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1
Q

what is a nutrient?

A

a Nutrient is a chemical substance found in food used the human body.

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2
Q

what are the 6 classes of nutrients?

A

Carbohydrates, lipids, vitamins, minerals and water.

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3
Q

what is an essential nutrient

A

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

nutrients that an 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

they are not considered an essential nutrients as the human diets can obtain energy from other sources without ill effect.

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6
Q

how is malnutrition caused?

A

is cause by a deficiency, imbalance or excess of nutrients in the diet.

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7
Q

what are the types of malnutrition?

A

overnutrition (too much), undernutrition (not enough), and inadequate utilisation of nutrients by the body.

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8
Q

what are common signs of malnutrition?

A

stunted growth, wasting and obesity.

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9
Q

how can the energy content of food be estimated?

A

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

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10
Q

what does the combustion of food sources cause?

A

causes the stored energy to be released as heat which raises the temperature of water

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11
Q

what is the amount of energy required to raise 1g of water by 1 degree celsius

A

1.48J

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12
Q

what is the equation for energy

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 unwanted loss of heat to the surrounding environment

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14
Q

what are the three nutrients commonly used as energy stores?

A

Carbohydrates, lipids (fats) and proteins

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15
Q

why are carbohydrates preferentially used as energy sources?

A

because they are easier to digest and transport.

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16
Q

why are lipids used for long-term storage?

A

they can store more energy per gram but are harder to digest and transport.

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17
Q

what does protein metabolism produce?

A

produces nitrogenous water products which must be removed from cells

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18
Q

how are proteins constructed?

A

they are constructed by amino acids

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19
Q

how many different amino acids are there?

A

there are 20 different universal amino acids

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20
Q

what are the three types of amino acids according to dietary requirements

A

essential, non-essential or conditionally non-essential

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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

essential amino acids can be produced by the body and 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 lower rates than requirement. they are essential at certain times only.

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24
Q

what does a shortage of one or more essential amino acids in the diet do?

A

the shortage will prevent the production of specific proteins.

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25
what is Phenylketonuria (PKU)
it is a genetic condition that results in impaired metabolism of the amino acid phenylalanine
26
what is a shortage of one or more essential amino acids know as?
this is known as protein deficiency malnutrition. The health effect will vary depending on the amino acid shortage.
27
what they of mutation if PKU
it is an autosomal recessive disease caused by a mutation on the gene encoding the enzyme Phenylalanine hydroxylase.
28
what is the role of Phenylalanine hydroxylase (PAH) within the body?
converts excess phenylalanine within the body into tyrosine
29
in people with PKU what does PAH do?
the escess phenylalanine is instead converted into phenylpyruvate.
30
what does the production of phenylpruvate cause
it casues a toxic build up of Phenylpyruvate in the blood and urine.
31
what can untreated PKU lead to?
can lead to brain damage and mental retardation as well as other serious medical problems
32
How is PKU diagnosed?
With a blood test for elevated levels of phenylalanine
33
How is PKU treated?
By enforcing a strict diet that’s restricts the intake of phenylalanine to prevent its build up in the body
34
How can humans synthesis most fatty acids?
Most fatty acids are synthesised from carbohydrates
35
What two cis-poly unsaturated fatty acids are considered essential?
Alpha-linolenic and linolenic acid
36
Why can humans not synthesis alpha-linolenic and linolecic acid
Humans lack the enzyme to introduce double bonds at the required position of the carbon chain
37
Why are essential fatty acids modified?
To make important lipid-based compounds
38
How are fats and cholesterol transported in the blood stream?
Since they cannot dissolve they are packaged with proteins to from lipoproteins for transport
39
Where do low density lipoproteins (LDLs) carry cholesterol?
From the liver to the body (hence raised blood cholesterol levels)
40
Where do high density lipoproteins carry cholesterol?
They carry excess cholesterol back to the liver for disposal (hence lower blood cholesterol levels)
41
What can directly influence the levels of cholesterol in the blood stream?
A mix of fatty acids consumed as part of a diet
42
What effect does saturated fatty acids have on the body?
They increase LDL levels, raising blood cholesterol
43
What effect does trans fats have on the body?
They increase LDL levels and lower HDL levels, raising blood cholesterol
44
What effect do cis-polyunsaturated fats have on the body?
Rise HDL levels, lowering blood cholesterol
45
What is atherosclerosis?
High cholesterol levels in the bloodstream lead to the hardening and narrowing of arteries
46
What happens to arteries when LDL levels are high in the bloodstream?
The LDL particles from deposits in the walls of the arteries
47
In arteries, what does accumulation of fat with an arterial wall lead to?
Leads to the development of plaques with restricted bloodflow
48
What happens when a coronary arteries become blocked?
Coronary heart disease will result. This includes heart attacks and strokes.
49
What are vitamins?
Vitamins are organic molecules with complex chemical structures
50
Why do you water soluble vitamins need to be constantly consumed?
Because any excess vitamins will be lost in urine e.e vitiman b & c
51
What happens to fat soluble vitamins once in the body?
They can be stored within the body e.e vitamin A, D, E and K
52
What are the functions of vitamins?
Vitamins are diverse although many function as cofactors, antioxidants or hormones
53
Are vitamins essential or nonessential?
Many vitamins are essential as they cannot be synthesised by the body, and the absence may cause a deficiency disease
54
What is absorbic acid?
Absorbic acid is a form of vitamin C that is required for a range of metabolic activities in animals and plants
55
How is absorbic acid used in mammals
It functions as a potent antioxidant and plays an important role in immune function. It is also involved in the synthesis of collagen and lipoproteins.
56
How is absorbic acid made?
It is made internally by most mammals from monosaccharides. It is not produced in humans. Humans must ingest vitamin c
57
What is the effect of a vitamin c deficiency?
Will lead to the development of scurvy, and a general weakening of normal immune function
58
In the body what is vitamin D involved in?
Vitamin D is involved in the absorption of calcium and phosphorus by the body, which contribute to buy mineralisation.
59
What happens to calcium and phosphorus if there is not sufficient amount of vitamin D?
They are excreted in faeces. This can lead to onset diseases, such as osteomalacia (bone softening) or Ricketts (bone deformity)
60
How can vitamin D be naturally synthesised?
When a chemical precursor is exposed to UV light
61
Where may vitamin D be stored?
Vitamin D can be stored by the liver oil levels are low e.g. in winter people with darker skin pigmentation produce vitamin D more slowly and require greater sun exposure.
62
What are dietary minerals?
They are chemical elements required as essential nutrients by organisms.
63
What are some important functions played by minerals in humans?
Major constituents of structures such as teeth and bones e.g Ca, P, Mg) Important components of body fluids e.g. Na, K, Cl Cofactors for specific enzymes, all components of proteins and hormones e.g. Fe, P, I
64
How is human appetite controlled?
Controlled by woman’s produced in the pancreas, stomach, intestines, and adipose tissues
65
What do appetite controlling hormones do?
They send messages to the appetite control centre of the brain within the hypothalamus
66
What ways can the release of hormones be triggered?
Stretch receptors in the stomach and intestine, become activated when ingested food distance of these organs Adipose tissue releases hormones in response to fat storage The pancreas will release hormones in response to changes in blood sugar concentrations
67
What hormones trigger a hunger response?
Ghrelin (from stomach) and glucagon (from pancreas)
68
What hormones released a satiety response?
Leptin from adipose tissue and CCK from intestine

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