1.1 Nutrition, Diet and Body Weight Flashcards
Name the four main pathways of metabolism
- Oxidative pathways
- Fuel storage and mobilisation pathways
- Biosynthetic pathways
- Detoxification pathways
What do oxidative pathways do?
Convert food into energy
What do fuel storage & mobilisation pathways do?
Allow fuel to be mobilised when we are not eating or need increased energy
What do Biosynthetic pathways do?
Produce basic building blocks for cells
What do detoxification pathways do?
Remove toxins
What are catabolic and anabolic processes?
Catabolic processes: Break down molecules to release energy in the form of reducing power
Anabolic processes: Use energy & raw materials to make larger molecules for growth and maintenance
All living things constantly require energy for…. (5)
- Biosynthetic work – synthesis of cellular components.
- Transport work – movement of ions & nutrients across membranes.
- Mechanical work – muscle contraction.
- Electrical work – nervous conduction.
- Osmotic work – kidney.
Cells use ___________ energy to drive energy-requiring activities
Chemical bond
(Most convenient form of energy in the body)
(Chemical bond is in ATP)
What does an ATP molecule consist of?
- Adenine ring
- Ribose sugar
- 3 phosphates (alpha-beta-gamma)
( ^ Right to left)
Which phosphate in ATP is responsible for energy production?
Gamma phosphate has phosphodiester bond that releases energy when broken to drive cellular processes
How is energy stored in the body?
Energy is stored in bonds which can potentially be broken to form ATP. (Don’t store ATP itself)
Fat (stored in adipose tissue) and glycogen (stored in liver and muscle)
Describe the ATP-ADP cycle
ATP –> ADP + Pi
The energy produced by the breakage of the phophodiester bond between the game and beta phosphate is used by:
- ion transport
- muscle contraction
- detoxification
- thermogenesis
- biosynthesis
ADP + Pi –> ATP
- Oxygen is required
Energy production by oxidation of:
- lipids
- carbohydrates
- protein
- alcohol (metabolites of alcohol cause damage)
- Carbon dioxide, water and heat are also produced
What is the official SI unit of food energy?
Kilojoules
Define 1 Kcal
Amount of energy needed to raise temperature of
one kilogram of water by one degree Celsius.
(Note: “calorie” in everyday use actually means kilocalorie
(i.e. 1000 calories)
How many kilojoules in 1Kcal?
4.2 kJ
7 food groups and what they provide
- Carbohydrate – mostly supplies energy
- Protein – energy and amino acids
- Fat - energy and essential fatty acids • Minerals – essential
- Vitamins – essential
- Water – maintains hydration
- Fibre – necessary for normal GI function
What is the general formula for carbohydrates?
(CH2O)n
Which functional groups do carbohydrates contain?
- Aldehyde
- Keto
- Multiple -OH groups
Define the categories of carbohydrates based on size and give examples for each
- Monosaccharide - single sugar units (3-9 C-atoms)
Triose sugar – 3 carbons
Pentose sugar – 5 carbons
Hexose sugar – 6 carbons e.g Glucose, C6H12O6
- Disaccharides - (2 units) e.g sucrose
- Oligosaccharides - (3 –12 units) e.g. Dextrins
- Polysaccharides (10 – 1000’s units) E.g glycogen, starch, cellulose
What are the major dietary carbohydrates? (7)
Starch (Carbohydrate storage molecule in plants. Polymer
of glucose). Alpha 1,4 glycosidic bonds between glucose monomers.
- Sucrose (Table sugar. Glucose-fructose disaccharide)
- Lactose (Milk sugar. Galactose-Glucose disaccharide)
- Fructose (Fruit sugar: Monosaccharide)
- Glucose (Predominant sugar in human blood)
- Maltose (Glucose-glucose disaccharide)
• Glycogen (Carbohydrate storage molecule in animals. Polymer of glucose)
Branches at periodic intervals - these chains are connected by alpha 1,6 glycosidic bonds
(Cellulose is a polymer of glucose found in plants )
Which process allows the conversion of carbohydrates onto something that can be absorbed into the blood?
Digestion converts larger carbohydrates to monosaccharides which are absorbed into blood
Proteins are composed of _________ joined by _________ to form _________ chains
- Amino acids
- Peptide bonds
- Linear
Digestion breaks down proteins into what? And how are these monomers used by the body?
- Digestion breaks down proteins to constituent amino acids which enter blood
- 20 different amino acids used for protein synthesis in body
- 9 Essential amino acids cannot be synthesised and must be obtained from diet
Note: Glucose can be formed from some amino acids
What are the nine essential amino acids?
Valine Leucine Isoleucine Phenylalanine Methionine Threonine Tryptophan Leucine Histidine
(Vanessa Likes Italian People More Than They Like Her)
When may certain amino acids be conditionally essential?
Conditionally essential = Essential when period of rapid growth
- Children
- Pregnant women
Children and pregnant women need an increased dietary intake of which non-essential amino acids and why?
Cystiene
Arginine
Tyrosine
- Body can’t make these at the required rate
Protein of which origin is considered
A) of high quality
B) of low quality
• Protein of animal origin considered “High
quality” (Contain all essential amino acids)
• Proteins of plant origin generally considered
“lower quality” since most are deficient in one or
more essential amino acids.
• Therefore essential that vegetarian diet obtains
protein from a wide variety of plant sources
What are lipids composed of?
Triacylglycerols (3 fatty acids esterified
to one glycerol.
- Can be saturated (single bonds) or unsaturated (double bonds) which can then be in the cis or trans conformation
5 uses for minerals
• Electrolytes establish ion gradients across membranes & maintain
water balance
- Calcium & Phosphorus essential for structure (Bones + teeth)
- Calcium also very important signalling molecule
• Enzyme co-factors (iron, magnesium, manganese, cobalt, copper,
zinc, and molybdenum)
• Iron essential component of haemoglobin
Vitamins:
- Required in which quantities?
- Describe their solubility
- What does inadequate intake result in?
- Micro or milligram
- Fat or water soluble
- Deficiency disease
Which conformation of lipids is naturally occurring?
Unsaturated Cis
Which disease are trans lipids associated with?
Coronary heart disease
Which state do…
A) saturated lipids
B) unsaturated lipids
…tend to be in At room temperature?
A) Solid
B) Liquid
From carbohydrates, proteins and fats; which yields the most energy and why?
- Fats
- Contain much less oxygen than carbohydrates or protein (i.e. more reduced so yields more energy when oxidised)
Roles of fat in the body (4)
- Provide energy
- Insulation and protection
- Required for absorption of the fat-soluble vitamins
(A, D, E & K) from the gut - Provide essential fatty acids e.g. linoleic and linolenic
acids which cannot be synthesised in body
What are DRVs (+4) and what do they depend on?
- Dietary Reference Values (DRVs) published by SACN are a
series of estimates of the amount of energy and nutrients
needed by different groups of healthy UK population.
•Reference Nutrient Intake (RNI) •Estimated Average Requirement (EAR) •Lower Reference Nutrient Intake (LRNI) •Safe intake (used when insufficient data)
- Values depend on age, gender and level of physical activity
What are RNI used for?
- Reference Nutrient Intake (RNI)
- RNI used for protein, vitamins and minerals
What are LRNI used for?
- Lower Reference Nutrient Intake (LRNI)
- Intakes below LRNI are insufficient for most people.
What are EAR used for?
- Estimated Average Requirement (EAR)
- EAR used for energy
Energy requirements vary between individuals depending on…
…age, sex, body composition and physical activity.
Daily energy expenditure is the sum of… (3)
• Basal metabolic rate (BMR)
• Diet-Induced Thermogenesis (DIT)
(energy required to process food)
• Physical activity level (PAL)
What is the daily energy expenditure with moderate physical activity of
A) 70kg adult male
B) 58kg adult female
A) 12,000 kJ /day
B) 9,500 kJ /day
What does the BMR consist of? (3)
- Basal Metabolic Rate: maintain as resting activities of body
- Maintenance of cells
•Ion transport across membranes
•Biochemical reactions
- Function of organs •Skeletal muscle ~30% BMR •Liver ~20% BMR •Brain ~20% BMR •Heart ~10% BMR •Other ~20% BMR
- Maintaining body temperature
5 factors affecting BMR
• Body size (surface area)
• Gender
(males higher than female)
• Environmental temperature
(increases in cold)
• Endocrine status
(increased in hyperthyroidism)
• Body temperature
(12% increase per degree)
Voluntary Physical Activity:
- Energy required depends on intensity
and duration of activity
- Reflects energy demands of … (3)
- Intensity
- Duration
- Skeletal muscle
- Heart muscle
- Respiratory muscles
Energy expenditure kJ/kg/day values for
• Sedentary person
• Moderate activity
• Very active
- Sedentary person = 30 kJ/Kg/day
- Moderate activity = 65 kJ/Kg/day
- Very active = 100 kJ/Kg/day
Greater proportion of fat in upper body, especially abdomen (apple shaped), compared with that on hips (pear shaped) associated with increased risk of:
- Insulin resistance
- Hyperinsulinism
- Type 2 diabetes
- Hypertension
- Hyperlipidaemia
- Stroke
- Premature death
Units for BMI
Kg/m^2
Formula for calculating BMI
Weight (kg) / Height^2 (m^2)
BMI range for: Underweight Desirable weight Overweight Obese Severely obese
Underweight
<18.5
Desirable weight
18.5-24.9
Overweight
25-29.9
Obese
30-34.9
Severely obese
>35
- Weakness of using BMI for certain patients
- Alternative measurement?
• Major weakness with vey muscular individuals who
may be wrongly classified as obese
• Alternative measurement: Waist/hip ratio
• Very _______ term stores of energy rich molecules in _______ – few
_______ worth
• Carbohydrate stores for immediate use - _______ or _______ depending
on activity
• Long term stores in _______ : ~_______ days worth
• Under extreme conditions _______ _______ can also be converted to
energy
• Very short term stores of energy rich molecules in muscle – few
seconds worth
• Carbohydrate stores for immediate use - minutes or hours depending
on activity
• Long term stores in adipose: ~40 days worth
• Under extreme conditions muscle proteins can also be converted to
energy
Define obesity and its cause
Excessive fat accumulation in adipose tissue which impairs health
Result of energy intake exceeding energy expenditure over a period
of years
Obesity is associated with an increased risk of developing … (3)
Some cancers,
cardiovascular disease and type 2 diabetes
Benefits of measuring metabolites in blood (3)
• Difficult to examine actual tissues in patients
(Could be dangerous to biopsy, expensive to perform)
• Blood can be readily obtained. Tests relatively inexpensive
• Concentrations of substances higher or lower than normal range can
help indicate nature of problem
- Normal values will vary within a
depend on age or sex
Name 4 dietary fibres
Cellulose
Lignin
Pectins
Gums
Why can humans not metabolise cellulose?
Like starch and glycogen, Cellulose is also a polymer of glucose. However humans do not produce the required enzymes to break the β-1,4 linkages in cellulose.
What is the recommended average intake of dietary fibre for adults?
18g
What is dietary fibre essential for?
Which problems is a low dietary fibre diet associated with?
- essential for
normal functioning of gastrointestinal tract - constipation and bowel cancer
Benefits of high fibre diet (2)
Reduce cholesterol and risk of diabetes
How does dietary fibre in the diet cause a reduction of cholesterol?
Cholesterol is used to produce bile salts which are released into the GI tract. Fibre absorbs the bile salts which contain cholesterol causing them to be passed out into the faeces. With less fibre in the diet, the cholesterol can be re-absorbed and recycled. With a high fibre diet, the body is made to use up more of the cholesterol.
Cause and symptoms of the disease Kwashiokor
- The main cause of kwashiorkor is a lack of protein and other essential nutrients, such as vitamins and minerals.
- Low protein intake can result in insufficient blood protein
synthesis (liver can’t make enough albumin) leading to a decreases in plasma oncotic pressure and oedema.
(Fluid moves from low oncotic pressure to high oncotic pressure)
What are the fat soluble vitamins?
A, D, E, K
