D1 Human nutrition Flashcards
(124 cards)
1
Q
What are nutrients?
A
Chemical substances found in foods that are ued in the human body
2
Q
What are the 6 classes of nutrients?
A
- Carbohydrates
- Proteins
- Lipids
- vitamins
- minerals
- water
3
Q
What are essential nutrients?
A
Nutrients that have to be ingested in the diet (only source is from food) as cannot be synthesized by the body.
* Cannot be synthesized in sufficient quantities
4
Q
What are examples of essential nutrients?
A
- Some amino acids
- some unsaturated fatty acids
- some minerals
- calcium
- vitamins
- water
5
Q
What are non-essential nutrients?
A
Nutrients that can be synthesised by the body or a suitable alternative can be used for the function
6
Q
What are examples of non-essential nutrients?
A
Glucose, starch and other carbohydrates are non-essential, because they are used in respiration to provide energy and lipids can be used instead
7
Q
What are some conditionally essential nutrients? Why?
A
In adults, Vitamin K is produced by the metabolism of symbiotic bacteria in the intestine.
But infants do nothave colonies of such bacteria at birth, they are ofen given a supplementary injection of vitamin K
8
Q
What is vitamin C?
A
A compound called ascorbic acid
9
Q
What is the use of ascorbic acid?
A
Syntehsis of collagen fibres that form part of many tissues in the body (i.e. skin and blood vessel walls)
10
Q
What can synthesize vitamin C?
A
- Vast majority of plants and animals
- Inclluding most mammals
11
Q
What leads to the inability to produce vitamin C?
A
Mutations in the GLO gene which codes for the production of the enzyme L-glulono-γ-lactone oxidase
12
Q
What does the GLO gene code for?
A
the enzyme L-glulono-γ-lactone oxidase
13
Q
What happened to teleost (a group of fish)?
A
They lost the ability to produce vitaminc C
14
Q
What are examples of fishes from teleost that lost their ability to synthesize vitamin C?
A
Cod, salmon and herring
15
Q
What mammals and primates can synthesize vitamin C?
A
Mammals: Dogs and cats
Primates: lorises and lemurs
16
Q
What are 3 primates that cant synthesize vitamin C?
A
- humans
- chimpanzees
- apes
17
Q
What is caused by a deficiency of vitamin C?
A
Scurvy
18
Q
How are the symptoms of scurvy alleviated by?
A
by intake of dietary sources of the compound
19
Q
What are the symptoms of scurvy?
A
- Skin discoloration & bruising
- Hemorrhaging
- Anaemia
- Dental issues
- Exhaustion/fatigue
- Sweeling of joints (edema)
20
Q
Out of 20 amino acids in proteins, around how much are essential?
A
About half
21
Q
What are essential amino acids?
A
Cannot be produced by the body and must be present in the diet
22
Q
What are non-essential amino acids?
A
can be produced by the body and are therefore not required as part of the diet
23
Q
What are conditionally non-essential amino acids?
A
Sometimes have to be ingested as the body does not have enough e.g. during pregnancy or early infancy
24
Q
What are two examples of conditionally essential amino acids?
A
Threonine and arginine
25
How is threonine a conditionally essential amino acid?
Threonine is a essential amino acid that can be synthesized by the body if phenylalanine is present
26
What can be synthesized if phenylalanine is present?
Threonine amino acid
27
Why is arginine conditionally essential?
* Sufficient arginine can normally be produced by a healthy individual
* however the synthesis pathway is not active in prematurely born infants so they must obtain it through their diet
28
What does the "omega-3" and "omega-6" refer to?
Refers to the position of a double bond in relation to the end of the molecule
29
What are two (cis)-polyunsaturated fatty acids that are considered essential?
ALpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid)
30
What are alpha-linolenic acid and linoleic acid used for?
For the biosynthesis of a number of other compounds
* Large quantities involved in the development of the brain and the eye
31
Although alpha-linolenic acid and linoleic acid is used to develop the brain and eyes, what is there no evidence of in terms of taking its supplements?
There is little or no evidence that supplementation of a normal balanced diet with omega-3 fatty acids, for example from fish oils, enhances brain or eye development
32
Which foods are rich in essential fatty acids (omega-3 and omega-6)?
Fish, leafy vegetables, nuts, avocado
33
What does the lack of essential amino acids affect?
Production of proteins
* the body cannot make enough of the proteins that it needs
34
What is the condition when you lack essential amino acids?
Protein deficiency malnutrition
35
Why may essential amino acids be lacking?
* due to an overall insufficiency of protein in the diet
* or imbalance in the types of proteins
36
What can protein deficiency malnutrition cause? (3)
* Lack of blood plasma, which results in fluid being retained in tissues causing swelling (edema)
* Child development may be both mentally and physically retarded, with stunted growth and developmental disailities
* Adults may undergo serious weight loss (wasting)
37
How much minerals are needed in a diet?
Relatively small amounts
38
How can minerals be distingushed from vitamins?
By their chemical nature
39
What are minerals?
Chemical elements, usually in ionic form
e.g. calcium, magnesium, iron, phosphorus, sodium, potassium, iodine and chlorine
40
What is resulted when any mineral is lacking from the diet?
A deficiency disease results
41
What is an example of a mineral deficiency disease?
Mineral iodine
42
What is iodine needed for?
needed by the thyroid gland for synthesis of the hormone thyroxin
43
What does thyroxin hormone stimulate?
the metabolic rate and ensures that enough energy is released in the body.
44
What is deficiency disease is caused by the lack of iodine?
iodine dificiency disorder (IDD)
45
What happens if a pregnant woman has IDD?
Her baby may be born with permanenet brain damage
46
What happens to children who suffer from IDD after birth?
Their mental development and intelligence are impaired
47
How can IDD be cured?
By taking **iodine supplementations**
* adding the **mineral to salt** sold for human consumption for **little cost**
48
What deficiency disease is caused by the lack of calcium?
Rickets (as well as a lack of vitaminn D)
49
What deficiency disease is caused by the lack of iron?
Anaemia - lack of haemoglobin, less O2 transported around the body = light headed, pale, fatigue
50
What are vitamins and how do we get them?
Vitamins are **organic compounds** that are needed in **very small amounts** because they **cannot be synthesized by the body** but must be **obtained from the diet**
51
What are a variety of roles of vitamins?
* Co-factors for enzymes
* anti-oxidants
* hormones
* help absorb digested food
52
Which vitamins do not have an amino group?
Vitamin A, C, D and E
53
What is vitamin C derived from?
from a monosacharride
54
What is vitamin A like?
* hydrophobic
* contains a hydrocarbon ring and chain
55
What is vitamin B₂ like?
* contains nitrogen rings
* is readily converted to the nucleotide FMN (flavin mononucleotide) by the addition of a phosphate to the carbohydrate within the molecule
56
How is vitamin B₂ readily converted to the nucleotide FMN (flavin mononucleotide)?
by the addition of a phosphate to the carbohydrate within the molecule
57
How can vitamins be categorised?
Water soluble and fat soluble
58
Water vs fat soluble vitamins?
Water soluble: need to be constantly consumed and any excess are lost in urine
Fat soluble: can be stored within the body
59
Water vs fat soluble vitamins?
Water soluble: need to be constantly consumed and any excess are lost in urine
Fat soluble: can be stored within the body
60
What are examples of water and fat soluble vitamins?
Water: Vit C and B
Fat: Vit A, D, E
61
What is malnutrition an outcome of?
A poor diet
62
What kind of diet can lead to malnutrition?
* low in quantity with low protein and calorie content
* unbalanced and fail to provide essential nutrients
* contain excess fats and refined carbohydrates
63
What is malnutrition often associated with?
Poverty
64
What is starvation a consequence of?
* a diet lacking in adequate protein and carbohydrates
* svere lack of intake of essential and non-essential nutrients
65
Where can obesity be observed in?
in **developing countries** as well as in the **lower socio-economic classes of developed nations**
* due to unhealthy diets with excess fat and refined carbohydrates
66
Obesity is a consequence of what kind of diet?
unhealthy diet with excess fat and refined carbohydrates
67
How is appetitie controlled by the hypothalamus?
In the **hypothalamus** of the brain, there is a centre that is **responsible for making us feel satisfied when we have eaten enough food (satiated)**
68
What is the appetite control centre?
A centre in the hypothalamus of the brain that is responsible for making us feel satisfied when we have eaten enough food (satiated)
69
What hormones do the appetitie control centre recieve to reduce the desires to eat?
* **Hormone PYY3-36** secreted from the small intestine when it contains food
* **insulin** secreted by the pancreas when the blood glucose concentration is high
* **hormone leptin** secreted by adipose tissue when amounts of stored fat increases
70
What problems does the appetite control centre avoid?
**Heath problems** due to **overeating**, including **excessive blood glucose levels** and **obesity**
71
What are two examples of nutrition related diseases?
Diabetes and hypertension
72
What diseases involve excessive excretion of urine?
Several diseases, all of which are forms of diabetes
73
What is diabetes mellitus?
When sugar is present in the urine
* the commonest form of diabetes
74
What are two ways diabetes mellitus can develop?
* Auto-immune destruction of insulin-secreting cells in the pancreas (Type I diabetes)
* Decreased responsiveness of body cells to insulin due to "burn-out" (Type II diabetes)
75
What is the study of epidemology?
The study of the rates and distribution of a disease, to try to find its causes
76
What are the risk factors that the increased blood concentration of fatty acids in type II diabetes is linked to?
* Diets rich in fat and low in fibre
* obesity due to overeating and lack of exercise
* genetic factors which affect fat metabolism
77
What are the risk factors that the increased blood concentration of fatty acids in type II diabetes is linked to?
* Diets rich in fat and low in fibre
* obesity due to overeating and lack of exercise
* genetic factors which affect fat metabolism
78
What are the 3 main symptoms of diabetes mellitus?
* Elevated levels of blood glucose
* glucose in the urine - this can be detected by a simple test
* dehydration and thirst resulting form excretion of large volumes of urine
79
What other health problems relating to the cardiovascular system can diabetes cause?
* Atherosclerosis (narrowing of arteries by fatty deposits)
* Hypertension (raised blood pressure)
* Coronoary heart disease (narrowing of the coronary arteries with the associated risk of heart attacks)
80
What other health problems realting to the cardiovascular system can diabetes cause?
* Atherosclerosis (narrowing of arteries by fatty deposits)
* Hypertension (raised blood pressure)
* Coronoary heart disease (narrowing of the coronary arteries with the associated risk of heart attacks)
81
What is cholesterol?
a normal component of plasma membranes in human cells
82
Why does cholesterol have a bad reputation?
research shown. acorrelation between high levels of cholesterol in blood plasma and an increased risk of coronary heart disease
83
Why may the advice to minimize dietary cholesterol intake not lower risk of CHD?
* research show only cholesterol in LDL is implicated in CHD not cholesterol levels in blood
* reducing dietary cholesterol often has a very small effect on blood cholesterol levels, therefore presumably have little effect on CHD rates
* Liver can synthesize cholesterol so dietary cholesterol is not the only source
* genetic factors are more important than dietary intake and members of some families have high cholesterol levels even with low dietary intake
* Drugs can be more effective in reducing blood cholesterol levels than through change in diet
* there is positive correlation between dietary intake of saturated fats and intake of cholesterol, so possible that saturated fats, not cholesterol cause the increased risk of CHD in people with high cholesterol intake
84
How does fatty acids consumed as part of a diet influence the levels of cholesterol in the bloodstream?
Saturdated fatty acids increase LDL levels, raising blood cholesterol levels
85
How does high cholesterol levels in the bloodstream lead to the hardening and narrowing of arteries (atheroschlerosis) and CHD?
Cholesterol can build up in the arteries forming plaques narrowing the lumen and restricting blood flow - increases blood pressure
CHD - when atherosclerosis occurs in coronary arteries -> heart attack, stroke, death
86
What is the relationship between excessive weight gain and hypertension?
A clear correlation
87
How does weight gain affect hormones?
increase the release of several hormones
88
How does weight gain lead to hypertension by causing changes in body physiology and anatomy?
* Weight gain leads to higher cardiac (heart) output which can raise blood pressure
* Abdominal obesity can increase vascular resistance which can raise blood pressure
* weight gain is associated with arteries becoming stiffer and narrower which can raise blood pressure
89
How does high salt intake affect hypertension?
Circulating salt has an osmotic effect, increasing water in the blood vessels, raising blood pressure
90
In the absence of dietary intake of energy sources, what will the body first do?
1. access glycogen stores
91
If there are no glucose available in the body, what will it do?
the body will break down its own muscle tissues to utilize the resulting amino acids as energy sources
amino acids are sent to the liver to be converted to glucose
92
What does using amino acids for glucose result in?
Loss of muscle mass
93
What can be observed from a child suffering from marasmus?
Thin limbs
* indicates that muscle tissue has been broken down as an energy source by his body
94
What does the term anorexia mean?
Reduced appetite
95
What is anorexia nervosa?
A psychiatric illness
* involved in voluntary starvation and loss of body mass
96
What causes the loss of body mass in people with anorexia?
Voluntary starvation
* the amounts of carbohydrate and fat consumed are too small to satisfy the body's energy requirements, so protein and other chemicals in the body are broken down
97
What are the consequences of anorexia?
* wasting of muscles = loss of strength
* thinner hair and can drop out
* dry skin and bruise easily
* a fine growth of body hair tends to develop
* blood pressure is reduced
* slow heart rate and poor circulation - reduced heart output
* infertility with no ovulation or menstrual cycles
98
As body weight in a person with anorexia falls, what else other than skeletal muscles get digested?
Heart muscles deteriorates
99
How does skeletal muscle mass reduce relative to cardiac mass?
to some degree, the skeletal muscle mass reduces disproportionately faster than the cardiac mass
100
What may result in the deterioration of muscle fibre
Lack of protein, electrylytes and micronutrients
101
What does the lack of dietary intake alter?
It alters the elctrylyte balance i.e. concentrations of calcium, potassium and sodium
102
How does the deterioration of muscle fibres and altered electrolyte balance affect contractions?
Both skeletal muscle and cardiac muscle do not contract normally under these circumstances
103
What was used as a model organism for studying scurvy?
Guinea pig
104
What did Holst and Frolisch do?
1. They caused scurvy by feedin guinea pigs with whole grains
2. then cured them through dietary modification including feeding fresh cabbage and lemon juice
3. Studied the factors that led to scurvy and the preventive value of different substances
4. Substituted guinea pigs for pigeons
5. found that guinea pigs were among the very few mammals capable of showing scurvy-like symptoms while pigeons were shown later to make their own vitamin C and could not develop scurvy
105
What is PKU?
Phenylketonuria
* A genetic disease caused by mutations of a gene coding for the enzyme that converts phenylalanine into tyrosine
106
What does the mutated gene in PKU prevent?
prevent the enzyme (phenylalanine hydroxylase) coded by the alleles to catalyse the conversion reaction from phenylalanine into tyrosine
107
In which individuals does PKU only occur in?
individuals with two recessive mutant alleles
108
Why does PKU only affect individuals with two recessive mutant alleles?
* The mutation produces alleles of the gene that code for enzymes umable to catalyse the conversion reaction of phenylalanine into tyrosine
* only one normal allele is needed for satisfactory conversion so allele is dominant
109
What happens to phenylalanine and tyrosine concentrations in a person with PKU?
Phenylalanine accumulates in the body and there can be a deficiency in tyrosine
110
What happens to phenylalanine and tyrosine concentrations in a person with PKU?
Phenylalanine accumulates in the body and there can be a deficiency in tyrosine
111
What are the consequence of having high phenylalanine levels?
* Reduced growth of head and brain
* mental retardation of young children
* severe learning difficulties
* hyperactivity
* seizures in older children
* lack of skin and hair pigmentation
112
What are the consequence of having high phenylalanine levels?
* Reduced growth of head and brain
* mental retardation of young children
* severe learning difficulties
* hyperactivity
* seizures in older children
* lack of skin and hair pigmentation
113
Why are PKU babies unaffected at birth?
mother's metabolism has kept phenylalanine and tyrosine at normal levels
* gives opportunity for early diagnosis and treatment
114
What is the treatment of PKU?
Strict diet
* eating a diet low in phenylalanine for the rest of their life
* i.e. mean, fish, nuts, cheese, peas and beans can only be eaten in small quantities
* tyrosine suplements may be needed
115
What is vitamin D needed for and why are its deficiency symptoms similar to those of calcium?
Vit D is needed for calcium absorption from food in the intestines
* so symtoms of Vit D deficiency are similar to calciums
116
What are rickets?
* Deficiency in Vit D
* skeletal deformities
117
Why doesnt Vit D fit the definition of a vitamin very well?
It can be synthesized in the skin
118
Who are recommened to eat 10μg of Vit D per day to supplement the amount made in their skin?
Children, pregnant women and elderly people
119
What are the dietary sources of vitamin D?
* oily fishes i.e. herring, mackerel, sardines, tuna
* egg and liver
* margarine and milk are artificially fortified with vit D
120
What are the harmful consequence of ultraviolet light?
mutations that can lead to skin cancer
121
What does melanin in the skin do?
intercepts and aosorbs light including the ultraviolet wavelengths
122
How is dark skin benefitical or harmful in terms of cancer and vit D?
* good protection against cancer
* but reduce vit D synthesis
123
How to determine the energy content of a substance?
through calorimetry
124
What is the formual to calculate the energy content of a substance (Q)?
Specific heat capacity of water is 4.186J
