Lecture 10 : Gastrointestinal System IV : Nutrition and Metabolism I Flashcards
Nutrient =
substance in food the body uses to promote normal growth, maintenance and repair
Categories of nutrients (5):
Macronutrients = fats, carbohydrates and proteins (make up most of what we eat)
Micronutrients = vitamins and minerals (required in smaller quantities)
Essential nutrients =
body can’t make as fast as we need – must be obtained through diet
Nonessential nutrients =
also vital for normal functioning, but body can synthesize through interconversions of one type of molecule to another
The ______ regulates the Nutrition Facts label
U.S. Food and Drug Administration (FDA)
Nutrition labels help us understand:
types of nutrients included in a packaged food
recommended serving size
number of calories per serving
whether we’re getting enough of the nutrients our bodies need
(% daily recommendations)
Nutrition labels are based on basal metabolic needs of an average person =
~2000 Calories/day
The energy value of foods is measured in _____
kilocalories
1 kilocalorie =
energy to raise temperature of 1 kg water by 1 degree C
1 kcal = 1 calorie (from nutrition labels)
Nutrient content of foods:
Carbohydrates = 4 kcal/gram
Protein = 4 kcal/gram
Fats = 9 kcal/gram
Metabolic rate =
number of kcal used per hour
varies depending on multiple factors:
activity, hormones, age
Carbohydrates
Dietary Sources:
sugars
starch
glycogen
Sugars =
(mono- and disaccharides) - most from plants
Fruits, sugar cane, sugar beets, honey, (exception: milk sugar)
Starch =
(polysaccharides)
Grains & vegetables
Glycogen =
negligible amount from meats
GLUCOSE
the body’s main fuel source for ATP production
Brain and red blood cells use glucose for energy
Either used or stored (glycogen and/or fat)
Other monosaccharides converted to glucose in liver
Pentose sugars in RNA, DNA, sugars in glycocalyx
POLYSACCHARIDES as sources of fiber:
Insoluble fiber – cellulose from vegetables (roughage) : increase bulk of stool
Soluble fiber – pectin from apples, citrus : balances blood cholesterol, sugar
Dietary Considerations =
____ of total calorie intake – ideally complex carbohydrates
45-65%
Dietary Considerations =
Get plenty of fiber _____
(25-30 gm/day)
Dietary Considerations =
Highly processed carbohydrates (candy, soda) – concentrated energy source without ______
benefits of other nutrients (empty calories)
Proteins
Made from 20 amino acid building blocks
9 out of the 20 proteins are _______ because we can’t synthesize them
essential amino acids
Dietary Sources:
Complete proteins =
contain all the essential amino acids for tissue maintenance and growth
Eggs, milk, fish, most meats, soybeans
Dietary Sources:
Incomplete proteins =
(lack one or more essential aa)
Legumes (peas & beans), nuts, cereal grains
Use amino acids to build proteins or burn for energy depending on:
All or none rule – all necessary amino acids must be present to make a protein – unused aa oxidized for energy or converted to carbs or fats
Used for ATP production if not enough carb or fat calories in diet
Anabolic hormones stimulate protein synthesis & growth, stress hormones (cortisol) break down protein and convert amino acids to glucose
Nitrogen balance =
rate of protein synthesis equals rate of protein breakdown and loss (healthy adults)
Positive balance during growth, pregnancy; negative balance during stress, starvation
Will vary based on age, size, metabolic rate and need (state of nitrogen balance); generally _____ – need to get essential amino acids from diet
~0.8 gm/kg body weight
Gluten sensitivity – Celiac disease (genetic) =
gluten breakdown products stimulate immune cells that attack intestinal epithelium – damage villi, decrease surface area for absorption - leads to malabsorption
_____ the most abundant dietary lipid
Triglycerides
Structure of _____ determines whether are solids or liquids at room temperature
fatty acid chain
Body’s most efficient and compact form of stored energy
lipids
Saturated fats =
(more H atoms, single bonds, solid at room temp)
Meat, dairy, coconut, hydrogenated oils
(trans fats: margarine or solid shortening)
Unsaturated fats =
(one or more double bonds, oils – liquid at room temp)
Seeds, nuts, olive oil, vegetable oils
Cholesterol =
(not used for energy)
Egg yolk, meat, organ meat, shellfish, milk products
____ are good fuel sources and are critical for normal cell physiology
Lipids
lipid uses in the Body:
Protect from heat loss, cushion body organs, energy store
____ create myelin and cell membranes
Phospholipids
___ precursor to hormones, stabilizes cell membranes
Cholesterol
Triglycerides are major fuel source for ______
skeletal muscle & hepatocytes
Presence of fats in diet aids in absorption of_____
fat-soluble vitamins
Dietary Considerations:
____of total calorie intake should be lipids
20-35%
Saturated should be less than ___ of total fat intake
10%
Limit cholesterol in diet – _____ makes 85% of what we use
liver
Liver can’t make 2 essential FA:
linoleic acid (omega-6 FA)
linolenic acid (omega-3 FA)
___ is vital for the proper function of the human body
Cholesterol