Wk 3 Fats Flashcards
Dietary fat classifications (3)
FA/triglycerides (95%)
Phospholipids eg lecithin
Sterols eg cholesterol
Types of unsaturated fat w/ examples
- Trans fats - partially hydrogenated oils
- Polyunsaturated fats - soybean oil; EPA/DHA
- Monounsaturated fats - nuts, avocado
Dietary fat - importance:
dense source of energy/cals, rich source of vitamins A D E K, provide essential fats - omega 3 and 6, makes food palatable.
Body fat - functions:
source of energy, insulate against heat loss, keep skin and other tissues soft and pliable, organ protection, structural; cell membranes, steroid hormones eg test, nerve insulation (myelin) - efficient transmission of nerve impulses. Protects against infection in skin and cushioning for organs by protecting from impact. Role in cell membrane synthesis.
What is white fat and brown fat?
white fat is adipose tissue around organs, stores energy, brown fat is used for insulation - esp in babies?
Fat can be stored in muscle as _
Triglyceride
Fat storage sites:
adipose tissue triglycerides (TAG), intramuscular triglyceride (IMTG), plasma triglyceride
What might limit the use of fat as a fuel?
Lipolysis
Removal of FAs from the fat cell and transport
Transport of FAs into the muscle cell
Transport of FAs into the mitochondria
Lipolysis =
breakdown of triglyceride to 3 fatty acids and glycerol
Lipolysis is regulated by _ which are stimulated by incr hormones eg _, _, _ and decr by _.
Lipolysis is regulated by lipases which are stimulated by incr hormones eg epinephrine, glucagon, cortisol and decr by insulin.
removal of FAs from the adipocyte into the bloodstream depends on…
the albumin concentration in the blood, number of free binding sites for FAs on albumin, blood flow to the adipose tissue.
Transport of FAs into the muscle cell increases linearly with increased _ _, regulated by _ proteins eg _/, _
Transport of FAs into the muscle cell increases linearly with increased blood concentration, regulated by carrier proteins eg fat/CD36, FABP
Transport of FAs into the mitochondria involves _ and _ of __ and the carrier _
Transport of FAs into the mitochondria involves degradation and synthesis of fatty acids and the carrier carnitine
Beta-oxidation =
Breakdown of fatty acids into acetyl Co-A by removing two carbons from the carbon chain
When are ketone bodies released?
When there is too little oxaloacetate to combine with Acetyl CoA, and there is excessive buildup of Acetyl CoA
Re-esterification =
rejoining of fatty acids to molecule chain
Crossover =
point at which breakdown of FAs cant keep up w exercise demands.
Fuel contribution during exercise - at 65% and 85% VO2max:
As incr intensity, like 65 vo2max, glycogen starts to increase and almost dominate as fuel source. Above 85 vo2max, muscle glycogen and blood glucose dominates. Plasma FA contribution decreases at very high fitness levels, but oxidation is more efficient.
types of ketones:
acetoacetate, B-hydroxybutyrate, acetone
Ketones are produced in the ___ in response to ___ or _____
Produced in the liver in response to starvation/very low CHO intake.
Typical ketone level is..
<0.5mmol/L.
Ketoacidosis can only be entered by ___
diabetics
Inability to slow production of ketone bodies leads to…
Diabetic coma caused by keotacidosis
Fat intake recommendations:
- 10% saturated FAs, avoid trans fats.
- Fat intake should not drop below 0.5g/kg body mass or 20% of total energy intake. - Total fat 20-35% of calories.
Exercise increases fat ___
oxidation
_____ switches off fat oxidation
carb feeding
Exercise leads to increased ____ and _____
icnr rate of lipolysis and incr FA release from adipose tissue.
After 1 hr of moderate exercise, plasma FAs may reach ___
1 mmol/L.
