Macronutrients Flashcards
What makes nutrients essential
Present in all healthy tissues
Concentration consistent between species
Not in diet causes similar withdrawal symptoms between species
Adding into diet prevents issues
Abnormalities produced by deficiencies cause biochemical changes
Ways to assess how much of a nutrient is required
Epidemiology Amount to rectify deficiency symptoms Amount excreted in faeces and urine Factorial Dose response
Epidemiology
if a population is experiencing no deficiency symptoms assume intake is adequate. Average intake of nutrient by population gives estimate
Imprecise and unsure if large overestimate
Factorial
Requirement = obligatory loss + retention / availability
Dose response
Is the point where the nutrient biomarker value does not vary anymore
What causes deficiency
Intake not meeting requirement Reduced absorption Increased requirement due to physical activity Increased losses Antagonists
Lower reference intake
2 S.D. below mean
Estimated average
Mean amount
Reference Nutrient
2 S.D. above mean
Joule
Energy required to move a mass of 1kg 1 metre with a force of 1 newton
Calorie
Amount of energy required raise temperature of 1kg by 1 degree
Joule to calorie conversion
1 cal = 4.184
How do you work out how much energy in food
Bomb calorimetry - gives total chemical energy
n.b. not all chemicals in food can be digested
Bomb calorimetry
Sample is burnt in pure O2 in a sealed container
Has a insulating jacket
Change in temperature of water is then compared to benzoic acid to understand amount of energy in food
Energy in fat
9kcal per gram
Energy in protein
4kcal per gram
Energy in carbohydrates
4kcal per gram
Total energy expenditure
Basal metabolism
Physical activity
Thermic effect of food
Basal metabolic rate
Keep organs functioning when not digesting or keeping warm. Difficult to measure as participant has to of just woken up so often use Resting Metabolic Rate
What causes slow BMR
Aging
Low thyroid
More fat
What increases BMR
Height
Muscle
Active energy expenditure
Duration, frequency and intensity of exercise
How do you measure energy expenditure
Prediction equations
Direct and indirect calorimetry
Isotopic methods
Energy requirements
Determined by age, sex and physiological state
Listed in SACN
which uses prediction equations
Protein digestion in stomach
HCL released from parietal cells Denatures protein Pepsinogen made active by low pH Pepsin cleaves non-polar lipophilic chains Phe, Leu, Trp, Tyr
How is HCL secreted
Cephalic phase
Histamine phase
gastric phase
Cephalic Phase
Sight and smell of food increases enteric neural activity
Increasing acetylcholine
Causing gastric acid to be secreted
Histamine phase
Increased acetylcholine increases histamine release
Histamine acts on H2 receptor causing HCL secretion
Gastric phase
Stomach distension and some chemicals in amino acids cause G cell to release hormones causing more gastric acid
Parietal cells
Surrounded by vesicle called tubulovesicles
Contain H+/K+ ATPase
Stimulated causing them to expand and H+ travels across lumen
Cl- follows H+
Protein digestion in small intestine
Pancreatic enzymes and brush border enzymes break down protein
Small peptides use protein transporters for specific amino acids.
Na+ and H+ needed
Protein pancreatic Enzymes
Trypsinogen
Chymotrypsinogen
Procarboxypeptidase
Brush Border enzymes
Elastase
Trypsinogen
Endopeptidase
cleave Lys and Arg of carboxy side
Chymotrypsinogen
Endopeptidase
Cleaves Phe, Tyr, Trp on carboxy side
Procarboxypeptidase
Exopeptidase
A - aromatic and branched amino acids on aliphatic side
B - Lys and Arg at COOH terminal
Protein Digestion in enterocyte
Degradation of oligopeptides into smaller peptides by brush border enzymes. Then degradation of tri and di peptides by intracellular peptides.
Protein uses
Structural Hormones Enzymes Immune Energy Muscle
Transamination
Transfer amine group to keto acid to create new keto acid and a new amino acid
Transaminase
Aminotransferase
Only in non-essential and conditionaly essential AA
Reversible
Deamination
Amino group removed from amino acid
Deaminase
Irreversible
Urea Cycle
Ammonia into urea – liver and some in the kidneys. 5 steps – first 3 in the mitochondria and last two in the cytoplasm
Naming lipids
C no. carbon atoms: No. double bond n- Location of double bond from methyl
Palmitic acid
Hexadecenoic acid
C16:0
Stearic acid
Octadecanoic acid
C18:0
Linoleic acid
Octadecadienoic acid
C18:2 n-9,12
alpha-linolenic acid
Octadecatrienoic acid
C18:3 n-9,12,15
yonder-linolenic acid
Octadecatrienoic acid
c18:3 n-6,9,12
Antioxidant role with lipids
Prevent oxidation of fatty acids on cell membrane
Lipid synthesis
Acetyl CoA + ATP + HCO3 -> Malonyl CoA
Add acetyl CoA to malonyl
Repeat adding acetyl (adds 2 extra carbond)
To de saturate need vitamins as coenzymes
Only add double bonds to n-9
Linoleic acid uses
Synthesis other fatty acids
yonder-linoleic acid
dihomo-y-linoleic acid
Arachidonic acid
Alpha linolenic acid uses
Synthesis
EPA
DHA
Phospholipids
2 fatty acids
1 phosphate
1 glycerol
Membrane structure
Phospholipids
Fluidity determined by number of unsaturated FA particularly PUFA
More PUFA means more liquid and more likely to be oxidised
Lipid digestion Stomach
Lingual lipase released in saliva becomes active in the stomach
Gastric lipase secreted by chief cells remove on FA leaving a free fatty acid and diglyceride
Stomach emulsify through mechanical mixing
Lipid digestion Small intestine
Mechanical mixing
When fat enters duodenum it causes CCK to be released in blood
Causes biled to be secreted into small intestine
CCK also stimulate pancreatic enzymes
Pancreatic lipase make MAG and anothe free fatty acid
Bile
Stimulated by CCK Derived from cholesterol Have a store of 2-4g double just to emulsify one meal Recirculated 3012 times a day
Lipid Absorption
Micelle pass through water layer and become adjacent to enterocyte
Passive absorption of the fatty acids and facilitated absorption by FABP and FAT transporter
In cell realign as TAG
Incorporated into a VLDL
Chylomicron
Lower the density of fat the higher the lipid:protein ratio
Inside chylomicron have lipase to hydrolyse TAG to free fatty acids to pass through capillary walls
Very low density lipoprotein
Main function transport TAG from liver to tissue
High TAG
Once at tissue and TAG removed becomes a LDL
Main outer protein is ApoB-100
Low density lipoprotein
High level of cholesterol
Main outer protein ApoB-100
High density Lipoprotein
Excess cholesterol in cell membrane taken up
In HDL free cholesterol is converted to cholesterol ester
ApoE on outer membrane allows liver to recognise and uptake
ApoB-100
Allows for secretion of VLDL from liver
Structural protein for VLDL, IDL and HDL
Acts as a ligan receptor for LDL
ApoB-48
Chylomicrons
Secretion of chylomicrons from intestine
Core structure protein
ApoE
Chylomicrons, VLDL, IDL, HDL
Ligand for binding IDL and remnants to LDLR and LRP
ApoC-II
Chylomicrons, VLDL, IDL, HDL
Activator of LPL
Allows recognition and binding of lipoprotein
Cardiovascular disease
High LDL and TAG in plasma and low HDL Oxidated LDL accumulate beneath leaky endothelial arteries Removed by white blood cells High concentration of cholesterol in macrophages causes fatty streaks Fatty streaks produce collage Causing fibrous plaque Narrowing lumen Reducing blood flow Encouraging blood to clot
How to combat cardiovascular disease
Lower LDL cholesterol
Increase HDL
Eat more unsaturated
Do not eat trans fats or saturated
Long chain fatty acids make
Eicosanoids Endocannabinoids lipoxins Resolvins Lipid rafts
Eicosanoids
Made by COX or lopoxygenase Prostaglandins - Vasodilator Prostacyclin - Vasodilator Thromboxane's - Vasoconstrictor Leukotrienes - Vasoconstrictor
Conjugated linoleic acid
Milk products
Intermediated during biohydrogentation
Linoleic acid but two double bonds next to each other
Functional food
Control of lipid metabolism
PPARs interact with DNA to increase and decrease amount of proteins
Leptin - makes you full
Maltose
Glucose-Glucose alpha 1-4 glyosidic bond
Isomaltase
Glucose-Glucose alpha 1-6 glyosidic bond
Lacotse
Galactose and glucose beta 1-4 glyosidic bond
Sucrose
Glucose + fructose alpha 1-2
Raffinose
Glucose, galactose and fructose
Carbohydrate digestion Mouth
Salivary alpha – amylase
Requires Ca2+ and Cl-
6.8pH optimum
Carbohydrate digestion Small intetine
Pancreatic alpha-amylase – releases maltotriose, maltose, isomaltose and some glucose
Requires Ca2+ and Cl-
6.8pH optimum
Brush boarder enzymes – maltase, isomaltase, sucrase and Lactase
SGLUT1
Apical membrane
Glucose and galactose enter enterocyte
Na+ enter allowing glucose and galactose to enter cell
Na+ leaves via K+/Na+ atpase
GLUT5
Fructose
GLUT2
Basolateral membrane for sugar to leave
GLUT family
single polypeptide chain of 500 amino acid. 12 transmembrane segments
GLUT4
Adipose and muscle tissue
Insulin dependent
Sugar Alcohol
Lack aldehyde or ketone
Sugar acid
Aldehyde of OH and C6 is oxidised to make COOH
Amino Sugar
Has an amine group substituted for an OH
Glycoproteins
Cell membrane
Serum in blood
Proteoglycans
Protein conjugate to glycosaminoglycan Structural components of lubricants Feature GAGs and link to serine Structure of GAG allows to interact with many proteins Growth factors, extracellular matric Role in molecular signalling
Mucoproteins
Key component of mucus
Lubricants
