Homeostasis

• What is thermoregulation?


  mechanism and control system that maintains a constant core temperature.
• what is an endotherm? example


  an animal that is dependent on the internal generation of heat

  mammals and birds
• what is an ectotherm?


  An animal dependent on the external conditions for heat

  cold-blooded
• what is homeostasis?


  the maintainance of constant internal environment
• What are the mechanisms to reduce body temperature?


  Sweating - water evaporates in sweat, from surface of skin and takes heat from the body.

  Hairs lie flat - less air trapped, so skin less insulated, heat lost more easily.

  Vasodilation - articles dilate near skin surface, more blood flows, more heat lost from skin by radiation.
• what are the mechanisms that increase the body temperature?


  shivering - muscles contract in spasms, more heat from increase respiration.

  Less sweat

  Hairs stand up - erector pili contract, more air trap, less heat loss

  vasoconstriction - arterioles constrict, less blood flow, less heat loss

  Hormones - releases adrenaline and thyroxine. increases metabolism and more heat produced.
• What part of the brain controls body temperature?

  hypothalamus
• what are the receptor’s called that receive information about temperature?

  thermoreceptors
• Explain the stages of negative feedback - temperature regulation

  Homeostasis:

  A) thermoreceptors detect change, hypothalamus signals eff

  B) blood vessels in skin dilate and heat escapes

  C) sweat glands secrete sweat that evaporates, cools body

  D) temperature rises above normal

  E) temperature falls below normal

  F) thermoreceptors detect fall, hypothalamus signals effec

  G) skeletal muscles rapidly contract (shivering)more heat

  H) blood vessels in skin constrict mminimizing heat loss