1 - Nutrition, Diet + Bodyweight Flashcards
what are the major components of energy expenditure (and rough values)
of average 70kg male, approx 12,000kJ
of average 58kg female, approx 9,500kJ
1 BMR (Basal Metabolic Rate) is the basal amount of energy required to maintain life (BMR = 100 x weight in kg)
- Skeletal Muscle 30%
- CNS 20%
- Liver 20%
- Heart 10%
2 Voluntary Physical Activity (BMR + 30% for sedentary, + 65% for moderate, and +100% for very active)
3 Diet Induced Thermogenesis (DIT) ie the amount of energy required to digest, absorb, distribute and store nutrients. Around 10% of energy content of food ingested.
list the essential components of the diet and explain why they are essential
- Carbohydrates as organs require a constant source of energy (or can make glucose via gluconeogenesis)
- Fats as lipids can be used as energy but also structurally as components of cell membrane. Fats have an energy yield 2.2x greater than carbs or proteins, but high levels of fat are associated with high BP and choslesterol.
- Proteins as they contain amino acids that are vital for protein synthesis and N-containing compounds. Can also be used as an energy source
- Water for cellular and metabolic processes, and for osmoregulation. Need to keep hydrated as 2.5 L of water is lost per day (urine, skin, faeces, sweat, expired air).
- Dietary fibre for normal bowel function
- Minerals and vitamins in more detail on seperate card
water is required as 30ml/kg/day
minerals required by the body (and some examples why)
electrolytes eg sodium, potassium and chloride
- establish ion gradients
- maintain water balance
minerals eg calcium, magnesium, phosphorus, sulphur, iron
- calcium + phosphorus essential for structure eg bone/teeth
- calcium for signalling
- enzyme co-factors eg iron, magnesium, manganese, cobalt, copper, zinc + molybdenum
- iron is essential for haemoglobin
vitamins required by the body, their deficiencies, and why
fat soluble
A - xerophthalmia
D - Rickets
E - Neurologic abnormalities
K - Blood clotting issues
water soluble
B1 - Beriberi
B12 - Anaemia
B6 - Dermatitis + Anaemia
Biotin - Alopecia, Scaly skin, CNS defects
C - Scurvy
Choline - Liver damage
Folate - Neural tube defects, anaemia
Niacin - Pellagra
Pantothenic Acid - Fatigue, apathy
Riboflavin - Aribofavlinosis
required in micro or milligram quanitities. Can have deficiency diseases if inadequate intake. Can also have hypervitaminosis where too much is toxic
why is dietary fibre important and where is it found
- found in cereals (bread, beans, fruit and veg)
- cellulose, lignin, pectins + gums
- can’t be broken down by human digestive enzymes but essential for normal functioning of GI tract
- recommended average intake for adults is 18g daily
- low fibre intake associated with bowel cancer and constipation
- high fibre diet can reduce cholesterol and risk of diabetes
what are the main factors affecting BMR (Basal Metabolic Rate)
this is energy required to maintain the resting activities of the body ie biochemical reactions and ion transport across membranes
- body size + surface area
- gender (males have higher BMR than females)
- environmental temp (increases in cold)
- endocrine status (increases in hyperthyroidism)
- body temperature (increases with higher temp)
what are the main energy stores
- very short term stores of energy rich molecules (few seconds), ie ATP too unstable to be transported around body
- carbohydrate stores (ie glycogen) for immediate use (minutes or hours depending on activity). Glycogen is not for long term storage as capacity is limited
- long term stores in adipose tissues (fat), around 40 days worth
- under extreme conditions, muscle proteins can also be converted to energy
how to calculate BMI and what is it for
BMI = weight (in kg) / height squared (m^2)
always write units
kg/m^2
used to clinically evaluate weight, shows good correlation with body fat measurements. Major weakness with very muscular individuals who might be wrongly classified as obese. Also can measure waist to hip ratio.
BMI value table and classifications
less than 18.5 underweight
18.5 - 24.9 desirable weight
25 - 29.9 overweight
30 - 34.9 obese
over 35 severely obese
not for kids or pregnant women, can’t be relied on. Always measure kg/m2
what is obesity, and what are the factors involved
excessive fat accumulation in adipose tissues, which impairs health, with a BMI over 30 kg/m^2
result of energy intake exceeding energy expenditure over a number of years.
- body fat distribution is clinically important
- greater proportion of fat above waist (apple shaped) is higher risk
- T2 diabetes, hypertension, hyperlipaedemia, stroke and premature death
factors involved
- lifestyle and working hours
- socioeconomic status
- education
- access to healthy foods
- genetics
- endocrine disorders
- drug therapy
explain the clinical consequences of protein + energy deficiency in humans
protein-energy malnutrition covers a spectrum of clinical conditions seen in starving people. Leads to loss of weight due to loss of subcutaneous fat + muscle wasting. Cold and weakness, GI tract and lung infections common …
marasamus
- most commonly seen in children under 5
- looks emaciated, obvious muscle wasting + body fat loss
- no oedema
- hair is thin + dry, diarrhoea is common, anaemia may be present
kwashiorkor
- typically in young child displaced from breastfeeding by a new baby, and fed a diet with some carbohydrate but low protein
- child is lethargic, anorexic + apathetic
- pitting oedema, and generalised oedema
- distended abdomen due to hetatomegaly and/or ascites
- serum albumin low
- anaemia is common
…mechanism for kwashiorkor on another card
pitting oedema = when an indentation is left behind when pressure applied to area
hepatomegaly = enlarged liver
ascites = accumilation of fluid in peritoneal cavity
what is the mechanism for kwashiorkor
- inadequate intake of protein
- low serum albumin concentration (protein produced by liver)
- therefore decreased plasma oncotic pressure in blood
- increases the flow of fluid from the capillaries into the interstitium
- results in water retention and oedema
fatty liver, why?
- production of lipoproteins are decreased
- fat is unable to be carried away from the liver as usual
- lipids accumulate in liver
- causes fatty liver and hepatomegaly
starling’s law of the capillary
what is re-feeding syndrome
- can occur when nutritional support given to severely malnourished patients
- electrolyte abnormalities, eg hyophosphataemia my occur
- re-feed at 5-10 kcal/kg/day and gradually increase over a week
- need to give the body time to adjust
rough mechanism
- rise in blood glucose level
- increased insulin
- increased stimulation of the sodium-potassium pump, driving K+ into cells
- decrease in amount of extracellular K+ (hypokalaemia)
- increase in insulin and effects on electrolyte migration are compounded by nutritional electrolyte deficiencies
define cell metabolism and explain its functions
the highly integrated network of chemical reactions that occur within cells and the network consists of a number of distinct metabolic pathways which link together
functions
- energy for cell functions and the synthesis of cell components (ATP)
- building block molecules that are used in the synthesis of cell components needed for the growth, maintenance, repair and ÷ of the cell
- organic precursor molecules that are used to allow the interconversion of building block molecules (eg acetyl CoA)
- biosynthetic reducing power used in the synthesis of cell components
describe the relationship between catabolism and anabolism
catabolic
- breaks down larger molecules into smaller ones (intermediary metabolites)
- release large amounts of free energy
- oxidative - release H atoms (reducing power)
anabolic
- synthesise larger important cellular components from intermediary metabolites
- use energy released from catabolism
- reductive (ie use H released in catabolism)
