communication & homeostasis

• why do animals need communication and homeostasis systems

  to respond to internal and external enviroments to coordinate the body into maintaining a steady temp
• negative feedback compared to positive feedback

  negative - reverses the change, positive feedback - reinforces the change
• what is homeostasis

  Maintaining a stable internal environment
• what is an effector


  Muscles or glands that bring about a response
• what is a receptor


  an organ or cell able to respond to stimuli
• what are endotherms


  Animals who maintain their own body temperature using physiological and behavioural responses
• what are ectotherms


  Animals whose body temperature is determined by their environment so just use behavioural responses
• endotherms cooling down physiological responses:

  vasodilation

  skin flushing - radiation lost

  conduction

  sweating

  body hairs relaxing
• endotherms warming up physiological responses:

  vasoconstriction

  less sweating

  raising hairs

  shivering
• how does vasodilation cool an organism down

  arterioles dilate

  blood goes to capillaries close to skin - skin flushes - radiation loses heat
• how does sweating help cool an organism down

  sweat evaporates heat trapped in water droplets
• How does shivering increase body temperature?

  When it's cold, muscles contract in spasms. muscles produce metabolic heat
• behavioural responses to alter body temp:

  lie in sun

  lie against cold surface

  burrow

  lie in mud/water

  become dormant

  deflate body

  wear coat