D.1 Human nutrition

Question 1

Define ‘nutrient’.

Answer 1

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

Question 2

What are the six classes of nutrients?

Answer 2

carbohydrates
proteins 
lipids
vitamins (A, C, D, K)
minerals (phosphorus, calcium, magnesium, iron)
water

Question 3

What is meant by ‘essential’ in terms of nutrients?

Answer 3

the body is incapable of synthesising these molecules so foods are the only possible source of the nutrient

Question 4

What is meant by ‘non-essential’ in terms of nutrients?

Answer 4

another nutrient can be used for the same purpose/ they can be made in the body from another nutrient

Question 5

What are some examples of essential nutrients in the diet?

Answer 5

amino acids
some unsaturated fatty acids
some minerals 
calcium
vitamins 
water

Question 6

What are some examples of non-essential nutrients in the diet?

Answer 6

glucose, starch and other carbohydrates

Question 7

What are ‘minerals’?

Answer 7

the inorganic substances that living organisms need for a variety of purposes

Question 8

What are minerals needed for?

Answer 8

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

Question 9

What are the consequences of mineral deficiency?

Answer 9

deficiency diseases -> impairs growth, mental development, brain damage

Question 10

What are ‘vitamins’?

Answer 10

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.

Question 11

What are vitamins needed for?

Answer 11

co-factors for enzymes, anti-oxidants and hormones

Question 12

Examples of vitamins and their traits

Answer 12

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

Question 13

What range amino acids are essential in humans?

Answer 13

about half of the 20 amino acids in proteins are essential whilst others can be made from simpler nitrogen compounds

Question 14

Examples of essential amino acids

Answer 14

Histidine, 
Isoleucine, 
Leucine, 
Lysine, 
Methionine, 
Phenylalanine, 
Tryptophan, 
Valine, 
Threonine (only if phenylalanine is not in diet), 
Arginine (required in the diet of infants)

Question 15

Examples of essential fatty acids

Answer 15

some omega-3 and omega-6 fatty acids

Question 16

What is ‘protein deficiency malnutrition’ and what causes it?

Answer 16

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

Question 17

What are the consequences of ‘protein deficiency malnutrition’?

Answer 17

• 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

Question 18

What is ‘malnutrition’?

Answer 18

Malnutrition may be caused by a deficiency, imbalance, or excess of nutrients in the diet.

Question 19

What are the consequences of malnutrition?

Answer 19

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

Question 20

How is appetite controlled?

Answer 20

Appetite is controlled by a centre in the hypothalamus.

Question 21

What is the ‘appetite control centre’?

Answer 21

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).

Question 22

How does the appetite control centre work?

Answer 22

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

Question 23

What are the consequences of being overweight?

Answer 23

overweight individuals are more likely to suffer hypertension and type II diabetes.