1. HOW WE USE NUTRIENTS
The Digestive System

2. DIGESTION There are four stages to digestion:
INGESTION: eat or taking in food
DEGESTION: breaking down food into nutrients
ABSORPTION: the uptake of nutrients into the body
EGESTION: elimination of waste from the body

3. DIGESTION MECHANICAL: tearing, ripping and beating down of food
There are two kinds of digestion:
MECHANICAL: tearing, ripping and beating down of food
CHEMICAL: using digestive enzymes to break down food

5. ORAL CAVITY
The oral cavity also contains two kinds of SALIVARY GLANDS:
PAROTID: secretes a fluid containing an enzyme that breaks down carbohydrates
BUCCAL: secretes mucus which coats the food to prevent it from damaging the digestive tract

6. ESOPHAGUS A long tube that travels from the mouth to the stomach
BOLUS: moisten ball of food
Food travels down to the stomach by a process called PERISTALSIS, which is a series of muscle contractions and relaxations.

7. STOMACH Can hold about 1 L of food
Does both mechanical and chemical digestion
Contains a chemical called HYDROCHLORIC ACID
The acid kills any microbes that may be in the food.
The acid also activates enzymes which aid in the breakdown of proteins

8. STOMACH
Also has mucus secreting cells that coat the stomach protecting it from the affects of the acid
The food exits the stomach as a thick liquid called CHYME

9. SMALL INTESTINE Location of the bulk of digestion in the body
It is also the location of ABSORPTION in the body
Contains millions VILLI which maximizes the surface area of the small intestine for absorption

10. SMALL INTESTINE
The chyme is acted on by three types of digestive juices:
BILE: helps the body absorb fats
PANCREATIC: contains enzymes that break down nutrients
INTESTINAL: works with the other fluids to break down food

11. LARGE INTESTINE
The location of the absorption of water and any other nutrients that the body may need.
Produces waste product (poo).

12. ACCESSORY ORGANS
There are organs that help the digestive system, but are not actively involved in digestion.
LIVER: produces bile
GALL BLADDER: stores bile
PANCREAS: produces pancreatic juices

13. DIGESTIVE SYSTEM AND NUTRTRIENTS
Carbohydrates are broken down into GLUCOSE
Fats are broken down into FATTY ACIDS
Proteins are broken down into AMINO ACIDS
Vitamins, minerals and water are not broken down; they are used as is

14. ABSORPTION OF NUTRIENTS
After digestion, the nutrients are absorbed into the bloodstream
The nutrients travel to the liver to be processed into forms that the body can use
Example: Amino acids can be converted to many different types of proteins
Nutrients that are not immediately needed can be stored for future use
Example: Excess glucose is converted into glycogen and stored in the liver.

15. HOW NUTRIENTS ARE USED
Nutrients are carried throughout the bloodstream to individual cells
They are used for specialized purposes
Example: Glucose is combined with oxygen to produce energy
Energy is used for AUTOMAIC PROCESSES (breathing, digestion, etc.) and PHYSICAL ACTIVITIES (exercise)

16. WASTE REMOVAL
After absorption some waste material and fibre is left in the small intestine
The waste is moved to the large intestine where water, potassium and sodium are removed
The waste is stored in the rectum until it is eliminated