TOPIC: NutritionAIM: What are the parts and functions of the digestive system?

2 Types of

Digestion

1.Mechanical

Digestion

•Large pieces of food are physically broken down into smaller pieces

•Increases surface area of food to speed up chemical digestion

•Makes food easier to swallow

•Example: Teeth

2.ChemicalDigestion

•Complex molecules are broken down into smaller molecules

•HOW? •By using digestive enzymes

•Carbs (starches) simple sugars (glucose)

•Proteins amino acids

Digestive

System

•One way tube

You are a tube inside a tube…

The tube starts here:

And although there are a few twists and turns along the way…

It comes out here:

Anything that goes into the mouth does not become part of the body until it is absorbed (taken in) in a part called the small intestine.

Function•Breakdown of food into pieces small enough for nutrients to diffuse into cells

Path of

Food

1. Mouth (oral cavity)

TEETH

Incisors

Canine

Premolars

Molars

“Wisdom”tooth

Tongue

Salivaryglands

Opening of asalivary gland duct

•Mechanical digestion (teeth)

•Saliva – produced by salivary glands a. moistens food

b. Chemical digestion•Enzyme that digests starch sugar

Epiglottis•Small flap of tissue

•Closes over windpipe when you swallow

•To prevent choking

2. Esophagusesophagus

•Connects mouth to stomach

•NO DIGESTION

•Peristalsis: muscular movement that pushes food along

3. Stomach

- Where protein digestion begins

•Where gastric juice is made.

•Gastric Juice contains: 1.Hydrochloric acid makes stomach acidic

2. Enzymes that chemically breaks down PROTEINS

b. Mucus = protects stomach wall

c. Mechanical digestion = food churned and mixed chyme (mixture of partially digested food)

4. Small intestine

•Length = 4-7 meters

•Where most chemical digestion occurs

•ALL digestion ends after the first part of the small intestine called the Duodenum. In the 2nd part

Of the SI, Absorption of Nutrients Occurs.

•Intestinal juice =•Contains enzymes that

digest food

Accessoryorgans

•Food DOES NOT pass through these organs

•Help the SI

Liver

Gall bladder

Duodenum

Pancreas

Stomach

Liver

•Produces bile•Bile travels to SI

•Emulsification of fats breaks down fat into smaller droplets

Big fat droplet

Gall Bladder

•Stores bile

Pancreas

•Makes pancreatic juice into SI

•Contains enzymes to chemically digest food

Villi

•Rest of small intestine lined with VILLI (tiny folds)

Villi

Outer wall

Inner wall

Pathway for Food

•Where nutrients diffuse (are absorbed) into blood

nutrients

•Increase surface area for nutrient absorption

5. Large intestine

•NO DIGESTION•Reabsorbs water•Forms feces (undigested food)

•Contains bacteria (make vitamins)

If you squeezed out all of the bacteria that lives in your intestines, you could almost fill up a coffee mug.

Anyone want a sip?

6.Rectum

•Last part of LI

•Stores feces

7. Anus•Where feces is egested

Did you know… -Your teeth started growing 3 months before you were even born. -The hardest substance in your body is the enamel on your teeth. -As you are sitting there listening, more than 100 million germs are swimming, feeding, reproducing, and making waste in the area behind your lips. In your mouth there are more living things than there are people in Australia and Canada combined…

•REVIEW• 1. Where does mechanical digestion

begin? How?• 2. Where does chemical digestion

begin? How?• 3. Where does chemical digestion end?• 4. Where does most chemical

digestion occur?• 5. What is the function of the liver?• 6. What are nutrients absorbed once

food has been completely broken down.

•Did you know....• An adult esophagus (also called

gullet) ranges from 10 to 14 inches in length, and 1 inch in diameter

• We make 1 to 3 pints of saliva a day• An adults stomach can hold

approximately 1.5 liters of material• Food sloshing in the stomach can

last 3-4 hours • The stomach's wall is lined with

three layers of powerful muscles

•Did you know....•The Average human being

consumes about 500kg of food per year.

•Within the colon, a typical person harbors more than 400 distinct species of bacteria

•On average, the stomach produces 2 liters of Hydrochloric Acid (HCl) daily

•Did you know....• A full grown horse’s coiled up

intestines are 89 feet long• Food stays in your stomach for 2 to 3

hours• Americans eat about 700 million

pounds of peanut butter. • Americans eat over 2 billion pounds

of chocolate a year. • In your lifetime, your digestive

system may handle about 50 tons!!

•Did you know....•What you ate for breakfast, that was not digested will come out in about 48 hours-normally.

•From intake to outlet, the digestive tract is about thirty feet long