1. Nutrition and Metabolism
Last topic of Digestive System → Test Tuesday on all of Digestive System
(Review Monday for test)

2. Do Now: Part 1: What do you know about nutrients that are needed by the body? Make a list below.

3. Do Now: Part 2: What is below?______________________
Try to label it with the names of the food groups we looked at in our nutrition menu activity from yesterday.
Then, predict how many servings of each group is recommended for daily consumption.

4. Nutrition
A nutrient is a substance in food that is used by the body to promote normal growth, maintenance and repair
Major nutrients:
Carbohydrates, lipids and proteins (what are these called?)
Vitamins and minerals
Water

5. Dietary Sources Carbohydrates (sugars):
Except for milk sugar and small amounts of glycogen in meats, all the carbohydrates we ingest are derived from plants
examples: fruits, sugar cane
Lipids:
Most dietary lipids are neutral fats – triglycerides
Saturated fat: in animal product, bad for you
Unsaturated fat: in vegetable product, good for you

6. Dietary Source Proteins:
Animal products contain the highest quality proteins
Egg, milk and most meat proteins are complete proteins that meet all of the body's amino acid requirements
Legumes (beans and peas), nuts are also protein- rich, but their proteins are nutritionally incomplete as they’re low in one or more of the essential amino acids

7. Dietary Source Vitamins:
Organic nutrients of various forms that the body requires in small amounts
No one food contains all the required vitamins
Most vitamins function as coenzymes- they act with an enzyme to accomplish a particular type of catalysis
Minerals (or elements): Body requires 7
Calcium, phosphorus, potassium, sulfur, sodium, chloride and magnesium
The most mineral-rich foods are vegetables, legumes, milk and some meats

8. Metabolism
Metabolism is a broad term referring to all chemical reactions that are necessary to maintain life:
Catabolism: Substances are broken down to simpler substances
Anabolism: Larger molecules or structures are built from smaller ones

9. Carbohydrate Metabolism
The cells of the body use carbs as their fuel to carry out functions:
Glucose, known as blood sugar, is the major breakdown product of carbohydrate digestion
It is also the major fuel used for making ATP in most body cells

10. Carbohydrate Metabolism
Homeostasis of blood glucose level is critically important:
Hyperglycemia: excessively high levels of glucose in the blood
Hypoglycemia: when blood glucose levels are too low

11. Fat Metabolism
The liver handles most lipid metabolism that goes on in the body:
The liver cells use some fats to make ATP for their own use
While fats are an important energy source, cholesterol is never used as a cellular fuel
What are examples of foods that contribute to good and bad cholesterol?

12. Protein Metabolism Ingested proteins are broken down to amino acids
Cells cannot build their proteins unless all the needed amino acids (20) are present:
Essential amino acid: 8 of the these amino acids cannot be made by the cells, they are available to the cells only through the diet

13. The Central role of the liver in metabolism
The liver cells:
Detoxify drugs and alcohol
Make substances vital to the body: cholesterol, clotting proteins
Can regenerate rapidly and easily (as little as 30% of original liver can return to full size)

14. The Central role of the liver in metabolism
The liver helps maintain blood glucose levels within normal range (100 mg glucose/100 ml of blood)
Glycogen: large polysaccharide made of glucose
Glycogenesis: Glucose converted to glycogen and stored
Glycogenolysis: Stored glycogen converted to glucose
Gluconeogenesis: Amino acids and fats converted to glucose

15. Cholesterol metabolism and transport
It is not used as an energy fuel
It serves as the structural basis of steroid hormones and Vitamin D
It is lost from the body when it is broken down and secreted in bile salts → leaves the body in feces

16. Lipoproteins
Lipoproteins: lipid protein complexes that transport fatty acids, fats and cholesterol
Low density lipoproteins (LDLs): Transport cholesterol and other lipids to body cells
(bad → builds up in tissues)
High density lipoproteins (HDLs): Transport cholesterol from the tissue cells to the liver for its disposal in bile and ultimately feces
(good→ removes cholesterol from body)