Lecture 4 - Fats Flashcards
What makes up a triglyceride molecule?
3 fatty acids + 1 glycerol
Key information about triglycerides?
- Largest energy store in the body
- Only macronutrient we can store indefinitely
- Major storage form of fats in the body
What reaction forms a triglyceride?
Esterification reaction
- Removal of a water molecule to form a bond, to have fatty acids attached to the glycerol
How do we classify different length fatty acids
Carbon chain length
SCFA - <4
MCFA - 6-12
LCFA - >14
Difference between long and small chain fatty acids
Longer the chain length the more solid and less liquid the fatty acid becomes at room temperature
State the difference between saturated and unsaturated fatty acids
Saturated:
- All carbons have a hydrogen bond
- Stimulate in the liver to form cholesterol (seen as ‘bad’ fat)
Unsaturated:
- There is a double carbon bond replacing a hydrogen bond
What are ‘trans fatty acids’?
- Umbrella term for anything modified by high heat and light
- Switching in atomic structure of hydrogen bonds
What is the omega number of an essential fatty acid?
- Refers to where the fatty acid becomes unsaturated
- ‘Omega 9’ for example means the double bond (where the fatty acid becomes unsaturated) is 9 carbons from the omega end
What does a higher n-3 compared to n-6 produced
Less inflammatory mediators produced
Explain about adipose tissue
- Most lipids are stored as adipose tissue
- Generally have more than 8-10KG of adipose tissue
- Not simply a fuel store but also a signalling tissue
- Too much has a negative effect on metabolism
Where is the majority of fat oxidised during exercise?
Muscle cells
Explain intramuscular triglycerides
- Available in the muscle
- Most immediate energy source with respect to lipids
Why are intramuscular triglycerides the most immediate energy source with respect to lipids?
- Lipids are stored in the myofibril spaces - very closed proximity to the mitochondria
- The lipid has to be oxidised in the mitochondria
- Meaning this process can happen quickly
- in obese/type II diabetes patients, these lipids are not available and therefore not used
How much energy can we store as fat and CHO
- CHO = 8,000KJ
- Fat = 450, 000KJ
Why is it important to tap into fat stores during exercise?
Can delay depletion of carbohydrate stores in the body and therefore exercise for longer
Why do both trained and obese individuals have similar amounts of IMTG, but trained individuals use it better?
In trained individuals, the IMTG are located next to the mitochondria, where they are oxidised. In obese individuals, the IMTG is located all over the muscle cell, therefore not easily oxidised
How much energy is stored as fat?
415, 000 KJ - 12KG
At what point do we start to use more CHO than fat?
65% VO2max
Why, at higher intensities do we use more CHO than fat?
CHO is a more efficient fuel due to less oxygen needed, therefore more convenient to use at high intensities
Plasma free fatty acid is increased by? Tick all the appropriate answer.
A. Decreased adipose tissue blood flow
B. Increased lipoprotein lipase activity
C. Increase hormone sensitive lipase activity
D. Insulin
B and C
Name 2 limitation of fat oxidation during exercise.
Adipose tissue oxidation
Uptake into muscles
What can increased fat intake do to glycogen stores?
Increased fat intake generally comes at a cost of CHO, therefore decreased muscle glycogen stores
How does depleted IMTG stores effect performance?
Depleted IMTG stores due to low fat decreases performance
How does high fat intake effect performance and why?
Generally shown to decrease performance
- Reduced glycogen stores and reduced efficiency of CHO in high intensity exercise
