Stomach, Intestines and Accessory

Organs

Do Now

List the path of this morning’s breakfast through the Digestive Tract, from start to finish

Do Now

Mouth

Pharynx

Esophagus

Stomach

Small Intestines

Large Intestines

Rectum

Gallbladder

Located right below liver

Stores bile

Helps break down large fat molecules into smaller particles

Fat gets absorbed, the then the bile is also reabsorbed back into the liver

Large Intestines

Last major part of the digestive system

Function is to remove water from indigestible food, and then pass waste material from the body

Takes approx. 16 hours to finish digestion

Liver

Important in metabolism, glycogen storage and detoxification

Many vital functions

Secretes bile

Cannot live without a liver

Small Intestines

Digestion using enzymes

Main site of absorption of nutrients

Includes Duodenum Jejunum Ileum

Don’t get punched in the jejunum…

https://www.youtube.com/watch?v=oHulRDk__ko

Review

STOMACH

The diameter and volume of the stomach varies depending on the amount of food it contains Can hold up to 1 gallon of food

When it is empty, it collapses inward and folds into “rugae”

Main functions “Storage tank” Food break down Minimal absorption

Stomach

Site of breakdown of proteins

Contains deep gastric pits which house protein-digesting enzymes What is an enzyme?

Cells produce Hydrochloric Acid creating a highly acidic nature in the stomach

Stomach maintains a pH of approx. 2.0 Very Acidic? Mildly Acidic? Mildly Basic? Very Basic?

pH Scale

Stomach

If the stomach is so acidic, why does it not eat away at itself? The Answer: Mucous

Ulcers are the result of gastric juice penetrating the lining of the stomach Caused by bacteria becoming present on the

stomach lining and prevents the secretion of mucous

Ulcers

Duodenum

First part of the small intestines

Chyme enters duodenum by spurts from the stomach Chyme?

Proteins and carbohydrates are now partially digested

Fats not yet started to become digested

Pancreas

Releases pancreatic juice into the small intestines

Neutralizes the acidic material from the stomach

Small Intestines

Approximately 3 meters long

Numerous projections called villi that function to increase surface area Total surface area of 500-600 square meters Why is increased surface area important?

Large Intestines

Also called the colon Colon cancer?

Receives approximately 10 liters of water per day 1.5 L from food 8.5 L is from secretions

Last major part of the digestive system

Function is to remove water from indigestible food, and then pass waste material from the body

Takes approx. 16 hours to finish digestion

Large Intestines

Also absorbs sodium and other ions

If water is not absorbed, diarrhea can result Causes dehydration and ion loss

Polyps

Small growths in the lining of the colon (large intestines)

Cancerous (malignant) or benign Benign?

Low-fat, high-fiber diets are recommened to protect against colon cancer

Homework

Read 3/31 p. 470-474

Split page notes – ATLEAST 1 page