Metabolic Fuels Flashcards
How do you calculate the caloric content of fat, carbohydrates, proteins, and alcohol in the diet?
Carbohydrate- 4 kcal/g
Protein- 4 kcal/g
Fat - 9 kcal/g
Alcohol- 7 kcal/g
What are the major metabolic fuels in the human body?
Carbohydrates - glycogen -> stored in the cytosolic granules in liver and muscle cells
Fat - triglycerides - 85% of stored fuel. 15% water. Stored in adipose tissue
Proteins - not really a food store- it provides structure and function
What does a 70 kg man store in fuels ?
Muscle glycogen - .15 kg or .4%
Liver glycogen - .08 kg or .2%
Fat - 15 kg or 85%
Protein - 6 kg or 14.5%
What is the basal metabolic rate (BMR)?
Energy required to maintain life at rest (circulation, breathing, etc.) It is based on age, sex, and weight. Dependent on lean mass, adipose tissue has lower metabolic levels and acts as an insulator.
What induces thermogenesis ?
Diet
How do BMR, physical activity, and thermogenesis contribute to the daily energy expenditure?
Daily energy expenditure composes of BMR, physical activity, diet-induced thermogenesis, wound repair and growth
What are the categories of the major nutrient groups in the diet?
Carbohydrates, fats, proteins, vitamins, minerals
What are the essential fatty acids?
4 polyunsaturated fats Linolenic acid (C18:3) - seeds, green leafy vegetables Linoleic acid (C18:2) - vegetable oils Eicosopentanoic acid (EPA, C20:5) - cold water fatty fish, yogurt, milk Docosahexaenoic acid (DHA, C22:6) - cold water fatty fish, yogurt, full fat milk
EPA and DHA are important for development of cognition and vision in young children
What are the essential amino acids?
PVT TIM HALL P= phenylalanine V= valine T= tryptophan T= Threonine I = Isoleucine M= Methionine H = Histidine A = Arginine L = Leucine L= Lysine
How many grams of proteins are required?
60 g protein/day
What happens to the excess dietary proteins?
They are not stored -> they get convert to glycogen/fat
What are vitamins?
They are organic chemicals required for growth and acquired through diet. Most are coenzymes, some are hormone receptors
What are minerals?
Calcium, magnesium, sodium, potassium, chlorine, phosphorus, sulfur,
What are the classical disease states associated with malnutrition?
Kwashiorkor
Marasmus
What is Kwashiorkor disease?
Caused by protein malnutrition. Negative nitrogen balance leads to inability to synthesize proteins. Diet has adequate caloric intake. Decreased serum proteins leads to edema (plump belly)
What is Marasmus disease?
Caused by caloric malnutrition. Diet is inadequate in caloric intake. Patient shows skin and bones
What is Body Mass Index (BMI)?
It is measured by weight/height^2 [kg/m^2]
Normal: 18.5-24.9
Overweight: 25-29.9
Obese: 30 or above
What is recommended by dietary recommendations of the “Dietary Guidelines for Americans” ?
Caloric intake much balance caloric expenditure
How does the availability of metabolic fuels change?
It depends on fed vs fasting states
What are the dietary requirements for life?
Amino acids, fats, vitamins, and minerals
What are the two mechanisms for disposing waste?
- Compounds generated by metabolism such as ammonia
- Foreign compounds taken in as food or drink that are not useful as fuel or structural components (xenobiotics)
What is ATP used for?
Chemical unit of energy that is used to fuel biosynthetic processes and physiologic processes such as nerve impulse and muscle contraction
What are the two mechanisms used to produce ATP?
Substrate-level phosphorylation - high-energy intermediates donate phosphate group
Oxidative phosphorylation - electrons are carried to form ATP
In metabolism, what is the role of oxygen
It is the final electron acceptor; oxidized fuels do not use the molecule oxygen
Where is fat usually stored?
In the adipose tissue. Sometimes, it can be stored in the liver, however, build-up of fats in the liver over time is a problem
What are branched metabolic pathways?
- Different fuels from many sources enter similar metabolic pathways
- Fates of metabolites are determined by energy status of organism (whether or not organism is actively moving or at rest)
What common substrates are produced from diverse fuels?
Acetyl CoA produced by several catabolic pathways; can be metabolized completely by oxidation to CO2 and H2O and stored as fatty acids and triglycerides
What does acetyl coA convert as stored fuel?
FAT
What are the major carbohydrates in the diet?
starch, sucrose, lactose, fructose ,and glucose
How are proteins used in the body?
Digested and burned for energy or reused.
What are triglycerides?
Three fatty acids esterified to a glycerol molecule
What is the difference between a fat and an oil?
Melting point
How are mono- and poly-lipids used?
They are used differently at organ vs. organism level
Poly -> great for the heart but not for the liver
How is ethanol oxidized
it is oxidized like other fuels to provide energy
How many calories in one kcal?
1 Calorie
This means that 1 kcal (energy) raises 1 liter of H2O at 1 degrees (change in temperature)
1 kcal = 4.128 kJ
How are glycogen and fat stores different?
Glycogen - hours
Fat - months
What is the creatine phosphate?
It is a mechanism of storing ATP equivalents in the tissue
it used when muscle needs large amounts of ATP for kinetic activity
Creatine phosphate is generated by creatine kinase from ATP and creatine to store “ATP equivalents”
In pregnancy, BMR is increased or decreased?
In pregnant woman, BMR is normally increased because more fuel is need to allow the fetus to grow
In physical activity, what are the changes that occur?
respiratory rate can go up 8-fold, more oxygen consumption, more calories burned, higher heart rate
What are the strategies for effective weight loss?
Weight loss occurs when caloric intake is less than caloric expenditure
Change eating habits and increase exercise
What is nitrogen balance?
Nin-Nout = nitrogen balance
Positive N balance = growing child, pregnant woman, body builders
Balanced N => intake equal losses ; adult needs 0.8 g/kg/day of high quality protein
What conditions result in negative N balance?
illness, surgery, stress
Kwashiorkor, Marasmus, Anorexia nervosa
Fasting, starvation (muscle protein degradation for gluconeogenesis)
Deficiency of single essential AA
