Aim: Why do humans digest food? DO NOW: Think about the term digestion. 1.What does it mean to you? 2.Draw a picture representing what digestion means to you. 3.Draw a picture representing what digestion is not to you.

DIGESTION What does it mean? To break down!!! This is a chemical process or reaction & enzymes are involved! Food  Nutrients (small molecules of food) Why? Cells need nutrients Nutrients enter cells by crossing the cell membrane What for? Energy … energy stored in nutrients needs to be converted to ATP energy by cellular respiration!

Digestive System Pathway Mouth  Esophagus  Stomach  Small Intestine  Large Intestine  Rectum  Anus Digestive System Function: to digest food into smaller pieces & simpler substances that can be used by body cells so that life processes can take place!

Mouth Mechanical digestion starts here as teeth grind up food Chemical digestion also takes place as salivary glands release saliva into the mouth, which contains enzyme salivary amylase  breaks down carbohydrates (starches) into sugar!

Mouth Image

Stomach Highly acidic environment (~ ) Hydrochloric Acid Gastric juice Enzyme pepsin breaks down food there  breaks down protein Has walls lined with mucus Stomach Ulcers may form: painful sores on lining ulcer#Causes2 ulcer#Causes2

Stomach Image

Small Intestine Villi of small intestine are finger-like structures that reabsorb nutrients back into the blood, by diffusion, so they can enter the cells of the body Surface area here is increased to allow for more reabsorption of nutrients into blood A lot of chemical digestion occurs here Process of digestion is finished here

Small Intestine Image

Large Intestine Main function: absorbs excess water out of waste Water goes into blood by diffusion

Large Intestine Image

Waste Product An end result of digestion is solid waste called feces aka POOP! Feces gets stored in the rectum Feces leaves the body by way of the anus  ELIMINATION Constipation may occur if too much water is taken out of waste before it leaves the body Diarrhea may occur if too much water is present in waste before it leaves the body

Digestive Accessory Organs Pancreas makes pancreatic juice that contains enzymes that goes into the small intestine & helps chemical digestion Liver produces bile that enters the small intestine & helps the mechanical breakdown of fats * Gallbladder stores excess bile

Images

Animation WT.ac=k-woar WT.ac=k-woar

Video ms/digestivesystem/ ms/digestivesystem/

Making Connections Think about the diffusion lab that we did! Q: Which molecule did not cross the baggie by diffusion? WHY?

Group Work Pair up! Task: Complete the following chart Organic Compound Simple Subunits Digestive Products Lipids (FATS) Carbohydrates (STARCHES) Proteins

Individual Work Answer the AIM on looseleaf & hand in! Aim: Why do humans digest food?

Homework Read txt. pgs Answer questions 1-4