On exposure to cold, a neonate shows all of the following mechanisms except
Ans. a. Shivering On exposure to cold and wet environment, the neonate tries to generate heat by increased activity (crying with agitated movement) and a sympathetic surge that causes vasoconstriction and non-shivering thermogenesis in the brown fat. Babies attempt to conserve heat by peripheral vasoconstriction." "Brown fat is a well-vascularized, sympathetically innervated lipid collection located in the axillae, groin, nape of the neck, interscapular area and perinea! area. Cold stress causes the release of norepinephrine that uncouples beta-oxidation in fat with resultant heat generation. Preterm and small-for-gestational age infants have immature thermogenic response because of scanty brown fat stores." Role of Brown Fat in Thermogenesis A newborn baby is more prone to develop hypothermia because of large surface area per unit of body weight. In infants, brown fat is an impoant site of thermogenesis. It results in the so-called non-shivering thermogenesis. Brown fat is located around the adrenal glands, kidney, nape of neck, interscapular and axillary region. Metabolism of brown fat leads to heat production. Blood flowing through the brown fat becomes warm and through circulation, transfers heat to other pas of the body. This mechanism oh heat production is known as non-shivering thermogenesise.Q
Shivering
Crying and flexion of body like fetus position
Cutaneous vasoconstriction
Increased production of noradrenaline for breakdown of brown fat in adipose tissue