thermoregulation

• radiation

  loss of heat via infrared rays
• all objects that are not at absolute zero radiate infared rays, a nude person at room temperature will loose 60% of their heat loss via radiation
• conduction

  transfer of heat through direct physical contact
• convection

  layer of air around our body is blown away
• body temp is dependant on

  time of day, age, menstrual variability
• enzymes have an optimum working temperature of 37
• sensors of thermoregulation

  peripheral: tips of nerves in epidermis, or central: spinal cord, hypothalamus, abdominal viscera, great veins
• control centres for thermoregulation

  anterior hypothalamus
• the bodies peripheral receptors are an example of anticipatory regulation, in which they detect change in core temperature before it happens
• too high effectors

  increased blood flow and vasodilation, sweating
• too low effectors

  reduced blood flow, vasoconstriction, shivering, increase in metabolic rate
• low sweating rates


  salt and water are reabsorbed, sweat is rich in urea, lactate, and potassium
• high sweating rates

  more salt than water is reabsorbed
• pyrogen


  substance that increases body temperature by resetting the hypothalamic temperature set point, can be exogenous (bacterial toxins) or endogenous (cytokines)
• contraction of arrector pili muscles stimulates hair to stand up, trapping warm air
• cold triggers increased T4 production, increasing metabolic rate