D.1 Human nutrition Flashcards
Define ‘nutrient’.
Nutrient is a chemical substance found in foods that is used in the human body
What are the six classes of nutrients?
carbohydrates proteins lipids vitamins (A, C, D, K) minerals (phosphorus, calcium, magnesium, iron) water
What is meant by ‘essential’ in terms of nutrients?
the body is incapable of synthesising these molecules so foods are the only possible source of the nutrient
What is meant by ‘non-essential’ in terms of nutrients?
another nutrient can be used for the same purpose/ they can be made in the body from another nutrient
What are some examples of essential nutrients in the diet?
amino acids some unsaturated fatty acids some minerals calcium vitamins water
What are some examples of non-essential nutrients in the diet?
glucose, starch and other carbohydrates
What are ‘minerals’?
the inorganic substances that living organisms need for a variety of purposes
What are minerals needed for?
The bones within our bodies require constant repair, requiring small amounts of calcium for that repair
-> Females need more iron in their diet than males because the blood lost during menstruation leads to a loss of iron
What are the consequences of mineral deficiency?
deficiency diseases -> impairs growth, mental development, brain damage
What are ‘vitamins’?
chemically diverse carbon compounds that
cannot be synthesized by the body.
-> organic compounds that are needed in very small amounts because they cannot be synthesized by the body but must be obtained from the diet.
What are vitamins needed for?
co-factors for enzymes, anti-oxidants and hormones
Examples of vitamins and their traits
Vitamin C: derived from a monosaccharide
Vitamin A is hydrophobic and contains a hydrocarbon ring and chain
Vitamin B2 contains nitrogen rings and is readily converted to the nucleotide FMN
What range amino acids are essential in humans?
about half of the 20 amino acids in proteins are essential whilst others can be made from simpler nitrogen compounds
Examples of essential amino acids
Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Tryptophan, Valine, Threonine (only if phenylalanine is not in diet), Arginine (required in the diet of infants)
Examples of essential fatty acids
some omega-3 and omega-6 fatty acids
What is ‘protein deficiency malnutrition’ and what causes it?
there is a shortage of one or more essential amino acids in the diet then the body cannot make enough of the proteins that it needs
–> Essential amino acids may be lacking due to an overall insufficiency of protein in the diet/ to an imbalance in the types of protein
What are the consequences of ‘protein deficiency malnutrition’?
- lack of blood plasma proteins -> fluid is retained in tissues
- child development may be both mentally + physically retarded, with stunted growth + developmental disabilities
- adults may go through serious weight loss
What is ‘malnutrition’?
Malnutrition may be caused by a deficiency, imbalance, or excess of nutrients in the diet.
What are the consequences of malnutrition?
Starvation is a consequence of a diet lacking in adequate protein and carbohydrates
Obesity is observed as a consequence of unhealthy diets with excess fat and refined carbohydrates
How is appetite controlled?
Appetite is controlled by a centre in the hypothalamus.
What is the ‘appetite control centre’?
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).
How does the appetite control centre work?
Adipose tissue secretes leptin when amounts of stored fat increase , small intestine secretes PYY3-36 when it contains food, pancreas secretes insulin when the blood glucose concentration is high -> all these hormones received by the appetite control centre -> reduces the desire to eat
What are the consequences of being overweight?
overweight individuals are more likely to suffer hypertension and type II diabetes.
