human nutrition

Question 1

factors affecting nutritional status

Answer 1

biological - genetic, phase of lifestyle
psychology -satiety, appetite, palatability of food
social - availability of food, cultural customs
energy expenditure
disease presence

Question 2

importance of nutrition in health + disease

Answer 2

prevention, progression + management of disease

excess weight -> covid 19 complications

Question 3

main class - carbohydrate

Answer 3

main energy source, some create long satiety for weight control, some are digested rapidly + stimulate craving

Question 4

main class - fats

Answer 4

main energy source + storage, linked to heart disease

Question 5

main class - proteins

Answer 5

provide cell structure
for cell functions, communication, signaling
‘last resort’ energy substrate

Question 6

main class - essential fatty and amino acids

Answer 6

essentials - cannot be synthesized de novo + must be obtained through diet
fatty acids = linoleic acid and a-linoleic acid
amino acids - 10 PVT TIM HALL

Question 7

main class - vitamin and minerals

Question 8

purpose of nutrients

Answer 8

supply energy needed for body to perform work
provide building blocks for synthesis of other important molecules
support function of metabolic pathways

Question 9

how is energy obtained from diet

Answer 9

food digested and absorbed -> products taken up by cells + oxidised to produce energy in ATP form

Question 10

energy expenditure + influencing factors

Answer 10

sum of basal metabolic rate (energy needed for normal physiological functions when body is at rest), energy used in physical activity (most important changeable variable), thermic effect of food (during digestion, absorption, metabolism)

Question 11

energy balance with weight gain / loss

Answer 11

subcutaneous fat, visceral fat, ectopic fat

obesity - high intake of high-calorie food / decrease in physical activity
losing weight - combination of diet + exercise + behaviour interventions

Question 12

dietary reference intake values

Answer 12

EAR - 50% healthy indiv requirement
RDA - margin of safety ~97-98%
AI - estimation. of nutrient intake
UL - highest level of daily nutrient uptake with no adverse effects

Question 13

MUST - malnutrition universal screening tool

Answer 13

BMI score -> weight loss score -> acute disease effect score -> overall risk of malnutrition -> management guidelines

Question 14

nutritional assessments

Answer 14

anthropometric - bmi (limitation in athletes / limb deformed), waist-to-hip ratio, mid-arm circum
(easy to administer, cheap, quick but more analysis needed)

biochemical - blood, urine, farces
(objective + quantities but affected by med+diseases)

dietary data - food frequency questionnaires, direct analysis of food

Question 15

classify vitamins and minerals

Answer 15

micronutrients - form prosthetic groups of enzymes / serve as cofactors, as hormones, as cell growth + proliferation + differentiation

Question 16

fat-soluble vs water-soluble vitamins

Answer 16

fat: absorbed alongside dietary fats into lymph, transported by carrier protein + receptors, stored in liver / fat tissues

water: directly absorbed into blood, excess removed

Question 17

vitamin A

Answer 17

as antioxidant, aura (retinal to produce rhodopsin), activation (gene expression, reproduction maintenance)

deficiency - night blindness, wound healing
excess - liver toxicity, birth defects

Question 18

vitamin D

Answer 18

1,25-dihydroxyvitamin D is active form
for calcium uptake

deficiency - rickets in children, osteomalacia in adults
excess - deposition of Ca in organ

Question 19

vitamin E

Answer 19

antioxidant

deficiency - haemolytic anaemia, neurological + neuromuscular dysfunctions, retinopathy

Question 20

vitamin K

Answer 20

blood clotting, gamma-carboxylation of proteins
crushed by warfarins, cannot be found in infants

deficiency - bleeding + bruising, anaemic

Question 21

vitamin B - energy-releasing 1,2,3,5,7

Answer 21

B1 thiamine - coenzyme in carb metabolism (with pyruvate to gen ATP), deficiency - beriberi
B2 riboflavin - for electron transfer, deficiency - skin lesions
B3 niacin - for electron transfer, defi- pellagra
B5 - component of coenzyme A
B7 - coenzyme in synthesis of fat, glycogen + amino acids defi- depression, muscle pain

Question 22

vitamin B - haematopoeitic 9,12

Answer 22

B9 floic acid - one-C metabolism, coenzyme in nuclei acid + amino acid metabolism, defi- megaloblastic anaemia
B12 coenzyme for reaction, defi-anaemia

Question 23

vitamin B6

Answer 23

coenzyme of various enzymes (in amino acid metabolism), deficiency - neurological symptoms + anaemia

Question 24

Vitamin C

Answer 24

antioxidant - protest cells from ROS
reducing agent - keep iron reduced -> collagen stability
deficiency - scurvy ( collagen - defective connective tissues)
excess - renal oxalate stones

Question 25

use off vitamin supplements

Question 26

sodium, chloride, potassium

Answer 26

regulation - what stays and leaves, electrolytes + body fluids sodium excess (hyponatremia) -> cerebral edema, hypernatremia -> dehydration potassium deficiency + excess (hypokalemia + hyperkalemia) -> arrhythmia chloride deficiency -> acid-base disturbance

Question 27

calcium, phosphate, magnesium

Answer 27

regulated by 3 key hormones - calcitriol (kidneys), parathyroid hormone + calcitonin (pth gland) ca deficiency - osteoporosis, arrhythmia, excess - kidney stones phosphate excess- calcification of soft tissues magnesium deficient - arrhythmia

Question 28

iron

Answer 28

component of heme binding to o2 - found in haemoglonin, myoglobin + redox enzymes non-heme: complexed to sulphur in proteins needed for normal amount of haemoglobin + cytochromes + iron-sulphur complexes for o2 transport defi- anaemia

Question 29

zinc

Answer 29

found in 100 enzymes used in carb + energy metabolism, protein + nuclei acid synthesis

Question 30

copper

Answer 30

remove superoxide, ROS deficiency - anaemia excess - liver cirrhosis

Question 31

enzymes to facilitate biochemical reaction

Answer 31

cells perform chemical reactions continuously or accomplish operations -> millions of reactions per second

Question 32

enzymes as catalysts

Answer 32

lower activation energy barrier one enzyme catalyses one reaction

Question 33

types of enzymes

Answer 33

oxidoreductases - transfer H + P atoms / electrons transferase hydrolyse isomerise lysase ligases

Question 34

specificity + location of enzyme reactions

Answer 34

active site - cleft, crevice formed by 1< regions of polypeptide chain lock-and key model — amino acid arranged in comp 3d surface to recognise substrate + bound h-bond / e. a induced-fit mode, — side chains of amino acid in active site reposition to interact with binded substrate

Question 35

enzyme rate + substrate conc

Question 36

bisubstrate enzymatic reaction

Answer 36

two substrate giving 2 products

Question 37

different factors affecting enzyme reaction rate

Answer 37

substrate concentration - rate increases when conc increase, maximum rate achieved at high velocity enzyme conc - rate increase linearly with conc pH - diff optimum range for diff pH depending on location in body temp - reaction fastest and optimum temp reached, high temp cause active site to lose its shape -> enzyme lose ability to catalyze reactions

Question 38

types of enzyme activity regulation

Answer 38

by inhibitors - compounds bind reversibly to active site (all products are reversible inhibitors of enzymes producing it) by conformation change - affect active site allosteric site activation + inhibition covalent modification - phosphorylation protein cleavage + break peptide bonds change amt of enzyme

Question 39

competitive vs non-competitive inhibition of enzyme activity

Answer 39

competitive - compete with substrate to bind with site + high sub conc can overcome inhibition non-competitive - affect binding, high sub conc cannot over on inhibition

Question 40

allosteric molecules for regulating enzyme

Answer 40

allosteric site = away from activity site ,bind to enzyme activator - change distorted site to complem shape inhibitor - change active site to distorted much stronger effect on enzyme velocity, can be non-substrate/product, rapid effect

Question 41

proteolytic cleavage for regulating enzyme

Answer 41

break peptide bonds between amino acids enzymes become functional (eg regulate blood clotting + activate protease when attaching to injury site -> clots formed)

Question 42

enzymes using multiple regulation