B1 Cell Biology

Human Health and Diet

Overweight or Underweight

A BMI of more than 30 means the person is obese, 25-30 is overweight, 20-25 is normal, less than 20 is underweight

To work out if a person is overweight or underweight you calculate their body mass index (BMI)

BMI = mass in kg / (height in m)2

Example: Tom W is 170cm tall and has a mass of 80kg. 170cm = 1.7m. BMI=80/1.7 squared = 27.7. Unfortunately Tom seems to be fat.

Some people may become ill as they choose to eat less than they need. This may be caused by low self-esteem, poor self-image or a desire for what they think is perfection.

Protein Intake

Proteins are needed for growth and so it is important to eat the correct amount

Plant proteins are called second-class proteins as they do not contain all the essential amino acids

This called the estimate average daily requirement (EAR)

It can be calculated using the formula: EAR in = 0.6 x body mass in kg

This may be affected by body mass, age, pregnancy or breast-feeding

Proteins from meat and fish are called first-class proteins

This is because they contain all the essential amino acids that cannot be made by the human body

Staying Healthy

Malaria

Malaria is caused by a protozoan called Plasmodium which feeds on human red blood cells

Plasmodium is carried by mosquitoes, which are called vectors.

Vectors are not affected by the disease they carry

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It is then transmitted from the vector to humans vie mosquito bites

Pathogens (disease causing organisms) produce the symptoms of an infectious disease by damaging the body's cells or producing waste products called toxins