metabolic fuels + other dietary components Flashcards
what is metabolism
the sum of the chemical reactions that take place within each cell of a living organism
what are the 4 main ways that dietary components are metabolised in cells
biosynthetic
fuel storage
oxidative processes
waste disposal
what are the two types of metabolic processes
anaobolic
catabolic
what are anabolic processes
synthesise larger molecules from smaller components
what are catabolic processes
break down larger molecules into smaller ones
are biosynthetic processes anabolic or catabolic
anabolic
are fuel storage processes anabolic or catabolic
anabolic
are oxidative processes anabolic or catabolic
catabolic
are waste disposal processes anabolic or catabolic
either
what does catabolism provide energy for
- for cell processes from ‘fuel’ molecules
- for anabolism
what does the oxidation of carbohydrates, lipids and proteins do
produces ATP
what does Krebs cycle generate
NADH & FADH2
what occurs during oxidative phosphorylation
energy is conserved via transfer of electrons in the inner mitochondrial membrane
what are the 3 electron accepting co enzymes
NAD+ —> NADH
NADP+ —> NADPH
FAD —> FADH
how does the electron transport chain produce ATP
It oxidises NADH and FAD2H which releases energy which is used to produce ATP
what does the electron transport chain consist of
4 complexes and associated compounds like ubiquinone
the complexes include cytochromes which contain haem
what is adipose tissue
85% fat
storage of energy rich molecules
what occurs in liver tissue
glyconeogenesis and removal of toxins
what are the 3 main dietary energy sources
carbohydrates
lipids
proteins
what are 7 dietary components
fuels
essential amino acids
essential fatty acids
vitamins
minerals
water
xenobiotics
how do we use dietary energy sources
dietary energy source + oxygen = ATP and CO2 and H20
what is a triglyceride
3 fatty acids esterilice to one glycerol molecule
more reduced that other energy sources
“ saturated “ with hydrogen
where is fat stored
adipose tissue
which is only 15% water
where are carbohydrates stored
as glycogen In the liver and muscles
where is protein stored
in muscle
which is 80% water
how much energy is released per gram of carbohydrate
4 kcal/g
how much energy is released per gram of protein
4 kcal/g
how much energy is released per gram of alocohol
7kcal/g
how much energy is released per gram of lipid
9 kcal/g
what is the primary source of ATP supplied to the body at rest and during low intensity activities
The oxidative system (aerobic)
It uses primarily carbohydrates and fats as substrates
What is basal metabolic rate BMR
energy needed to stay alive at rest
It is a measure of the energy required to maintain non excercise bodily functions
which functions are maintained by BMR (5)
respiration
Contraction of the heart muscle
biosynthetic processes
repairing and regenerating tissue
ion gradients across cell membranes
what are the conditions essential for measuring BMR (6)
post absorptive (12 hour fast)
lying still at physical and mental rest
thermo neutral environment ( 27-29 degrees Celsius)
No tea/coffee/nicotine/alcohol in past 12 hours
No heavy physical activity on previous day
Establish steady state ( around 30 mins)
what happens if the conditions for BMR are not met
we refer to resting energy expenditure (REE) or resting metabolic rate (RMR)
effect of age on BMR
BMR decreases with age
because as we get older we gain fat and lose muscle
what factors affect BMR (8)
age
gender
dieting / starvation
hypothyroidism
decreased muscle mass
body weight (BMI)
ambient temperature
fever / infection / chronic disease
how does muscle mass affect BMR
muscle cells require more energy to maintain than fat cells so people with higher muscle to fat ratio will have higher BMR
how does body weight affect BMR
BMR increases with body weight (Bm)
effect of ambient temperature on BMR
low ambient temperature increases BMR
effect of fever/ infection / chronic disease on BMR
they increase it
what are the 3 equations for estimating BMR in health
Harris Benedict equations (1919)
Schofield equations ( 1985)
Henry equations (2005’
how can you adjust the henry equation (3)
- do it with or without height because in a
clinical setting it can be hard to obtain height & other variables can invalidate the advantages of including height - can also adjust for metabolic stress
- can adjust for activity and diet induced thermogenesis
what are the NHS nutrition guidelines for patients who are not severely ill or injured
25 - 35 kcal/kg/day
what occurs if you fast overnight
insulin level decreases
glycogenolysis occurs because glucose must be formed from non carbohydrate sources
how much glucose does the brain require a day
about 150g
what occurs if you starve for 2-4 days
insulin level decreases
cortisol level increases
lipolysis and proteolysis occur (breakdown of proteins and triglycerides via a hydrolysis reaction)
what occurs if you starve for 2-4 days
insulin level decreases
cortisol level increases
lipolysis and proteolysis occur (breakdown of proteins and triglycerides via a hydrolysis reaction)
what does gluconeogenesis use
lactate
amino acids - muscle, intestine & skin
glycerol - for fat breakdown
what occurs if you starve for more than 4 days
liver –> ketones from fatty acids
the brain adapts tp using ketones
BMR decreases to accommodate
define malnutrition
a state of nutrition with a deficiency, excess or imbalance of energy, protein or other nutrients, causing measurable adverse affects
what is affected by malnutrition
tissue/body form - shape, size, composition,
body function
clinical outcome
define refeeding
the potentially fatal shifts in fluids and electrolytes that may occur in malnourished patients receiving artificial refeeding
These shifts result from hormonal and metabolic changes and may cause serious clinical complications.
what occurs in refeeding
the re distribution of phosphate, potassium, magnesium etc due to insulin
switch back to carbohydrates as the main fuel which requires phosphate and thiamine
which essential nutrients can the body not synthesise
essential amino acids
essential fatty acids
vitamins
minerals
what are micronutrients
vitamins and minerals needed by the body in very small amounts
uses of micronutrients (4)
co factors in metabolism
gene expression
structural components
antioxidants
what is the name for vitamin C
abcorbic acid
what foods provide vitamin C
fruit and veg
uses of vitamin C (3)
collagen synthesis
improve iron absorption
antioxidant
uses of vitamin B12 (5)
protein synthesis
dna synthesis
regenerate folate
fatty acid synthesis
energy production
what is the name for vitamin B1 and what does it do
thiamine
helps with energy production in your body
what is the name for vitamin B2 and what does it do
riboflavin
helps with energy production in your body
helps your body use other B vitamins
what is the name for vitamin B3 and what does it do
niacin
helps your body to use protein, fat and carbohydrate to make energy
helps enzymes work properly
what does biotin do
allows your body to use protein, fat and carbohydrates from food
what is the name for vitamin B6 and what does it do
pyridoxin
helps your body to make and use protein and glycogen
helps form haemoglobin which carries oxygen in your blood
what do low levels of vitamin B12 cause
anameia
what is the name for vitamin B12
cobalamin
what is the name for folate and what does it do
folic acid
helps to produce and maintain DNA and cells
helps to make red blood cells and prevent anaemia
getting enough folic acid lowers the risk of having a baby with birth defects like spina bifida
what does vitamin C do (4)
- help prevent cel damage and reduce risk for certain cancers , heart disease and other diseases
- collagen synthesis - helps heal cuts and wounds and keeps gums healthy
- protects from infection by keeping immune system healthy
- increases amount of iron body absorbs from foods
what does vitamin A do
- helps to see
- protects from infection by keeping skin and other body parts healthy
- promotes normal growth & development
what do carotenoids do
they are not vitamins but some types can turn into vitamin a in the body
they act as antioxidants which protect your body from damage caused by free radicals
what does vitamin d do (3)
- increases amount of calcium and phosphorous your body absorbs from foods
- deposits calcium and phosphorous in bones and teeth making them stronger
- protects against infection by keeping immune system healthy
what does vitamin E do
- helps to maintain a healthy immune system and other body processes
- acts as an antioxidant and protects cells from damage
what does vitamin K do
- makes proteins that cause our blood to clot when you are bleeding
- involved in making body proteins for your blood, bones and kidneys
what is a prudent diet
- 5+ servings of fruit and veg
- base your meals around starchy carbohydrate foods
- no more than 5% of the energy we consume should come from sugars
- 0.8g/kg/day protein
- average man should have no more than 30g of saturated fat a day and women 20g
- adults should have no more than 2.4 g of sodium per day, which is equal to 6g of salt
- not to regularly drink more than 14 units of alcohol a week
- avoid excess dietary supplementation
- adequate calcium
