Q.Non-shivering thermogenesis in neonates produces heat through:

Brown and White Adipose Tissue

Fat is not just fat. The body stores it in two very different kinds of adipose tissue, and the contrast between them is a lovely example of how the same raw material (stored lipid) can be used for two opposite jobs — saving energy versus burning it to make heat.

White adipose tissue — the energy store

White adipose tissue (WAT) is the ordinary fat most people picture. Each cell holds a single large droplet of fat that pushes the nucleus and cytoplasm to one side. Its job is energy storage: it banks surplus energy as fat to be released when the body needs fuel. It also cushions organs and provides insulation. White fat cells contain relatively few mitochondria, because their role is to hold energy, not spend it.

Brown adipose tissue — the heat generator

Brown adipose tissue (BAT) looks and behaves very differently. Its cells contain many small fat droplets and a large number of mitochondria — and it is the mitochondria (rich in iron-containing pigments) that give the tissue its brown colour. Its purpose is heat production (thermogenesis). …