Transcript Organ Systems of the Human Body

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. (50o ml produced per day)
• Enzyme (amylase) in saliva chemically break down starch.
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.