What are the 4 phases of processing food in your body?
Ingestion, digestion, absorption and elimination
What is digestion?
The process that breaks down food into small molecules so they can move into the blood stream
What does food pass through?
What are the major organs of the digestive tract?
Mouth, esophagus, stomach, small intestine, large intestine, rectum and anus
What are the 3 oragans that food does not pass through, but store enzymes & chemicals that help break down food as it passes through the digestive tract?
Liver, pancreas and gallbladder
What are enzymes?
Molecules that speed up the rate of chemical reactions in your body
Where does mechanical digestion take place?
It takes place when food is chewed and mixed in the mouth and churned in your stomach
Chemical digestion uses acids and enzymes to break down large molecules of food into smaller ones. Where does this take place?
Mouth, stomach and small intestine
What is the watery substance in your mouth called?
What does saliva contain?
Mucus and salivary amylase
What does salivary amylase do?
It starts the breakdown of food from a starch to a sugar
How much saliva is produced by your body each day?
How long does it take for food to pass through the esophagus?
Four to ten seconds
When food moves throgh the esophagus, muscles behind the food contract (squeeze) and push the food forward. Muscles in front of the food relax. What is this process called?
What is the stomach?
A powerful muscular bag that expands when food enters it.
How may ways does the stomach digest food?
Two - mechanically and chemically
What happens in mechanical digestion?
Food is mixed by the muscular walls of the stomach.
What happens in chemical digestion?
Food is also mixed with strong digestive juices, which include hydrochloric acid and enzymes.
What are the two reasons the stomach produces mucous?
It lubricates the food, making it slick. It also prtects the stomach from the strong digestive juices.
What would happen if the stomach did not have mucous or produced more acid than the mucous could handle?
The digestive juices would burn our stomach. The damage would soon stop the stomach from working.
How long does it take for food to move through the stomach?
What does food look like after it has moved through the stomach?
It has been changed to a thin, watery liquid calle chyme that moves next into the small intestine.
Where do the digestive juices added to the small intestine come from?
The liver and pancreas.
What does the liver do?
It produces a greenish fluid called bile, which is stored in the gallbladder. The acid from the stomach makes large fat particles float to the top of the liquid. Bile physicallly breaks these fat particles into smaller pieces.
What does the pancreas do?
It helps make insulin, a hormone that allows glucose to pass from the bloodstream into your body's cells.
What is insulin?
A hormone that allows glucose to pass from the bloodstream into your body's cells.
The walls of your small intestine are not smooth. They have many ridges and folds. These ridges and folds are covered with tiny, fingerlike projections called what?
How is food absorbed?
The chyme is like a soup, and it is ready to be absorbed through the cells on the surface of the villi. Molecules of nutrients from your school lunch pass by diffusion, osmosis or active transport into the blood vessels in the villi. Whatever is not absorbed is moved to the large intestine.
What is the main job of the large intestine?
It is to absorb water from the undigested mass of chyme. This is so large amounts of water can be returned to the body.
How long does chyme stay in the large intestine and what happens to it?
It becomes more solid and can stay as long as three days.
We have bacteria that feed on our undigested waste. Is this a good or bad thing?
It is a good thing because they produce vitamins that we all need.
What is the GIST of digestion?
We digest food so we don't starve. Without digestion, our bodies wouldn't be able to use the food we eat to build and nourish cells, and provide energy.