Download Systems in Our Bodies

2.2 THE DIGESTIVE SYSTEM
Function
•Breaks down food, absorbs nutrients, and eliminates solid
waste
•The body’s digestive system completes four tasks:
1) Ingestion – take in food
2) Digestion – break food down
3) Absorption – absorb nutrients into bloodstream
4) Elimination – remove waste
Anatomy of the Digestive System
Digestive Pathway:
mouth
esophagus
stomach
small intestine
large intestine
rectum
Mechanical Digestion
Chemical Digestion
-food is broken down into
smaller pieces
-substances in our digestive
organs are released that
change food particles into
particles that are chemically
different
Example:
- Chewing (mouth)
- churning of the stomach to
mix food
Example:
-Acids
-Bases
-Enzymes (a protein
molecule that speeds up
chemical reactions)
Functions of the Parts
Mouth – mechanical digestion (chewing), produces saliva
to moisten food (wet food is called bolus)
Esophagus- pushes food down to the stomach using
muscle contractions called peristalsis
Stomach- a muscle that contracts and
relaxes to churn and mix food with acid
Small Intestine- site where most digestion occurs. Food is broken
down into tiny nutrients such as sugars, fatty acids and amino acids.
These nutrients are then absorbed into the blood stream (capillairies
line the outside of this organ to accomplish this).
Large Intestine – absorbs water
Rectum - stores feces (waste) until it is ready to be eliminated
Helper Glands
Pancreas
-secretes a base into the small intestine to
neutralize the acid in the food coming
from the stomach
-helps to digests fats and carbohydrates
Liver
-makes bile that breaks down fats
Gall Bladder
-small pouch under the liver that stores
extra bile
Salivary Glands
-found in the mouth and create saliva that
breaks down carbohydrates
What is a FART?????????
A release of methane gas created by bacteria that help to
digest your food
You release approximately 100L of gas each year!!!!!!!
Cellular Respiration
Sugar (glucose) made during the digestion of your food
can’t be used directly by your cells….it must be converted!
Glucose reacts with oxygen from your respiratory system to
make energy for your cells in the form of ATP as well as
carbon dioxide and water
Homework:
1. What is the difference between mechanical and chemical digestion?
2. What four tasks must the digestive system complete? List the organs that
are responsible for each task.
3. a) what parts of the digestive system are involved in mechanical
digestion?
b) What parts of the digestive system are involved in chemical digestion?
4. Explain how food is pushed down the esophagus
5. What are the helper glands that assist the digestive system?
6. What is cellular respiration?
7. How does the circulatory system, respiratory system and digestive system
work together?