1 - 7/31/15 Flashcards
What are the 6 classes of nutrients utilized by humans?
Lipids, carbohydrates, protein, vitamins, minerals, water
What are the 3 purposes of nutrients?
Supply energy for work
Provide building blocks for synthesis of other molecules
Necessary to perpetuate metabolic pathways
What is the unit for nutrients-based energy?
Kilocalorie (kcal)
Listed as calories on nutrition labels
What is the energy content of nutrients utilized by humans? (Per one gram burned)
Carbohydrates and proteins = 4.1 kcal/g
Lipids = 9.3 kcal/g
What is the energy content of alcohol?
7 kcal/g
DRI
Dietary reference intake
Values that represent intake of 6 different nutrients
AI
ULI
EAR
RDA
AI
Adequate intake, used when RDA cannot be determined, assumed to be adequate intake based on observations of a group of healthy people
UL
Highest average daily nutrient intake level unlikely to pose risk of adverse health effects
Based on age and gender
EAR
Estimated average requirement, Average daily nutrient intake level that meets the requirements of 50% of individuals in a group
Based on age and gender
RDA
Recommend dietary allowance, value that represents amount of nutrients consumed that keeps 98% of a population healthy
Population is of same age/life stage and gender
RDA carbs, protein, and lipids?
Carbs = 60% of kcal (1200) Protein = 30% of kcal (600) Lipids = 10% of kcal (200)
Kwashiorkor and sx
Type of malnutrition that occurs when protein intake is deficient
Irritability, emaciated, edema in feet and hands, swollen moon face, distended abdomen, skin discoloration and lesions, enlarged fatty liver
Prevalent in children from developing countries
Marasmus and sx
Malnutrition caused by calorie-deficient diet lacking adequate carbs and protein
Emaciated, no distended abdomen
Emaciation
Extreme weight loss and thinness due to loss of subcutaneous fat and muscle
“Wasting away”
Distended
Bloating, ballooned, enlarged
What are nutrients?
Organic and inorganic molecules that support growth and survival of living organisms
Those utilized by humans are divided into 6 classes
Total Energy Expenditure
amount of calories needed to meet the body’s energy demands
TEE = BMR x PAL
variables include age, weight, gender, diet, physical activity, overall health.. expressed as BMR, TEF, and PAL
BMR
basal metabolic rate, at rest.. amount of calories required to maintain normal physiological functions, counts for 60-70% of total energy expenditure
variables include age, gender, health, and hormone levels
bigger people will have a higher BMR
TEF
thermic effect of food, calories utilized for digestion, absorption, and metabolism of nutrients
accounts for 10% of total body energy expenditure
PAL
physical activity level, accounts for calories required to support certain levels of physical exertion (range 1.4-2.4)
How many kcal = 1lb of fat?
3500 calories
BMI
vague indicator of one’s “fatness”, body mass index, weight(kg) / height (m^2)
four categories: underweight, healthy, overweight, obese
How many kg per 1 lb?
0.45 kg / 1 lb
Ways health can effect BMR?
running a fever increases metabolic rate and thus BMR, hyperthyroidism (graves disease) increases BMR, hypothyroidism (Hashimoto thyroiditis) decreases BMR
What are vitamins?
heterogeneous class of organic materials that do not provide energy but are essential for normal function
lipid-soluble, water-soluble
Lipid-soluble vitamins
ADEK, synthesized de novo or obtained from diet
when obtained from diet: packed in micelles for absorption by enterocytes/villus cells in the intestines, transported on plasma lipoproteins and stored in liver and adipose tissue
NOT excreted, may reach toxic levels in the liver
Vitamin A forms
B-Carotene: antioxidant, has derivatives..
Retinal: used to produce retinal pigment rhodopsin
Retinoic Acid: nuclear hormone that binds to transcription factors and influences gene transcription, contributes to proper differentiation of epithelial cells
topical version, tretinoin, is used to treat acne and wrinkles, isotretinoin is a teratogen and shouldn’t be used during pregnancy
Vitamin A disorders
night blindness and other visual impairments (dry eyes/xerophythalmia, Bitot’s spots/keratin debris), growth impediment, poor wound healing, dry skin, follicular hyperkeratosis, sudden hair loss/alopecia, bronchitis and pneumonia)
liver toxicity and join pain
Vitamin D forms
active form is calcitriol, base form cholecalciferol (D3 formed via UV irradiation of skin and produced in intestinal cells)
cholecalciferol undergoes two hydroxylations (by 25-hydroxylase in liver, then 1-a-hydroxylase in kidneys)
calcitriol binds to transcription factors that influence genes that stimulate: absorption of calcium and phosphates from the intestines, reabsorption of calcium in kidneys, promotes resorption of calcium from bone.. the net result is an increased blood concentration of calcium and phosphates to perpetuate proper bone mineralization/bone density
*PTH positively regulates calcitriol, calcitriol has negative feedback effect on its own formation mechanism
Vitamin D disorders
normal range for blood calcium levels on a CMP/BMP is 8.4-10.2, if levels are below normal.. consider..
inadequate dietary intake, lipid absorption disruptions, poor functioning liver or kidneys (CKD), hypoparathyroidism, lack of sunlight exposure (geographical location and season, excessive sunscreen application).. all of these effect calcitriol synthesis
Vitamin D deficiency presents itself as: brittle bones (Rickets in children), osteomalacia in adults (pathological fractures), hypocalcemia tetany (involuntary muscle contractions)
Vitamin D in excess can cause hypercalcemia and hypercalciuria, patient will appear dazed with a poor appetite, may also cause sarcoidosis
Sarcoidosis
presence of clusters of immune cells (granulomas) in various tissues such as the lungs, skin, and lymph nodes
Vitamin E forms
gama-tocopherol and a-tocopherol, a-tocopherol more actively retained in body
Vitamin E has a long hydrophobic tail that helps it anchor it to cellular membranes
serves as antioxidant to protect cell membranes against free radicals and LDL from oxidation (oxidized LDL is more atherogenic than unaltered LDL)
Atherogenic
promotes formation of fatty plaques in arteries
Vitamin K forms
active for is reduced, called vitamin K hydroquinone, serves as cofactor for gama-carboxylase
gama-carboxylase carboxylates glutamate residues on precursor clotting factors turning them into mature clotting factors, mature clotting factors can bind to calcium ions which further allows them to bind to phospholipids on the membranes of platelets, endothelial cells, and vascular cells which leads to blood clotting/coagulation
*Warfarin interferes with enzymes that create active form of Vitamin K (Vitamin K hydroquinone)
Water-soluble vitamins
NOT stored, excreted in urine and therefore toxic levels are rarely ever reached
Deficiencies due to inadequate intake and alcoholism
There are 9 water-soluble vitamins:
- involved in redox (transfer of electrons): B2, B3, C
- involved in non-redox (removal or transfer of chemical groups): B1, B5, B6, B12, Biotin, Folate
Vitamin B2
Riboflavin, FMN and FAD (flavin mononucleotide and flavin adenine dinucleotide), reduction generates FMNH2 and FADH2 (essential role players in nutrient metabolism and energy production)
Vitamin B3
Niacin, NAD+ and NADP+ (nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate), reduced to NADH and NADPH where serve as electron carriers and reducing agents (provide electrons)
Vitamin C
antioxidant and reducing agent, aka ascorbic acid
necessary for formation of collagen, deficiencies cause scurvy with petechiae
Scurvy and Petechia
Scurvy includes spongy and bleeding gums with poor wound healing
Petechia presents as purple hemorrhagic spots on the skin caused by minor bleeds
Folate
Water-soluble vitamin that is a necessary role-player in the growth mechanism of rapidly dividing cells (intestines, hair follicles, oral mucosal cells)
What is the function of water in the human body?
Acts as solvent or a reagent in biological reactions, solvent for components of blood, medium for the excretion of wastes, regulates body temperature, comprises 70% of body weight
Minerals
heterogeneous class of inorganic nutrients that function as electrolytes, enzyme cofactors, and signaling molecules
two categories: macroelements (most abundant) and microelements
Macroelements
K^+, Cl^-, Na^+, Ca^2+, Mg^2+, and PO4^-3
Most abundant minerals because they’re required in over 100mg/d
Concentrations, higher outside cell: Na, Ca, Cl
Concentrations, higher inside cell: K, Mg, PO4
Major cations: Na, K
Major anions: Cl, PO4
Microelements
aka trace elements, required in less than 100mg/d
Fe, Zn, Cu, Mo (molybdenum), Mn (manganese), Co (cobalt), Cr (chromium), S, Se, I, and F (fluorine)
What are the major electrolytes?
Na, Cl, K
main electrolytes that maintain osmotic pressure and acid-base balance (pH)
their concentration gradients perpetuate nerve conduction and muscle activation
Na involved with nutrient absorption in kidneys and intestines, K involved with regulation of insulin secretion
Significance of kidneys in maintenance of homeostasis
Kidneys filter blood and make sure nutrients are reabsorbed and waste (urea and ammonia) are excreted in urine
Thus, they assist in regulation of electrolytes.. which regulates pH and volume of bodily fluids
K disorders
hypokalemia: caused by low dietary intake or diarrhetic use, sx include: myalgia, cramps, constipation, arrhythmias, flaccid paralysis
hyperkalemia: kidney disease, drugs (spironolactone), sx include: palpitations, arrhythmias
Na disorders
hyponatremia: caused by increased renal excretion (HCTZ or other diuretics, excessive aldosterone) or excessive water reabsorption from kidneys (due to excessive secretion of ADH, CHF, or chronic liver disease), sx include convulsions and cerebral edema
hypernatremia: caused by decreased renal excretion or decreased water reabsorption from kidneys (insufficient ADH due to DI), sx include confulsions and cerebral edema, lack of ADH can cause dehydration
ADH
anti-diuretic hormone, aka vasopressin
Cl disorders
hypochloremia: caused by vomiting, sc include chronic repirators acidosis and metabolic alkalosis
hyperchloremia: caused by intravenous saline, diarrhea, drugs, sx include: weakness, labored breathing, intense thirst
What minerals are stored as salts in collagen matrix of bone and teeth?
Ca, PO3, Mg
bone is a resorvoir for these ions and degrades when they need to be mobilized to other parts of the body for various functions
Ca represents 1.5-2% of the body’s mass, found floating freely/attached to albumin/bound to phosphates in bone mineral hydroxyapatite, PO3 is roughly 1%
Important functions of the three minerals stored in hydroxyapatite
Ca, Mg, PO3
Ca: contraction of skeletal, cardiac, and smooth muscle, involved in propagation of nerve impulses, important component of blood clotting/coagulation cascade
Mg: contraction of skeletal, cardiac, and smooth muscle, involved in propagatino of nerve impulses, important cofactor for many enzymes (especially ones that utilize ATP), plays role in hormone-receptor binding, neurotransmitter release, and gating of transmembrane cation channels
PO4: component of nucleic acids, component of high-energy bonds in ATP (which are hydrolyzed to release energy), used to phosphorylate (activate and deactivate enzymes), helps trap glucose inside cells
Three hormones that regulate blood Ca and PO4 levels
Calcitriol: active for of Vit D, produced in kidneys, increases blood levels of Ca and PO4
PTH: parathyroid hormone, produced and secreted by parathyroid glands, increases blood Ca and decreases blood PO4 levels, lower blood PO4 levels allows Ca to circulate more freely
Calcitonin: decreases blood Ca and PO4 levels, produced by thyroid gland
What are the most abundant microelements?
Zn, Fe, Cu
All come from grains, Fe and Zn come from meat, Cu comes from poultry/fruits/chocolate, Fe comes from dark green veggies
*Zn absorption is inhibited by certain minerals and bran
