Option D.1: Human physiology – Human nutrition
A balanced diet is essential to human health.
• Understanding: Essential nutrients cannot be synthesized by the body, therefore they have to be included in the diet.
Nutrient: chemical substance found in foods and used in the human body
Essential nutrient: nutrient that must be obtained from food (included in diet) as it cannot be synthesized by the body
Example: water, some amino acids, some fatty acids, vitamins and minerals
• Understanding: Dietary minerals are essential chemical elements.
Dietary mineral: essential chemical elements (often in ion form) that must be included in diet for use in human body
Example: sodium, potassium, calcium, iron
• Understanding: Vitamins are chemically diverse carbon compounds that cannot be synthesized by the body
Vitamins: chemical diverse carbon compounds that cannot be synthesized by the body
Water soluble vitamin: C, B (B1, B2, B3, B5, B6, B7, B9, B12)
Fat soluble vitamin: A, D, E, K
• Understanding: Some fatty acids and some amino acids are essential.
Essential fatty acids: omega-3 and omega-6 fatty acids
Essential amino acids: less than half (around 9) of the amino acids
• Understanding: Lack of essential amino acids affects the production of proteins.
Protein deficiency: low consumption of essential amino acids hinder protein production
Consequences of protein deficiency
Not enough proteins in blood causes fluid not to be returned
Fluid accumulate in tissues causing swollen abdomens (kwashiorkor)
• Understanding: Malnutrition may be caused by a deficiency, imbalance or excess of nutrients in the diet.
Malnutrition: caused by a deficiency, imbalance or excess of nutrients in diet
• Understanding: Appetite is controlled by a centre in the hypothalamus.
Control of appetite in human in hypothalamus
Leptin: produced by and secreted from adipose tissues when there is a large fat deposit
Insulin: produced by and secreted from the pancreas when there is high blood glucose level
PYY3-36: produced by and secreted from the small intestine when it contains food
• Understanding: Overweight individuals are more likely to suffer hypertension and type II diabetes.
Overweight individuals with diabetes
Type II diabetes: caused by body cells not being able to response to insulin
Overweight individuals are likely to have a high fat or sugar intake
High sugar intake result in high glucose level causing diabetes
Overweight individuals with hypertension
Hypertension: high blood pressure in the blood vessels of the body
High body mass from overweight individuals cause the cardiac output to increase
Abdomen obesity can increase vascular resistance
• Understanding: Starvation can lead to breakdown of body tissue.
Starvation: lack of nutrient intake by the body
Body first depletes the glycogen storage, then begin to break down muscle tissues to be converted into glucose
Body tissues are continually broken down as an energy source during starvation
• Application: Production of ascorbic acid by some mammals, but not others that need a dietary supply.
Ascorbic acid: also known as vitamin C, that is used in the production of collagen fibres and as anti-oxidant
Production of vitamin C: ascorbic acid can be produced by some mammals but not in others (i.e. humans, guinea pigs)
Need as dietary supply: the GLO gene in synthesising ascorbic acid can be mutated in various evolutionary history
Rebound nutrient: in high vitamin C intake, body adjust to high levels and large excretion that is maintained even
after intake levels have dropped, resulting in a loss in availability of body
• Application: Cause and treatment of phenylketonuria (PKU).
Phenylketonuria (PKU): disease that causes a build-up of phenylalanine in the body causing reduced head and brain growth
Cause of phenylketonuria: phenylalanine hydroxylase that breaks phenylalanine to tyrosine is not produced
A balanced diet is essential to human health.
• Understanding: Essential nutrients cannot be synthesized by the body, therefore they have to be included in the diet.
Nutrient: chemical substance found in foods and used in the human body
Essential nutrient: nutrient that must be obtained from food (included in diet) as it cannot be synthesized by the body
Example: water, some amino acids, some fatty acids, vitamins and minerals
• Understanding: Dietary minerals are essential chemical elements.
Dietary mineral: essential chemical elements (often in ion form) that must be included in diet for use in human body
Example: sodium, potassium, calcium, iron
• Understanding: Vitamins are chemically diverse carbon compounds that cannot be synthesized by the body
Vitamins: chemical diverse carbon compounds that cannot be synthesized by the body
Water soluble vitamin: C, B (B1, B2, B3, B5, B6, B7, B9, B12)
Fat soluble vitamin: A, D, E, K
• Understanding: Some fatty acids and some amino acids are essential.
Essential fatty acids: omega-3 and omega-6 fatty acids
Essential amino acids: less than half (around 9) of the amino acids
• Understanding: Lack of essential amino acids affects the production of proteins.
Protein deficiency: low consumption of essential amino acids hinder protein production
Consequences of protein deficiency
Not enough proteins in blood causes fluid not to be returned
Fluid accumulate in tissues causing swollen abdomens (kwashiorkor)
• Understanding: Malnutrition may be caused by a deficiency, imbalance or excess of nutrients in the diet.
Malnutrition: caused by a deficiency, imbalance or excess of nutrients in diet
• Understanding: Appetite is controlled by a centre in the hypothalamus.
Control of appetite in human in hypothalamus
Leptin: produced by and secreted from adipose tissues when there is a large fat deposit
Insulin: produced by and secreted from the pancreas when there is high blood glucose level
PYY3-36: produced by and secreted from the small intestine when it contains food
• Understanding: Overweight individuals are more likely to suffer hypertension and type II diabetes.
Overweight individuals with diabetes
Type II diabetes: caused by body cells not being able to response to insulin
Overweight individuals are likely to have a high fat or sugar intake
High sugar intake result in high glucose level causing diabetes
Overweight individuals with hypertension
Hypertension: high blood pressure in the blood vessels of the body
High body mass from overweight individuals cause the cardiac output to increase
Abdomen obesity can increase vascular resistance
• Understanding: Starvation can lead to breakdown of body tissue.
Starvation: lack of nutrient intake by the body
Body first depletes the glycogen storage, then begin to break down muscle tissues to be converted into glucose
Body tissues are continually broken down as an energy source during starvation
• Application: Production of ascorbic acid by some mammals, but not others that need a dietary supply.
Ascorbic acid: also known as vitamin C, that is used in the production of collagen fibres and as anti-oxidant
Production of vitamin C: ascorbic acid can be produced by some mammals but not in others (i.e. humans, guinea pigs)
Need as dietary supply: the GLO gene in synthesising ascorbic acid can be mutated in various evolutionary history
Rebound nutrient: in high vitamin C intake, body adjust to high levels and large excretion that is maintained even
after intake levels have dropped, resulting in a loss in availability of body
• Application: Cause and treatment of phenylketonuria (PKU).
Phenylketonuria (PKU): disease that causes a build-up of phenylalanine in the body causing reduced head and brain growth
Cause of phenylketonuria: phenylalanine hydroxylase that breaks phenylalanine to tyrosine is not produced
