Metabolism 2 Study guide Exam 1 1 Explain the DRI The goal of the DRI is to prevent chronic diseases not to prevent deficiencies The focus is now on malnutrition from over nutrition DRI started in 1835 with lemons on ships Then first RDA was in 1949 with the focus to prevent deficiency in the military not important to know Changed because it was too broad focus on healthy people and too many fat unhealthy people Now have EAR RDA AI and UP This is pretty much a fancy graph made up from years of data on what the ideal amount of nutrients the population should be consuming in order to prevent chronic diseases Or at least lower their chances The RDA is the recommended dietary allowance which is pretty much the DRI This is what 98 of the population should be consuming for the respective nutrient The EAR is a form of the DRI that only encompasses 50 of the population So this value is what is recommended for half the population but the RDA covers 98 of the population s nutritional needs The UL is the limit of a nutrient that is safe for consumption Most vitamins have upper limits where above this value is detrimental to health An extreme example is with vitamin A At sufficient doses Vitamin A produces an acute untreatable and routinely fatal liver toxicity The action was initially discovered when several scientists doing Arctic research consumed polar bear liver for dinner Polar bear liver has enormous amounts of Vitamin A They all died It was unfortunate given the native Inuits had warned them not to eat bear liver The Eskimos already knew that was not a good thing to do Little extra information The AI is a value assigned to a nutrient when there is not enough research to derive an RDA for So they choose a value high enough that seems the best Minerals in General 1 What is the classification for minerals Minerals are defined as elements that are only 4 or our total nutrition yet they are just as important as the vitamins This 4 is divided into the macro micro minerals and the ultra trace The macro minerals are present in 1g or higher for every 60 70kg of our body weight or they are required in amounts of 100mg or more daily Ca P K Na Mg S Cl The micro minerals are like the name says much less yet still just as essential These are present in the body in 1g or less per ever 60 70 kg or you need less that 100mg daily Pretty much everything that is not one of the macro minerals is a trace mineral There is another class called ultra trace and is required in less than 1mg daily But these aren t that important 2 What is essentially How is it decided for minerals Essential means required to support normal growth health and reproductive health when all other nutrients are optimal so we know it s the mineral effect and not other nutrients or lack of Ways that experts figured out what was essential was by looking at populations with certain genetic disease that lead to a mineral deficiency Menken s Syndrome Cu deficient Acrodemattis Zn deficient With minerals it is determined when its removal causes certain physiological and biochemical impairment and when you add it back the impairment is reversed Essentiality can be hard to determine when other nutrients aren t optimal cause then you don t know if the lack of the mineral or the nutrient is causing it or when there is some mineral interaction going on 3 What is the bioavailability and interaction of minerals This is the amount of the mineral in the food that the body could actually absorb and differs among the minerals Certain factors can decrease the bioavailability and some can increase it The ones that decrease it are if chelation is present if there is competition with other nutrients or if the mineral has other antagonists and they are present The ones that increase it are other food constitutes synergism or intestinal environment It will be different for every mineral 4 What are the general roles of the minerals Every mineral is different but the general roles are all the same Most of them are for structure some are catalytic and others are for signal transduction Ones that we didn t go over in detail are Na K and Cl and these are involved in osmotic pressure and membrane potential The exact role varies with minerals but the general roles are the same We know Cu deficiency leads many different pathologies Zn deficiency leads to stunted growth and reproductive problems and Mn deficiency leads to reproductive problems and ataxia 5 Go over the GI tract basics This is the pathway that food follows after eating to the small intestine First you chew and swallow the food it goes down the pharynx and then the esophagus to get to the stomach Once in the stomach it mixes the HCl and other juices and gets partially digested and then enters the more basic environment in the small intestine This in a 3 part organ broken into the duodenum 1ft long the jejunum 9 ft and the ileum 9ft this is where all the absorption occurs The food is absorbed across the microvilli contain enterocytes where the food is absorbed specifically that line the small intestine These enterocytes are replaced every 3 5 days Also have the colon which gets rid of unabsorbed shit The pancreas liver and the gallbladder are also part of the GI tract Calcium 1 What are the main properties and what are the characteristics of calcium This is one of the macro minerals and the DRI is 1000 mg which 99 is in the bones The only number you ll probably need to memorize is the circulating concentration of Ca and this is 8 5 10 5 mg dl always have this amount either in the blood or bones more on this later Some characteristics of Ca are that it is the most abundant cation that circulates in the body yet only 1 of the total Ca is circulating other 99 is in bones Then if you want to break it down to its forms in circulation 50 is active 40 is bound to albumin and globulin and 10 is in a complex with other shit 2 What are the functions of Calcium Everyone knows the Ca is a huge mineral of bone but it also has other roles If you look at just the extracellular Ca it does the following A cofactor is blood clotting Involved in muscle contraction Need Ca to do any type of contraction Nerve conduction again need Ca to do anything Cell membrane structure Now a very low amount is intracellular and in the cells it perform this roles which are still important Key is the second messenger cAMP Binds to several proteins like Calmodulin involved with an enzyme and calbindin this increases Ca absorption 3 What
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