ADIPOSE TISSUE - TWO TYPES

1. WHITE ADIPOSE TISSUE - STORE ENERGY
2. BROWN ADIPOSE TISSUE - GENERATION OF HEAT

• PROTEIN IN THE MITOCHONDRIA OF THE BROWN TISSUE THERMOGENIN (also called UNCOUPLING PROTEIN) THE UNCOUPLING OF PROTON FLOW RELEASES THE ENERGY OF THE ELECTROCHEMICAL GRADIENT OF THE PROTON AS HEAT
• THE BROWN TISSUE PROVIDE THE NONSHIVERING THERMOGENISIS
• NONSHIVERING THERMOGENISIS → HORMONAL STIMULUS PRODUCING HEAT WITHOUT THE ASSOCIATION OF MUSCLES OF SHIVERING
• THERMOGENISIS START BY RELEASE OF FREE FATTY ACID FROM TRIGLYCERIDE (ADIPOCYTE STORAGE)

• THE BROWN ADIPOSE TISSUE SHOWS THE UNCOUPLED PROTEIN EXPRESSION.THE MITOCHONDRIA IN THE BROWN ADIPOSE TISSUE CONTAIN THE PROTEIN CALLED THERMOGENIN
• WHEN THE NOREPINEPHRINE IS RELEASED IN RESPONSE TO COLD SENSATIONS BIND TO THE ADRENERGIC RECEPTOR ON THE SURFACE OF THE BROWN
• ADIPOCYTE TRIGGER THE ACTIVATION OF THE cAMP AND FURTHER ACTIVATION OF THE cAMP PROTEIN DEPENDENT KINASE
• THIS RESULTS IN THE PHOSPHORYLATION AND HORMONE SENSITIVE LIPASE
• THE FREE FATTY ACID RELEASED BIND TO THERMOGENIN TRIGGERING THE DISSIPATION OF THE PROTON GRADIENT
• THUS , THE PHOSPHORYLATION IS UNCOUPLED FROM OXIDATION LEADING TO THE RELEASE OF ENERGY AS HEAT

OR

• Brown adipose tissue produces heat by uncoupling proton flow, releasing the energy of the electrochemical proton gradient as heat (a normal physiological

function). Its brown color is due to a high density of mitochondria in adipose cells, which contain thermogenin.

• Thermogenin increases proton permeability of the inner mitochondrial membrane, dissipates the proton gradient, and uncouples oxidation from phosphorylation,

releasing energy as heat.