L17 - energy release from fat Flashcards
uses of lipids
membranes hormone precursors (cholesterol) long term fuels (TGs)
describe the process of TG breakdown
- TG lipase breaksdown TG to DG and one FA is released
- DG lipase removes anther FA
- MG lipase removes final FA leaving glycerol
what activates lipase?
adrenaline
glucagon
what happens to FA from broken down TGs
enter blood plasma and bind to albumin
go to tissues in need (muscle/heart/liver)
what happens to glycerol from broken down TGs
diffuses in bloodstream to tissues for conversion to pyruvate in glycolysis then enters TCA cycle
what happens to glycerol from broken down TGs in liver during starvation
enters glycolysis pathway but is converted from pyruvate to glucose (gluconeogenesis)
by what method is fatty acyl CoA transported into mitochondria
carnitine shuttle
overall what happens during B oxidation
fatty-acyl-CoA is broken down to FA which is 2C shorter + acetyl CoA
how many
NADH
FADH2
are produced from 1x B oxidation
1 of each
how is fat metabolism regulated
- release of FA from adipose tissue (adrenaline and glucagon - TG lipase)
- rate of entry into M matrix (carnitine shuttle)
- rate of reoxidation of NADH and FADH2 (ETC)
what happens to odd numbered FAs during B oxidation?
they end in C3 which cant be split further so they’re converted to succinyl CoA (by adding CO2) which enters TCA cycle
when does ketogenesis occur?
when fat metabolism is main source of energy
(in starvation / type 1 diabetes
how are ketone bodies formed?
- FA oxidation in liver = increase in [Acetyl CoA] which exceeds TCA capacity
- excess Acetyl CoA converted to ketone bodies in liver
name the 2 ketone bodies
Acetoacetate
B hydroxybutyrate
what can/cant liver use as sources of energy
yes - FA / glucose
no - ketone bodies
