Chapter 7- Human Nutrition Flashcards
What are examples of some essential nutrients?
Amino acids Unsaturated fatty acids Minerals Calcium Vitamins Water
Why are some nutrients essential and some non-essential
The nutrients that are non essential, another nutrient can be used for the same purpose or because they can be made in the body from another nutrient - essentials can’t
Examples of no -essential nutrients?
Glucose
Starch
Carbohydrates
What is an example of conditionally essential nutrients
Vitamin K is produced by the metabolism of symbiotic bacteria in the intestine- infants don’t have colonies of this bacteria so at birth they are given supplementary injections
What is vitamin C what does it do
Is a compound called ascorbic acid- needed for the synthesis of the collagen fibres that form
Part of the tissue in the body- most plants and animals can synthesis vitamin c in the body
Why in some animals do it they not produce vitamin C?
Due to mutations that led to genes no longer producing the protein necessary to make vitamin C- due to mutation in the GLO gene which codes for the production of the enzyme l-guluno- lactone oxidase
Examples of mammals that cannot produce Vitamin C
Fish- Ray-finned-cod, salmon, herring
Humans
Chimpanzees
Apes
What can be the cause of a lack of vitamin C
Scurvy
Why are some amino acids essential in the body?
-of the 20 amino acids only half are that essential because they cannot be synthesized in sufficient quantities- other half can be made from nitrogen compounds
Example of essential amino acids in body
1) threonine and arginine are conditionally essential
Threonine can be synthesized if phenalanine is present
Arginine is produced by healthy living individuals
Example of essential fatty acids?
Omega-3
Omega-6
They cannot be synthesized in the body
Name 3 essential amino acids
Threonine
Arginine
Lysine
Valine
What does a lack of essential amino acids affect?
The production of proteins
What is a lack of essential amino acids that affects the production of protein called?
Protein deficiency malnutrition
Why may essential amino acids by lacking?
Due to overall insufficiency of protein in the diet or to an imbalance in the types of protein
Consequences of protein deficiency malnutrition?
Causes a lack of blood plasma proteins which results in fluid being retained in tissues - causes swelling
Child development may be mentally and physically retarded with stunted growth and development disabilities
Adults may undergo serious weight loss
How much minerals are needed on the diet?
Relatively small quantities
What are minerals
Chemical elements
Example of mineral deficiency
Iodine- needed by thyroid gland to produced thyroxin - this stimulates the metabolic rate- lack of iodine squads IDD (iodine deficiency disorder)
- pregnant lady may be born with brain damage, mental development and intelligence are impaired
What are vitamins
Chemically diverse carbon compounds that cannot be synthesises by the body
What do vitamins do?
Serve a variety of roles such as co factors for enzymes, anti-oxidants and hormones
What is malnutrition caused by?
Is the outcome of a bad diet- could be a deficiency , imbalance or exceeds of nutrients in the diet
What is starvation ?
Is a consequence of a diet lacking in adequate protein and carbohydrates
Where is appetite controlled from?
Hypothalamus of the brain- appetite control centre
What hormones do the appetite control centre receive to reduce the desire to eat?
Small intestine secrets PYY3-36 when it contains food
Pancreas secreted insulin when blood glucose level is high
Adipose tissues secrets leptin when amounts of fat stored increases
What are the two main consequences of obesity?
Hypertension and type II diabetes
What is diabetes mellitus?
Sugar is present in the urine
Can be developed 2 Ways-
1) auto immune destruction of insulin secreting cells
2) decreased responsiveness of body cells to insulin due to ‘burn out’
Type II diabetes have increased blood concentrations of fatty acids - linked to following risk factor ?
Diets rich in fat and low in fibre
Obesity due to overeating and lack of excercise
Genetic factors which affect fat metabolism
What are the symptoms of diabetes II
Elevated levels of blood glucose
Glucose in urine
Dehydration and thirst resulting from excretion of large volumes of urine
What are the results of diabetes if not treated?
Atherosclerosis (narrowing of arteries by fatty deposits)
Hypertension (raised blood pressure)
Coronary heart disease
What is there a correlation between with excessive weight gain.
And hypertension
What can lead to hypertension?
Weigh gain leads to higher cardiac output which can raise blood pressure
Abdominal obesity can increase vascular resistance which can raise blood pressure
Weigh gain is associated with arteries becoming stiffer and narrower
Can be caused from high salt intake
How does starvation lead to the breakdown of body tissue?
In absence of dietary intake of energy sources the body will first access glycogen stores- if no glucose it will break down its own muscle tissue to utilise the resulting amino acids as an energy storage - amino acids are sent to liver where they are converted to glucose- results in loss of muscle mass
Why does anorexia occur
Amounts of carbohydrates and fat consumed are too small to satisfy the body’s energy requirements, so protein and other chemicals on body are broken down
What happens in anorexia
Skin becomes dry and bruises easily
Fine growth of hair tends to develop
Blood pressure is reduced
Infertility
What happens when the body weight in a person with anorexia fall?
Skeletal muscle is digested
Heart muscle deteriorates
Evidence of scurvy not just being specific to humans
Holst and frolisch- produced papers by causing scurvy in Guinea pigs
Had been a lucky substituting Guinea pigs for pigeons as pigeons make there own vitamin c
Causes of phneylketonuria (PKU)
Is a genetic disease
Caused by mutation of a gene coding for enzyme that converts phenylaline into tyrosine
Mutation produces alleles of the gene that cannot catalase the conversion reaction
Symptoms of PKU only show in those who have the two recessive genes
Consequences of PKu
High phenylaline levels cause reduced growth of head and brain with mental retardation of young children and severe learning difficulties
Seizures
Lack of skin and hair pigmentation
Why are PKU babies unaffected at birth?
Mothers metabolism has kept phyenylalanine and tyrosine levels normal- doctors can diagnose it there as the phyenylalanine levels rise- give supplements and different diet- fatal consequences can be avoided
What can lack of vitamin D cause?
Affect bone minerlizaration and rickets or oseomalacia
Why is vitamin D special?
Can be synthesized in the skin when sunlight or another source strikes the skin - if teenagers or adults spend enough time outside they don’t need vitamin D in the diet
Children and elderly peeps told to eat vitamin D in diet - oily fishes, eggs and liver
What is there a correlation between in high levels of cholesterol and what?
High levels of cholesterol in blood plasma and an increased risk of coronary heart disease
3 reasons why advice given to minimise dietary heart diseases wil not certainly Lower the risk of coronary heart disease
1) reducing dietary cholesterol often has small effects on blood cholesterol levels so presumably has little effect on CHD rates
2) the liver can synthesis cholesterol so It is not the only source
3) genetic factors are more important than dietary intake and members of some families have high cholesterol levels even with low dietary intake
What can essential nutrients not be synthesized by?
The body- therefore have to be included in the diet
