Communication, Homeostasis and Energy Flash Cards

flash cards on major processes in Communication Homeostasis and Energy Unit 4 Biology OCR

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Negative/Posistive Feedback

Negative feedback is a process that brings about reversal of cahnge in conditions. Ensures that optimum or steady state is maintained. Essential for homeostasis

  • change from optimum which receptor detects
  • communication systems informs effector
  • effector reacts to reverse change
  • return to optimum conditions

Positive feedback is less common. It increases the original change, destabilises system and is harmful.Sometimes benefical. (eg oxytocin in pregnancy contractions)

  • optimum condition
  • change away from optimum which receptor detects
  • Communication systems informs effector
  • Effector reacts to increase the change.
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Temperature Regulation in Ectotherms

Ectotherms temperature fluctuates with external temperature. They change behaviour or physiology to increase absorption of heat from its environment.

  • Exposing body to sun: enables more heat to be absorbed
  • Orientate body to sun: exposes larger surface area for more heat absorption
  • Orientate body away from sun: exposes lower surface area so that less hear is absorbed
  • Hide in burrow: Reduces hear absorbtion by keeping out of the sun
  • Alter body shape: exposes more or less surface area to the sun
  • Increase breathing movements: evaporates more water
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Temperature regulation in Endotherms

physiological mechanisms:

  • sweat glands in skin: sweat when temp is high to evaporate and cool body, less sweat is secreted so less loss of latent heat
  • Lungs nose and mouth: panting increases evaporation of water when warm, when cold animal doesn't pant
  • Hairs on skin lie falt when warm, they stand up when cold to trap air for insulation
  • arterioles leading to capillaries in skin vasodilate when warm, and vasoconstrict when cold
  • liver cells: rate of metabolism reduced when warm, metabolism is increased when cold
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