Optin D Human Physilgy D.1 Human Nutritin D.1 Essential idea: A balanced diet is essential t human health. Nature f science: Falsificatin f theries with ne thery being superseded by anther scurvy was thught t be specific t humans, because attempts t induce the symptms in labratry rats and mice were entirely unsuccessful. D.1 U1 Essential nutrients cannt be synthesized by the bdy, therefre they have t be included in the diet. Nutrients: chemical substances, fund in fds, that are used in the human bdy. Essential: fd is the nly surce f this nutrient. Such as amin acids, sme unsaturated fatty acids, sme minerals, calcium, vitamins, and water. Nn- essential: anther nutrient can be used fr the same purpse r because they can be made in the bdy frm anther nutrient. Such as glucse, starch and ther carbs because they are used in respiratin t prvide energy and lipids can be used instead. Sme essential nutrients are cnditinally essential: In adults Vitamin K is prduced by metablism f symbitic bacteria in intestine, since infants dn t have clnies at birth they are given supplementary injectins f vitamin K. Applicatin D.1.1: Prductin f ascrbic acid by sme mammals, but nt thers that need a dietary supply. Vitamins C is ascrbic acid. Needed t make cllagen fibers that frm tissues f bdy (skin and bld vessel walls). Mst plants and animals can make vitamin C. Mutatins have led t genes that n lnger prduce prtein need t make vitamin C. This inability is due t mutatins in the GLO gene which cdes t make the enzyme L-guln-ylactne xidase. (this catalyzes the final reactin t make vitamin C. Sme fish called telest (cd, salmn, and herring) have lst the ability t prduce vitamin C. Mst mammals can (carnivres like dgs and cats) but primates (humans, chimps, and apes) cannt but the mre primitive nes can (like lemurs) Symptms f vitamin C deficiency (scurvy) can be eliminated by dietary surces. D.1 U4 Sme fatty acids and sme amin acids are essential. Of the 20 amin acids in prteins half are essential in humans. Other half can be made frm ther simpler nitrgen cmpunds. Threnine and arginine are cnditinally essential. Threnine can be synthesized if phenylalanine is present. Arginine can be prduced in a healthy individual but in premature infants the pathway is nt active s must get frm diet. Sme mega-3 and mega-6 fatty acids are essential in diet. Omega-3 and-6 refers t psitin f duble bnd in relatin t end f mlecule. Alpha-linlenic acid and linleic acid are used t make a number f cmpunds s are needed in bdy but in large quantities in brain and eye. Hwever, diet supplements f these d nt enhance brain r eye develpment. Histidine Isleucine Leucine Lysine Methinine Essential amin acids Phenylalanine Tryptphan Valine Threnine (nly if phenylalanine is nt in diet) Arginine (required in the diet f infants)
D.1 U5 Lack f essential amin acids effects the prductin f prteins. If shrtage f amin acids in diet then bdy can t make enugh f the prteins it needs. Knwn as prtein deficiency malnutritin. Essential a.a. may be lacking due t insufficiency f prtein in diet r imbalance in types f prteins. Ex. Can cause a lack f bld plasma prteins which results fluid being retained in tissues causing swelling (edema) in abdmen. Child develpment can be mentally and physically retarded with stunted grwth and develpmental disabilities. Adults underg serius weight lss (wasting) D.1 U2 Dietary minerals are essential chemical elements. Needed in diet in small quantities (milligrams r micrgrams) Can be distinguished frm vitamins by chemical nature. Minerals: chemical elements, usually in inic frm. Ex. Calcium 2+ ins. Lacking in diet causes deficiency disease, can be serius. Ex. Idine is needed by thyrid gland t make hrmne thyrxin which stimulates metablic rated and release f energy. A lack causes idine deficiency disrder (IDD). If pregnant baby may be brn with permanent brain damage. Can cause mental develpment and impaired intelligence if baby brn with it. Many peple affected by this and an idine supplement can be given by adding mineral salt t diet. D.1 U3 Vitamins are chemically diverse carbn cmpunds that cannt be synthesized by the bdy. Vitamins are rganic cmpunds needed in small amunts because can t be made by bdy but must be btained frm diet. Rles such as c-factrs fr enzymes, anti-xidants and hrmnes. Vitamin C cmes frm mnsaccharide, vitamin A is hydrphbic and has hydrcarbn ring and chain, Vitamin B2 has nitrgen rings and is cnverted t Flavin mnnucletide by additin f phsphate t carb. Within mlecule. Can be fat r water sluble. Water have t be cnstantly cnsumed and any excess is lst in urine. Fat can be stred in bdy.
D.1 U6 Malnutritin may be caused by a deficiency, imbalance f excess f nutrients in the diet. Malnutritin results frm a pr diet. Diets can be lw in verall quantity with lw prtein and calric cntent, can be unbalanced and fail t prvide essentials, r can cntain excess gats and carbs. Malnutritin ften assciated with pverty, starvatin results frm diet lacking in adequate prtein and carbs. Obesity bserved in develping cuntries as well as lwer classes as a result f unhealthy diets with excess f fat and refined carbs. D.1 U7 Appetite is cntrlled by a centre in the hypthalamus. Hypthalamus is lcated in brain and makes us feel satisfied when we have eaten enugh. Called appetite cntrl center. Small intestine secretes hrmne (PYY3-36) when it has fd. Pancreas secretes insulin when bld glucse cncentratin is high. Adipse tissue secretes hrmne leptin when amunts f stred fat increase. If appetite cntrl center receives these hrmnes it reduces the desire t eat. This aids in aviding health prblems due t vereating including excessive bld glucse levels and besity. Hypthalamus in Brain receives these signals and tells us we are full
D.1 U8 Overweight individuals are mre likely t suffer hypertensin and type II diabetes. Unhealthy diets with excess fat and refined carbs. Have health cnsequences. Ex. Diabetes and hypertensin. Several diseases cause excessive excretin f urine, all f which are frms f diabetes. In cmmnest frm sugar is preset in urine (diabetes mellitus) and affects many. Can develp 2 ways: 1. Aut-immune destructin f insulin-secreting cells in pancreas (Type I) 2. Decreased respnsiveness f bdy cells t insulin due t burn-ut (Type II) Type II is rising in many cuntries. Epidemilgy (study f rates and distributin f a disease) have implicated increased bld cnc. Of fatty acids, linked t the risk factrs: diets rich in fat and lw in fiber, besity due t vereating and lack f exercise, genetic factrs that affect fact metablism. Big variatin between ethnic grups in rates f type II. China has less than 2 percent and Pima Indians having 50%. Symptms are nt always recgnized s all peple nt diagnsed. Symptms include: elevated levels f bld glucse, glucse in urine, dehydratin and thirst resulting frm excretin f large vlumes f urine. Diabetes can cause health prblems if nt managed. Several cmplicatins relate t cardivascular system: athersclersis (narrwing f arteries by fatty depsits), hypertensin (raised bld pressure), crnary heart disease (narrwing f crnary arteries with risk f heart attacks) Link between cardivascular disease and bld lipid cncentratins: links between high cnc. f chlesterl high cnc. f LDL and lw cnc. Of HDL. Clear crrelatin between excessive weight gain and hypertensin. Weight gain can increase release f hrmnes as well as cause changed in bdy physilgy and anatmy which all can lead t hypertensin: weight gain leads t higher cardiac utput and can raise bld pressure; abdminal besity can increase vascular resistance which can raise bld pressure; weight gain assciated with arteries becming stiffer and narrwer which can raise bld pressure. Hypertensin can be caused by high salt intake. D.1 U9 Starvatin can lead t breakdwn f bdy tissue. Occurs due t severe lack f essential and nnessential nutrients. In absence f energy surces the bdy will first access glycgen stres, then it will break dwn its wn muscle tissue t utilize amin acids as energy surces. The a.a. are sent t liver and cnverted t glucse. This results in lss f muscle mass. Applicatin D.1.2: Cause and treatment f phenylketnuria (PKU) Phenylketnuria (PKU) is a genetic disease caused by mutatins f a gene cding fr the enzyme that cnverts phenylalanine int tyrsine. Mutatins prduce alleles enzyme that is unable t catalyze the reactin. Only ne nrmal allele is needed fr nrmal cnditin s the disease is nly inherited when tw recessive mutant alleles are acquired. As a result phenylalanine accumulates in bdy and can als be a deficiency in tyrsine. High levels cause reduced grwth f head and grain, mental retardatin f yung children, hyperactivity and seizures in lder children. PKU babies are unaffected at birth because mther s metablism kept nrmal levels. Test are carried ut at 24 hurs after birth when phenylalanine cncentratins have started t rise. Treatment invlves eating a diet lw in phenylalanine. Meat, fish, nuts, cheese, peas and beans eaten in small quantities. Tyrsine supplements may be needed. Harmful effects can be avided with diet.
Applicatin D.1.3: Lack f Vitamin D r calcium can affect bne mineralizatin and cause rickets r stemalacia Vitamins D needed fr calcium absrptin frm fd in the intestines. Symptms are similar t thse f calcium deficiency. Vitamin D is synthesized in the skin when expsed t sunlight r anther light surce cntaining ultravilet light with wavelengths in the range 290-310nm. Children, pregnant wmen and elderly need t eat 10ug per day t supplement amunt in their skin. Dietary surces include ily fish (herring, mackerel, sardines and tuna), eggs, liver gd with margarine, milk are artificially frtified with vitamin D. Ultravilet light has harmful cnsequences: mutatins in skin (dark skin gives prtectin against cancer but it als reduce vitamin D synthesis) In indigenus human pp. skin clr balances the twin risks f vitamin D deficiency and cancer r ther damage due t ultravilet light. After ppulatin migratins there can be prblems. In 1970 immigrants with dark skin frm Indian subcntinent living in United Kingdm shwed symptms f vitamin D deficiency. Immigrants frm nrthern Eurpe with light skin living in Australia, were fund t have high rates f malignant melanma. Australians with light skin were then advised t stay f bright sunlight, cver their skin r apply sun-blck. Applicatin D.1.4: Breakdwn f heart muscle due t anrexia Anrexia means reduced appetite. Anrexia nervsa is a psychiatric illness which invlves vluntary starvatin and lss f bdy mass. The amunts f carb. and fats cnsumed are t small t satisfy bdy s energy requirements s prtein and ther chemicals in bdy are brken dwn resulting in a wasting f muscles and lss f strength. Hair becmes thinner, skin becmes dry and bruises easily. Fine grwth f hair all ver bdy. Bld pressure reduced, pr circulatin. In females infertility is cmmn and n vulatin r menstrual cycles. As bdy weight falls heart muscle deterirates. Skeletal muscle mass reduces disprprtinately faster than cardiac mass. Lack f prtein, electrlytes and micrnutrients result in muscle fiber deteriratin, and alters cnc. Of calcium, ptassium, and sdium and muscles d nt cntract nrmally. Reduced bld pressure, slwer heart rate and reduced heart utput is als bserved. Applicatin D.1.5: Chlesterl in bld as an indicatr f the risk f crnary heart disease. Chlesterl is a nrmal cmpnent f plasma membranes in human cells. Research has shwn a crrelatin between high levels f chlesterl in bld plasma and an increased risk if crnary heart disease. Advice is ften given t minimized dietary chlesterl intake, but is it nt certain that this will actually lwer risk f CHD fr a variety f reasns: Research has invlved ttal bld chlesterl levels, but nly chlesterl in LDL (lwdensity lipprtein) is implicated in CHD. Reducing chlesterl ften has small effect n bld chlesterl levels Liver can synthesize chlesterl s dietary chlesterl is nt nly surce. Genetic factrs are mre imprtant and sme families have high chlesterl and lw dietary intake. Drugs can be mre effective than reducing dietary intake Psitive crrelatin between dietary intake f saturated fats and intake f chlesterl, s pssible that saturated fats, nt chlesterl cause the increased risk f CHD in peple with high chlesterl intakes
Skill: Determinatin f the energy cntent f fd by cmbustin. Calrimetry: determinatin f the energy cntent f a substance. The specific heat f water: it takes 4.186J f heat energy t raise the temperature f 1 gram f water by 1 degree Celsius. Q= mass f water x specific heat capacity x change in temperature The apparatus cnsists f a thermmeter t detect change in temp. A vessel cntain a knwn mass f water (1ml f water has a mass f 1g). The sample t be tested fr its energy cntent is ignited and placed belw the cntainer cntaining the water and the temperature change is nted.
Use these results t estimate the energy cntent the nut per gram: Data: Mass f nut = 0.60g; vlume f water = 25ml; initial water temperature = 20 C; final water temperature = 65 C Yur answer: Skill: Use f databases f nutritinal cntent f fds and sftware t calculate intakes f essential nutrients frm a daily diet. Balanced diet: cmbinatin f fds that will prvide essential and nn-essential nutrients in the crrect balance. Fresh fruit and vegetables shuld make up largest part f diet fllwed by carbs, prteins and then dairy prducts. Fata and sugars are n charge because they shuld make up smallest part f diet. (See fd wheel belw) Cmputer applicatins can be used t keep recrd f fd cnsumed. Check ur Super Tracker available frm the US Department f Agriculture (USDA)