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Biology IB HL > D1 Human Nutrition > Flashcards

D1 Human Nutrition Flashcards

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1
Q

What is a nutrient?

A

A nutrient is a chemical substance found in foods that is used in the human body

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2
Q

What are the 6 classes of nutrient?

A

There are six classes of nutrients – carbohydrates, proteins, lipids, vitamins, minerals and water

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3
Q

What are essential nutrients?

A

Essential nutrients are those that cannot be synthesised by the body and must be ingested as part of the diet

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4
Q

What are non-essential nutrients?

A

Non-essential nutrients can be made by the body or have a replacement nutrient which serves the same dietary purpose

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5
Q

Are carbohydrates essential nutrients?

A

NO
Carbohydrates are not considered essential nutrients as human diets can obtain energy from other sources without ill effect

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6
Q

What is malnutrition?

A

Malnutrition is a health condition caused by a deficiency, imbalance or excess of nutrients in the diet

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7
Q

What can cause malnutrition? 2

A

It can be caused by an improper dietary intake of nutrients – e.g. overnutrition (too much) or undernutrition (not enough)

It can be caused by the inadequate utilisation of nutrients by the body – e.g. due to illness or disease

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8
Q

Are symptoms of malnutrition the same for each imbalance?

A

NO

The symptoms of malnutrition will vary according to the specific nutrient and the type of imbalance involved

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9
Q

What are common signs of malnutrition?

A

Common signs of malnutrition included stunted growth and wasting (undernutrition), as well as obesity (over nutrition)

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10
Q

How can the energy content of food be estimated? (experimentally)

A

The energy content of food can be estimated by burning a sample of known mass and measuring the energy released via calorimetry

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11
Q

What does combustion of food release?

A

Combustion of the food source causes the stored energy to be released as heat, which raises the temperature of water

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12
Q

What is the equation used to calculate the energy content of food via calorimetry?

A

Energy (joules) = Mass of water (g) × 4.2 (J/gºC) × Temperature increase (ºC)

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13
Q

WHat is the biggest source of error in calorimetry?

A

The biggest source of error in calorimetry is usually caused by the unwanted loss of heat to the surrounding environment

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14
Q

What should be kept constant in calorimetry?

A

The food sources should be burnt at a constant distance from the water to ensure reliability of results

The initial temperature and volume of water should also be kept constant (1 g of water = 1 cm3 or 1 ml)

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15
Q

Which nutrient is most commonly used an energy source and why?

A

Carbohydrates are preferentially used as an energy source because they are easier to digest and transport

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16
Q

What type of energy are lipids used for and why?

A

Lipids can store more energy per gram but are harder to digest and transport (hence are used for long-term storage)

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17
Q

What happens when proteins are used for energy?

A

Protein metabolism produces nitrogenous waste products which must be removed from cells

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18
Q

What are amino acids?

A

Amino acids are the monomeric building blocks from which proteins are constructed

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19
Q

How many amino acids are there?

A

here are 20 different amino acids which are universal to all living organisms

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20
Q

What categories do amino acids fit into?

A

Amino acids can be either essential, non-essential or conditionally non-essential according to dietary requirements

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21
Q

WHat are essential amino acids?

A

Essential amino acids cannot be produced by the body and must be present in the diet

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22
Q

What are non-essential amino acids?

A

Non-essential amino acids can be produced by the body and are therefore not required as part of the diet

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23
Q

What are conditionally non-essential amino acids?

A

Conditionally non-essential amino acids can be produced by the body, but at rates lower than certain conditional requirements (e.g. during pregnancy or infancy) – they are essential at certain times only

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24
Q

What happens if there is a shortage of one or more of the essential amino acids?

A

A shortage of one or more essential amino acids in the diet will prevent the production of specific proteins

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25
Q

What is a lack of amino acids called?

A

This is known as protein deficiency malnutrition and the health effects will vary depending on the amino acid shortage

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26
Q

What is PKU?

A

Phenylketonuria (PKU) is a genetic condition that results in the impaired metabolism of the amino acid phenylalanine

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27
Q

What does PKU affect regarding genetics?

A

It is an autosomal recessive disease caused by a mutation to the gene encoding the enzyme phenylalanine hydroxylase

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28
Q

What is the typical role of PAH?

A

Phenylalanine hydroxylase (PAH) normally converts excess phenylalanine within the body into tyrosine

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29
Q

What happens as a result of the lack of PAH?

A

In people with PKU, the excess phenylalanine is instead converted into phenylpyruvate (also known as phenylketone)

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30
Q

What happens when phenylalanine is constantly being converted into phenylketone?

A

This results in a toxic build up of phenylketone in the blood and urine (hence phenylketonuria)

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31
Q

What can untreated PKU lead to?

A

Untreated PKU can lead to brain damage and mental retardation, as well as other serious medical problems

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32
Q

How are infants with PKU at birth?

A

Infants with PKU are normal at birth because the mother is able to break down phenylalanine during pregnancy

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33
Q

How is PKU diagnosed?

A

Diagnosis of PKU is made by a simple blood test for elevated phenylalanine levels shortly after birth

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34
Q

How is PKU treated?

A

PKU is treated by enforcing a strict diet that restricts the intake of phenylalanine to prevent its build up within the body

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35
Q

What does a PKU diet contain?

A

This low-protein diet should include certain types of fruits, grains, vegetables and special formula milk

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36
Q

What should a PKU diet be supplemented with?

A

This diet should be supplemented with a medical formula that contains precise quantities of essential amino acids

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37
Q

Is a person able to live normally with PKU?

A

Patients who are diagnosed early and maintain this strict diet can have a normal life span without damaging symptoms

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38
Q

Why are most fatty acids non-essential? What are the exceptions (general)?

A

Humans can synthesise most fatty acids from carbohydrates, but two (cis)-polyunsaturated fatty acids are considered essential

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39
Q

What are the 2 essential fatty acids?

A

Alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid) cannot be synthesised by the body

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40
Q

WHy are these 2 fatty acids essential?

A

this is because humans lack the enzyme required to introduce double bonds at the required position of the carbon chain

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41
Q

What are essential fatty acids used for?

A

Essential fatty acids are modified by the body to make important lipid-based compounds (such as signalling molecules)

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42
Q

What is linked to a deficiency of essential fatty acids?

A

There is evidence to suggest dietary deficiencies of these fatty acids may be linked to impaired brain development (e.g. depression) and altered maintenance of cardiac tissue (e.g. abnormal heart function) – although this evidence is contested

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43
Q

What are foods rich in essential fatty acids?

A

Foods rich in essential fatty acids (omega-3 and omega-6) include fish, leafy vegetables and walnuts

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44
Q

How are fats and cholesterol transported?

A

Fats and cholesterol cannot dissolve in the bloodstream and so are packaged with proteins (to form lipoproteins) for transport

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45
Q

What are LDLs?

A

Low density lipoproteins (LDLs) carry cholesterol from the liver to the body (hence raise blood cholesterol levels)

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46
Q

What are HDLs?

A

High density lipoproteins (HDLs) carry excess cholesterol back to the liver for disposal (hence lower blood cholesterol levels)

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47
Q

What does the mix of fatty acids consumed affect?

A

The mix of fatty acids consumed as part of a diet directly influences the levels of cholesterol in the bloodstream:

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48
Q

How do saturated fatty acids affect the levels of cholesterol in the bloodstream?

A

Saturated fats increase LDL levels within the body, raising blood cholesterol levels

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49
Q

How do trans fats affect the levels of cholesterol in the bloodstream?

A

Trans fats increase LDL levels and lower HDL levels, significantly raising blood cholesterol levels

50
Q

How do Cis-polyunsaturated fats affect the levels of cholesterol in the bloodstream?

A

Cis-polyunsaturated fats raise HDL levels, lowering blood cholesterol levels

51
Q

What do high cholesterol levels in the bloodstream lead to?

A

High cholesterol levels in the bloodstream lead to the hardening and narrowing of arteries (atherosclerosis)

52
Q

What happens when there are high LDL levels in the bloodstream?

A

When there are high levels of LDL in the bloodstream, the LDL particles will form deposits in the walls of the arteries

53
Q

What does the accumulation of fat in arterial walls lead to?

A

The accumulation of fat within the arterial wall leads to the development of plaques which restrict blood flow

54
Q

What happens if coronary arteries become blocked?

A

If coronary arteries become blocked, coronary heart disease (CHD) will result – this includes heart attacks and strokes

55
Q

What are vitamins?

A

Vitamins are organic molecules with complex chemical structures that are quite diverse and hence categorised by groups

56
Q

Is there a limit to the consumption of water soluble vitamins?

A

Water soluble vitamins need to be constantly consumed as any excess is lost in urine (e.g. vitamins B, C)

57
Q

Where can fat soluble vitamins be stored?

A

Fat soluble vitamins can be stored within the body (e.g. vitamins A, D, E, K)

58
Q

What are many functions of vitamins? (3)

A

The functions of vitamins are as diverse as their structure, although many function as cofactors, antioxidants or hormones

59
Q

Are many vitamins non/essential?

A

Many vitamins are essential as they cannot be synthesised by the body and their absence may cause a deficiency disease

60
Q

What is ascorbic acid and its use?

A

Ascorbic acid is a form of vitamin C that is required for a range of metabolic activities in all animals and plants

61
Q

What is the role of ascorbic acid in mammals? (4)

A

In mammals it functions as a potent antioxidant and also plays an important role in immune function
It is also involved in the synthesis of collagen (a structural protein) and in the synthesis of lipoproteins

62
Q

Can humans produce ascorbic acid?

A

NO

Ascorbic acid is made internally by most mammals from monosaccharides – but it is not produced by humans

63
Q

How do most humans consume ascorbic acid?

A

Consequently, human must ingest vitamin C as part of their dietary requirements in order to avoid adverse health effects

64
Q

What does a vitamin C deficiency lead to?

A

A deficiency in vitamin C levels will lead to the development of scurvy and a general weakening of normal immune function

65
Q

What are common sources of vitamin C?

A

Common food sources of vitamin C include citrus fruits and orange juice

66
Q

What is the role of vitamin D?

A

Vitamin D is involved in the absorption of calcium and phosphorus by the body – which contribute to bone mineralisation

67
Q

What happens to elements associated with vit D if there is a deficiency?

A

In the absence of sufficient amounts of this vitamin, these elements are not absorbed but instead excreted in the faeces

68
Q

What does a vit D deficiency lead to?

A

This can lead to the onset of diseases such as osteomalacia (where bones soften) or rickets (where bones are deformed)

69
Q

Can vit D be synthesised?

A

yes

Vitamin D can be naturally synthesised by the body when a chemical precursor is exposed to UV light (i.e. sunlight)

70
Q

Where can vit D be stored?

A

The vitamin D may be stored by the liver for when levels are low (e.g. during winter when sun exposure is reduced)

71
Q

What may affect vit D synthesis?

A

Individuals with darker skin pigmentation produce vitamin D more slowly and hence require greater sun exposure

72
Q

Who are vit D deficiencies usually restricted to?

A

Vitamin D deficiencies are usually restricted to individuals with highly limited sun exposure (e.g. elderly, certain ethnicities)

73
Q

What is the problem with sun exposure?

A

While excess sun exposure is beneficial for vitamin D production, it also increases the risks of developing skin cancers

74
Q

What are dietary minerals?

A

Dietary minerals are chemical elements required as essential nutrients by organisms

75
Q

What minerals are considered non-essential?

A

Minerals present in common organic molecules are not considered essential – e.g. C, H, O, N, S

76
Q

What are examples of minerals?

A

Minerals include calcium (Ca), magnesium (Mg), iron (Fe), phosphorus (P), sodium (Na), potassium (K) and chlorine (Cl)

77
Q

What is the use of Ca, P, Mg?

A

Major constituents of structures such as teeth and bones (e.g. Ca, P, Mg)

78
Q

What is the use of Na, K, Cl?

A

Important components of body fluids (e.g. Na, K, Cl)

79
Q

What is the use of Na, K, Cl?

A

Important components of body fluids (e.g. Na, K, Cl)

80
Q

What is the use of Fe, P, I?

A

Cofactors for specific enzymes or components of proteins and hormones (e.g. Fe, P, I)

81
Q

What will happen if there is a deficiency in one or more minerals?

A

A deficiency in one or more dietary mineral can result in a disorder (e.g. lack of calcium can affect bone mineralisation)

82
Q

Apart from animals, what organism requires minerals?

A

Minerals are also important in plant development, making fruits and vegetables a good source of certain dietary minerals

83
Q

What is the role of magnesium in plants?

A

Magnesium is an important component of chlorophyll (required for photosynthesis)

84
Q

What is the role of potassium in plants?

A

Potassium is an inorganic salt found within the sap of a plant (maintains water potential)

85
Q

What is the role of calcium in plants?

A

Calcium is important for plant root and shoot elongation

86
Q

What controls appetite?

A

Appetite is controlled by hormones produced in the pancreas, stomach, intestines and adipose tissue

87
Q

Where are the hormones secreted by organs involved in appetite control sent?

A

These hormones send messages to the appetite control centre of the brain (within the hypothalamus)

88
Q

What will hormonal signals trigger?

A

Hormonal signals will either trigger a feeling of hunger (promote feasting) or satiety (promote fasting)

89
Q

What 3 organs can release hormones involved in appetite?

A

stomach
adipose tissue
pancread

90
Q

How does the stomach release appetite hormones?

A

Stretch receptors in the stomach and intestine become activated when ingested food distends these organs

91
Q

How does the adipose tissue release appetite hormones?

A

Adipose tissue releases hormones in response to fat storage

92
Q

How does the pancreas release appetite hormones?

A

The pancreas will release hormones in response to changes in blood sugar concentrations

93
Q

What can hormones (related to appetite) do? (basic)

A

Hormones will either stimulate or inhibit the appetite control centre to promote sensations of hunger or satiety

94
Q

What hormones trigger a hunger response?

A

Hormones that trigger a hunger response include ghrelin (from stomach) and glucagon (from pancreas)

Ghrelin Grows Hunger

95
Q

What hormones trigger a satiety response>?

A

Hormones that trigger a satiety response include leptin (from adipose tissue) and CCK (from intestine)

Leptin Lowers Hunger

96
Q

What can change in diet/ appetite control result in?

A

Changes in diet and appetite control may result in individuals over-indulging or under-indulging during meals

97
Q

What will happen in individuals who overeat?

A

Individuals who overeat are likely to gain weight and develop obesity-related illnesses

98
Q

What will happen in individuals who undereat?

A

Individuals who undereat are likely to lose weight and exhibit starvation symptoms

99
Q

What is clinical obesity?

A

Clinical obesity (BMI > 30) describes a significant excess in body fat

100
Q

What 2 factors cause obesity?

A

Increased energy intake

Decreased energy expenditure

101
Q

How does increased energy intake contribute to obesity?

A

overeating or an increased reliance on diets rich in fats and sugars

102
Q

How does decreased energy expenditure contribute to obesity?

A

less exercise resulting from an increasingly sedentary lifestyle

103
Q

What are individuals who suffer from obesity more prone to?

A

Individuals who are overweight or obese are more likely to suffer from hypertension (abnormally high blood pressure)

104
Q

How does excess weight contribute to hypertension?

A

Excess weight places more strain on the heart to pump blood, leading to a faster heart rate and higher blood pressure

105
Q

How does high cholesterol lead to hypertension?

A

High cholesterol diets will lead to atherosclerosis, narrowing the blood vessels which contributes to raised blood pressure

106
Q

What is hypertension a precursor to ?

A

Hypertension is a common precursor to the development of coronary heart disease (CHD)

107
Q

What other illness are overweight/obese people likely to suffer from?

A

Individuals who are overweight or obese are also more likely to suffer from type II diabetes (non-insulin-dependent)

108
Q

When does Type II diabetes occur?

A

Type II diabetes occurs when fat, liver and muscle cells become unresponsive to insulin (insulin insensitivity)

109
Q

What type of diet causes type II diabetes?

A

This typically results from a diet rich in sugars causing the progressive overstimulation of these cells by insulin

110
Q

Generally, who is more likely to develop type II diabetes?

A

Hence overweight individuals who have a high sugar intake are more likely to develop type II diabetes

111
Q

What is starvation?

A

Starvation describes the severe restriction of daily energy intake, leading to a significant loss of weight

112
Q

What happens to the body due to starvation?

A

As the body is not receiving a sufficient energy supply from the diet, body tissue is broken down as an energy source

113
Q

What is the effect of prolonged and severe starvation?

A

This leads to muscle loss (as muscle proteins are metabolised for food) and eventually organ damage (and death)

114
Q

What is anorexia nervosa?

A

Anorexia nervosa is an eating disorder in which individuals severely limit the amount of food they intake

115
Q

In whom is anorexia nervosa most common?

A

It is most common in young females with body image anxiety and can potentially be fatal if left untreated

116
Q

What is the most common cause o death due to anorexia?

A

In severe anorexia, the body begins to break down heart muscle, making heart disease the most common cause of death

117
Q

How does anorexia lead to heart disease?

A

Blood flow is reduced and blood pressure may drop as heart tissue begins to starve

The heart may also develop dangerous arrhythmias and become physically diminished in size

118
Q

What is the RDI?

A

The recommended daily intake for a nutrient (RDI) is the daily dietary level required to meet the requirements of health

119
Q

What causes the RDI to vary?

A

It is an estimate only and will vary according to age, gender, activity levels and medical conditions

120
Q

What are the recommendations of the RDI based off of?

A

The recommendations are based on a daily energy intake of 8400 kJ (2000 kcal) for healthy adults

121
Q

How is the RDI found on food packages?

A

On food packages, this information is usually presented as a percentage of a daily total (based on identified serving size)

122
Q

How can weight change be monitored?

A

Dietary intake can be recorded and compared against levels of energy expenditure in order to monitor weight change

Biology IB HL (56 decks)

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