Digestive System pg 24

The Digestive System•The digestive system physically and

chemically breaks down food, absorbs nutrients into your body, and egests waste.

carbohydrates from foods such as cereals, potatoes, pasta, fruit

glucose

Carbohydrates provid the energy needed for:

normal body functions

(such as heartbeat, breathing, digestion and brain activity) exercise

(like biking, walking, running and resistance training)

Lipids (fats) from foods such as nuts, seeds & meat

fatty acids

proteins

from foods such as meat, milk, eggs, nuts, & seeds

20 amino acids

Having enough protein (all 20 amino acids) in your diet …..

….is essential to build muscle …… and ……..

…..skin, hair……..

…..blood cells…..

….finger and toe nails….

….and internal organs.

Step 1. The Mouth• The teeth and tongue physically break down food.• Saliva moistens food.• Enzyme (amylase) in saliva chemically break down

starch.

(50o ml produced per day)

Step 2. Swallowing• The epiglottis prevents food from travelling

down the trachea when swallowing.

When we swallow, what we are really doing is closing a trap door in our throat called the epiglottis. This sends food down the esophagus and prevents food from going down the trachea (or windpipe) and into our lungs

Muscular movements called peristalsis move the food down the esophagus to the stomach.

Step 3. The Stomach• The stomach mixes and

churns food to further break it down.

• Hydrochloric acid and enzymes mix with food to chemically digest the nutrients.

• Mucous prevents the walls of the stomach from being damaged.

The food is moved around in the stomach and mixed with the chemicals for 3-4 hours. When the stomach is finished with it, the food is a creamlike liquid call chyme.

Step 4. The Small Intestine

• Nutrients are broken down chemically by enzymes from the small intestine and pancreas.

• Bile from the liver emulsifies (breaks down) fat into tiny droplets. Bile is stored in the gall bladder.

Bile is a yellow substance that emulsifies fat so that it can be absorbed by the intestines.

Gallstone are hardened deposits of digestive fluid that may sometimes form in the gallbladder which may need to be surgically removed.

http://www.webmd.com/digestive-disorders/gallstones

Nutrients are absorbed by villi – microscopic projections that increase the surface area of the small intestine.

Step 5. The Large Intestine (Colon)• Water is reabsorbed.• Vitamin K is produced by bacteria.(Vitamin K is known as the clotting vitamin,

because without it blood would not clot.)

http://www.nlm.nih.gov/medlineplus/ency/article/002407.htm

Step 6. Egestion•Waste is stored in the rectum until it is

eliminated.•Feces is made up of dead bacteria, live

bacteria undigested material (fiber), dead cells and mucous.

1000 different species of bacteria live in the gut – 100 trillion in total

It takes 12 – 24 hours to fully process a meal.

The entire digestive tract is about 20 – 30 feet long.