The digestive system consists of the gastrointestinal tract and glands. It ingests, digests, absorbs and excretes food and waste. The major parts include the mouth, esophagus, stomach, small intestine, large intestine, liver, gallbladder and pancreas. The mouth contains teeth for chewing and salivary glands for digestion. The stomach contains cells that secrete acid and enzymes to digest food into a liquid. The small intestine further digests this liquid and absorbs nutrients with help from the pancreas and liver. The large intestine absorbs water and excretes waste.

1. DIGESTIVE SYSTEM
SUBMITTED BY-
Ambika Bagora
(RN)

2. The digestive system consist of gastrointestinal
tract (alimentary canal) and its gland. The
functions of G.I.T. are -
a. Ingestion
b. Digestion
c. Absorption
e. Excretion of waste products.

3. • Parts of digestive system-
Digestive system consist of following parts-
1. Mouth
2. Pharynx
3. Oesophagus
4. Stomach
5. Small intestine
6. Large intestine
7. Rectum
8. Anus

4. MOUTH – It is upper expanded portion which
forms the beginning of alimentary canal. The
important structure of mouth are:
a. Tongue
b. Teeth
c. Salivary gland

5. 1. Tongue- Tongue lie in the floor of the mouth and
it is attached to hyoid bone. Tongue contains:
* A root at which blood vessel and nerves pass.
* There are four types of taste bud present on the
upper surface-
a. Circumvallate papillae
b. Fungiform papillae
c. Filiform papillae
d. Folate papillae

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7. • TEETH- Teeth are concerned with mastication.
Depending on the age at which they are arises,
teeth can be classified as-
a. Permanent teeth- 32
b. Temporary teeth- 20
Each half of the upper and lower jaw contains 8
Teeth. They are:
2 incisors,
1 canine,
2 premolars,
3 molars

9. Salivary gland- There are three pair of salivary
glands in mouth. They are:
1. Parotid- One on each side is present below
and anteriorly front of each ear. These are
largest of the salivary gland
2. Submandibular- It is a major pair pair of
salivary gland located beneath the lower jaws.
3. Sublingual- It is situated inferior to the
tongue, and anterior to the submandibular
glands.

11. Processes of the mouth-
• Mastication (chewing) of food.
• Mixing masticated food with saliva to produce
easy digested food called bolus.
• Saliva contain enzyme amylase which convert
starch into maltose.
• Initiation of swallowing by tongue.
• Allowing for the sense of taste.

12. PHARYNX
• Nasopharynx- It is not the part of digestive
system
• Oropharynx- It is situated posterior to oral
cavity.
• Laryngopharynx- It is situated below the
oropharynx and connected to the oesophagus.

13. OESOPHAGUS
 It runs from pharynx to stomach.
 It is about 25 cm.
 It is a mucus muscular membrane lined tube.
They perform peristalsis movement
(involuntary rhythmic muscle contraction).

15. STOMACH
It is located on the left side of the abdominal
cavity.
 Region of stomach-
Cardiac region
Fundus region
Body
Pyloric region
Food empties into the small intestine at the
pyloric sphincter.

17. CELLS IN STOMACH:
1. Mucus cells- It secrete the alkaline mucous for
protecting the epithelium from hydrochloric
acid.
2. Parietal cells- It secrete hydrochloric acid; the
acid activates release of pepsin for protein
digestion. The acid also kills micro-organisms
swallowed with the food.
3. Chief cells- It secrete pepsin. These cells are
located in the fundic region.
4. G-Cells- It secrete gastrin which stimulates the
secretion of hydrochloric acid.

18. PANCREAS
The pancreas is closely associated with
duodenum of the small intestine.
 The head of pancreas is located in C-shaped
curve of the duodenum and its tail is against
the spleen.

19. • PANCREATIC JUICE- It contains enzymes
that digest carbohydrate, fats, and protiens.
1. Amylase- It breaks starch into glucose.
1. Lipase- It breaks fat into fatty acids and
glycerol.
1. Tripsin & chymotrypsin- It is proteolytic
enzymes that digest protien.

20. LIVER
• It is reddish brown structure, located in the
upper right quadrant of the abdominal cavity.
• Liver is highly vascuarized, enclosed in a
fibrous capsule and divided into 4 lobe.

21. Liver Functions-
a. It store glycogen, iron, and vitamins A, B12
and D. It can also store 200-400ml of blood.
b. Liver’s role in digestion is formation of bile.
BILE- It is yellowish green liquid that hepatic
cells continuously secrete. Bile emulsify fats
and aid in absorption of fatty acids.

22. GALL BLADDER
* It is pear shaped sac like structure locater in a
depression on the inferior surface of liver. It
store approx. 30-50 ml bile.

23. SMALL INTESTINE
• Small intestine is the part of alimentary canal
which extended from the pyloric end of
stomach to caecum (first part of large
intestine).
• Following are the parts of small intestine-
a. Duodenum
b. Jejunum
c. Ileum

25. 1. Duodenum- It is C-shaped fixed structure
which is attached to posterior abdominal wall
by peritoneum. The bile duct and pancreatic
duct open together at duodenum.
2. Jejunum- It is the continuation of duodenum
and it is the middle portion of small intestine.
3. Ileum- It forms the last part of small intestine.

26. Digestion in small intestine-
The acidic chyme from the stomach enters
into the duodenum. There it mixes with –
• The alkaline intestinal juice called succus
entericus (the clear to pale yellow watery
secretions from the glands lining the small
intestine walls.)
• The alkaline secretions from liver (bile) and
pancreas (amylase, lipase etc.)

27. • Absorption in small intestine- The absorption
of digested food occurs in small intestine
through intestinal villi.
Villi- They are minute finger like projections
which are present in the inner mucous coat
of the intestine .

28. LARGE INTESTINE
It extends from the end of ileum to rectum.
Large intestine consist of following parts-
a. Caecum
b. Appendix
c. Ascending colon
d. Transverse colon
f. Descending colon
e. Sigmoid colon

30. Functions of large intestine-
1. Digestion- This is carried out by microorganism of
colon. They are act on the undigested and unabsorbed
residue from small intestine.
2. Absorption- All carbohydrate, protiens and fat are
already absorbed in small intestine. Only water and
glucose are absorbed in the colon.
3. Secretion- Mucin is the only secretion. It lubricates
the colon and facilitates the passage of fecal matter.
4. Excretion- Iron and some purgatives are excreted in
large intestine.

31. RECTUM
It occupies the lower posterior part of pelvis. It
extends between sigmoid colon and anus. The
lower part of rectum is dilated and it is called
RECTAL AMPULLA.
ANUS
It is a small canal measuring about one inch in
length. The opening of anus is guarded by a
sphincter called anal sphincter. This sphincter is
under voluntary control.

32. DEFECATION
It is defined as evacuation of the fecal matter of
the rectum. Defecation is a reflex mechanism.
But this reflex is under voluntary control. The
reflex for defecation occurs when sufficient
quantity of feces accumulates in the rectum.
• This produces stretching of rectal walls and also
increases pressure in the rectum.
• When the pressure exceeds 40mm Hg the nerve
endings of rectum are stimulated.
• The impulses for defecation are carried to the
rectum through motor nerves.

33. PERITONEUM
It is a serous membrane which lines the
abdomen and covers the abdominal organs. It
consists of the following two layers-
a. Parietal peritoneum
b. Visceral peritoneum