S16) Nutrition, Diet and Body Weight Flashcards
What is energy?
Energy is the capacity to do work
Which five cellular processes occuring in living things require energy to occur?
- 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
Illustrate the ADP-ATP cycle in terms of energy usage and energy production
What is the unit of food energy?
Kilojoule (kJ) is official SI unit of food energy
What is a Kcal and how many kJ are found in it?
1 Kcal = amount of energy needed to raise temperature of one kilogram of water by one degree Celsius
1 kcal = 4.2 Kilojoules
In terms of nutrition, identify the 7 possible nutrients obtained and the respective functions of each
- Carbohydrates – 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
Identify the two types of essential components of the diet
- Macronutrients
- Micronutrients
Identify some macronutrients
- Proteins
- Carbohydrates
- Lipids
Identify some micronutrients
- Vitamins
- Minerals
Describe the molecular structure of carbohydrates
General formula (CH2O)n
- Contain aldehyde (-C=OH) or keto (-C=O) group
- Multiple –OH groups
Describe the molecular structure of the following carbohydrate units:
- Monosaccharides
- Disaccharides
- Oligosaccharides
- Polysaccharides
- Monosaccharides: single sugar units (3-9 C-atoms)
- Disaccharides: two sugar units
- Oligosaccharides: 3-12 units e.g. dextrins
- Polysaccharides: 10-1000’s units e.g. glycogen, starch, cellulose
Identify and describe the seven major dietary carbohydrate molecules
- Glucose: predominant sugar in human blood
- Maltose: glucose-glucose disaccharide
- Fructose: fruit sugar (monosaccharide)
- Sucrose: table sugar (glucose-fructose disaccharide)
- Lactose: milk sugar (galactose-glucose disaccharide)
- Starch: carbohydrate storage molecule in plants (polymer of glucose)
- Glycogen: carbohydrate storage molecule in animals (polymer of glucose)
Describe the molecular structure of proteins
Proteins are composed of amino acids joined to form linear chains
20 different amino acids used for protein synthesis in body. However, 9 amino acids cannot be synthesised and must be obtained from diet.
Identify the essential amino acids
- Isoleucine
- Leucine
- Threonine
- Histidine
- Lycine
- Methionine
- Phenylaline
- Tryptophan
- Valine
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Arginine is a conditionally essential amino acid.
What does that mean?
- Arginine can be synthesised in the body
- A dietary supply needed only during periods of active growth e.g pregnancy
Tyrosine is a conditionally essential amino acid.
What does it mean?
- Tyrosine can be synthesised in the body from phenylaline
- Essential only if the diet is low in phenylaline
Cysteine is a conditionally essential amino acid.
What does this mean?
- Cysteine can be synthesised in the body from methionine
- Essential only if the diet is low in methionine
In terms of high quality and lower quality proteins, explain why the vegetarian diet must obtain protein from a wide variety of plant sources
- Protein of animal origin considered “high quality” and contain all essential amino acids
- Proteins of plant origin generally considered “lower quality” since most are deficient in one or more essential amino acids
Describe the molecular structure of lipids
Lipids are composed of triacylglycerols (3 fatty acids esterified to one glycerol
Provide four reasons as to why are lipids important to the diet
- Greater energy yield than carbs (2x)
- Absorption of fat soluble vitamins
- Structural components of the cell membranes
- Provides essential fatty acids e.g. linoleic and linolenic acids
Briefly explain the role of vitamins in the body
- Vitamins are essential for life and required in micro- or milligram quantities
- Deficiency diseases occur if inadequate intake
Identify 4 fat soluble vitamins as well as their associated deficiency diseases
- Vitamin A – xerophthalmia
- Vitamin D – rickets
- Vitamin E – neurological abnormalities
- Vitamin K – defective blood clotting
Identify 6 water soluble vitamins
- Vitamin C (ascorbic acid) – scurvy
- Vitamin B1 (thiamin) – beriberi
- Vitamin B<strong>2</strong> (riboflavin) – ariboflavinosis
- Vitamin B<strong>3</strong> (niacin) – pellagra
- Vitamin B6 – dermatitis, anaemia
- Vitamin B12 – anaemia
What is the function of minerals in the body?
Electrolytes establish ion gradients across membranes & maintain water balance
Identify 5 trace elements in the body
- Fe (Iron)
- Zn (Zinc)
- I (Iodine)
- Cu (Copper)
- Mn (Manganese)
Identify 5 major minerals in the body
- Na (Sodium)
- K (Potassium)
- Ca (Calcium)
- Cl (Chlorine)
- P (Phosphorous)
What is dietary fibre and why is it important?
- Fibre is non-digestible plant material found in cereal foods e.g. bread, beans, fruit, veg
- -* Needed for normal bowel function
Describe the consequences of low fibre and high fibre diets respectively
- Low fibre intake associated with constipation and bowel cancer
- High fibre diet shown to reduce cholesterol and risk of diabetes
What is the daily energy expenditure for an average male and female respectively?
- Energy expenditure of 70 kg male = `12 000 kJ
- Energy expenditure of 58 kg female = `9500 kJ
Which factors affect the energy requirements in individuals?
- Age
- Sex
- Body composition
- Physical activity
Which three measurements compose the daily energy expenditure?
- Basal metabolic rate
- Diet-induced thermogenesis (energy required to process food)
- Physical activity level
What is basal metabolic rate?
BMR maintains the resting activities of the body:
- Maintenance of cells
- Function of organs
- Maintenance of body temperature
Which factors affect 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 reflects the energy demands of which muscles?
- Skeletal muscle
- Heart muscle
- Respiratory muscles
Explain how the relationship between energy intake and energy expenditure influence body weight
- Energy intake = expenditure → body weight stable
- Energy intake exceeds expenditure → energy stores (fat) will increase
- Energy expenditure exceeds intake → energy stores deplete
What is BMI and how is it calculated?
BMI is a simple way to estimate one’s desirable body weight
BMI = weight (kg)/height (m) 2
Identify the 5 categories for BMI (including ranges)
What is waist to hip ratio?
Waist to hip ratio is when the waist circumference is measured divided by the hip circumference to give a ratio
Why is waist to hip ratio a preferred measurement of ideal body weight?
It is increasingly used as a better measure of obesity and risk of CVD
What classifies as obese in waist to hip ratio measurements?
- Males > 0.9
- Females > 0.85
What is obesity?
Obesity is a chronic condition characterised by excess body fat and is most often defined on the basis of Body Mass Index (BMI)
What does body weight in most adults depend on?
The balance between energy intake and energy expenditure
Identify 3 other factors which contribute to weight gain
- Genetics
- Drug therapy
- Endocrine disorders
Identify 5 diseases which obese people are at increased risk of developing
- Insulin resistance
- Hyperlipidaemia
- Stroke
- Diabetes Type II
- Hypertension
What is marasmus?
Marasmus is a type of protein-energy malnutrition most commonly seen in children < 5
Identify 5 signs and symptoms of marasmus
- Emaciated
- Muscle wasting
- Thin & dry hair
- Diarrhoea
- No oedema
What is kwashiorkor?
Kwashiorkor is a disease which occurs typically in a young child displaced from breastfeeding and fed with a high carbohydrate, very low protein diet
Identify 5 signs and symptoms of kwashiokor
- Anaemic
- Lethargic
- Anorexic
- Generalised oedema
- Low serum albumin
In four steps, explain why kwashiorkor leads to the development of oedema
⇒ Distended abdomen due to hepatomegaly and ascites
⇒ Insufficient amino acids for albumin production by the liver
⇒ Reduction in blood proteins decreases plasma oncotic pressure
⇒ Fluid moves from capillaries into the interstitium
What are malabsorption conditions?
- Malabsorption conditions are caused by the failure to digest and/or absorb ingest nutrients e.g. Coeliac disease and Crohn’s disease
- Under-nutrition may result from eating disorders like anorexia and bulimia nervosa or from reduced availability of food such as in developing countries
