Nutrition and Metabolism Flashcards
What is a nutrient?
Nutrient: a substance in food that promotes normal growth, maintenance, and repair of cells
Some nutrients include…
Nutrients include carbohydrates, lipids, proteins, vitamins, minerals (and water)
What is an essential nutrient?
A nutrient that cannot be synthesized by the body, and thus must be obtained from a dietary source
What is a calorie?
The calorie (cal) is the amount of energy needed to raise the temperature of one gram of water by one degree Celsius
What is a food calorie?
The food calorie (Cal) is defined in terms of the kilogram rather than the gram. It is equal to 1000 calories (kcal)
Why are carbohydrates important?
a. Glucose is the fuel used by cells to make ATP
i. Neurons and RBCs rely almost entirely upon glucose
ii. Excess glucose is converted and stored as glycogen or fat
What are sugars?
a. Sugars (simple carbohydrates – usually mono- or disacharides)
b. Sugar, jams, fruit drinks, honey, etc
What is starch?
a. Starch (complex carbohydrates)
b. Green vegetables, grains, starchy vegetables, beans, lentils
What are two types of fibers?
a. Insoluble fiber: cellulose in vegetables; provides roughage
b. Soluble fiber: pectin in apples and citrus fruits; reduces blood cholesterol levels
What are lipids? Name and describe three types.
a. Triglycerides and fatty acids
b. Saturated fatty acids found in meat, dairy foods, and tropical oils (coconut, palm kernel or palm oils)
c. Unsaturated fats found in seeds, nuts, olive oil, and most vegetable oils (corn, peanut, soybean or sunflower oils)
d. Essential fatty acids
i. Linoleic and linolenic acid, found in most vegetable oils
ii. Must be ingested in diet
What is the importance of lipids?
a. Help absorb fat-soluble vitamins
b. Major fuel of hepatocytes and skeletal muscle
c. Phospholipids are essential in myelin sheaths and all cell membranes
d. Adipose tissue
i. Protective cushions around body organs
ii. Insulating layer beneath the skin
iii. Concentrated source of energy
e. Prostaglandins
i. Control of blood pressure
ii. Inflammation
f. Cholesterol – found in egg yolk, meats, organ meats, shellfish, and milk products
i. Stabilizes membranes
ii. Precursor of bile salts and all steroid hormones
How is cholesterol transported?
Cholesterol cannot dissolve in the watery blood plasma, so it must be carried around the body by transport proteins called lipoproteins.
Which cholesterol is considered good and bad? Why
a. Low density lipoprotein (LDL) is considered bad because it gets stuck in arteries
b. High density lipoprotein (HDL) is considered good because it doesn’t get stuck
How many proteins are there? How many are essential and nonessential?
a. 20 amino acids
b. 9 essential, 11 nonessential
What are complete proteins?
Complete proteins are those that contain all 9 essential amino acids in sufficient quantity – these are typically animal-based proteins
What are incomplete proteins?
Incomplete proteins are those that don’t contain all 9 essential amino acids, or don’t have sufficient quantities of them to meet the body’s needs, and must be supplemented with other proteins.
Describe the use of amino acids in the body (all or none rule, caloric intake)
a. All-or-none rule- All amino acids needed must be present for protein synthesis to occur
b. Adequacy of caloric intake- Protein will be used as fuel if there is insufficient carbohydrate or fat available
What is the importance of protein? (don’t memorize)
a. Structural materials: keratin, collagen, elastin, actin, myosin, microtubules, cilia, flagella, centrioles, etc.
b. Most are functional molecules: enzymes, receptors, transporter proteins, hemoglobin, antibodies, some hormones, transcription factors, etc.
