Flashcards in 2: Lipids and Health Deck (20):
What two types of molecule are used as stores of energy in living organisms?
- lipids (fats or oils)
- carbohydrates (glycogen or starch)
What energy source do the seeds of plants contain?
starch or oil
How do humans store energy?
- as glycogen in liver or muscle cells
- as fat in adipose tissue
What are the advantages of using lipids rather than carbohydrates for long-term energy storage?
- amount of energy released in cell respiration per gram of lipids is DOUBLE the amount released from a gram of carbohydrates
- therefore: the SAME amount of energy stored as a lipid adds HALF as much to body mass
- in fact: mass advantages of lipids is even greater because fats form pure droplets in cells with no water associated, whereas each gram of glycogen is associated with about 2 grams of water
- therefore: lipids are actually 6 times more efficient in the amount of energy that can be stored per gram of body mass
This is an advantage because: we have to carry energy stores around with us wherever we go. It is even more important for flying creatures.
Is it possible to asses whether a person's body mass is at a healthy level by weighing them?
What is used to assess whether a person's body mass is at a healthy level? What are the units of this measurement?
What does BMI stand for? What is the formula for BMI?
- body mass index
BMI = mass (kg)/ (height (m))^2
What are the possible conclusions you can draw from the BMI formula or nomogram (BMI chart thing)?
- normal weight
According to the BMI formula, when would a person be said to be underweight?
Under 18.5 kg/m^2
According to a BMI chart, when would a person be said to be normal weight?
18.5 - 24.9 kg/m^2
According to a BMI chart, when would a person be said to be overweight?
24.9 - 29.9 kg/m^2
According to a BMI chart, when would a person be said to be obese?
Without using the formula, how else could you work out someone's BMI?
using a nomogram
What should you use when using a nomogram?
- a ruler
- the nomogram itself
How are transfats produced?
mostly artificially produced
Why are transfats banned in some countries?
- there is a positive correlation between amounts of transfats consumed and rates of coronary heart disease (CHD)
Can we be sure that transfats cause coronary heart disease (CHD)?
- other risk factors have been tested to see if they can account for the correlation but the do not
- trans-fats therefore probably do cause CHD
- in patients who have died from CHD, fatty deposits have been found to contain high concentration of trans-fats = more evidence of a causal link
Where can saturated fatty acids be found?
in animal fats and vegetable oils
What is the relationship between saturated fats and coronary heart disease (CHD)?
- positive correlation between saturated fatty acid intake and rates of CHD in many research programs
- BUT some populations do not fit correlation: e.g Maasai tribe of Kenya have diet of foods rich in saturated fats yet CHD is very rare
- it is possible that the actual cause of CHD is not saturated fat itself, but another factor correlated with saturated fat intake, such as low amounts of dietary fibre