Int Phys Exam 3
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What is the energy Balance equation? what is the difference between energy ratio and mass ratio?
- Energy In = energy out + Energy Stored
- Energy Ratio - 55% carbohydrates; 15% Proteins and 30% Fat
- Energy ratio takes into account the kJ per gram of each substance where as mass ratio is the ratio between grams of each substance
What is RMR, MET, PAL, and the thermic effect of feeding adn what do they have to do with the Energy Balance Equation?
- RMR - Resting Metabolic Rate
- MET - Metabolic Equivalent (multiple of RMR)
- PAL - Physical Activity Level
- Thermic effect of feeding - ~10% of energy ingested (higher for proteins and carbs than fats)
- These 4 things are the contributing factors in the Energy Out portion of the Energy balance equation
How are carbohydrates classified?
- Sugars (mono- and disacharrides) - glucose, fructose, galactose, sucrose, lactose, maltose
- Oligosacharrides (3-9) - maltodextrins - glucose polymer produced from corn and potatoes
- Polysacharrides (many) - Starch - long polymers of alpha-glucose Cellulose - long polymer of beta-glucose
How are carbohydrates stored?
- Average adult has ~500g of carbohydrates stored
- 200 g as glycogen in the liver
- 250 g as glycogen in the muscles
- 50 g as glucose in the body fluids (only ~5 g in blood)
What are carbohydrates necessary for?
- 1. Energy homeostasis
- 2. Form the carbon skeletons of amino acids
- 3. glycoproteins - mucins, antibodies, clotting factors
- 4. proteoglycans - "junk" between your cells
Why is continual consumption of carbohydrates critical for energy homeostasis?
Only about 500 g of carbohydrates are stored in the body, only enough to last us about 1.5 days, this means we must have a continual income of carbohydrates to meet metabolic needs
What does glycemic index tell you about a food?
- how quickly does a food enter the blood as glucose
- GI of 100 means that the food enters the blood as quickly as glucose
What are the types of lipids and what are they used for?
- Triglycerides - fat storage
- Phospholipids - key components of cell membranes
- Sterols - building other molecules
How are lipids transported through the body?
- Transported as lipotroteins (clump of lipids with apolipoprotieins embedded)
- Chylomicron - made in intestine, transport lipids from food into blood and liver, short lived in blood (15-30 mins) critical for transporting A, D, E, and K to liver
- VLDL - Made in liver, transport fatty acids from liver to heart, muscles, and adipose tissue
- LDL - Whats left of VLDLs, Primarily cholesterol, transport cholesterol to liver and other tissues
- HDL - made in liver and intestine, transport cholesterol from tissues back to liver
What is the difference between essential and nonessential fatty acids?
Essential FA cannot be synthesized by the body, nonessential FA can
What is the difference between saturated, unsaturated and trans-FA?
- Saturated - no double bonds
- Unsaturated - contains double bonds
- Trans-Fats - unsaturated but behave like saturated fats
What are the effects of obesity and of types of fats on lipoprotein levels and health?
- Obesity - LDL (bad) high ; HDL (good) low
- Saturated Fats - LDL very high ; HDL high
- Cis - LDL low; HDL high
- Trans - LDL very high ; HDL low
Why can BMI and Body Fat % be different?
They tell you differeent things based upon how muscular the person is.
What four proteins account for ~50% of your total protein mass? How much of your daily energy consuption is devoted to protein turnover (making and breaking down proteins)?
- Collagen, myosin, actin, Haemoglobin
- You break down and synthesize ~500g of protein daily
- This protein turnover accounts for ~20% of all ATP consumed
what is the difference between indispensable, conditionally indispensable, and dispensable amino acids?
- Indispensable - absolute
- dietary necessities if normal growth is to be maintained
- Conditionally Indispensable - whose synthesis can be carried out by mammals but can be limited by a variety of factors
- Dispensable - Can be synthesized by mammals
How do animal proteins, legumes, cereals, and tubers rank in terms of providing indispensable amino acids?
Animal proteins > legumes > cereals > tubers
What foods are high and low in: methionine, lysine, threonine, and tryptophan?
- Methionine - high in cereals and sesame seeds; low in legumes
- Lysines - High in legumes; Low in cereals (essentially absent from wheat, corn, and rice)
- Threonine - high in animal products (cottage cheese), legumes, sesame seeds; absent in rice
- Tryptophan - high in animal products, legumes, sesame seeds; absent from corn (precursor for seratonin-melatonin synthesis
What is the difference between marasmus and kwashiorkor in terms of clinical presentation adn causes?
- Marasmus: severe energy deficiency - not enough protein
- Characterized by emaciation adn is cuased by absolute deficiency of protein (energy)
- Kwashiorkor: Wasting and edema
- Characterized by emaciation and edema and its causes are unknown, but may be related to micronutrients or aflatoxins
What is the basic evidence supporting maladaptive diet syndrome (diseases of nutritional excess) hypothesis? What is hormesis?
- Examples (Obesity, CHD, Type II diabetes (fat, sugar) Hypertension, CHD (fat, salt) Alcoholism (alcohol)
- Ancestrally adaptive behaviors have become maladaptive in the modern human environment
- 1. Sugars, fats, salts, and alcohol are nutritionally important, but were historically scares.
- 2. sugars, fats, salts, and alcohol all show hormesis
- hormesis - the term for generally favorable biological responses to low exposures to toxins and other stressors (description of J-shaped curve between the dose of a substance and its effect on health)
Define vitamine and list the fat- and water-soluble vitamins?
- Vitamin - organic molecules that cannot be synthesized in sufficient amounts and that are required for biochemical reactions
- Fat-soluble: A, D, E, K
- Water-Soluble- B, C
What are good sources of each vitamin?
- A - Plants (beta-carotene) and Animal foods (retinol, retinal, retinoic acid)
- D (cholecalciferol) -
- E (tocopherol) - nuts and oils
- K (glutamic acid) - green vegetables
- B - Cereals and animal products
- C - Citrus Fruits
whart are the different forms of Vitamin A and what are their functions?
- Retinoic Acid - critical regulator of gene expression; determinant of differentiation in epithelial cells: low retinoic acid causes cells to secrete keratin rather than mucus
- Retinal - used for sight
What are the two pathways by which vitamin A deficiency affects vision/
- Night Blindness (reduced retinal) is caused by reduction in turnover of rhodopsin (opsin +11-cis-retinal) which means there is a deficiency in the pathway that interconverts 11-cis-retinal and all trans retinal
- Keratinization (reduced retinoic acid) comes from xerophthalmia and respiratory infections
what is the difference between rickets and osteomalacia?
- Rickets only occurs in children, effects growth by reduced calcification of growing bones
- Osteomalacia - occurs in adults and reduces bone density
Where do you get vitamin K and why do infants receive a vitamin K shot?
- You find it in green vegetables and is synthesized by bacteria in large intestine. It is not stored
- Newborns recieve a shot because vit K is fat soluble and that causes it to not cross the placenta well which means that the GIT of newborns is essentially empty of vit K
What roles do the B vitamins play in the body and what are good sources of each of them?
- Cofactors, coenzmes
- Thiamine (B1)- Cofactor necessary for carbohydrate metabolism
- Riboflavin (B2) - consitituent of FAD (critical electron donor/acceptor) Good Source - animal products, leafy green veggies
- Niacin (B3) - constituent of NAD (ATP production); can be synthesized by tryptophan
- B6 - Cofactor necessary for synthesis of 1. Heme 2. neurotransmitters (seratonin, catecholamines) 3. niacin from tryptophan
- Folic Acid - critical for synthesis of nucleotides and tend to affect rapidly dividing tissues.
- B12 - Stored in liver; requires co-factor in stomach, critical for the synthesis of nucleotides and tend to affect rapidly dividing tissues
What are wet and dry beriberi? What is Wernicke-Korsakoff Syndrome?
- Wet Beriberi - Reduced ATP available for heart function, increased heart rate, peripheral edema
- Dry Beriberi - Damage to peripheral nerves, extensive sensory/motor neural deficits, wrist and ankle drop, loss of sensation
- Wernicke-Korsakoff syndrome - buildup of metabolism byproducts --> encephalopathy
- Seen in chronic alcoholics
- All of these come from deficiency in B1 (thiamine)
What is Pellagra?
- Diarrhea, dermatitis, dementia
- Often associated with high corn diets: low niacin, deficient in tryptophan
- Stems from deficiency in B3 (niacin)
What is scurvy?
- Reduced synthesis of collagen and elastin
- Causes bone fractures, edema, infections, poor wound healing
- Stems from deficiency in Vitamin C
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