human digestive system

1. DEPARTMENT: PHARMACY
FACULTY :( B.H.M.S) 1st semester
ASSIGNMENT: ANATOMY
TOPIC: DIGESTIVE SYSTEM
SUBMITED
TO:
Dr.KANWAL
SUBMITED
BY:
TAYYEBA
AZAM

2. DIGESTION:
Definition:
The process, by which large, complex,
insoluble, organic food substances are
broken down into smaller, simple,
soluble moleculeby the action of
enzymes, isknown as digestion.
DIGESTIVE SYSTEM:
Definition:
Arrangementof organs which involved in
the process of digestion; in a proper way,
makes a system, called as digestive
system.
Synonyms:
Digestive system is also known as Alimentary canal
OR
Gastro-intestinaltrack (GIT).
More About GIT:
 Itis about 5-7mlong.
 GITis one way tube, having two opening, i.e. Mouth and Anus lined by
mucous membrane.

3. ORGANSOF GIT:
Oralcavity: Itis divided into following parts:
a) Lips
b) Teeth
c) Gums
d) Tongue
e) Cheeks
f) Palate (softand hard)
g) Mucous membrane.
 Pharynx
 Esophagus
 Stomach
 Small intestine
 Large intestine
 Rectum
 Anus
AssociatedGlands:
 Salivary glands:[Parotid Gland, Sublingualgland, Submandibular]
 Liver
 Gall bladder
 Pancreas
Main Function of GIT:
 Ingestion
 Propulsion
 Digestion
 Absorption
 Elimination

4. THE ORAL CAVITY:
Lips, teeth, gums, tongue,
cheeks, palate are formed
oral cavity.
Structure of Oral
Cavity:
 Wide cavity, supported
by bones of skull.
 Externally, bounded by
lips and cheeks.
 Internally, by gums
and teeth.
 Lateral walls made up
muscles of cheeks
 Superiorly, roof made
frompalate.
 Inferiorly, floor madefrom
tongue.
Structure of Tooth:Humans
have two sets of teeth:
a) Deciduous or milk teeth
(20 in numbers)
b) Permanent (32 in numbers)
 Each tooth consist of 3 main
parts:
a) Neck
b) Crown
c) Root

5. Functions of Teeth:Functionally divided into four categories:
a) Incisor: cutting and biting.
b) Canines: pointed teeth to tearing.
c) Premolar: grinding.
d) Molar: grinding and crushing.
Functions of Oral Cavity:
 LIPS: helps in ingestion of food.
 CHEEKS: secretion of mucous and sometimes modified to formsaliva.
 GUMS: fixation of teeth.
 TONGUE: act as spoon, mixing saliva with food.
 PALATE: formed roof of oral cavity.
Associated Glands Of
Oral Cavity:
Salivary Glands: Three types of
salivary glands:
a) Parotid: Located below.
b) Submandibular: Located
under the angle of jaw.
c) Sublingual: Located under
the mucous membraneof
mouth.

6. Functions of Glands:
 Lubrication of food.
 Purifies and moisturizethe oralcavity.
 Secretion of digestive enzyme.
PHARYNX:
 Muculo-membranous passageof
GIT.
 Itmeasures about 12-14cmlong.
 Itpushes down the bolus into
esophagus.
Parts of Pharynx:
 Itconsistof 3 parts;
a) Naso pharynx
b) Oropharynx
c) Laryngeopharynx
 Only Oropharynx is associated with
digestive system.
ESOPHAGUS:
 Some time called as “FOOD PIPE”.
 Long muscular tube which connects pharynxto
the stomach.
 Itmeasureabout 25cmlong
 Itlocated in thorasic cavity infrontof vertebral
column.

7.  Esophagus started from6th
cervical vertebraeto the 11th
vertebrae.
Parts of Esophagus:
According to its position in body, divided into the following parts:
a) Cervical part: Lies with trachea.
b) Thorasic part: Lies between trachea and vertebralcolumn.
c) Abdominal part: Covered with peritoneum located at the level of
10th
thorasic vertebrae.
Functions:
 Propulsion of food by the help of peristaltic waves.
STOMACH:
 Itis hollow, muscular sac like organ
 Most dilated partof alimentary canal.
Position:Itis located between end of esophagus and beginning of small
intestine and diaphragm.
Structure: Divided into
four main regions;
a) Cardia: Surrounded
the superior
openingof
stomach.
b) Fundus: Rounded
portion superior to
and to left of the
cardia.

8. c) Body: Inferior to fundusisthe large central portion of the
stomach.
d) PyloricPart: It is the partof stomach connected with duodenum.
INTERNAL STRUCTURE: It contains 3 types of cell:
a) Chief or peptic orzymogenic cells: These are typical type of protein-
synthesizing cells and sourceof digestive enzymelike Pepsinogen.
b) Oxyntic or parital cell:
1. They activated the inactivated digestive enzyme into pepsin.
2. They may secrete “HCL” of PH 1.5-2.5.
3. They also kill microbes.
c) Mucous Cells:
1. Itsecrete mucous.
2. Itlubricates the food.
Functions of stomach:
 Temporary storageof food.
 Itsecretes gastric juice.
 Chemical digestion takes place by pepsin which converts protein to
polypeptides.
 Mechanical breakdown by smooth muscle layer which performing
peristaltic movement.
 Absorption of some chemicals and water take place.

9. SMALL INTESTINE:
Itis long coiled tube, which almost fills the whole abdominal cavity.
Location: Itis located in abdominalcavity it is continuity as the stomach at
the pyloric sphincter and leads to large intestine.
Structure: divided into following;
 Duodenum
 Jejunum
 Ileum
I.Duodenum:
Itis the shortestand widest partof small intestine.
Importance: The secretion of gall bladder and
pancreas are released into duodenumby a
Hepatopancreatic duct.
II. Jejunum:
It is thicker and more vascular then ileum.
III. Ileum:
It is the last and longest part of small intestine.
Importance; It havefinger like microscopic projection called Villi.

10. Villi:
 Tiny finger like projection of mucosal
layer.
 Visible to naked eye.
 Large and numerous in duodenum but
smaller and fewer in ileum.
 Their walls are richly supplied with blood
vessels and lymph vessels.
Functions of Small Intestine:
Completion of digestion of carbohydrates, protein, and fats in the enterocytes of
the villi.
LARGE INTESTINE:
Itis the second intestinal part, not
coiled but has segmented.
Location: Itcovers all nine regions
of abdomen.
Structure: Partof large intestine is
divided into Caecum, ascending colon,
transversecolon, descending colon,
sigmoid colon.

11. Caecum: Itis the firstpart of colon.
 Blind ended pouch.
 Itgives a 10cmlong finer like projection called Vermiformappendix.
 Vermiform appendix is fine tube, closed at one end which leads fromthe
Caecum.
Ascending colon:
 Itis 15cmlong
 Itpasses upward from Caecumto the level of liver whereit is curveacutely
to the left.
Transverse colon:
 Itis 50cmlong.
 Loop of colon that extent across the abdominal cavity infront of duodenum
and stomach.
Descending colon:
 It is about 25cm long.
 It passes down the left side of the abdominal cavity then curves towards
midline.
Sigmoid Colon:
 Begins at the inlet of lesser pelvis, where it continues with descending
colon.
 It forms a loop which varies greatly in length average about 4cm.
 S- Shaped curve in pelvis, that continues downward to become the rectum.

12. Functions of Large Intestine:
 In the large intestine absorption of water take place.
 Minerals, salts, vitamins and drugs are also absorbed by blood capillaries in
large intestine.
 The large intestine is heavily colonized by certain types of bacteria, which
synthesize vitamin K and Folic acid
RECTUM
Itis the last portion; it is slightly dilated, continues with sigmoid colon and
terminates in anal canal.
Itis about 13cmlong
Functions:
Rectum stores feaces for some time when feaces enter into rectum it bring
about a desire for defecation, process called egestion.
PANCREAS:
 Itis soft, lobulated gland.
 Itis both exocrine and endocrine
gland.
Location:
It is situated transversely behind the
stomach between the spleen and
duodenum.

13. Structure:
Itis leaf like shape, present in oblique position. Itconsistof three parts:
a) Head: Broad extremity called head which directed downward.
b) Body: Head connected to main part, the body by a slightly constricted
neck.
c) Tail: Left extremity is transverseand terminates closely to spleen.
Function: Its function both as endocrinegland and exocrine gland.
As Endocrine Pancreas:
 The endocrine part of pancreas consists of group of specialized cells called
Isletof Langerhans.
 The islet has no duct, so hormones diffuses directly into blood.
 The endocrine pancreas secretes two types of hormones which control
blood glucoselevel.
a. Glycogen by A cell.
b. Insulin by B cell.
As Exocrine Pancreas:
 The exocrine pancreas is a lobulated, branched partsurrounded and
partially divided into lobules.
 Each lobule is derived by a tiny duct and these unite eventually to forma
pancreatic duct.
 Pancreatic duct secretes Pancreatic juice into duodenum which contain
enzymes that help in digestion of carbohydrates, protein and fats.

14. LIVER:
 Itis the largestgland of whole
body.
Structure: consist of 4 lobes:
Lobes of Liver:
 Liver is divided into two main lobe
i.e. Right and Left lobe.
 Left is further divided into two
lobes and is much smaller than
right lobe.
 The Quadrate
and Caudate
lobes are part
of left lobe.
Functions:
 Carbohydrate
metabolism.
 Protein
metabolism.
 Fat metabolism.
 Dotoxification of
drugs.
 Storageof vitamins
A, D, E, K, B12.
 Secretions of Bile.
 Production of heat.

15. GALL BLADDER:
 The gallbladder is a hollow organ that
present justbeneath the rightlobe of
the liver.
 Humans can live without a gallbladder.
Structure:
 Anatomically, the gallbladder is
divided into three sections:
 Fundus
 Body
 neck
Function:
 The secretion of gallbladder is Bile.