DEPARTMENT: PHARMACYFACULTY :( B.H.M.S) 1st semester ASSIGNMENT:
ANATOMYTOPIC: DIGESTIVE SYSTEMSUBMITED TO: Dr.KANWALSUBMITED BY:
TAYYEBA AZAMDIGESTION:Definition:The process, by which large,
complex, insoluble, organic food substances are broken down into
smaller, simple, soluble molecule by the action of enzymes, is
known as digestion.DIGESTIVE SYSTEM:Definition:Arrangement of
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-intestinal track
(GIT).More About GIT: It is about 5-7m long. GIT is one way tube,
having two opening, i.e. Mouth and Anus lined by mucous
ORGANS OF GIT:Oral cavity: It is divided into following parts:a)
Lips b) Teethc) Gums d) Tonguee) Cheeksf) Palate (soft and hard)g)
Mucous membrane. Pharynx Esophagus Stomach Small intestine Large
intestine Rectum AnusAssociated Glands: Salivary glands:[Parotid
Gland, Sublingual gland, Submandibular] Liver Gall bladder
PancreasMain Function of GIT: Ingestion Propulsion Digestion
Absorption EliminationTHE 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 from palate. Inferiorly,
floor made from 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) Neckb) Crownc)
RootFunctions 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
Functions of Oral Cavity: LIPS: helps in ingestion of food.
CHEEKS: secretion of mucous and sometimes modified to form saliva.
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
membrane of mouth.Functions of Glands: Lubrication of food.
Purifies and moisturize the oral cavity. Secretion of digestive
PHARYNX: Muculo-membranous passage of GIT. It measures about
12-14cm long. It pushes down the bolus into esophagus.Parts of
Pharynx: It consist of 3 parts; a) Naso pharynxb) Oropharynxc)
Laryngeopharynx Only Oropharynx is associated with digestive
ESOPHAGUS: Some time called as FOOD PIPE. Long muscular tube
which connects pharynx to the stomach. It measure about 25cm long
It located in thorasic cavity infront of vertebral column.
Esophagus started from 6th cervical vertebrae to 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 vertebral
column.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: It is hollow, muscular sac like organ Most dilated part
of alimentary canal.Position: It is located between end of
esophagus and beginning of small intestine and diaphragm.Structure:
Divided into four main regions;a) Cardia: Surrounded the superior
opening of stomach.b) Fundus: Rounded portion superior to and to
left of the cardia.c) Body: Inferior to fundus is the large central
portion of the stomach.d) Pyloric Part: It is the part of 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 source of digestive enzyme like
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. It
secrete mucous.2. It lubricates the food.Functions of stomach:
Temporary storage of food. It secretes 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.
SMALL INTESTINE:It is long coiled tube, which almost fills the
whole abdominal cavity.Location: It is located in abdominal cavity
it is continuity as the stomach at the pyloric sphincter and leads
to large intestine.Structure: divided into following; Duodenum
Jejunum IleumI. Duodenum:It is the shortest and widest part of
small intestine.Importance: The secretion of gall bladder and
pancreas are released into duodenum by 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 have
finger like microscopic projection called Villi.
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
LARGE INTESTINE:It is the second intestinal part, not coiled but
has segmented. Location: It covers all nine regions of abdomen.
Structure: Part of large intestine is divided into Caecum,
ascending colon, transverse colon, descending colon, sigmoid
Caecum: It is the first part of colon. Blind ended pouch. It
gives a 10cm long finer like projection called Vermiform appendix.
Vermiform appendix is fine tube, closed at one end which leads from
the Caecum.Ascending colon: It is 15cm long It passes upward from
Caecum to the level of liver where it is curve acutely to the
left.Transverse colon: It is 50cm long. 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.
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
RECTUMIt is the last portion; it is slightly dilated, continues
with sigmoid colon and terminates in anal canal.It is about 13cm
long Functions:Rectum stores feaces for some time when feaces enter
into rectum it bring about a desire for defecation, process called
PANCREAS: It is soft, lobulated gland. It is both exocrine and
endocrine gland.Location: It is situated transversely behind the
stomach between the spleen and duodenum.
Struct ure:It is leaf like shape, present in oblique position.
It consist of 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
transverse and terminates closely to spleen.
Function: Its function both as endocrine gland and exocrine
gland.As Endocrine Pancreas: The endocrine part of pancreas
consists of group of specialized cells called Islet of Langerhans.
The islet has no duct, so hormones diffuses directly into blood.
The endocrine pancreas secretes two types of hormones which control
blood glucose level.a. Glycogen by A cell.b. Insulin by B cell.As
Exocrine Pancreas: The exocrine pancreas is a lobulated, branched
part surrounded and partially divided into lobules. Each lobule is
derived by a tiny duct and these unite eventually to form a
pancreatic duct. Pancreatic duct secretes Pancreatic juice into
duodenum which contain enzymes that help in digestion of
carbohydrates, protein and fats.
LIVER: It is the largest gland 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. Storage of
vitamins A, D, E, K, B12. Secretions of Bile. Production of
GALL BLADDER: The gallbladder is a hollow organ that present
just beneath the right lobe of the liver. Humans can live without a
gallbladder. Structure: Anatomically, the gallbladder is divided
into three sections: Fundus Body neckFunction: The secretion of
gallbladder is Bile.