14.4 Nutrition (use for whiteboard notes)
6 major classes of nutrients:
1. Carbohydrates
a. Used as energy source in the body
b. Some can be stored as glycogen (a storage polymer) in the liver and muscles and quickly
converted back to glucose
c. Excess is converted by the body to be stored as fat
d. Glycemic index: a measure of how quickly a carbohydrate is digested and glucose is
absorbed from the small intestine to the bloodstream. The higher the GI, the quicker
the release of glucose.
e. Simple carbohydrates:
i. Quick to break down – sugar released quickly
ii. High glycemic index
iii. E.g. potatoes, white flour
f. Complex carbohydrates:
i. Slower to break down – sugar is released slowly
ii. Lower glycemic index
iii. E.g. whole grains, oats, beans
iv.
2. Proteins
a. Used to build enzymes, muscle tissue, plasma proteins, hormones
b. Excess cannot be stored and is converted to fat with nitrogenous waste begin disposed
of in urine
c. Eight essential amino acids (body cannot make, must be consumed in diet)
d. 20 amino acids total
e. High protein foods include: meat, beans, dairy, eggs, nuts
3. Lipids
a. Used as high energy source
b. Include fats, oils, and cholesterol
c. Serve as high energy source: each gram of a lipid contains 2.5 times more calories than
a gram of protein or carbohydrate
4. Two general categories of fatty acids:
a. Unsaturated fatty acids
i. Liquid at room temp.
ii. Oils, plant fats (generally)
b. Saturated fatty acids
i. Solid at room temp.
ii. Butter, animal fats (generally)
5. Essential fatty acids
a. Fatty acids the body can’t make must be in diet
6. Types and Functions of Lipids
a. Triglycerides
i. from three molecules of fatty acids and one glycerol molecule
ii. crucial in the body for energy storage
b. Steroids
i. benefit the body by helping determine and control the structure of plasma
membrane
c. Phospholipids
i. key role in constituting cell membranes.
d. Glycolipids
i. play an important role in boosting the body’s immune system
e. Lipoproteins (cholesterols)
i. help fat move around the body in the bloodstream
ii. exist in the form of Low Density Lipoprotein (HDL) and High Density Lipoprotein
(LDL)
f.
iii.
Waxes
i. extremely common lipids
ii. can be found on animal feathers, in human ears and even on the leaves of
plants
iii. primary function is one of protection