Nutrition, Metabolism and Energy Balance
a substance in food the body uses to promote normal growth, maintenance and repair.
See Macro and micro nutrients
Make up the bulk of what we eat: Carbohydrates, lipids, and proteins
Required in minute amounts: Vitamins and minerals
Cannot be made fast enough to meet the body's needs, must be provided by our diet.
As long as we ingest all the essential nutrients the body can synthesize the hundreds of additional molecules required for life.
Insoluable fiber/soluable fiber
Insoluable fiber probides roughage- found in fruits and vegetables.
Soluable fiber- pectin found in apples and citrus fruits reduces blood cholesterol levels.
Monosaccharide - Glucose
the carbohydrate molecule ultimately used as fuel by our body to produce ATP. For optimal protein synthesis the diet must supply sufficient carbohydrate or fat calories for ATP production.
Small abouts of pentose sugars are also used to synthesize nucliec acids. A variety of sugars are attached to externally facing plasma membrane proteins and lipids.
Carbohydrate digestion also yields fructose and galactose, these are convered by the liver to glucose before they enter general circulation.
Neurons and and RBCs rely on glucose for energy needs.
Any glucose in excess of what is needed for ATP synthesis is converted to glycogen or fat and stored for later use.
The most abundant dietary lipids.
major fuel for skeletal muscle and hepatocytes.
Saturated fats are found in meat and dairy, coconut, hydrogenated oils (trans Fats) like margarine and shortnening.
Unsaturated fats are found in seeds, nuts, olive oil and vegetable oils.
Liver converts one fatty acid to another, but cannot synthesize linoletic acid.
Not used for energy.
Cholesterol is a stabilizing component of plasma membranes and is the precursor to bile salts, steroid hormones
Found in egg yolk, meats, organ meat, shellfish, milk products.
The liver produced 85% of blood cholesterol regardless of dietary intake.
Uses of fats in the body
provides a protective cushion. Phospholipids are integral component of myelin sheaths and cellular membranes. Cholesterol is a stabilizing component of plasma membranes and is the precursor to bile salts, steroid hormones. PGE regulate molecules formed from lineoleic acid to arachidonic acid for muscle contraction, BP control and inflammation. TGL major fuel for skeletal muscle and hepatocytes. Fats help the body absorb fat soluable vitamins.
Supply essential amino acids and raw materials for making nonessential amino acids and various nonprotein nitrogen containing substances. Animal products are the highest quality protein with the greatest amount of essential amino acids required for tissue maintenance and growth.
Eggs, milk, fish, most meats. Legumes, nuts and protein rich cereals are nutritionally incomplete proteins because they are low in one or more of the essential amino acids.
all or none rule
all amino acids needed to make a particular protein must be present in a cell at the same time and in sufficient amounts.
The body is in nitrogen balance when the amount of nitrogen ingested in proteins equals the amount excreted in the urine and feces.
Negative nitrogen balance occurs when protein breakdown for energy exceeds the amount of protein being incorporated into tissues. Can occur during physical and emotional stress when the quality or quantity of dietary protein is poor (starvation)
Organic compounds needed in minute amounts for growth and good health. Without vitamins all the carbohydrates, proteins, and fats we eat would be useless. Most vitamins are not made in the body so we must ingest them in foods or vitamin supplements, exception is Vitamin D, small amounts of B vitamins and vitamin K which is synthesized by the intestinal bacteria. B vitamins act as coenzymes when glucose is oxidized for energy.
Vitamins function as coenzymes which act as an enzyme to accomplish a particular chemical task.
Vitamins are either water or fat soluable. Water soluable vitamins (B and C) are absorbed along with water from the GI tract. B12 to be absorbed must bind with intrinsic fact which is a stomach secretion.
Fat soluable vitamins (ADEK) bind to ingested lipids and are absorbed along with their digetion products