Answer the following questions based on the video.1. What is the gateway to the

digestive system?2. What is the tube that runs

from your mouth to the stomach?

3. What is the first part of the small intestine where liquified food goes?

4. What is made in the liver and stored in the gallbladder?

5. What part of the digestive system absorbs water and salt?

The Different Organs of Digestion

4th Quarter

Digestion• the process by which food is

broken down into smaller components that the body can absorb to nourish its cells.

Functions of the Digestive System• ingestion or taking in food

into the mouth• digestion and absorption –

processing of food into a form that will be assimilated into the living cells• excretion 0r elimination of

indigested substances and certain wastes

Phases of Digestion• Mechanical

phase – chewing or mastication• Chemical phase –

enzymes are secreted together with the digestive juices

Two Main Parts of the Digestive System• digestive or alimentary tract

– (mouth, pharynx, esophagus, stomach, small and large intestines, rectum and anus)• accessory organs – (salivary

glands, liver, gallbladder and pancreas)

Two Main Parts of the Digestive System

The Mouth• digestion begins; entrance of

food• teeth, tongue and salivary

glands• Teeth – break down food into

small pieces• Tongue – muscular organ;

mixes food with the saliva, aids in swallowing

• Salivary glands – secrete saliva that lubricates food

The Mouth• Saliva – contains enzymes

that help in the chemical digestion of carbohydrates

• mechanical and chemical digestion of food

• Bolus – a lubricated, chewed, ball-shaped mass of food

The Pharynx• throat• located posterior to the

mouth• common passage way for

digestion and respiration• breathing and swallowing do

not happen at the same time

The Pharynx• cardiac sphincter – a circular muscle valve at the upper end of the stomach, relaxes to allow the food into the stomach• epiglottis – prevents the bolus from entering the trachea

The Esophagus• muscular tube through which food passes from pharynx to the stomach• Peristalsis – a series of rhythmic wavelike contractions of the muscles of the esophagus to push down food into the stomach

The Esophagus

The Stomach• expanded organ located

between the esophagus and small intestine

• muscular, elastic , pear-shaped organ

• storing of the swallowed food• mixing food with the

digestive juice it produces• conveying its contents slowly

into the small intestine

The Stomach• Pyloric sphincter – circular valve muscle at the lower end of the stomach that remains closed when food enters the stomach• Chyme – semifluid partially digested food

The Small Intestine• Three parts: duodenum,

jejunum and ileum• organ of complete digestion• secretes enzymes that change

food materials into their simplest components

• longest organ of the digestive system

• Intestinal Villi – very tiny projection that increase the absorbing capacity of the small intestine

The Large Intestine• colon• the next organ after the small

intestine• the larger organ because of its

diameter• temporary stores fecal

materials• absorbs vitamins produced by

certain symbiotic bacteria in the colon

• reabsorbs water from the undigested residue

The Large Intestine• has three distinct part:

ascending colon, transverse colon and descending colon

• cecum – the proximal part of the ascending colon; a blind sac that bears the vermiform appendix

• Sigmoid colon – named because it is somewhat S-shaped

The Large Intestine• rectum – the last part of the

large intestine• anus – lower opening that

functions as exit point for fecal material

• defecation or bowel movement – the process of propelling the feces out of the body through the anus controlled by a sphincter in the brain

The Accessory OrgansSalivary Glands• located in the mouth • Three types: parotid,

sublingual and submandibular

The Accessory OrgansSalivary Glands• saliva – secreted by the

salivary gland; a chemical substance that is a combination of watery fluid and mucus

• mucus part lubricates the mouth that aids in swallowing

• serous part contains salivary amylase ptyalin that digests carbohydrates in the mouth

The Accessory OrgansLiver and Gallbladder• liver – largest organ in the

body• produces bile from bilirubin, a

waste product formed when red blood cells are being destroyed

The Accessory OrgansLiver and Gallbladder• Two important functions:

emulsification of fats and neutralization of the partly digested food from the stomach

• gallbladder – stores the bile• 500 – 1,000 ml 0f bile is stored

and concentrated in the liver daily

The Accessory OrgansPancreas• large, elongated

gland that lies posterior to the stomach

• a yellowish organ that functions as exocrine and endocrine gland

The Accessory OrgansPancreas• Islets of Langerhans – the

endocrine part; secrete hormones important in the metabolism of sugar

• Pancreatic acini – the exocrine part; secrete the digestive enzymes directly into the duodenum

• amylopsin, trypsin, steapsin and nuclease – secreted by the acinar cells

Synthesis:• Trace what will happen to the food you ate at breakfast as it enters your mouth up to the time it reaches your small intestine.

Identify the parts of the digestive system.

Assignment:• Study for a quiz on Thursday, February 4

Topic: Digestive System