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Year 1 Semester 1 Medical Cell Biology and Genetics > S16) Nutrition, Diet and Body Weight > Flashcards

S16) Nutrition, Diet and Body Weight Flashcards

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1
Q

What is energy?

A

Energy is the capacity to do work

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2
Q

Which five cellular processes occuring in living things require energy to occur?

A
  • 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
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3
Q

Illustrate the ADP-ATP cycle in terms of energy usage and energy production

A
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4
Q

What is the unit of food energy?

A

Kilojoule (kJ) is official SI unit of food energy

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5
Q

What is a Kcal and how many kJ are found in it?

A

1 Kcal = amount of energy needed to raise temperature of one kilogram of water by one degree Celsius

1 kcal = 4.2 Kilojoules

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6
Q

In terms of nutrition, identify the 7 possible nutrients obtained and the respective functions of each

A
  • 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
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7
Q

Identify the two types of essential components of the diet

A
  • Macronutrients
  • Micronutrients
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8
Q

Identify some macronutrients

A
  • Proteins
  • Carbohydrates
  • Lipids
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9
Q

Identify some micronutrients

A
  • Vitamins
  • Minerals
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10
Q

Describe the molecular structure of carbohydrates

A

General formula (CH2O)n

  • Contain aldehyde (-C=OH) or keto (-C=O) group
  • Multiple –OH groups
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11
Q

Describe the molecular structure of the following carbohydrate units:

  • Monosaccharides
  • Disaccharides
  • Oligosaccharides
  • Polysaccharides
A
  • 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
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12
Q

Identify and describe the seven major dietary carbohydrate molecules

A
  • 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)
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13
Q

Describe the molecular structure of proteins

A

Proteins are composed of amino acids joined to form linear chains

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14
Q

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

A
  • Isoleucine

- Leucine

- Threonine

- Histidine

- Lycine

- Methionine

- Phenylaline

- Tryptophan

- Valine

Mnemonic: If Learned, This Huge List Might Prove Truly Valuable

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15
Q

Arginine is a conditionally essential amino acid.

What does that mean?

A
  • Arginine can be synthesised in the body
  • A dietary supply needed only during periods of active growth e.g pregnancy
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16
Q

Tyrosine is a conditionally essential amino acid.

What does it mean?

A
  • Tyrosine can be synthesised in the body from phenylaline
  • Essential only if the diet is low in phenylaline
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17
Q

Cysteine is a conditionally essential amino acid.

What does this mean?

A
  • Cysteine can be synthesised in the body from methionine
  • Essential only if the diet is low in methionine
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18
Q

In terms of high quality and lower quality proteins, explain why the vegetarian diet must obtain protein from a wide variety of plant sources

A
  • 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
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19
Q

Describe the molecular structure of lipids

A

Lipids are composed of triacylglycerols (3 fatty acids esterified to one glycerol

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20
Q

Provide four reasons as to why are lipids important to the diet

A
  • 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
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21
Q

Briefly explain the role of vitamins in the body

A
  • Vitamins are essential for life and required in micro- or milligram quantities
  • Deficiency diseases occur if inadequate intake
22
Q

Identify 4 fat soluble vitamins as well as their associated deficiency diseases

A
  • Vitamin A – xerophthalmia
  • Vitamin D – rickets
  • Vitamin E – neurological abnormalities
  • Vitamin K – defective blood clotting
23
Q

Identify 6 water soluble vitamins

A
  • 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
24
Q

What is the function of minerals in the body?

A

Electrolytes establish ion gradients across membranes & maintain water balance

25
Q

Identify 5 trace elements in the body

A
  • Fe (Iron)
  • Zn (Zinc)
  • I (Iodine)
  • Cu (Copper)
  • Mn (Manganese)
26
Q

Identify 5 major minerals in the body

A
  • Na (Sodium)
  • K (Potassium)
  • Ca (Calcium)
  • Cl (Chlorine)
  • P (Phosphorous)
27
Q

What is dietary fibre and why is it important?

A
  • Fibre is non-digestible plant material found in cereal foods e.g. bread, beans, fruit, veg
  • -* Needed for normal bowel function
28
Q

Describe the consequences of low fibre and high fibre diets respectively

A
  • Low fibre intake associated with constipation and bowel cancer
  • High fibre diet shown to reduce cholesterol and risk of diabetes
29
Q

What is the daily energy expenditure for an average male and female respectively?

A
  • Energy expenditure of 70 kg male = `12 000 kJ
  • Energy expenditure of 58 kg female = `9500 kJ
30
Q

Which factors affect the energy requirements in individuals?

A
  • Age
  • Sex
  • Body composition
  • Physical activity
31
Q

Which three measurements compose the daily energy expenditure?

A
  • Basal metabolic rate
  • Diet-induced thermogenesis (energy required to process food)
  • Physical activity level
32
Q

What is basal metabolic rate?

A

BMR maintains the resting activities of the body:

  • Maintenance of cells
  • Function of organs
  • Maintenance of body temperature
33
Q

Which factors affect BMR?

A
  • 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
34
Q

Voluntary physical activity reflects the energy demands of which muscles?

A
  • Skeletal muscle
  • Heart muscle
  • Respiratory muscles
35
Q

Explain how the relationship between energy intake and energy expenditure influence body weight

A
  • Energy intake = expenditure → body weight stable
  • Energy intake exceeds expenditure → energy stores (fat) will increase
  • Energy expenditure exceeds intake → energy stores deplete
36
Q

What is BMI and how is it calculated?

A

BMI is a simple way to estimate one’s desirable body weight

BMI = weight (kg)/height (m) 2

37
Q

Identify the 5 categories for BMI (including ranges)

A
38
Q

What is waist to hip ratio?

A

Waist to hip ratio is when the waist circumference is measured divided by the hip circumference to give a ratio

39
Q

Why is waist to hip ratio a preferred measurement of ideal body weight?

A

It is increasingly used as a better measure of obesity and risk of CVD

40
Q

What classifies as obese in waist to hip ratio measurements?

A
  • Males > 0.9
  • Females > 0.85
41
Q

What is obesity?

A

Obesity is a chronic condition characterised by excess body fat and is most often defined on the basis of Body Mass Index (BMI)

42
Q

What does body weight in most adults depend on?

A

The balance between energy intake and energy expenditure

43
Q

Identify 3 other factors which contribute to weight gain

A
  • Genetics
  • Drug therapy
  • Endocrine disorders
44
Q

Identify 5 diseases which obese people are at increased risk of developing

A
  • Insulin resistance
  • Hyperlipidaemia
  • Stroke
  • Diabetes Type II
  • Hypertension
45
Q

What is marasmus?

A

Marasmus is a type of protein-energy malnutrition most commonly seen in children < 5

46
Q

Identify 5 signs and symptoms of marasmus

A
  • Emaciated
  • Muscle wasting
  • Thin & dry hair
  • Diarrhoea
  • No oedema
47
Q

What is kwashiorkor?

A

Kwashiorkor is a disease which occurs typically in a young child displaced from breastfeeding and fed with a high carbohydrate, very low protein diet

48
Q

Identify 5 signs and symptoms of kwashiokor

A
  • Anaemic
  • Lethargic
  • Anorexic
  • Generalised oedema
  • Low serum albumin
49
Q

In four steps, explain why kwashiorkor leads to the development of oedema

A

⇒ 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

50
Q

What are malabsorption conditions?

A
  • 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

Year 1 Semester 1 Medical Cell Biology and Genetics (23 decks)

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