The Digestive SystemThe Digestive System

The mysterious process The mysterious process uncovered!uncovered!

The BeginningThe Beginning

► Oral cavity: Both physical and chemical

digestion takes place in the mouth. 

► Saliva: secreted to moisten food, protect the mouth from abrasions buffer against acids in food, kill some

forms of bacteria begin carbohydrate digestion with

the enzyme SALIVARY AMYLASE.   ► Tongue:

is used for taste, manipulates food while chewing and

prepares food for swallowing by forming it into a ball called a bolus.

Down the hatchet (or Pharynx Down the hatchet (or Pharynx and esophagus)!and esophagus)!

► Pharynx Commonly called the throat. Intersection of the glottis

and opening to the esophagus is found here.

Epiglottis is a flap that closes the glottis when the act of swallowing occurs.

► Esophagus Connects the pharynx and

the stomach. Peristalsis, wave-like

contractions of the smooth muscles push food down toward the stomach.

Into The StomachInto The Stomach► J shaped expandable organ located on the left side of the

abdominal cavity. ► Stores up to 2 liters of food while mixing and digesting it. ► secrete GASTRIC JUICES and HCl making the pH around

2 very acidic ► The hormone GASTRIN is secreted by the stomach cells

to regulate the production of gastric juices. ► Fat Digestion: Bile emulsifies fat. This creates a larger

surface area for the enzyme lipase to digest it. ► Carbohydrate Digestion: Disaccharide digestion is

under the control of the enzymes maltase, lactase, sucrase, all of which are mainly found in saliva.

Stomach PhotoStomach Photo

Small Intestine and VilliSmall Intestine and Villi

► It is more than 6 meters in length with smaller diameter than large intestine.

► It is divided into 3 sections: duodenum, jejunum, and ileum

► Pancreas, Liver, and Gall Bladder: accessory organs, add digestive enzymes, juices and

hormones into the small intestine. Pancreas-helps digest starch and protein digestion Gall bladder-storage for bile which helps digest fats Liver-secretes bile for fat digestion and filters blood of

toxins

AbsorptionAbsorption

► Absorption and distribution of nutrients:

Small intestine is lined with small finger-like projections called Villi

The nutrients except fat are absorbed into the capillaries, while the fat enters the lacteal.

All the contents of the blood enter the liver The liver regulates the contents of the blood.

Pancreas and VilliPancreas and Villi

                                   

          

Large IntestineLarge Intestine

► Colon is connected to the small intestine at a T junction called the cecum.

The appendix is found attached to the end of the cecum.

► The main function of the colon is to reabsorb water from the small intestinal material.

► The bacteria Escherichia coli live in this area of the body. They produce odor, and Vitamin K.

► Waste is excreted through the rectum and out through the anus

Now, who’s hungry?Now, who’s hungry?► Digestion Transit Times:Digestion Transit Times:

Mouth: ►one minute

Esophagus: ►two to 3 seconds

Stomach: ►2-4 hours

Small Intestine: ►1-4 hours

Large Intestine: ►10 hours to several days!

► Digestion is now complete, time to eat again!Digestion is now complete, time to eat again!► Review rubric for digestion t-shirt and digestion Review rubric for digestion t-shirt and digestion

creative writing assessment!creative writing assessment!