班级：班级： 0909 级五班二组级五班二组 组长：杨磊组长：杨磊 演讲：朱兴兴演讲：朱兴兴 时间：时间： 2011/11/152011/11/15

The digestive systemThe digestive system

IntroductionIntroduction digestive tractdigestive tract (gastrointestina (gastrointestinal tract, GI tract) (mouth, pharyl tract, GI tract) (mouth, pharynx, esophagus, stomach, small nx, esophagus, stomach, small intestines, and large intestines) intestines, and large intestines) and accessory organs (liver, paand accessory organs (liver, pancreas, gall bladder, teeth, salivncreas, gall bladder, teeth, saliv

ary glands). ary glands).

Functions of the Digestive Functions of the Digestive SystemSystem::

DigestionDigestion – chemical break down of – chemical break down of food by enzymatic, hydrolysis, or acidsfood by enzymatic, hydrolysis, or acids

IngestionIngestion – insert in mouth by – insert in mouth by conscious choiceconscious choice

AbsorptionAbsorption – movement across – movement across digestive epithelium to interstitial digestive epithelium to interstitial fluidsfluids

ExcretionExcretion – removal of wastes and – removal of wastes and indigestible residueindigestible residue

The Oral CavityThe Oral Cavity

(Buccal cavity): bound by (Buccal cavity): bound by the cheeks and lips (the cheeks and lips (labialabia),), the mouth opens intothe mouth opens into oral cavity, start of theoral cavity, start of the digestive tract digestive tract

TheThe TeethTeeth Deciduous teethDeciduous teeth (20 baby teeth) (20 baby teeth) SSecondary dentition or permanent econdary dentition or permanent

teethteeth (32 adult teeth): (32 adult teeth):

TypesTypes IncisorsIncisors – blade shaped teeth at the fron – blade shaped teeth at the fron

t of the mouth (8). Single roott of the mouth (8). Single root CuspidsCuspids – (canines) conical with a point – (canines) conical with a point

ed tip (4). Single rooted tip (4). Single root BicuspidsBicuspids – (premolars) flattened crown – (premolars) flattened crown

s that crush/grind (8). Single or double rs that crush/grind (8). Single or double rootoot

MolarsMolars – large flattened crowns that exc – large flattened crowns that excel at crush/grind (12). 3 or more rootsel at crush/grind (12). 3 or more roots

The Tongue The Tongue

The tongue exends acroThe tongue exends across the floor of the orass the floor of the oral cavity and is attachel cavity and is attached by muscles to the lod by muscles to the lower jaw bone .wer jaw bone .

papillae can sense flavpapillae can sense flavors ,such as sweet ,bitors ,such as sweet ,bitter, salty, and sour.ter, salty, and sour.

PalatePalate

Forms the roof of the Forms the roof of the mouth.mouth.

Divided into two Divided into two parts: the hard palate parts: the hard palate and the soft palateand the soft palate

TheThe PharynxPharynx

muscles of the pharynx contract and muscles of the pharynx contract and push bolus down to the esophagus. push bolus down to the esophagus. Peristaltic waves push the bolus down Peristaltic waves push the bolus down the esophagus to the stomach the esophagus to the stomach

The EsophagusThe Esophagus

(or throat) is a long (or throat) is a long muscular tube that muscular tube that serves as a serves as a passageway for food passageway for food from the mouth to the from the mouth to the esophagus and as a esophagus and as a passageway for air passageway for air from nose to the from nose to the windpipe. windpipe.

TheThe StomachStomach

A pouch-like located in the upper part A pouch-like located in the upper part of the abdominal cavity ,connects the of the abdominal cavity ,connects the esophagus with the small intestine.esophagus with the small intestine.

When the stomach is empty, the mucoWhen the stomach is empty, the mucous membranes lining its walls are highus membranes lining its walls are highly folded;ly folded;

As the stomach fills, the rugae unfoldeAs the stomach fills, the rugae unfolded d

Fundus of stomach

Body of stomach

Pyloric antrumPyloric canal

Pyloric part

Cardia

The Small IntestineThe Small Intestine

(small bowel) is the (small bowel) is the region of the gut where region of the gut where nearly all of the chemical nearly all of the chemical digestion of the digestion of the nutritional components of nutritional components of food takes place.food takes place.

Divided into three Divided into three sections:sections:

the duodenum, the the duodenum, the jejunum, the ileum. jejunum, the ileum.

duodenuduodenumm

jejunujejunumm

ileumileum

The Large IntestinesThe Large Intestines

Compared with the small intestine, Compared with the small intestine, the larger intestine is relatively the larger intestine is relatively inactive and has mach less functions.inactive and has mach less functions.

The CecumThe Cecum A pouch on the right sA pouch on the right s

ide, is connected to thide, is connected to the small intestine by the small intestine by the ileocecal valve, whie ileocecal valve, which controls the passagch controls the passage of fluid waste from te of fluid waste from the small intestine inthe small intestine into the large intestine. o the large intestine.

The ColonThe Colon Which comprised Which comprised

the main length of the main length of the large intestine.the large intestine.

Has three divisions: Has three divisions: the ascending, the the ascending, the transverse, and the transverse, and the descending.descending.

The sigmoid colon, The sigmoid colon, shaped like an S. shaped like an S.

The RectumThe Rectum

Serves as a reservoir for Serves as a reservoir for feces.feces.

Accessory Digestive organsAccessory Digestive organs

The liverThe liver

The The gallbladdergallbladder

The The pancreaspancreas

The LiverThe Liver A large glandular A large glandular

organ located in the organ located in the upper right quadrant upper right quadrant of abdomen, of abdomen, produces a greenish produces a greenish fluid called bile.fluid called bile.

Other functions: Other functions: manufactures blood manufactures blood proteins, removes proteins, removes poisons, sores and poisons, sores and releases glycogen.releases glycogen.

The GallbladderThe Gallbladder

A pear-shaped sac A pear-shaped sac behind the lower behind the lower portion of the liver, portion of the liver, stores bile, which is stores bile, which is continuously continuously secreted by the secreted by the hepatic cells hepatic cells between meals.between meals.

The GancreasThe Gancreas An elongated organ An elongated organ

just behind the just behind the stomach, stomach, manufactures manufactures digestive juice digestive juice containing enzymes containing enzymes (amylase and lipase ) (amylase and lipase ) that aid in the that aid in the digestion of proteins, digestion of proteins, starches and fats.starches and fats.

Listening and watchingListening and watching

The digestive system The digestive system

Can you speak themCan you speak them ？？ the oral cavity

Pharynx

Liver

Stomach

Duodenum Large i

ntestine

Esophagus

Pancreas

Jejunum Ileum

StomachPancreasLarge intestine

StomachPancreas

Jejunum

Large intestine

StomachPancreas

Ileum

Jejunum

Large intestine

StomachPancreas Duodenu

m

Ileum

Jejunum

Large intestine

StomachPancreas

Liver

Duodenum

Ileum

Jejunum

Large intestine

StomachPancreas

Liver

Duodenum

Ileum

Jejunum

Large intestine

StomachPancreas

Esophagus

Liver

Duodenum

Ileum

Jejunum

Large intestine

StomachPancreas

Esophagus

Liver

Duodenum

Ileum

Jejunum

Large intestine

StomachPancreas

Esophagus

Liver

Duodenum

Ileum

Jejunum

Large intestine

StomachPancreas