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

2 Types of Digestion

Large pieces of food are physically broken down into smaller pieces 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

Complex molecules are broken down into smaller molecules 2.Chemical Digestion 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… 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. It comes out here:

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 Salivary glands Opening of a salivary gland duct

Mechanical digestion (teeth)

Saliva – produced by salivary glands a. moistens food

b. Chemical digestion Enzyme that digests starch  sugar

Closes over windpipe when you swallow Epiglottis Small flap of tissue Closes over windpipe when you swallow To prevent choking

2. Esophagus esophagus

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

Food DOES NOT pass through these organs Accessory organs Food DOES NOT pass through these organs Help the SI

Liver Stomach Gall bladder Duodenum Pancreas

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 54

Where nutrients diffuse (are absorbed) into blood

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