Nutrition, Diet, Body Weight Flashcards
What drives the chemical reactions of our bodies?
the fuels in our diet
What do the chemical reactions enable us to do?
growing/developing/moving/thinking/fighting infection/reproducing
What does the diet provide that are essential cell components?
vitamins, minerals, water
What should be included in our diet for the normal functioning of the gastrointestinal tract?
indigestable material like fibre
What do we mostly obtain our fuel from?
carbs, fats, proteins consumed in our diet
What happens to the food we eat?
digested in the GI tract and products are absorbed into the body to circulate in the blood
What role do the body tissues play?
continuously remove the circulating fuels to provide energy they require
What happens to the fuel that exceeds the body’s immediate energy needs?
stored as fat in adipose tissue or as glycogen in liver and muscle
What is energy?
the capacity to do work
What do living cells require energy for?
biosynthetic work, transport work across cell membranes, mechanical work, electrical work
What is the SI unit of food energy?
kilojoule (kJ)
How many kcal of energy does a “1 cal” drink contain?
1Kcal
How many kJ is 1kcal?
1 kcal = 4.2 kJ
What is chemical bond energy used to do?
drive the energy-requiring activities in the cells of the human body
What is an exergonic reaction?
energy released is greater than the energy input
What is an endergonic reaction?
energy input is greater than the energy released
Why is the energy released from chemical bonds used directly without being converted to heat?
the human body is isothermal so remains the same temp
What is coupling?
reactions that require an input of energy are driven by reactions that release energy - usually via the ATP - ADP cycle
How is the chemical bond energy released in fuel molecules and what happens to it?
by oxidation, some is conserved by the formation of ATP and the remainder is lost as heat
What are the 3 components of daily energy expenditure?
-basal metabolic rate
-energy for voluntary physical activities
-diet-induced thermogenesis
What is the BMR?
a measure of the basal energy required to maintain life at physical, digestive, emotional rest
What are the main tissues contributing to the BMR?
skeletal muscle, CNS, liver, heart
How can you roughly estimate the BMR of non-obese individuals?
multiplying the body weight in kg by 100, (kJ/24hrs)
What are the factors that can affect BMR?
weight, thyroid hormones
Why is the BMR lower for women?
women have more adipose tissue that is less metabolically active
What increases BMR?
-rise in body temp
-hyperthyroidism
-pregnancy
-lactation/breastfeeding
-exercise
What is diet-induced thermogenesis?
the energy required to process the food we eat - digestion, absorption, distribution, storage
How is daily energy expenditure calculated?
the sum of the BMR plus energy required for physical activity plus 10% of these values for DIT
How do we maintain our body weight?
stay in energy balance
What is the RDA?
recommended dietary allowence, the quantities of nutrients that are required to keep the general population in good health. replaced by the Dietary Reference Values now
What is the EAR?
estimated average requirement
From what foods do we obtain energy from in our diets?
fats carbs and metabolism of proteins and alcohol
What is associated with the excessive intake of saturated fats?
high blood cholesterol and heart disease
How many kcal are recommended for men and for women each day?
2500 for men, 2000 for women
Why are fats important?
higher energy yield than carbs/proteins, are needed for the absorption of fat-soluble vitamins, certain polyunsaturated fatty acids are structural components of cell membranes
Which vitamins are fat-soluble?
A D E K
What is zero nitrogen balance?
N2 intake = N2 loss
Who may show a positive or negative nitrogen balance?
+ = growing children and pregnant women
- = starvation and tissue wasting diseases
Why is it important that a vegatarian diet contains a mixture of vegetables?
proteins of animal origin usually contain a high proportion of the essential amino acids, unlike proteins of vegetable origin which may be deficient in one or more of the essential amino acids
What is the average water loss from the body a day?
~2.5L a day, mainly through urine, then expired in air, then through skin, and then in faeces
How are vitamins classified?
as water soluble or as lipid soluble
Which vitamins have important antioxidant properties?
C E selenium
How do you calculate the BMI of someone?
weight (kg) / height^2 (m^2)
What is the desirable range for BMI?
18.5 - 24.9
What are the unhealthy BMI ranges?
overweight - 25 - 29.5
obese - 30 - 34.9
severely obese - >35
What is a better measure of obesity?
waist to hip ratio
What is associated with excess body fat?
increased risk of hypertension, heart disease, stroke, type 2 diabetes, cancer, gall bladder disease, osteoarthritis
What risks are associated with a greater proportion of fat in the upper body?
insulin resistance, hyperinsulinism, type 2 diabetes, hypertension, hyperlipidaemia, stroke
Why is initial weight loss faster?
water is also lost, as there is a reduction in liver glycogen stores that are used to provide glucose to the brain. these glycogen stores contain more water than fat
Why is total starvation not preferred?
protein metabolism increases to maintain blood glucose by gluconeogenesis - lean body mass will disappear, and liver begins to convert fatty acids to ketones to be used as a fuel by the CNS
Why are ketones a problem?
they can disturb blood pH - dehydrated
What is the best tool available to screen for malnutrition?
malnutrition universal screening test (MUST)
What is malnutrition?
any condition caused by an in-balance between what someone eats and what someone needs to maintain health
What is protein energy malnutrition?
covers the spectrum of clinical conditions seen in starving patients - infections of GI tract and lungs are common
What is marasmus?
most common PEM seen in kids under 5 - patient looks emaciated with signs of muscle wasting and loss of body fat - NO oedema. thin dry hair, diarrhoea, anaemia
What is kwashiorkor?
typically in a young child displaced from breastfeeding by a new baby and fed a diet with some carbs but low protein content. patient is lethargic, loss of appetite, oedema (pitting), distended abdomen. low albumin and anaemia
Why is albumin low in patients with Kwashiorkor?
not enough amino acids for liver to make the blood protein, decreases the plasma protein pressure, so increased flow of fluid from capillaries
What is refeeding syndrome?
the rapid refeeding of energy rich foods in starved/malnourished patients will rapidly increase blood sugar and insulin, causing glycogen/fat/protein synthesis - using phosphate, magnesium, potassium from the body stores that are already depleted - resulting in electrolyte abnormalities like hypophosphataemia
What happens to nutrients in body tissues?
degradation to release energy, synthesis of cell components, storage, interconversion to other nutrients, excretion
What is cell metabolism?
the highly integrated network of chemical reactions that occur within cells
What is the breakdown of larger molecules into smaller ones?
catabolism
What is the build up of smaller molecules into larger ones?
anabolism
What is the statement generally about catabolic and anabolic pathways?
catabolic - oxidative, release large amounts of free energy, produce intermediary metabolites
anabolic - reductive, use intermediary metabolites and energy
When can a reaction occur spontaneously?
when deltaG is negative
How is creatine phosphate made?
creatine + ATP <–> creatine phosphate + ADP
What can the daily excretion of creatine be used as an indicator of?
skeletal muscle mass - increased excretion may indicate muscle wasting
What can the measurements of the concentration of creatinine in blood and urine also be used for?
an indicator of kidney function - high blood creatinine with low urinary creatinine could indicate reduced kidney function
