Flashcards in Lipids 5 Deck (12):
What is the key physiological role of brown adipose tissue?
Maintenance of core body temperature
What is shivering thermogenesis?
Involuntary muscle contraction
Elevates heat production in cold climates
In adult humans it can reach intensities equivalent to 40% of maximum oxygen consumption and involve the oxidation of mainly lipids and carbohydrates
What is brown adipose tissue?
A thermogenic tissue
Where was BAT first discovered?
Main function of BAT?
Heat production when activated by cold exposure (cold exposure results in massive blood flow increases to rodent brown adipose tissue)
What is white adipose tissue like?
Low in mitochondria
Fat sits in lipid vesicles
What's brown adipose tissue like?
Lots of little lipid vesicles
What is the proton circuit?
UCP1 causes a proton leak across the inner membrane of the mitochondria, thereby dissipating chemical energy in the form of heat
Brown fat adipocytes are energy inefficient for ATP production but energy efficient for...
What carries protons across membranes like UCPI?
DNP; 2,4 dinitrophenol
What activates BAT?
1. Stimulation of B-adrenergic receptors by norepinephrine (increases levels of cAMP)
2. Stimulation of deiodinase enzyme (D2)- converts thyroid pro hormone (thyroxine T4)
3. T3 stimulates expression of UCP-1 (increases UCPI; uncoupling of mito-respiration, loss of energy as heat; activation leads to increased uptake of substrate)