiology of the gastrointestinal tract. It describes the gastrointestinal tract as over 10 meters long, starting at the mouth and ending at the anus. It discusses the roles and structures of the mouth, teeth, tongue, esophagus, stomach, small intestine, large intestine, and associated accessory organs. It also outlines the main functions of the gastrointestinal tract as ingestion, digestion, absorption, and egestion.

1. Lecturer : Umar Tariq
Msc OTT/ Anaesthesia

2. Anatomy and physiology of
gastrointestinal tract
 Gastrointestinal tract is a gate through which nutritive
substances, vitamins, minerals, fluids enter the body
 The digestive tract is more than 10 meter (30 feet) long from
one end to the other.
 Starting at the mouth, passing through the pharynx, the
esophagus, the stomach, the small and large intestines and
ending in the rectum and finally into the anus.
 Associated with it are accessory organs of digestion: teeth
,tongue,salivary glands, liver and pancreas.

3.  From the mouth ,the chewed food mixed with saliva passes
into the pharynx,then into the oesophagus which is a 25 cm
long fibromuscular tube lined with mucous membrane.
 The contraction and expansion movement of its wall called
peristaltic movements cause the food to pass into the
stomach .
 From the stomach the food passes into small intestines, the
first part of small intestines is duodenum which is about 25
cm long and shaped like letter (C). Then jejunum which is
about 2.5 metres long and the ileum which is about 3.5
metres long.

4.  The small intestines then merge with the large intestines ,which are
wider than the small intestines.
 The large intestines are divided into nine parts.
 Starts with the caecum into which the ileum opens.
 Then there is the vermiform appendix which is about 7.5cm in length
 Next there is the ascending colon which passes up along the right
side of the abdomen and lead into the transverse colon and then
descending colon which goes down the left side of the abdomen to
sigmoid colon and the rectum which is 12.5-15 cm long
 The exit of which guarded by two sphincter muscles is known as
anus.

5. FUNCTIONS OF DIGESTIVE SYSTEM
The GI tract is responsible for breaking down food and
supplying the body with water, nutrients and electrolytes
needed to sustain life. This is brough about the following
processes
1. Ingestion involves
 Placing food into the mouth
 Chewing the food into smaller pieces(mastication)
 Moistening the food with salivary secretions
 Swallowing the food(deglutition)

6. 2. Digestion :
During digestion, food is broken down into small particles
by grinding action of the GI tract and then degraded by
digestive enzymes into usable nutrients.
3. Absorption :
during absorption , nutrients, water and electrolytes are
transported from the GI tract(mainly from small
intestines) to circulation.
4. Egestion :
during egestion, the undigested food along with various
secretions and sloughed-off epithelial cells from GI tract,
pass into rectum and constitute the faeces which are
voided through the anus at periodic intervals.

7. MOUTH(oral cavity)
The mouth is lined by mucous membrane which consists of
stratified squamous epithelium containing mucous
secreting glands.
BOUNDARIES
1. Anteriorly : by lips
2. Posteriorly : it is continuous with oropharynx.
3. Laterally : by muscles of cheeks.
4. Superiorly : by bony hard palate and muscles of soft
palate.
5. Inferiorly : by soft tissues of floor of mouth and tongue.

8. TONGUE
 The tongue is a voluntary muscular structure.
 It is attached by its base to the hyoid bone and by
frenulum(a fold of mucous membrane) to the floor of
mouth.
 Its superior surface consists of stratified squamous
epithelium with little projections called papillae. The
papillae contains taste buds.
 It plays an important role in chewing, swallowing,
speech and taste.

9. TEETH
 The teeth are embedded in sockets of mandible and
maxilla. Each person has two sets of teeth: temporary
and permanent
1. TEMPORARY TEETH : they are 20 in number, ten in
each jaw. They begin to erupt at the age of six
months and all are present at the age of 24 months.
2. PERMANENT TEETH ; They are 32 in number and
begin to replace the temporary teeth in the 6 years of
age. It is usually complete by 24th year.

10. Functions of teeth
 The incisor and canine teeth have cutting surfacesand
are used to bite pieces of food
 The premolars and molars have broad and flat surfaces
and are used to chew (or grind) food.