Lecture notes chapter 40

Behavioral moving to a location that is warmercooler

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Unformatted text preview: od in veins approaches the center of the body, it is almost as warm as the body core Result: countercurrent heat exchange minimizes heat loss as a result of supplying blood to body parts immersed in cold water Cooling by Evapora2ve Heat Loss: If environmental temperatures are above body temperatures, animals gain heat from the environment as well as metabolism * evaporation in these cases is the only way to keep body temperature from raising rapidly Many terrestrial animals have sweat glands controlled by the nervous system that enhances evaporaCve cooling Dog’s pant to enhance evaporaCve cooling Sweat glands at work Behavioral: moving to a location that is warmer/cooler; social behavior- huddling AdjusBng Metabolic Heat ProducBon: Shivering thermogenesis: muscle activity produces heat Nonshivering thermogenesis: •  Thyroid hormone and norepinephrine can sCmulate the mitochondria to increase their metabolic acCvity and produce heat rather than ATP •  Many animals (including humans) contain brown fat that is specialized for rapid heat producCon via nonshivering thermogenesis What is brown fat? Single large lipid droplet Liele cytoplasm Unusual nucleus Light color Few mitochondria MulCple lipid droplets More cytoplasm Normal nucleus Dark color More mitochondria Brown Fat White Fat How does non ­shivering thermogenesis generate heat in brown fat cells? Triglycerides are broken down to faey acids and glycerol and most of the faey acids are immediately oxidized in the mitochondria * however, the oxidative phosphorylation process is uncoupled and most of the energy generated from the oxidation of the fatty acids goes towards heat production What is uncoupled oxida2ve phosphoryla2on? Uncoupling Protein Result: less atp is produced a...
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